The role of observers in MWI

Quoting Marchesk

According to the Many Worlds Interpretation of quantum mechanics, the entire universe is in a massive superposition for all quantum states of every particle.

Also superposition of which particles exist in the first place.

A "world" is when a huge ensemble of entangled particles contains observers for whom the universe appears to be classical, at least until they devise experiments showing coherence.[/quote]No, a world is not a relation with an observer. Not sure where you get this. If you like, you can assign a world in relation to an event-state, but calling the system an observer seems to suggest a very different interpretation.

A potential issue arises here. What of all the entanglements that don't support observers?

Observers as such play no role. Think systems in a state, such as a classic rock at time T. Anything that rock has measured (a subset of what's in its past light cone) is part of the entangled state of that system.

Which means observers are fundamental for saying what counts as a world.

If you want to define 'world' that way, sure, but it's just a language definition then. The physics cares not if it is observed by say something you'd qualify with the word 'conscious', which seems to be what you're hinting as being an observer.

The universal wave equation makes no such distinctions. In fact, "observers" and "worlds" are classical concepts.

Yes.

Quoting noAxioms

Yes.

Problem is you have to square this with actual observations, which have classical results when a measurement is performed.

Quoting noAxioms

Observers as such play no role. Think systems in a state, such as a classic rock at time T. Anything that rock has measured (a subset of what's in its past light cone) is part of the entangled state of that system.

I'll refer you back to what Bohr had to say regarding experiments. Experiments have to be described in terms of the language of performing the experiment, not the mathematical formalism used to model what happens during the experiment. Rocks didn't come up with the Schrodinger equation or the Born rule. Physicists did after observing or learning about experimental results.

Quoting noAxioms

No, a world is not a relation with an observer. Not sure where you get this. If you like, you can assign a world in relation to an event-state, but calling the system an observer seems to suggest a very different interpretation.

If there's no observation, there's no world, since as we both agree, a world is a system that appears to be classical. Without an observer, you just have superpositions. Decoherence only matters in this context for explaining why observers don't notice the superpositions.

Quoting Marchesk

Problem is you have to square this with actual observations, which have classical results when a measurement is performed.

I don't see how classical observations in any way would have difficulty 'squaring' with that to which I answered 'Yes'.

I'll refer you back to what Bohr had to say regarding experiments. Experiments have to be described in terms of the language of performing the experiment, not the mathematical formalism used to model what happens during the experiment. Rocks didn't come up with the Schrodinger equation or the Born rule. Physicists did after observing or learning about experimental results.

Just so, but I'm not claiming rocks are the source of quantum theory. They only obey it, acting as a classic system as much as any human-body system (dead, alive, asleep, whatever), which is after all still just a classical physical system differing from the rock only in arrangement of material.

If there's no observation, there's no world, since as we both agree, a world is a system that appears to be classical.

I think you're going to need to define your use of the word 'observer' here, because I don't think we both agree with this given the common definition. I can think of only one obscure interpretation of quantum physics (Wigner) in which a living thing plays a special role, and even Wigner abandoned it after some time.
Yes, a classical rock takes measurements. If that makes it an observer, then fine. It doesn't need to know about Schrodinger's equation in order to measure a classical world. If you don't count that as an observation, then I completely disagree with your statement above. Use the word 'measurement' and not 'observation', or pick some other word that includes whatever the rock does.

As for the definition of 'world', that is a term added later on by DeWitt I think. Keep the following in mind:
[quote=Tegmark]What Everett does NOT postulate:
"At certain magic instances, the the world undergoes some sort of metaphysical “split” into two branches that subsequently never interact"[/quote]

Reply to noAxioms Everett doesn't control how the interpretation develops after him. Sean Carrol, a current proponent of MWI, talks of universes splitting. There's a Universe Splitter app: https://cheapuniverses.com/universesplitter/

Quoting noAxioms

Yes, a classical rock takes measurements. If that makes it an observer, then fine. It doesn't need to know about Schrodinger's equation in order to measure a classical world. If you don't count that as an observation, then I completely disagree with your statement above.

There aren't classical rocks or observations in MWI. And yet we make a classical observation, which some call the wave function collapse in other interpretations, every time a measurement is made. You can say the detector or a rock also makes the same observation. But the universal wave function doesn't make such a distinction. Every quantum state is still in superposition.

The point about human observers is we're the ones interpreting the mathematical formalism as meaning reality is this or that. Some physicists, mathematicians and philosophers say the wave function describes the universe. If it does, then the classical appearance of our world needs to be derivable from that equation.

Quoting Marchesk

Sean Carrol, a current proponent of MWI, talks of universes splitting.

I talk of universes splitting. It's part of the language of the subject.

Quoting Marchesk

There aren't classical rocks or observations in MWI.

Don't know what you mean by this. Certainly not that empirical evidence of rocks constitute a falsification of MWI. A rock is a system and a system is part of MWI. A rock, in a state, can be described by a wave function. It very probably is not a closed system.
Quoting Marchesk

Some physicists, mathematicians and philosophers say the wave function describes the universe. If it does, then the classical appearance of our world needs to be derivable from that equation.

Our classical appearance needs to be part of a valid solution to the universal wave function, and nothing says it is not.

Quoting noAxioms

Our classical appearance needs to be part of a valid solution to the universal wave function, and nothing says it is not.

Sabine Hossenfelder says it's not:

Quoting noAxioms

A rock, in a state, can be described by a wave function. It very probably is not a closed system.

A rock? Is it possible to do this? Over a short time interval my casual guess of 99.999% probability of its state is what a "wave function" might provide.

Reply to jgill As an aside, I was listening to Sean Carol being interviewed, and he made it sound like the very low probability events didn't happen, at least not over the time period since the Big Bang (not nearly enough time had passed). However, they should be happening in the sense of being expressed as superpositions by the universal wave function in MWI.

So there's some states where the particles of the rock are located in other parts of the universe, under the understanding that a particle's position ranges over the entire universe, with most of the positions within the place we'd expect to measure them. But there still would be a few spread out everywhere else.

There should even be some human-like observers seeing a rock teleport some distance, or just vanish into being spread out all over the place, and all sorts of scenarios in between, even if it's a vanishingly small subset of observers.

Reply to Marchesk :cool:

As an old math person my suspicion is that "superposition" and "collapse of wave function" is nothing more than experimenting to discover which of multiple solutions of the partial differential equations describing phenomena actually apply in a particular instance. Multi worlds I consider science fantasy.

Reply to Marchesk So what do you make of David Deutsch's arguments in favor of the MWI?

(previously post here)

Reply to 180 Proof He has a very interesting idea on how to put MWI and wave-function collapse interpretations to the test. Assuming we can build a conscious AGI quantum computer.

The rest of what he says sounds similar to Sean Carrol's arguments for thinking MWI is likely correct. That it explains the interference patterns seen in experiments when a measurement isn't made, that there's no clear dividing line between the classical and the quantum, and entanglement means all the particles making up classical stuff should be quantum. And that any other interpretation would have be at least as complex as MWI, and probably more so.

That being said, my understanding is that the probabilities we use to calculate the likelihood of what to expect when a measurement is made still needs to be derived within the Schrodinger equation in a self-consistent manner without adding it in post hoc, since the wave function is supposed to describe the universe we live in, if MWI is true. So deriving the Born rule within MWI is an ongoing project.

Quoting noAxioms

Think systems in a state, such as a classic rock at time T.

By the principles of classic rock I would say there are many worlds for sure. Let time T be the time of John Lennon's "Imagine". Clearly there were many worlds at this time because the world "as one" is purely imaginary.

Quoting Marchesk

Sean Carrol, a current proponent of MWI, talks of universes splitting.

Not sure exactly what he suggests or how he words it, but there seems to be problems with two different universes (one with each measurement) existing. If there's all these universes/worlds and they exist, the more probable ones either have to 'exist more' than the lesser ones, or maybe there's just more of them. What does it even mean for one thing to exist harder than another?

Quoting Marchesk

Sabine Hossenfelder says it's not

Hossenfelder indeed seems to find issues the interpretation. This seems to be part of a series taking down each of the interpretations in turn, with a similar argument. Anyway, which comment in there (at what time) do you think counters my suggestion that a rock in a certain state is part of a valid solution to the universal wave function at some time in the past of the rock state?

Quoting Marchesk

There should even be some human-like observers seeing a rock teleport some distance

Yes, there should.

I didn't get where in the 2nd vid that Deutsch suggested some kind of empirical test that should yield different results from one interpretation to the next. I'm very skeptical of that.

Quoting jgill

As an old math person my suspicion is that "superposition" and "collapse of wave function" is nothing more than experimenting to discover which of multiple solutions of the partial differential equations describing phenomena actually apply in a particular instance. Multi worlds I consider science fantasy.

If, as is my understanding, there is no way to decide on a correct interpretation of QM empirically, it becomes not fantasy, but metaphysics. Or maybe just baloney.

Reply to noAxioms What in your view is the problem for which MWI is a solution? In other words, what would proponents of MWI such as David Deutsch and Sean Carroll be obliged to acknowledge if it could be shown that this interpretation was untenable?

Quoting T Clark

If, as is my understanding, there is no way to decide on a correct interpretation of QM empirically, it becomes not fantasy, but metaphysics. Or maybe just baloney.

I think (for what it's worth, probably not much) that there are more and less credible interpretations. I rather like Chris Fuchs QBism, from which:

[quote=Qanta; https://www.discovermagazine.com/the-sciences/quantum-physics-is-no-more-mysterious-than-crossing-the-street]Q: You’ve written critically about the Many Worlds (or Everettian) Interpretation of quantum mechanics. What are its main shortcomings?

A: Its main shortcoming is simply this: The interpretation is completely contentless. I am not exaggerating or trying to be rhetorical. It is not that the interpretation is too hard to believe or too nonintuitive or too outlandish for physicists to handle the truth (remember the movie A Few Good Men?) It is just that the interpretation actually does not say anything whatsoever about reality. I say this despite all the fluff of the science-writing press and a few otherwise reputable physicists, like Sean Carroll, who seem to believe this vision of the world religiously.

For me, the most important point is that the interpretation depends upon no particular or actual detail of the mathematics of quantum theory. No detail that is, except possibly on an erroneous analysis of the meaning of “quantum measurement” introduced by John von Neumann in the 1930s, which is based on a reading of quantum states as if they are states of reality. Some interpretations of quantum theory, such as the one known as QBism, reject that analysis.

Q: So your position is that the Many Worlds Interpretation isn’t useful because it doesn’t constrain our theories of physics?

A: Allow me to get a bit technical to try to get the point across: Would Many Worlds work if quantum mechanics were based on real vector spaces instead of on complex ones? I would say yes. Would it also work if quantum mechanics used a different product structure than the tensor product? Yes. Would it work if quantum mechanics were nonunitary, i.e., didn’t obey the Schroedinger equation? Yes. And so it goes. One could even have a Many Worlds Interpretation of classical physics — as David Wallace, one of the most careful philosophers of the Many Worlds interpretation, once reluctantly admitted in a conference I attended.

The Many Worlds Interpretation just boils down to this: Whenever a coin is tossed (or any process occurs) the world splits. But who would know the difference if that were not true? What does this vision have to do with any of the details of physics?[/quote]

Quoting Wayfarer

What in your view is the problem for which MWI is a solution?

Don't know how to answer this. All interpretations are supposed to yield the same empirical results, so if there is an empirical problem to be solved (like getting a quantum computer to work), the problem is with quantum theory.
I didn't get a reply to my last question asking exactly what Deutsch thinks MWI can do that the others cannot. I didn't want to wade through a long video link to try to find it.

[quote=Quanta interview]It is just that the interpretation actually does not say anything whatsoever about reality.[/quote]
MWI is and isn't a realist interpretation. It, like any almost all interpretations (QBism included), does not hold to the principle of counterfactual definiteness (that things really exist in the absence of measurement). Only under that principle is there 'spooky action at a distance", or faster-than-light cause/effect.
OK, so maybe I don't know what (presumably Fuchs?) is trying to say here. He indicates this von Neumann definition as the problem to be solved, which is seemingly an answer of the type which you are seeking about MWI. His example of Wallace admission is a good example of what is seen as the emptiness of MWI. The protest at the end seems empty:
[quote=Qanta]Whenever a coin is tossed (or any process occurs) the world splits. But who would know the difference if that were not true? What does this vision have to do with any of the details of physics?[/quote]Such a statement can be crafted of any interpretation.
I send a photon to the slits and it in fact goes through one slit or another before striking the plate. But who would know the difference if that were not true? What does this vision have to do with any of the details of physics?

A cool app, goes by the rather modest name umiverse splitter

Well go on then, split the universe! :party:

Quoting Wayfarer

I think (for what it's worth, probably not much) that there are more and less credible interpretations. I rather like Chris Fuchs QBism,

Seems like the text you quoted is consistent with my position. One part in particular - "Many Worlds Interpretation isn’t useful because it doesn’t constrain our theories of physics," is similar to what I wrote -

Quoting T Clark

there is no way to decide on a correct interpretation of QM empirically

Although I was speaking of all interpretations, not just the many worlds.

I hadn't head of QBism. I looked it up. Thanks for the new information.

Quoting Agent Smith

Well go on then, split the universe! :party:

Just did, nobody noticed. Or ever will.

Quoting noAxioms

What in your view is the problem for which MWI is a solution?
— Wayfarer

Don't know how to answer this.

Might I suggest that the motive for accepting the MWI interpretation is to avoid the philosophical conundrum of the 'collapse of the wave function'? That is at the root of the so-called 'observer problem' or 'measurement problem' in quantum physics, to wit 'The observer effect is the phenomenon in which the act of observation alters the behavior of the subject of observation. This is due to the ambigious nature of sub-atomic particles, which means that they can exist in multiple states simultaneously. When an observer measures a particular property of a particle, they are effectively collapsing the wave-function of that particle, causing it to assume a definite state.' The difficulty is how the act of observation can be considered 'causal' in this context. The approach of the MWI is to declare that the so-called wave-function collapse doesn't occur - but at the cost of there being many worlds.

Quoting Wayfarer

Just did, nobody noticed. Or ever will.

How does it work? Did you go into the mechanics of it? All I can recall from a video on the app is that a photon is split into two. What happens after that I haven't a clue. Google it?! :grin:

Quoting Wayfarer

Might I suggest that the motive for accepting the MWI interpretation is to avoid the philosophical conundrum of the 'collapse of the wave function'?

If one is seriously averse to wave function collapse, the list of interpretations on wiki (about 13) has only half of them supporting collapse. Point is, there are others to choose from besides MWI.
Interestingly, the list is sorted by date, and the ones without collapse lean more to the front of the list (older) and it is the more recent ones where collapse prevails. This suggests a trend and growing acceptance of collapse.

to wit 'The observer effect is the phenomenon in which the act of observation alters the behavior of the subject of observation'

OK, this is like a double slit setup with a which-slit detector behaves differently than a setup without one. That's not especially profound. If you get into the act of observing now changes something in the past, that's quite interpretation dependent.

This is due to the ambgious nature of sub-atomic particles, which means that they can exist in multiple states simultaneously.

Again an interpretation dependent statement. Not all interpretations suggest that a thing an exist in multiple states simultaneously. Bohmian mechanics for instance has but one state for anything. It is a hard realist interpretation where stuff is where it is. On the other hand, it necessitates backwards causation where decision not yet made can affect what a particle does now. I personally find that more offensive than collapse.

When an observer measures a particular property of a particle, they are effectively collapsing the wave-function of that particle, causing it to assume a definite state

Causing what to assume a definite state? The particle? Only some interpretations suggest this. With some (original Copenhagen for instance), the wave function is epistemological, describing only what one knows about a system. You take a measurement and your knowledge of the system changes, but the system is not affected by your acquisition of this knowledge.
RQM is another example, where a wave function of system X (Mars, 10 minutes ago) relative to system Y (Earth, now) changes upon some measurement. Say we observe a gamma emission. That changes the wave function of X relative to Y, but only because the new Y (post measurement) is now entangled with a particular outcome of a measurement. The ontology of the state of Mars relative to Y has changed (the gamma emission is now real instead of being in superposition), but nothing on Mars objectively changed, especially since there is no objective state under RQM.

So I guess I need to ask what you mean by an act of observation being considered 'causal'. Do you mean that shining a light on leaf to look at it will affect he leaf? Sure, that's pretty easy and is forward causality. I think you mean something deeper like the Mars example where the past ontology of some state changes relative to some present measurement.

The approach of the MWI is to declare that the so-called wave-function collapse doesn't occur - but at the cost of there being many worlds.

Something you apparently consider a substantial cost. I'm fine with that since I don't hold to the premise that there should be only one world, especially in the absence of evidence supporting that premise. My dismissal of MWI comes from other grounds.

MWI is simple. That might be the lead reason for its acceptance. I've heard critique (in linked things above) that it is simple to the point of emptiness.

Quoting noAxioms

So I guess I need to ask what you mean by an act of observation being considered 'causal'.

That prior to observation the particle doesn't exist in any specific place, that its possible properties are described by the wave-function, and that the act of measurement reduces all of the possibilities, except for the one in which it was measured, to zero. Cribbed from a website: 'Consider a photon shot from the laser gun. Soon enough, the photon is detected as a little dark dot on the photographic plate. Physicists would say that it has been “measured.” “Measured” really means that the photon has had an interaction with something in the physical universe. This interaction allows us to detect the photon. In this case, the photon is absorbed by an electron in the photographic plate, which creates a dark spot on the plate. Upon measurement, that is, this interaction, the probabilities calculated by the wave function instantaneously convert to a 100% probability for the specific dark spot and 0% everywhere else. The wave function has “collapsed.”

So that's how the act of observation is considered causal. Is that not correct?

Quoting noAxioms

I don't hold to the premise that there should be only one world, especially in the absence of evidence supporting that premise.

I would think that for this kind of hypothesis, the unity of the world is assumed and one would only require evidence for the contrary.

Quoting noAxioms

With some (original Copenhagen for instance), the wave function is epistemological, describing only what one knows about a system. You take a measurement and your knowledge of the system changes, but the system is not affected by your acquisition of this knowledge.

I don't recall reading anything like that about Bohr and Heisenberg's interpretation, it seems more like QBism which I mentioned above.

Quoting Wayfarer

That prior to observation the particle doesn't exist in any specific place, that its possible properties are described by the wave-function, and that the act of measurement reduces all of the possibilities, except for the one in which it was measured, to zero.

Don't get the last bit. It would seem that if you measured something's location, it is the location possibility which gets reduced to some much smaller deviation, and the others (momentum say) which are still just probabilities of what will be measured. The first bit talks about 'existing in a specific place' which is counterfactual terminology. Most interpretations do not hold to counterfactual definiteness, which means particles don't have actual positions (and other properties) in the absence of measurement. BM would say a photon exists en-route. Just pointing out the minefield of using terms like 'exists' which are defined differently from one interpretation to the next.
So far this isn't a whole lot different from classical physics. The championship game was played last week, but I don't know the outcome, so I have this function (something akin to a wavefunction) that describes the probabilities in detail. Then I pick up the paper and learn of the winner and of the spread and such, and the function collapses, reducing the possibilities to a much shorter list of unknowns.

So that's how the act of observation is considered causal. Is that not correct?

The measurement changed the wavefunction (relative to to the screen at least), so yea, that was caused by the interaction. Did the measurement change the photon? No, it's more like the photon caused the measurement. I'm trying to see the problem here.
Again, the wavefunction is different from one interpretation to the next. If it's epistemological (Bohm, Copenhagen), then the interaction just changes what we know. I see the dot and now know where it hits where before it would be a guess regardless of how much information I had on the system beforehand. If the wavefunction is metaphysically descriptive (RQM say), then the photon hit that spot on a screen with the dot. Much intuitive language doesn't work beyond that. It gets hard to describe. Maybe the example should be something like Objective Collapse interpretation(s), except I'm not very familiar with them. MWI could consider the wave function to be proscriptive, which means nothing changes upon the measurement, which takes place everywhere. Tegmark put out his mathematical universe hypothesis (MUH) and the draw of MWI to him is probably that it allows (does not demand) a proscriptive treatment of the wave function.

I don't recall reading anything like that about Bohr and Heisenberg's interpretation, it seems more like QBism which I mentioned above.

Don't know much about QBism, but it sounds a bit like all the idealism stops being pulled out. It defines existence in terms of beliefs and such, if I read it right.

Quoting noAxioms

Don't get the last bit. It would seem that if you measured something's location, it is the location possibility which gets reduced to some much smaller deviation, and the others (momentum say) which are still just probabilities of what will be measured.

But the point is, the object has no specific location until measured. You can't say 'the photon caused the measurement' because this assumes that it has some definite existence in some unknown location prior to being measured. There is no 'something' hiding in an unknown location until measured - the measurement makes it 'something'. Which is precisely the point at issue! That is why, indeed, 'exists' and 'real' have to be put in scare quotes in this context.

QBism is not really like idealism. Chris Fuchs has this to say about idealism:

Q: Does that mean that, as Arthur Eddington put it, the stuff of the world is mind stuff?

QBism would say, it’s not that the world is built up from stuff on “the outside” as the Greeks would have had it. Nor is it built up from stuff on “the inside” as the idealists, like George Berkeley and Eddington, would have it. Rather, the stuff of the world is in the character of what each of us encounters every living moment — stuff that is neither inside nor outside, but prior to the very notion of a cut between the two at all.

That's, I think, nearer to phenomenology than idealism.

Perhaps located in a grey zone where we are not sure which laws of physics, befween the large and thd very small pertain?

Quoting Marchesk

A potential issue arises here. What of all the entanglements that don't support observers? Those aren't considered worlds since there's no observers for things to appear classical. Which means observers are fundamental for saying what counts as a world.

Per MWI, worlds are persistent structures that emerge as a consequence of decoherence. In that sense, an MWI world doesn't depend on observers.

David Wallace on worlds:

Quoting Decoherence and Ontology - David Wallace

“Worlds” are mutually dynamically isolated structures instantiated within the quantum state, which are structurally and dynamically “quasiclassical”. The existence of these “worlds” is established by decoherence theory.

David Wallace on observers:

Quoting Everett and Structure - David Wallace

However, the structural approach is committed to an approach to the mind which ... denies observers some uniquely special status, but describes them as emergent as structures and patterns in lower-level physics (specifically, in lower-level classical physics, itself to emerge from unitary quantum physics via decoherence);

Quoting Marchesk

That being said, my understanding is that the probabilities we use to calculate the likelihood of what to expect when a measurement is made still needs to be derived within the Schrodinger equation in a self-consistent manner without adding it in post hoc, since the wave function is supposed to describe the universe we live in, if MWI is true. So deriving the Born rule within MWI is an ongoing project.

You might be interested in Sean Carroll's post on Why Probability in Quantum Mechanics is Given by the Wave Function Squared.

Reply to 180 Proof

Quoting Marchesk

?180 Proof He has a very interesting idea on how to put MWI and wave-function collapse interpretations to the test. Assuming we can build a conscious AGI quantum computer.

Quoting noAxioms

I didn't get where in the 2nd vid that Deutsch suggested some kind of empirical test that should yield different results from one interpretation to the next. I'm very skeptical of that.

Here's the relevant part of the conversation between physicists David Deutsch and Markus Arndt:

Quoting Are There Many Worlds? David Deutsch in conversation with Markus Arndt

6:12 Deutsch: When we have quantum computers, we will be able to have very large, very complex entities existing in super positions. So, in principle, I suggested long ago before this was remotely on the cards experimentally, that if we had a quantum computer on which an artificial-intelligence program was running, say, with human level artificial-intelligence then this entity would be able to experience interference in its own consciousness.

6:46 Arndt: Well, some people would say that your consciousness would collapse your reality.

6:50 Deutsch: Yes, so if that happened that would refute the Everettian interpretation or, as I would say, it would refute quantum theory. That would be a very interesting problem and that's one of the reasons why scaling up both the size and the complexity and the mass of phenomena that I experimentally observe, but that can only be explained by quantum theory, is very important.

7:17 Arndt: I fully agree. We need to do that.

7:21 Deutsch: We just need to close the gap between that and the AI because the AI would not be having this conversation. Or, at least, the AI would not be able to make the argument that you just made. It would have to say I've only got evidence of many worlds on the scale of my mind, but not bigger so - and I guess that will always be true.

Essentially, Deutsch's proposed experiment would implement the Wigner's Friend thought experiment.

In Deutsch's proposal, Wigner would be a human-level AI running on a quantum computer, with the friend (also a human-level AI) and the measured qubit being internal and isolated subsystems of Wigner.

By conducting an interference experiment on the joint friend/qubit subsystem, the Wigner AI would be able to determine whether physical collapse happened or not. If physical collapse were detected, then that would falsify standard quantum theory (and MWI along with it).

Reply to Andrew M I put this question to NoAxioms but he wasn't sure how to respond, so I'll try again, as you seem to have insight into this area.

On face value, the many-worlds interpretation of quantum physics seems the opposite of parsimomious. It seems to say that the world or universe splits or divides at the point of measurement or observation of a sub-atomic particle. So the question is, what problem does the interpretation of quantum physics try to solve? What would its proponents such as Wallace and Deutsch be obliged to acknowledge (apart from the obvious fact that they were mistaken), if by some means it was shown to be untenable?

Quoting Andrew M

Deutsch's proposed experiment would implement the Wigner's Friend thought experiment.

I had read that this had been done in 2019.

Quoting Wayfarer

Deutsch's proposed experiment would implement the Wigner's Friend thought experiment.
— Andrew M

I had read that this had been done in 2019.

It's similar, and in that experiment Wigner observes interference as predicted by quantum theory (which the paper describes as observer-dependence, since the friend observes a definite outcome). The important difference is that the agents are each represented by single photons. Whereas Deutsch envisages Wigner and the friend as human-level AI's. It would therefore be a test of whether very large, complex and (artificially) intelligent entities exhibit interference.

Quoting Wayfarer

On face value, the many-worlds interpretation of quantum physics seems the opposite of parsimomious. It seems to say that the world or universe splits or divides at the point of measurement or observation of a sub-atomic particle.

It depends on how parsimony is understood. Many Worlds has the biggest universe but also the fewest postulates.

Quoting Wayfarer

So the question is, what problem does the interpretation of quantum physics try to solve? What would its proponents such as Wallace and Deutsch be obliged to acknowledge (apart from the obvious fact that they were mistaken), if by some means it was shown to be untenable?

The problem that the interpretation should solve is to explain the interference phenomena that we observe. Not merely to predict observations - that's what the formalism does. If Many Worlds were shown to be untenable, Wallace and Deutsch would say that we have no viable explanation (that we know of).

Deutsch comments on just this issue in the video:

Quoting Are There Many Worlds? David Deutsch in conversation with Markus Arndt

0:54 Arndt: The familiar problem that we all try to solve is why is there this unitary evolution of quantum mechanics which seems to explain everything very naturally and, all of a sudden, during a measurement this evolution has to be reduced, collapsed in the Copenhagen interpretation and that's I think something that David doesn't like. He wants to have everything on the same mathematical formalism. But if you follow it through it leads to realities which seem to multiply and then my question to you is what is really the meaning of reality to you because I experience only my single reality here.

1:30 Deutsch: Yes, you put it in terms of how do we make sense of the unitary evolution compared with what we see at a measurement and so on. I would want to start before that. I think we want to understand the world. We want to understand how the world is and that that is not necessarily what we perceive. Our perceptions are at the end of a long chain of physical processes of which themselves we only have scientific knowledge or indirect knowledge.

So I would start with the question, how do we explain quantum phenomena like interference? Not how do we make sense of quantum theory which gives the right prediction but, first, before that, how do we explain quantum phenomena?

So there's an interference process and we have an interference pattern which we can see without any quantum mechanics that the result of the experiment cannot be explained by the events that we see. Now this is not very unusual. This happens a lot, you know, in physics and ultimately every observation is made very indirectly so we have to infer things that are not there. Although infer is the wrong word. We have to conjecture explanations. So that's where I would start.

...

7:44 Arndt: Yeah, but there's something in the formulation of phrasing of our sentences where we're getting also doubtful. When I talk about these things about super positions I always make these quote-unquote when I say a particle is at the same time here and there because there are two words that I don't understand, three words I don't understand.

First the word is 'reality', the second word is what does 'time' really mean, and the third one what does 'space' really mean and we don't have any experimental evidence that the particle is at the same time here and there we just have a physical description the quantum mechanical description that the wave function behaves 'as if' and how can we make the step to the Many-Worlds."

8:23 Deutsch: I think we have something slightly more than that. Again you come from the theory. But, I think, prior to the theory we have the experience that this thing cannot be explained by single trajectories.

8:38 Arndt: Definitely.

8:39 Deutsch: We don't have to believe quantum mechanics to see that. So we rule out single trajectory explanations and that we have before we have quantum mechanics. If we didn't have quantum mechanics, it would be a mystery. We would say that there simply is no explanation.

...

12:40 Arndt: Although other scientists would say shut up and measure - calculate actually. Just don't talk about things that you cannot see and the other part of the other branches you don't see. So why do you dare not to shut up?

12:56 Deutsch: Yes, well, first of all I think that that attitude involves saying that there are certain questions about reality that you're not allowed to ask. You're allowed to ask how the experiment was prepared. You're allowed to ask what will the results be. You're not allowed to ask how were the results brought about by the preparation. So therefore it's not an explanation in my terms.

But as for shut up, that's really another way of trying to evade the consequences in terms of reality. Like my favorite example is of dinosaurs in the past. So there are people who say nobody ever saw a dinosaur and nobody ever will and therefore it's just a frivolity to say that they really exist. At most we can say fossils behave as though dinosaurs existed.

But no paleontologist would accept talking that way even though there is no experimental way of disproving that manner of speaking. And that's because paleontologists are only interested in paleontology because they want to know what really happened. If they were interested in fossils they would be geologists.

Quoting Are There Many Worlds? David Deutsch in conversation with Markus Arndt

The familiar problem that we all try to solve is why is there this unitary evolution of quantum mechanics which seems to explain everything very naturally and, all of a sudden, during a measurement this evolution has to be reduced, collapsed in the Copenhagen interpretation and that's I think something that David doesn't like

That's the crux. To avoid the 'observer effect'.

Quoting Wayfarer

That's the crux. To avoid the 'observer effect'.

There's an 'observer effect' in Einsteinian relativity which nobody objects to. That's not the problem.

As Deutsch puts it, what we want to understand is, "How were the results brought about by the preparation?" Why is it that we observe interference effects?

Reply to Andrew M I'll refer to John Wheeler's paper, Law without Law:

The dependence of what is observed upon the choice of experimental arrangement made Einstein unhappy. It con­flicts with the view that the universe exists "out there'' inde­pendent of all acts of observation. In contrast Bohr stressed that we confront here an inescapable new feature of nature, to be welcomed because of the understanding it gives us. In struggling to make clear to Einstein the central point as he saw it, Bohr found himself forced to introduce the word "phenomenon."' In today's words Bohr's point - and the central point of quantum theory - can be put into a single, simple sentence. "No elementary phenomenon is a phenom­enon until it is a registered (observed) phenomenon."

That's what I think the various many-worlds interpretations are rejecting. They view the lacuna at the bottom of the whole process as meaning that quantum theory itself is forever incomplete. I'm sure that's why Deutsch says that sans 'many worlds', we don't have a theory. They're wanting to hold on to what they consider scientific realism, albeit at the cost of 'splitting the universe'. It really is a philosophical problem, about not being able to deal with the fact that there is something fundamental that we can't know.

Apart from that, I can only refer back to the earlier quote I provided from QBism in this post.

Thanks for the post and transcript effort Andrew.

Quoting noAxioms

I didn't get where in the 2nd vid that Deutsch suggested some kind of empirical test that should yield different results from one interpretation to the next. I'm very skeptical of that.

Quoting Are There Many Worlds? David Deutsch in conversation with Markus Arndt

6:50 Deutsch: Yes, so if that happened that would refute the Everettian interpretation or, as I would say, it would refute quantum theory.

This seems to suggest that it is quantum theory that would be falsified given, well, apparently some sort of confirmation of 'consciousness causes collapse', except that in itself is another quantum interpretation (the Wigner interpretation) which was abandoned by Wigner himself due to it leading to solipsism, not because it in any way refuted quantum theory.

In my opinion, Deutsch is answering what seems to be a naive comment, not really describing a test result that differ empirically from one interpretation to the next. Consciousness causing collapse is not an empirical thing.

Quoting Andrew M

Essentially, Deutsch's proposed experiment would implement the Wigner's Friend thought experiment.

OK. Do any of the interpretations predict a different outcome of this experiment than the others? It's pretty straight-forward. The friend comes out and only remembers classical stuff. The experience of being in superposition relative to the box exterior is in no way different than the same thing without the box. You can no more get interference of the friend than you can get the dead and live cat to interfere with each other. Perhaps this is not the case with the quantum AI, in which case is kind of isn't the Wigner friend thing exactly.

In Deutsch's proposal, Wigner would be a human-level AI running on a quantum computer, with the friend (also a human-level AI) and the measured qubit being internal and isolated subsystems of Wigner.

By conducting an interference experiment on the joint friend/qubit subsystem, the Wigner AI would be able to determine whether physical collapse happened or not.

OK. I remain skeptical of any claim that this kind of thing can be measured without interpretation-specific assumptions.

- - - - -

Wayfarer, I do see your conundrum and cannot satisfactorily resolve it.
Quoting Wayfarer

But the point is, the object has no specific location until measured.

Interpretation dependent, but true in any local interpretation.

You can't say 'the photon caused the measurement' because this assumes that it has some definite existence in some unknown location prior to being measured.

The measurement became entangled with the emitting event? That sort of makes it sound like the measurement caused the emitting event. I have no problem with this given a relational view where ontology sort of works temporally backwards. A measurement causes the existence of something in the past (the moon say). Until it is meansured by you, it doesn't exist to you even if it exists relative to something else. Ontology as a relation.
MWI doesn't in any way make existence dependent on measurement as far as I know. There are worlds with the moon and worlds without, and you just happen to be coherent with one with a moon

There is no 'something' hiding in an unknown location until measured

That again seems the same as it existing, unmeasured. If so, not sure what changes upon the measurement.

- the measurement makes it 'something'.

So Rovelli would say I think. Copenhagen might say that measurement makes us aware of it, depending if the interpretation is taken as epistemological or metaphysical. There are forms of both, and I don't know how the latter would frame this.

That is why, indeed, 'exists' and 'real' have to be put in scare quotes in this context.

Agree with the quotes. Do the words mean different things? The problems you point out is a good part of why I am skeptcal of realism.

Reply to noAxioms :up: Thank you.

Quoting Wayfarer

It really is a philosophical problem, about not being able to deal with the fact that there is something fundamental that we can't know.

It's a different philosophical temperament. Deutsch's argument (from the earlier quote) is that, "that attitude involves saying that there are certain questions about reality that you're not allowed to ask".

Quoting noAxioms

This seems to suggest that it is quantum theory that would be falsified given, well, apparently some sort of confirmation of 'consciousness causes collapse', except that in itself is another quantum interpretation (the Wigner interpretation) which was abandoned by Wigner himself due to it leading to solipsism, not because it in any way refuted quantum theory.

In my opinion, Deutsch is answering what seems to be a naive comment, not really describing a test result that differ empirically from one interpretation to the next. Consciousness causing collapse is not an empirical thing.

Deutsch's experiment provides a way of distinguishing between linear interpretations such as RQM/ QBism/Many Worlds and non-linear interpretations such as consciousness-causes-collapse/objective collapse theories like GRW. So it would enable us to rule out an entire class of interpretations.

Quoting noAxioms

OK. Do any of the interpretations predict a different outcome of this experiment than the others? It's pretty straight-forward. The friend comes out and only remembers classical stuff. The experience of being in superposition relative to the box exterior is in no way different than the same thing without the box. You can no more get interference of the friend than you can get the dead and live cat to interfere with each other. Perhaps this is not the case with the quantum AI, in which case is kind of isn't the Wigner friend thing exactly.

In the Wigner's friend thought experiment, the friend's lab is a closed/isolated system. A quantum computer provides a way to realize that isolation for a large, complex and artificially-intelligent entity (the friend AI). Then we can test for interference.

Quoting Andrew M

that attitude involves saying that there are certain questions about reality that you're not allowed to ask.

It would be better to simply recognise there are things science is unable to ascertain and leave it at that. As a general rule, knowing you don’t know something is preferable to thinking you know something that you don’t.

Quoting Wayfarer

On face value, the many-worlds interpretation of quantum physics seems the opposite of parsimomious.

Quoting Andrew M

It depends on how parsimony is understood. Many Worlds has the biggest universe but also the fewest postulates.

Wayfarer, I know you have a hard time with a 'bigger' universe, but many of us don't. These same sentiments were expressed when it was discovered that the stars were other suns, and then that there were other galaxies as far as you can see. People balked every time it got bigger, but they got over it.
Personally, I think the other interpretations (at least the realist ones) are tasked with explaining the unitary evolution.

Einstein didn't like God playing dice, but some of the interpretations seem to require it, and I think Einstein would have preferred one of the ones that don't. I don't think any of them were on the table at the time he said that.

[quote=Andrew M]The problem that the interpretation should solve is to explain the interference phenomena that we observe. Not merely to predict observations - that's what the formalism does. If Many Worlds were shown to be untenable, Wallace and Deutsch would say that we have no viable explanation (that we know of).[/quote]Totally agree here, but I think the effect with which MWI has trouble explaining is the Born rule. It's been a strong piece of criticism.

If you one of the types that actually think that MWI implies the creation/generation of ontologically separate worlds, then one also has to deal with how some of them are more probable than others, that meaning must be given to "X exists more than Y". That issue goes hand in hand with the Born rule thing.

Quoting Andrew M

There's an 'observer effect' in Einsteinian relativity which nobody objects to. That's not the problem.

There is? There are dependencies on frames (what velocity has object X?, a completely frame dependent question since Galileo), but I've not heard that observers have any effect at all. That seems to be confined to QM effects.

Quoting Andrew M

Deutsch's experiment provides a way of distinguishing between linear interpretations such as RQM/ QBism/Many Worlds and non-linear interpretations such as consciousness-causes-collapse/objective collapse theories like GRW. So it would enable us to rule out an entire class of interpretations.

That sounds cool. In my experience, new evidence just moves the goal posts. An interpretation like the consciousness one will just adjust its story if the linearity of QM can be demonstrated. Others may actually fall out of contention.

[quote=Andrew M]In the Wigner's friend thought experiment, the friend's lab is a closed/isolated system. A quantum computer provides a way to realize that isolation for a large, complex and artificially-intelligent entity (the friend AI). Then we can test for interference.[/quote]
I am actually very unfamiliar with how they do such tests. I mean, the double slit thing is pretty obvious, but how do they test for superposition of spin? Far worse, they've succeeded in putting something large enough to see with the eye, in superposition of vibrating or not. My question is, how was that demonstrated? How might one actually attempt to do the sort of test your're talking about with the computer?

Quoting noAxioms

Wayfarer, I know you have a hard time with a 'bigger' universe,

Notice the quotes around 'bigger'. What I think you actually mean is, 'many'. They're very different things.

Einstein didn't like the uncertainty principle or the 'quantum leap' because he was a determinist.

Quoting noAxioms

I am actually very unfamiliar with how they do such tests

Thank you for a moment of honesty. These discussions are like the surface of a sphere, with the actual physics being the interior. It's always amazed me how physicists create the mechanisms to do these experiments. Isolating a single photon? Determining spin,etc.? You can get a PhD in experimental physics and many do - it's not all mathematically enhanced theory.

Quoting Andrew M

distinguishing between linear interpretations . . .

The mathematics is linear - a specific kind of function or operation - and this gets confused with "linear interpretation", I think. And then there are "collapses" and so on. How is it possible to even discuss these things without a deep knowledge of the machinery of experiments? That's why its called the measurement problem, ascertaining a quality of an infinitesimal system without altering that quality or another quality. It's beyond me.

Quoting jgill

How is it possible to even discuss these things without a deep knowledge of the machinery of experiments?

PBS SpaceTime video on the double-slit experiment.

Dr Quantum video on the double-slit - short and to the point.

They both cover the same basic subject matter. The basic point is graspable without any deep knowledge of physics, but of course learned exposition on the competing interpretations - why we see what we see - is a different matter.

The observer problem is a problem because there’s nothing in the maths to indicate where the observer must come into the picture. But the act of observation seems to be fundamental to determining the result. This undermines the principle of objectivity, that things are ‘just so’ irrespective of whether they’re observed or not. And that is one of the planks of Galilean science. As soon as the observer has to be acknowledged - that’s where the trouble starts, as far as science is concerned.

Quoting Wayfarer

It would be better to simply recognise there are things science is unable to ascertain and leave it at that. As a general rule, knowing you don’t know something is preferable to thinking you know something that you don’t.

We don't know that science is unable to ascertain it. Note that Deutsch follows Popper. MWI is a conjecture, and the quantum AI experiment that he describes is a test of that conjecture.

Quoting noAxioms

Totally agree here, but I think the effect with which MWI has trouble explaining is the Born rule. It's been a strong piece of criticism.

Yes, though it's not a problem unique to MWI. It's a bit like asking why the Pythagorean Theorem holds (and why Fermat's equation doesn't, for powers greater than 2). The answer is of general interest independent of one's interpretation.

Quoting noAxioms

If you one of the types that actually think that MWI implies the creation/generation of ontologically separate worlds, then one also has to deal with how some of them are more probable than others, that meaning must be given to "X exists more than Y". That issue goes hand in hand with the Born rule thing.

You might be interested in Sean Carroll's post on Why Probability in Quantum Mechanics is Given by the Wave Function Squared.

Per your comment, "one also has to deal with how some of them are more probable than others", the basic idea (from Zurek - see the above post) is that paths that are not equally probable can be mathematically reduced to paths that are. For example, a beam splitter with a 2:1 transmission/reflection ratio is equivalent to a beam splitter with a 1:1:1 ratio once a 1:1 beam splitter is added to the transmission path.

Quoting noAxioms

There's an 'observer effect' in Einsteinian relativity which nobody objects to. That's not the problem.
— Andrew M
There is? There are dependencies on frames (what velocity has object X?, a completely frame dependent question since Galileo), but I've not heard that observers have any effect at all. That seems to be confined to QM effects.

Yes, I'm referring to frame dependency. The observer on the train platform describes events differently to a passenger in the moving train. Similarly Wigner describes the friend's result differently to how the friend does. While the laws of physics are the same for all observers, they may describe things differently from their respective reference frames.

For a nice visualization of this, see How does a quantum particle see the world?

Quoting noAxioms

That sounds cool. In my experience, new evidence just moves the goal posts. An interpretation like the consciousness one will just adjust its story if the linearity of QM can be demonstrated. Others may actually fall out of contention.

Yes, one issue there would be whether the human-level quantum AI should be considered conscious.

Quoting noAxioms

I am actually very unfamiliar with how they do such tests. I mean, the double slit thing is pretty obvious, but how do they test for superposition of spin? Far worse, they've succeeded in putting something large enough to see with the eye, in superposition of vibrating or not. My question is, how was that demonstrated?

For spin, via a Stern–Gerlach experiment. For large objects, as I understand it, if you can couple them to a qubit then you can test for interference.

Quoting noAxioms

How might one actually attempt to do the sort of test your're talking about with the computer?

Suppose a qubit is prepared in the zero state (i.e., |0>). The friend AI applies a transformation to put the qubit into the plus superposition state (i.e., |0> + |1>, or |+>). Then the friend AI measures the qubit (which, in standard quantum theory, is a unitary transformation resulting in the lab being in superposition).

Wigner then runs the entire transformation in reverse, thus undoing the friend AI's measurement and restoring the qubit to the initial zero state. Then Wigner measures the qubit. If the qubit is measured to be in the one state (i.e., |1>) then that falsifies standard quantum theory. That's because the only way that outcome could occur is if the friend AI's measurement reduced the qubit state to either the zero or the one state, via a physical collapse. In that case, Wigner's inverse transformation would have transformed the qubit to either the plus or minus superposition states, which then gives the possibility of measuring the one state.

Here's the experiment in further detail:

Quoting Testing quantum theory with thought experiments, p17 - Nurgalieva, Renner

4 Wigner-Deutsch thought experiment

Two central questions that came up repeatedly in our discussions so far are (i) “Does Alice see a definitive measurement outcome?” and (ii) “Is Alice’s lab after the measurement indeed in a superposition state?” Deutsch [23] proposed an extension of the thought experiment described in Section 3, which turns these questions into (in principle) experimentally testable statements.

Quoting jgill

The mathematics is linear - a specific kind of function or operation - and this gets confused with "linear interpretation", I think. And then there are "collapses" and so on. How is it possible to even discuss these things without a deep knowledge of the machinery of experiments? That's why its called the measurement problem, ascertaining a quality of an infinitesimal system without altering that quality or another quality.

It's possible to abstract over the machinery, using quantum logic gates. For example, to place a qubit in superposition, a Hadamard operation is applied.

The crux of Deutsch's experiment is to test whether measurement results in an irreversible physical collapse, or not.

Quoting Andrew M

...the quantum AI experiment that he describes...

You mean this?

Quoting Are There Many Worlds? David Deutsch in conversation with Markus Arndt

if we had a quantum computer on which an artificial-intelligence program was running, say, with human level artificial-intelligence then this entity would be able to experience interference in its own consciousness.

You think that is remotely close to what Popper would consider 'falsifiable by empirical evidence'?

‘When we create an artificial human using technology that doesn’t exist yet, all will be revealed!’

Quoting Wayfarer

if we had a quantum computer on which an artificial-intelligence program was running, say, with human level artificial-intelligence then this entity would be able to experience interference in its own consciousness.
— Are There Many Worlds? David Deutsch in conversation with Markus Arndt

You think that is remotely close to what Popper would consider 'falsifiable by empirical evidence'?

‘When we create an artificial human using technology that doesn’t exist yet, all will be revealed!’

I put the question to ChatGPT:

Me: Would Popper consider the Wigner-Deutsch quantum experiment to be falsifiable by empirical evidence?

ChatGPT: According to Popper's criterion of falsifiability, a scientific theory must be able to make testable predictions that could, in principle, be shown to be false. The Wigner-Deutsch quantum experiment is a proposed thought experiment in quantum mechanics, which is based on the idea of creating a quantum system that can perform a universal set of quantum gates, a set of operations that can be used to perform any quantum computation. The experiment proposes that if such a system could be created, it would be possible to demonstrate the existence of quantum parallelism and quantum entanglement in a more direct way than is currently possible.

The Wigner-Deutsch quantum experiment is a theoretical concept, and it has not been physically implemented yet. While the experiment is purely theoretical, it's still an interesting concept and it could be considered as scientific by Popper's standard. Popper would argue that the thought experiment is falsifiable, because it makes predictions that can be in principle tested, if the technology and resources become available. If the experiment is performed and it fails to demonstrate the existence of quantum parallelism and quantum entanglement, it would falsify the thought experiment.

In summary, Popper would consider the Wigner-Deutsch quantum experiment as a scientific theory, because it makes testable predictions that could in principle be shown to be false, even though it's not been physically implemented yet.

Reply to Andrew M Fantastic answer from ChatGPT. But there's a lot of 'in principle' there. I agree, it's 'in principle' testable, in a way that much speculative physics is not, but a lot would have to happen first. I'm confident you and I will never see it, it will remain 'in principle', possibly forever.


Deutsch is a very imaginative individual, and this whole many-worlds idea appeals on that level. But the Copenhagen attitude is much more modest, in my view. May not be as exciting.

I remember reading years ago the Guardian review of Brian Greene's book on the multiverse (which I know is a different thing to the many worlds interpretation, but still)....

Quoting Ned Denny, TheGuardian

When Moses asks to see who or what he has been conversing with on Mount Sinai, he is placed in a crevice and told to look out once the radiance has passed (no peeking now!). Anything more than a glimpse of God's receding back, the story implies, would blow his mortal fuses. The equivalent passage in Hindu scripture occurs in the Bhagavad Gita – and, as befitting that most frank of all religions, is more explicit about the nature of the fatal vision. Krishna responds to the warrior Arjuna's request by telling him that no man can bear his naked splendour, then goes right ahead and gives him the necessary upgrade: "divine sight". What follows is one of the wildest, most truly psychedelic episodes in world literature.

No longer veiled by a human semblance, Krishna appears in his universal aspect: a boundless, roaring, all-containing cosmos with a billion eyes and mouths, bristling with "heavenly weapons" and ablaze with the light of a thousand suns. The sight is fearsome not only in its manifold strangeness but because its fire is a consuming one. "The flames of thy mouths," a horrified Arjuna cries, "devour all the worlds … how terrible thy splendours burn!"

Until recently, a physicist would have regarded this scene as the picturesque delirium of a pre-scientific age. Most still would. And yet the contemplation of the unspeakable flowering of an infinity of worlds is no longer the province of "mystics, charlatans and cranks", as the leading string theorist Michio Kaku has written, but instead occupies "the finest minds on the planet".

Welcome to the multiverse.

Quoting Andrew M

There's an 'observer effect' in Einsteinian relativity which nobody objects to.

The "observer effect" is actually the significant feature of relativity theory in general. I believe Galileo showed that observations of planetary motions based on a Ptolemaic description could accurately be transformed to be consistent with observations based on a Copernican description. The principle of invariance demonstrates consistency between the two. The 'observer effect' comes about as a result of the subtle differences between the two, where exceptions to the laws need to be applied. We can call these exceptions the effect of observational perspective, hence 'observer effect'. So one observational perspective will deal with the subtle differences, making exceptions to the principles, in a way which is completely different from another. Analysis of this 'observer effect' can guide us in judging one observational perspective as better than the other (Copernican is better than Ptolemaic).

What Einstein does with "special relativity" is to give 'special' status to light, freeing it from the principles of relativity, to allow that its motion is not relative to the motions of material bodies. This amplifies the 'observer effect' by greatly increasing the possibilities for subtle differences. Now there is a need for principles like time dilation, length contraction, relativistic mass, and things like that. These concepts are the 'observer effect', the need to adjust fundamental principles of measurement to allow for the possibility of the multiple observational perspectives implied by relativity theory. It is very important to understand these differences if one wants to consider the likelihood of a true perspective.

Using the expression, "observer effect" in QM conjures an image of the scientist staring at the particle, which is as bad as the "Earth in a basketball net" describing gravity's effect in cosmology. Even Einstein criticized the use of geometry to describe gravitational forces.

To take a bit of the woo out of QM, instead one should speak of the "measurement effect", which alludes to the machinery doing that task, not the scientist, Gandolf.

Reply to jgill The question as to whether observation must consist of a conscious act is a contentious one.

[quote=“Quantum Mysticism, Gone but not Forgotten; https://phys.org/news/2009-06-quantum-mysticism-forgotten.html“] In 1958, Schrödinger, inspired by Schopenhauer from youth, published his lectures Mind and Matter. Here he argued that there is a difference between measuring instruments and human observation: a thermometer’s registration cannot be considered an act of observation, as it contains no meaning in itself. Thus, consciousness is needed to make physical reality meaningful. As Schrödinger concluded, "Some of you, I am sure, will call this mysticism.…’[/quote]

Quoting Wayfarer

Deutsch is a very imaginative individual, and this whole many-worlds idea appeals on that level. But the Copenhagen attitude is much more modest, in my view. May not be as exciting.

Yes, Copenhagen can be understood as the operational interpretation - shut-up-and-calculate. But without the shutting up, as Scott Aaronson likes to say!

Apropos:

Quoting Carl Sagan (Cosmos) [via Nurgalieva and Renner]

Imagination will often carry us to worlds that never were. But without it we go nowhere.

Quoting Metaphysician Undercover

Analysis of this 'observer effect' can guide us in judging one observational perspective as better than the other (Copernican is better than Ptolemaic).

Yes, and excellent post MU.

Quoting jgill

To take a bit of the woo out of QM, instead one should speak of the "measurement effect", which alludes to the machinery doing that task, not the scientist, Gandolf.

It's a can of worms - "measurement" is also a contested term. I think Nurgalieva and Renner have some useful comments on this:

Quoting Testing quantum theory with thought experiments, p4-5 - Nurgalieva and Renner

2 Observers in quantum mechanics

The notion of an observation is crucial for linking the theoretical formalism of quantum theory to experiment, and in this sense to physical reality. In an experiment, an observation is the outcome of a measurement that is carried out by an observer, which may be a device or a human. How this observer should be treated in theory is however debated. Is the observer just an ordinary system that can itself be described by quantum theory, or should it be regarded as something external to it, or is it even both? The answer to this question exhibits some of the key differences between the different interpretations of quantum theory, and we thus discuss it in more detail in this section.

The notion of an observer gained importance in physics already before the development of quantum theory. One of its most prominent appearances is in Einstein’s original article on special relativity [27]. Here the “Beobachter” plays a key role, for quantities such as time and spatial locations are only defined relative to them. Special and general relativity still portray the observer in a passive light — the observer is understood as a reference frame, thus giving rise to a coordinate system in spacetime [28, 29]. Other theories view observers as users of the theory. For example, Bayesian statistics [30, 31] consists of a set of reasoning rules that a rational agent should follow to make predictions and decide on future actions based on past observations. A Bayesian observer thus takes a more active role. In quantum theory, both of these roles may be relevant, depending on the interpretation. We will therefore use the terms agent and observer interchangeably.

...

While most physicists today don’t resort to the (vague) notion of consciousness,4 they still haven’t reached an agreement on how to resolve the paradox around Wigner’s friend. The ambiguity is not within the formalism of quantum theory, but lies in how the formalism should be applied to such experiments — a question that the formalism itself cannot answer. In their search for answers, quantum physicists came up with a variety of ideas and proposals, which are nowadays known as different interpretations of quantum theory (see Table 1 for a summary and Figure 3 for an illustration).

Quoting Andrew M

Yes, Copenhagen can be understood as the operational interpretation - shut-up-and-calculate.

I’m sure that’s not right, either. That infamous phrase was, I believe, coined by David Mermin, mainly in respect to the attitudes of the many working physicists who were employed in roles that require expert knowledge of quantum physics and couldn’t afford to spend time wondering about the implications.

Likewise, Bohr was often misinterpreted as being a positivist, but that is far from the case. Heisenberg relates a story where Bohr lectured the Vienna Circle positivists on the implications of quantum mechanics, and afterwards they all politely applauded and murmured approval. This is when Bohr uttered the often-quoted remark that ‘if you are not shocked by quantum physics, then you cannot have understood it.’

Bohr, Heisenberg, Schrödinger, Pauli, and others of that generation were deeply cultured individuals with deep knowledge of philosophy both Eastern and Western. The ‘shut up and calculate’ generation were mainly Americans after WW2. Totally different mindset.

Quoting Wayfarer

Bohr, Heisenberg, Schrödinger, Pauli, and others of that generation were deeply cultured individuals with deep knowledge of philosophy both Eastern and Western. The ‘shut up and calculate’ generation were mainly Americans after WW2. Totally different mindset.

Yes, they were actually shutting up. :-)

Quoting Interpretive cards (MWI, Bohm, Copenhagen: collect ’em all) - Scott Aaronson

As for Copenhagen, I’ve described it as “shut-up and calculate except without ever shutting up about it”! I regard Bohr’s writings on the subject as barely comprehensible, and Copenhagen as less of an interpretation than a self-conscious anti-interpretation: a studied refusal to offer any account of the actual constituents of the world, and—most of all—an insistence that if you insist on such an account, then that just proves that you cling naïvely to a classical worldview, and haven’t grasped the enormity of the quantum revolution.
...
But the basic split between Many-Worlds and Copenhagen (or better: between Many-Worlds and “shut-up-and-calculate” / “QM needs no interpretation” / etc.), I regard as coming from two fundamentally different conceptions of what a scientific theory is supposed to do for you. Is it supposed to posit an objective state for the universe, or be only a tool that you use to organize your experiences?
...
This is not like picking a race horse, in the sense that there might be no future discovery or event that will tell us who was closer to the truth. I regard it as conceivable that superintelligent AIs will still argue about the interpretation of QM … or maybe that God and the angels argue about it now.

Reply to Andrew M Well, you know, Zen Buddhists are famous for eschewing all written teachings yet their canon comprises thousands of volumes.

And I generally agree with Aaronson’s descriptive categories. I am very impressed with Christian Fuchs’ philosophy of QBism which I guess puts me in the second category. Deutsch et al seem to want to preserve the principle of objectivity above all else.

Quoting Interpretive cards (MWI, Bohm, Copenhagen: collect ’em all) - Scott Aaronson

or maybe that God and the angels argue about it now.

Incidentally, the oft-ridiculed Medieval meme of ‘how many angels can dance on the head of a pin?’ actually started about a debate as to whether two incorporeal intelligences can occupy the same location. Somehow, this reminds me of 'super-position'. (Although perhaps the very possibility is excluded by the medieval equivalent of Pauli's principle, although I haven't dug that deep into it.)

Quoting Andrew M

Yes, and excellent post MU.

Thank you Andrew. Compliments are very rare around here so they are appreciated when received.

Quoting Testing quantum theory with thought experiments, p4-5 - Nurgalieva and Renner

The notion of an observer gained importance in physics already before the development of quantum theory. One of its most prominent appearances is in Einstein’s original article on special relativity [27]. Here the “Beobachter” plays a key role, for quantities such as time and spatial locations are only defined relative to them. Special and general relativity still portray the observer in a passive light

I believe that the notion of a 'passive' observer is actually inconsistent with relativistic physics. Passive observation must be from a "rest frame', or else it cannot be said to be "passive". And, the position of "rest" provides a foundation for the concepts of "mass" and "inertia" as the defining features of rest.
These features are described as the resistance to change. So "rest" implies a special power or capacity, resistance to change, which is the capacity to continue to be at rest. We can say that staying the same as time passes, i.e. 'being at rest', is the base attribute of mass, and the larger the quantity of mass, the greater the capacity to resist change. However, under Newton's laws, any constant motion is equivalent to being at rest in its resistance to change. This allows for relativity theory, and true "rest" is fundamentally incompatible with relativity theory such that a designation of "rest", or a "rest frame" is basically arbitrary. This feature is what provides for the wide ranging applicability and the great practical power of relativity theory.

Since the other necessary condition of "rest", or "staying the same", is "as time passes", the arbitrariness by which we can designate "rest", which relativity theory provides us with, also has an effect on our capacity to measure time. The position of "rest" is the base observational perspective from which change is noted, and recorded , providing the principles for measuring time. If "rest" ever became truly, or absolutely arbitrary, then our measurements of the passage of time would also be absolutely arbitrary.

The precepts of special relativity place a limit to the arbitrariness of rest by using the speed of light as a cap or a ceiling to the maximum velocity a thing can be moving, and still be "at rest", or a "rest frame". But this produces some "subtle differences" (as mentioned in my last post) with respect to our understanding of mass and inertia. Strictly speaking, through true application of special relativity, a photon moving at the speed of light cannot have inertia, or mass, because it cannot be at rest relative to any object. Therefore it cannot provide what is required for a rest frame. Nor can it have the capacity to resist change, nor any temporal duration of existence, these being the attributes of mass.

But "energy", as the defining attribute of a photon, something necessarily in motion, (instead of mass as the defining attribute of something at rest), is truly observed to have temporal duration, persistence. This requires that the photon be assigned a "relativistic mass" to allow that energy is a temporal constant. In my understanding, the difference between rest mass (invariant mass) and relativistic mass accounts for the difference in how the passage of time is conceptualized from the two different observational perspectives. These being the perspective of energy, and the perspective of mass. From the observational perspective of mass, the passage of time is relative. From the observational perspective of energy the passage of time is absolute.

So any particle which is assigned a velocity that is measured relative to the speed of light (measured as moving energy), rather than measured relative to other particles (measured as moving mass), requires a "relativistic mass". This means the particle of energy's mass (resistance to change) is determined according to an absolute principle of temporal duration (energy), rather than a relative principle of temporal duration (mass). It ought to be evident to you, that there is a fundamental incompatibility between the two observational perspectives. These two are the perspective of energy , (employing an absolute conception of the passage of time), and the perspective of mass, (employing a relative conception of the passage of time).

There is a good article on inertia in Stanford Encyclopedia of Philosophy. If you take the time to read it, you might notice the incompatibility described above, along with the conventional resolution, explained in sections 2.2 - 2.5. You'll see that the resolution is found in how general relativity employs "rotation". Rotation is an ancient concept (described by Aristotle as eternal circular motion) which allows for a central point of rest (absolute), with motion relative to that absolute.

https://plato.stanford.edu/entries/spacetime-iframes/#QuasInerFramNewtCoroVI

Quoting Wayfarer

And I generally agree with Aaronson’s descriptive categories. I am very impressed with Christian Fuchs’ philosophy of QBism which I guess puts me in the second category. Deutsch et al seem to want to preserve the principle of objectivity above all else.

From the MWI side, the claim is that QBism is solipsist and empty of content:

Quoting Why QBism is completely empty - Mateus Araújo

A good friend of mine, Jacques Pienaar, has recently converted to QBism, as often happens to people that spend too much time around Chris Fuchs. Saddened by these news, I’ve decided to write a blog post explaining why QBism doesn’t contribute anything to understanding Nature. On the contrary, it is a step backwards, as it doesn’t accept the basic premise that there is a world out there and that our job is to understand it. QBism insists that all the puzzles and paradoxes of quantum mechanics don’t actually matter because it’s all subjective anyway.

The post is of particular interest because Araújo and Pienaar (both physicists active in Quantum Foundations) have a great exchange in the comments, with Pienaar providing a useful summary of QBism. As a bonus:

Quoting Comment by Jacques Pienaar

“Get out of agents’ heads?” So you think that `experience’ happens inside agents’ heads: you’re stuck in a Cartesian worldview. For you, subjective means `of the mind’, and objective means `of the mind-independent world’. To be fair, this is what most physicists would understand by those words, having been brought up in the Cartesian way of thinking. And on these terms, I think it would be fair to call QBism solipsist. But that would [be] missing the point, because QBism explicitly says that is not how we should think about experience, objectivity, and subjectivity.

Pienaar highlights one of the most important issues affecting philosophy, which is Cartesian Dualism. So it's great to see the issue getting some airtime. The issue is manifest in the varied uses of terms such as "observer", "observer effect" and "measurement", including in this thread.

Quoting Metaphysician Undercover

I believe that the notion of a 'passive' observer is actually inconsistent with relativistic physics. Passive observation must be from a "rest frame', or else it cannot be said to be "passive".

I understand your point, however the specific contrast being made was between an observer qua reference frame and an observer qua rational agent. Only the latter can be understood as a user of quantum theory, and thus active in that sense.

Unfortunately, I was not able to easily follow the rest of your post. Perhaps you could concisely state your claim and quote specifically from SEP what you're arguing for (or against).

Quoting Why QBism is completely empty - Mateus Araújo

it doesn’t accept the basic premise that there is a world out there and that our job is to understand it.

I'm still persuaded by Pienaar. This 'basic premise', the division of self and world, is after all what is being called into question, and with good reason, as we are not ultimately outside of or apart from reality. Reality includes the observer, who is the subject of experience, the being to whom the world is meaningful. Pienaar's remarks about Cartesianism also make sense to me, see the Cartesian Anxiety.

Quoting Wayfarer

I put this question to NoAxioms but he wasn't sure how to respond, so I'll try again, as you seem to have insight into this area.

On face value, the many-worlds interpretation of quantum physics seems the opposite of parsimomious. It seems to say that the world or universe splits or divides at the point of measurement or observation of a sub-atomic particle. So the question is, what problem does the interpretation of quantum physics try to solve? What would its proponents such as Wallace and Deutsch be obliged to acknowledge (apart from the obvious fact that they were mistaken), if by some means it was shown to be untenable?

To resolve the contradiction mon ami, that's one way to look at it. Schrödinger's cat (call PETA asap) is both dead and alive (this is impossible in one world) and so the world splits, one in which the cat's alive and one in which it's dead.

Quoting Wayfarer

Notice the quotes around 'bigger'. What I think you actually mean is, 'many'. They're very different things.

They are very different things, and I meant ‘bigger’. Still one universe, but more of it than the story you found comfortable as a child. There were other universe theories (the only reasonable alternative to the intelligent design argument) long before Everett came along, so having other worlds is hardly a painful step.

Einstein didn't like the uncertainty principle or the 'quantum leap' because he was a determinist.

He also held to locality, so I think he would have liked an interpretation that was both local and deterministic.

Quoting Wayfarer

The observer problem is a problem because there’s nothing in the maths to indicate where the observer must come into the picture.

I suspect that decoherence calculations do just that.

This undermines the principle of objectivity

That it does. I’ve discarded that principle, as do most of the interpretations. The science doesn’t care. Quantum theory is not concerned with what goes on in the absence of interaction between systems.

Quoting Andrew M

Per your comment, "one also has to deal with how some of them are more probable than others", the basic idea (from Zurek - see the above post) is that paths that are not equally probable can be mathematically reduced to paths that are. For example, a beam splitter with a 2:1 transmission/reflection ratio is equivalent to a beam splitter with a 1:1:1 ratio once a 1:1 beam splitter is added to the transmission path.

What if the ratio isn’t rational?

[quote=Andrew M]There's an 'observer effect' in Einsteinian relativity which nobody objects to. That's not the problem.[/quote]
[quote=noAxioms]There is? There are dependencies on frames (what velocity has object X?, a completely frame dependent question since Galileo), but I've not heard that observers have any effect at all.[/quote]
Quoting Andrew M

Yes, I'm referring to frame dependency.

That is a dependency on a choice of coordinate system. No actual observer need be present, or be stationary, in an arbitrary choice of coordinate system. The people on the platform and the train may (or may not) just happen to make different choices. You make different choices for yourself, such as using one frame to describe where your house is, and a completely different one to describe what Neptune is doing (which is moving faster than c in the frame you probably chose for your house).

While the laws of physics are the same for all observers, they may describe things differently from their respective reference frames.

That’s quite different than the interaction (measurement) actually changing the system being measured, which is what this topic is about.

Quoting Metaphysician Undercover

What Einstein does with "special relativity" is to give 'special' status to light, freeing it from the principles of relativity

On the contrary, he brought light to be included in the principle of relativity, that it moving at c was such a law of physics that was unchanging, part of the principle of relativity. He freed light speed from being relative to a medium, or possible relative to that which emitted it, in both cases being different from one frame to the next. We each see the same things differently. I see it as bringing light into PoR, and you see it as being taken out.

to allow that its motion is not relative to the motions of material bodies.

But it’s motion IS relative to material bodies, or rather relative to any inertial frame including the one in which the material body is stationary. The second premise says that directly.

This amplifies the 'observer effect' by greatly increasing the possibilities for subtle differences. Now there is a need for principles like time dilation, length contraction, relativistic mass, and things like that.

But those are all frame effects, not observer effect. For instance, a clock coming at you fast will tick slow in your inertial frame, but it will be observed to run fast. Observer effects and frame effects are not the same.
There are objective demonstrations of say length contraction, contraction that is real regardless of observer or choice of frame. That makes length contraction part of ‘a true perspective’, if that phrase is to have any meaning.

Quoting Agent Smith

Schrödinger's cat (call PETA asap) is both dead and alive (this is impossible in one world)

Shouldn’t the cat simply be dead or alive then? What’s the difference when the box hasn’t yet been opened, other than the epistemological one where the lab guy doesn’t know the state of the cat. That would be a classic state like a coin tossed and caught, but not yet revealed. What makes the cat different if the world has already split?

Quoting Andrew M

I understand your point, however the specific contrast being made was between an observer qua reference frame and an observer qua rational agent. Only the latter can be understood as a user of quantum theory, and thus active in that sense.

Unfortunately, I was not able to easily follow the rest of your post. Perhaps you could concisely state your claim and quote specifically from SEP what you're arguing for (or against).

I figured you wouldn't easily follow the post. It's an unconventional perspective, therefore adjustments to fundamental assumptions are required for understanding. So I'll give you the gist in a more straight forward way.

The first point is that I do not accept the proposed contrast between "observer qua reference frame and an observer qua rational agent". All observations are human (rational agent) based activities. We can however, make a separation between the types of tools used by human beings in observation. We can distinguish the use of theories as tools, from the use of material objects as tools. It's easy to see that these two types of tools are fundamentally different, so this provides good grounds for a separation of distinct types of observational tools.

So we can start with the "frame of reference", and understand this as a theoretical tool intended to aid in the interpretation of information received in observation. It is a feature of basic relativity theory which allows for choice in observational interpretation. All that is required is a valid "rest frame", or in the terms of the referred article, "inertial frame". The rest frame provides a grounding for the application of temporal measurement through the assumption of uniformity or constancy in the existence of mass relative to the passing of time. This is what is required for Newton's first law to be applicable. This law being a description of the existence of material bodies relative to the passage of time. So whenever the motion of an object is constant relative to that of another, we have the means for representing those objects relative to an independent measurement of time, and therefore a choice of inertial frames. Each is a valid inertial frame as constant relative to an independent measurement of time.

The point I made in the last post is that special relativity effectively robs us of that choice of inertial frames by denying the validity of the independent measurement of time. Instead, it assigns an absolute value to the speed of light. There is still the illusion of a choice of inertial frames, but any such choice must be rectified in relation to light, so the absolute value assigned to light actually nullifies any truth to such a choice.

Under special relativity the passage of time is not represented as relative to the inertial frame (as Newton's first law describes it with the constant, or uniform existence of mass), it is relative to the electromagnetic activity. In other words, the passage of time is not understood as, and measured as a constant relative to moving bodies, it is understood as a constant relative to the activity of light. The important point is that this means that there is no true inertial frame. Mass was defined as the temporal constant, now light gives the temporal constant. The concept of "inertial frame" is rendered invalid because no frame of reference can be constant. Each frame is moving relative to light, and time is understood as relative to light, so there can be no valid rest frame. The result is that uniform or constant motion, the property of an inertial frame, which is how Newton relates the passage of time to the existence of mass, is not a valid concept. Therefore there is no valid concept whereby the passage of time is related to the existence of mass.

That, as I understand it, describes the theoretical aspect of observational physics. There are two distinct theoretical frameworks for interpreting information received in observation, the Newtonian perspective of "inertial frame", of the temporal continuity of mass, and the Einsteinian perspective which I'll call "energy". One bases the passage of time, therefore the standards for understanding time, in the constant uniform existence of mass, the other bases the passage of time in electromagnetic activity, "energy". There is an inconsistency between these two theoretical tools, which is displayed by the concept of "relativistic mass".

From here, we can move toward understanding the other type of observational tool, the material objects which are employed as aids in receiving information. Consider an observational glass like a magnifying glass. Interpreting information received through the use of such a tool requires an extra layer of theory. We need theory as to how the light is affected by the glass prior to being observed by the human eye. This is the theory which goes into the production of the glass. Understanding the theory by which the glass affects the light, and by which the glass was produced, is an important feature required for a proper interpretation of the information received through the glass.

Now consider the equipment used in typical wave-particle experiments, detectors and things like that. Within the equipment itself, there is built-in interpretive theory. So the information received by the observational equipment is interpreted according to the applied theory, and presented to the human being as already interpreted, an interpretation based in that theory. And, as explained above, we have two inconsistent theories with respect to temporal information, the inertial frame perspective (Newtonian), and the Einsteinian perspective, "energy". Therefore it is very important that we know exactly how (by which theories) the equipment interprets temporal information.

Quoting noAxioms

On the contrary, he brought light to be included in the principle of relativity, that it moving at c was such a law of physics that was unchanging, part of the principle of relativity.

I believe this is an improper interpretation noAxioms. The principle of relativity makes all motions equally relative to each other. To stipulate that one movement, "c", is exempt from that principle, is to remove it from the application of that principle, "relativity", and give it special status, and we are left with "special relativity".

Quoting noAxioms

I see it as bringing light into PoR, and you see it as being taken out.

I think you are "seeing" it incorrectly then. Prior to Einstein there appeared to be no way to make the motion of light compatible with the principle of relativity. It was a practical problem involving the difficulty in measuring the speed of light. If light was included within the application of the relativity principle, then the person on the embankment, and the person in the train car, would have to measure the light from the same source as having a different speed. Einstein saw that as very impractical, (and of course the difference is very small in proportion), so he suggested that we just stipulate that the speed of light is always the same, and we produce principles to make adjustments to the different frames of reference accordingly.

Therefore, he does not bring light "into PoR" as you suggest. He leaves light as exempt from PoR and makes adjustments to PoR to allow that light can be related to it. So we have the substance of material bodies (mass) understood as obeying the principle of relativity, and light which is in a separate category of substance which does not obey relativity. Special relativity states the principle by which these to distinct substances can be related to each other. General relativity works out the details of this relation. The problem is that the whole idea that we can employ the relativity principle, and arbitrarily exempt something like light from it, for simplicity sake, is fundamentally flawed. That special exemption produces all sorts of problems which cannot be resolved. The result is two distinct and fundamentally incompatible (evidenced by "relativistic mass") temporal perspectives, space and time from the theoretical framework of light, and space and time from the theoretical framework of mass.

Quoting noAxioms

But it’s motion IS relative to material bodies, or rather relative to any inertial frame including the one in which the material body is stationary. The second premise says that directly.

You are using "relative" ambiguously, and you need to be careful not to equivocate. In the relativity principle, the motion of bodies is "relative" in the sense that velocity varies according to the frame of reference. But the motion of light is constant, "an absolute" in relation to the motion of material bodies, not variable or relative in that sense. Therefore it is not "relative" in the sense of the relativity principle. So when you say the motion of light is "relative to material bodies" you are using "relative" in a way other than it is used in relativity theory, because every body regardless of its relative motion (according to relativity principle) is essentially at rest "relative" to light.

Quoting noAxioms

But those are all frame effects, not observer effect. For instance, a clock coming at you fast will tick slow in your inertial frame, but it will be observed to run fast. Observer effects and frame effects are not the same.
There are objective demonstrations of say length contraction, contraction that is real regardless of observer or choice of frame. That makes length contraction part of ‘a true perspective’, if that phrase is to have any meaning.

I think our respective understanding of terms is too far apart for me to properly address this, but I'll try anyway. To put it simply, the observer chooses the frame, so "frame effects" are observer effects. They are effects produced by interpretive theory. Special relativity impairs the observer's capacity to employ the relativity principle by producing those special effects. Those effects are the result of giving light the special status which exempts it from the relativity principle, yet still allowing light a special relation to the bodies whose motion the relativity principle is applicable to.

Quoting Wayfarer

It would be better to simply recognise there are things science is unable to ascertain and leave it at that. As a general rule, knowing you don’t know something is preferable to thinking you know something that you don’t.

The irony in this statement is that it seems to be based on you thinking that you know what science can and cannot ascertain, rather than leaving it as an open question to be determined by further inquiry.

That said, I agree that when it comes to first person experience; there seems to be no imaginable way that science could study it apart from accepting first person reports as to what it is, or what it seems to be, since it is not an inter-subjectively observable phenomenon. Because their veracity does not seem to be independently checkable, accepting first person reports would seem to be outside the scope of the scientific method as generally conceived.

But does it follow that no one should try to come up with some approach that has not been previously thought of or tried? It seems that Dennett has proposed something along these lines with his heterophenomenology. I don't know enough about current neuroscientific work to say whether this kind of approach is actually being practiced, or practiced widely. Another approach which I think is being practiced, possibly more widely, is neurophenomenology

Quoting Janus

The irony in this statement is that it seems to be based on you thinking that you know what science can and cannot ascertain, rather than leaving it as an open question to be determined by further inquiry.

It's not just my opinion. I think what is known as the 'Copenhagen interpretation' and also QBism both acknowledge this. Remember Heisdenberg's ''What we observe is not nature itself, but nature exposed to our method of questioning.' I think the 'Copenhagen intepretation' (which is not a theory or an hypothesis but an attitude) is very mindful of what can't be said on the basis of quantum physics. Whereas those interpretations that insist on preserving so-called 'objectivity' are then obliged to posit infinitely dividing universes to accomodate their requirements.

Reply to Wayfarer Apparently I thought I was in a different thread; so I was addressing what I thought was a claim that science can never investigate the first person nature of consciousness. I should have looked more closely before responding.

That said, I think the MWI is just another speculative attempt to address the apparently paradoxical character of the collapse of the wave-function. The Copenhagen interpretation, decoherence and hidden variables are others, as far as I know, and what counts as an "observer" seems to be the crux of the issue, but admittedly I don't know much about the subject.

If I am right and they are all just interpretations, then it would seem there could be no decidable resolution as to which is the "correct" one. In any case which interpretation is the correct one, even if it were possible to decide, really has no bearing on the practice of QM. Scientific theories are never provably true; we just know they work or don't work as predictive tools.

Quoting noAxioms

Schrödinger's cat (call PETA asap) is both dead and alive (this is impossible in one world)
— Agent Smith
Shouldn’t the cat simply be dead or alive then? What’s the difference when the box hasn’t yet been opened, other than the epistemological one where the lab guy doesn’t know the state of the cat. That would be a classic state like a coin tossed and caught, but not yet revealed. What makes the cat different if the world has already split?

I thought that superposition is a fact and not just a hole in our knowledge. In other words the coin is heads and tails and not that it's either heads or tails, only we don't know which.

Quoting Agent Smith

I thought that superposition is a fact and not just a hole in our knowledge. In other words the coin is heads and tails and not that it's either heads or tails, only we don't know which.

You thought correctly. And importantly this is a testable hypothesis that has been experimentally verified.

Quoting PhilosophyRunner

You thought correctly. And importantly this is a testable hypothesis that has been experimentally verified.

I should've worked harder in high school.

Quoting noAxioms

But it’s motion IS relative to material bodies, or rather relative to any inertial frame including the one in which the material body is stationary. The second premise says that directly.

Try looking at it this way noAxioms. By the principle of relativity no body can be truly at rest unless all bodies are at rest. So "inertial frame" is a sort of arbitrary designation requiring only constancy, uniformity. Motion which stays the same as time passes is the principle of relativity's "rest". And as you say, the motion of light "c" is relative to any inertial frame. But "inertial frame" is a feature of the theory, it is a theoretical observational tool derived from the uniformity observed in the passage of time. What defines the "inertial frame" is the uniform, constant passage of time. Therefore the speed of light is not grounded in, or relative to any material bodies, it is relative to the defining feature of the "inertial frame", which is the uniform passage of time.

Quoting Agent Smith

I thought that superposition is a fact and not just a hole in our knowledge. In other words the coin is heads and tails and not that it's either heads or tails, only we don't know which.

Wikipedia:

Quantum superposition is a fundamental principle of quantum mechanics. It states that, much like waves in classical physics, any two (or more) quantum states can be added together ("superposed") and the result will be another valid quantum state; and conversely, that every quantum state can be represented as a sum of two or more other distinct states. Mathematically, it refers to a property of solutions to the Schrödinger equation; since the Schrödinger equation is linear, any linear combination of solutions will also be a solution(s)

. . .

In quantum physics, a quantum state is a mathematical entity that provides a probability distribution for the outcomes of each possible measurement on a system

The cat really is either dead or alive, not in some mystical sense, both. Probabilities, on the other hand, are not definitive.

Reply to jgill Well then what explains all the Sturm und Drang mon ami?! Why the hullabaloo if the cat is simply dead OR alive?

Quoting Agent Smith

?jgill
Well then what explains all the Sturm und Drang mon ami?! Why the hullabaloo if the cat is simply dead OR alive?

No one really knows exactly whats going on at the quantum level. If you simply follow the math and avoid all this metaphysical stuff, you do well at predicting. Apparently. Once the science popularizers get into the game, however, you see the Earth in basketball nets. Best to let the Q-physicists argue it out. My opinion. FWIW. Not much.

Quoting jgill

No one really knows exactly whats going on at the quantum level. If you simply follow the math and avoid all this metaphysical stuff, you do well at predicting. Apparently. Once the science popularizers get into the game, however, you see the Earth in basketball nets. Best to let the Q-physicists argue it out. My opinion. FWIW. Not much

Danke! I recall saying that Schrödinger's =n is not a mathematical contradiction but is an English (natural language) contradiction.

Quoting jgill

No one really knows exactly whats going on at the quantum level. If you simply follow the math and avoid all this metaphysical stuff, you do well at predicting. Apparently. Once the science popularizers get into the game, however, you see the Earth in basketball nets. Best to let the Q-physicists argue it out. My opinion. FWIW. Not much.

Leave the metaphysics to be done by the physicists? Surely that's a mistake. Metaphysics consists of different principles which physicists have not been trained in.

Quoting Metaphysician Undercover

Metaphysics consists of different principles which physicists have not been trained in.

Suppose I am a typical Q-physicist, following the mathematics but paying little attention to authorities in my subject babbling woo about interpretations. Please elucidate the training program in metaphysics I would need to complete to be considered competent in metaphysics. Be specific as possible.

Would I need to attend the University of Metaphysics? Would a bachelor's degree be sufficient?

Reply to jgill :up:

Quoting noAxioms

What if the ratio isn’t rational?

Any irrational number can be approximated to an arbitrary degree of accuracy by a rational number. From the associated paper:

Quoting Self-Locating Uncertainty and the Origin of Probability in Everettian Quantum Mechanics - Sebens and Carroll, 2015

For any wave function with irrational squared-amplitudes there exist arbitrarily similar wave functions with rational squared-amplitudes (as the rationals are a dense subset of the reals).

Quoting noAxioms

"While the laws of physics are the same for all observers, they may describe things differently from their respective reference frames." - Andrew M

That’s quite different than the interaction (measurement) actually changing the system being measured, which is what this topic is about.

Yes, it is quite different. As is the effect you mention of a clock travelling fast towards you that appears to be ticking faster than it is. Perhaps we can call them (classical) perceptual effects, (relativistic) frame effects, and (quantum) measurement effects to disambiguate them for the purposes of this discussion.

Anyway, whether or not the interaction changes the system being measured is what the Deutsch quantum AI experiment would test. That is, whether physical collapse occurs and interrupts the unitary evolution.

A related test has been carried out at a microscopic level (using photons instead of AI's) where it was shown that physical collapse does not occur.

Quoting Experimental test of local observer-independence - Proietti, et al., 2019

In a state-of-the-art 6-photon experiment, we realise this extended Wigner’s friend scenario, experimentally violating the associated Bell-type inequality by 5 standard deviations. If one holds fast to the assumptions of locality and free-choice, this result implies that quantum theory should be interpreted in an observer-dependent way.

Quoting Metaphysician Undercover

So I'll give you the gist in a more straight forward way.

Unfortunately, I didn't find your comment straightforward - I'm now not clear whether you accept special relativity or not. Can I suggest focusing on a single point, and stating it concisely. It might also be helpful to provide a quote from an authoritative source (such as SEP or a peer-reviewed paper) that backs up your point (or, alternatively, that you're disputing).

Quoting Metaphysician Undercover

The principle of relativity makes all motions equally relative to each other.

Not quite. All motion can be specifed relative to a frame, specifically an inertial frame. Light speed is specified relative to (and is fixed only relative to) any inertial frame, so it isn’t an exception.

To stipulate that one movement, "c", is exempt from that principle

Never said that. You’re saying it, and it’s wrong since it would exempt it from the principle. Light has no special status in this regard.
You seem to see an exception when I don’t. Mathematically, how does this work? How does it differ from say a neutrino (a massive particle) traveling here at almost c, such that we actually detect it from a supernova before we detect the light? Are neutrinos now also exceptions? We could have the Alice & Bob scenario with the train and the platform, but use neutrinos (or buses) instead of light, with the same result. Are we going to add these things to your exception list then?

is to remove it from the application of that principle, "relativity", and give it special status, and we are left with "special relativity".

The principle of relativity is one of the postulates of special relativity. Being part of that theory doesn’t mean anything gets special status. The word ‘special’ means a special case of no gravity being involved. With gravity, there are no longer non-local inertial frames and fixed speed of light goes away.

I think you are "seeing" it incorrectly then.

I realize you think that, and I’m trying to actually grok your opinion to the contrary. But as I say, mathematically it doesn’t work. Light obeys the same rules as everything else, just like PoR says it should.

Prior to Einstein there appeared to be no way to make the motion of light compatible with the principle of relativity.

This statement also seems to contradict what you’re asserting. Anyway, post-Michelson–Morley at least, new rules were needed since Newton’s application of PoR wasn’t working. In particular, relative velocity addition needed modification.

It was a practical problem involving the difficulty in measuring the speed of light. If light was included within the application of the relativity principle, then the person on the embankment, and the person in the train car, would have to measure the light from the same source as having a different speed.

First of all, one-way SoL still cannot be measured by any means, hence the speed being fixed being an additional premise, not something derived or measured. Secondly, the assertion you make (that these two observers would have to measure different speeds) does not follow from PoR.
There are alternative theories that do not posit identical light speed relative to any frame. I think you’d like them. AFAIK, it took around a century to come up with a generalized version of such a theory, but it has been done. It involved doing away with the big bang and black holes and such, but empirically, it seems to hold water.

The problem is that the whole idea that we can employ the relativity principle, and arbitrarily exempt something like light from it, for simplicity sake, is fundamentally flawed.

Again I agree that such an exception would constitute a fundamental flaw, but this seems to be exactly what you’re suggesting.

space and time from the theoretical framework of light

This has no meaning under relativity theory, or for that matter any of the alternatives.

You are using "relative" ambiguously, and you need to be careful not to equivocate. In the relativity principle, the motion of bodies is "relative" in the sense that velocity varies according to the frame of reference.

Not necessarily so. Velocity might be specified relative to a frame of reference, but it just might by chance be the same from one frame to the next. PoR does not demand otherwise.

But the motion of light is constant, "an absolute" in relation to the motion of material bodies, not variable or relative in that sense.

It is exactly relative in that sense. For one thing, a given pulse of light might be heading north relative to one frame and east relative to another. But the magnitude of that velocity would be the same, yes, which is exactly what you’d compute if you performed a Lorentz transform from one frame to another You find this fixed speed to be a contradiction, but PoR does not forbid it. It just says the rules of physics are frame independent. You cannot locally detect your motion in an inertial frame. If you can show how that could be done, then I’d accept that some kind of exception was being made. It could be done under Newtonian physics, and M+M tried to measure just that: a detection of local motion as the understanding of the PoR suggested at the time.

Therefore it is not "relative" in the sense of the relativity principle. So when you say the motion of light is "relative to material bodies" you are using "relative" in a way other than it is used in relativity theory, because every body regardless of its relative motion (according to relativity principle) is essentially at rest "relative" to light.

When you say ‘relative to light’, it is you that is using the term incorrectly. ‘Light ‘does not specify a frame, and you know that (or at least I hope you at least know that much).

I'll try anyway. To put it simply, the observer chooses the frame, so "frame effects" are observer effects.

OK, I choose a roller-coaster track in a circle, and the frame where that track is stationary. We pack it with cars with no space between them. Then we get them going around the track together, and due to length contraction, spaces form between the cars. Are you going to tell me that there is an observer somewhere that doesn’t measure these spaces between the cars? That’s what I mean by the effects (length contraction in this case) being real, not just coordinate effects.

Quoting Metaphysician Undercover

By the principle of relativity no body can be truly at rest unless all bodies are at rest.

Not even then, but motion would admittedly be pretty meaningless in a universe where time itself is meaningless.

So "inertial frame" is a sort of arbitrary designation requiring only constancy, uniformity.

Sounds like you’re now in denial of what an inertial frame is, perhaps suggesting that any inertial frame with something moving (or accelerating) in it isn’t a real one

Motion which stays the same as time passes is the principle of relativity's "rest".

The principle does not define ‘rest’, and certainly does not suggest that there is but one rest frame, a direct violation of the principle.

And as you say, the motion of light "c" is relative to any inertial frame. But "inertial frame" is a feature of the theory, it is a theoretical observational tool derived from the uniformity observed in the passage of time. What defines the "inertial frame" is the uniform, constant passage of time.

OK, this is pretty much rhetoric from the relativity denialist literature. You’re entitled to this opinion, but none of this is part of relativity theory.

Therefore the speed of light is not grounded in, or relative to any material bodies, it is relative to the defining feature of the "inertial frame", which is the uniform passage of time.

OK, so where should light be at the rate of one hour per hour (just guessing at the rate)? IOW, what the heck does that statement even mean? What if time passed at one second per day? How would that affect where goes or what we see?

Quoting Agent Smith

I thought that superposition is a fact and not just a hole in our knowledge.

Yes, so we either have two or more worlds in a box, or they’re not really worlds. Either way, it’s different than there being just one state and we just don’t know.
OK, they’re not actually going to do it with a cat because there’s no way they’re going to get a live cat state to interfere with a dead cat state. The cat may be both dead and alive in the box, but superposition is more than that, requiring some sort of interaction (interference) between the two states.

Quoting Andrew M

Any irrational number can be approximated to an arbitrary degree of accuracy by a rational number. From the associated paper:

Ouch. It would really such if nature allowed such approximations. I’d always envisioned pure mathematics behind the physics, not digital mathematics where all numbers are representable with finite states.

Yes, it is quite different. As is the effect you mention of a clock travelling fast towards you that appears to be ticking faster than it is. Perhaps we can call them (classical) perceptual effects, (relativistic) frame effects, and (quantum) measurement effects to disambiguate them for the purposes of this discussion.

The discussion was about observer effect (the observer causing effects), not observed effects (effects merely noticed by the observer), Relativity effects seem to fall under the latter category, prompting my foul call.

A related test has been carried out at a microscopic level (using photons instead of AI's) where it was shown that physical collapse does not occur.

Not sure what this is. Got a link for this one?

Quoting noAxioms

Ouch. It would really such if nature allowed such approximations. I’d always envisioned pure mathematics behind the physics, not digital mathematics where all numbers are representable with finite states.

We may still be able to have a precise geometrical representation. For example:

Quoting Square root of 2

Geometrically, the square root of 2 is the length of a diagonal across a square with sides of one unit of length; this follows from the Pythagorean theorem.

So a balanced beam splitter will have a 1/sqrt(2) amplitude for each path. Nature doesn't encode a digital representation of that number (either finite or infinite), but the information content is there by virtue of the beam splitter being balanced.

Quoting noAxioms

The discussion was about observer effect (the observer causing effects), not observed effects (effects merely noticed by the observer), Relativity effects seem to fall under the latter category, prompting my foul call.

Fair enough.

Quoting noAxioms

"A related test has been carried out at a microscopic level (using photons instead of AI's) where it was shown that physical collapse does not occur." - Andrew M

Not sure what this is. Got a link for this one?

It was in the earlier post:

Quoting Experimental test of local observer-independence - Proietti, et al., 2019

In a state-of-the-art 6-photon experiment, we realise this extended Wigner’s friend scenario, experimentally violating the associated Bell-type inequality by 5 standard deviations. If one holds fast to the assumptions of locality and free-choice, this result implies that quantum theory should be interpreted in an observer-dependent way.

Quoting noAxioms

Yes, so we either have two or more worlds in a box, or they’re not really worlds. Either way, it’s different than there being just one state and we just don’t know.
OK, they’re not actually going to do it with a cat because there’s no way they’re going to get a live cat state to interfere with a dead cat state. The cat may be both dead and alive in the box, but superposition is more than that, requiring some sort of interaction (interference) between the two states.

I'm just surprised that the statement that describes the Schrödinger =n isn't that of ignorance (The cat may be dead or the cat may be alive, we don't know) but of knowledge (the cat is both dead and alive, we know).

Reply to Agent Smith You're dealing with probabilities in the quantum world, not deterministics. The probability of the cat being alive might be .3 and dead .7. Doesn't mean the poor cat hovers between life and death. It may be alive.

Wikipedia:

Schrödinger did not wish to promote the idea of dead-and-alive cats as a serious possibility; on the contrary, he intended the example to illustrate the absurdity of the existing view of quantum mechanics.

Reply to jgill 'Whenever I hear of Schrodinger's cat, I reach for my gun' ~ Stephen Hawking.

Quoting jgill

Please elucidate the training program in metaphysics I would need to complete to be considered competent in metaphysics. Be specific as possible.

I don't know if there's a course about it, but there are a number of books by qualified quantum physicists who are deeply versed in it, beginning with Werner Heisenberg's Physics and Philosophy. There's Bernard D'Espagnat, who studied under the quantum pioneers and was a senior scientist at CERN, whose books also include one called Physics and Philosophy. Shimon Malin, Nature Loves to Hide, is another. Another two recent books that I've read cover-to-cover are Quantum, Manjit Kumar, and Uncertainty, David Lindley. There's a writer called Tim Maudlin who writes on the metaphysics of physics. I'm sure there'd be graduate course on physics and metaphysics floating around which makes reference to one or more of these books. There's probably a bunch of lectures on Youtube. Michel Bitbol's lecture on Kantian Quantum Physics is a good one.

Reply to jgill So it was all hype, no substance, but then the absurdity.

'What did you do the cat, Erwin? Looks half dead!' ~ Ms Schrodinger.

Quoting jgill

Suppose I am a typical Q-physicist, following the mathematics but paying little attention to authorities in my subject babbling woo about interpretations. Please elucidate the training program in metaphysics I would need to complete to be considered competent in metaphysics. Be specific as possible.

Would I need to attend the University of Metaphysics? Would a bachelor's degree be sufficient?

I would say any university with a good philosophy program, and adequate courses in metaphysics. I'm not about to judge the merits of any particular university though.

Quoting noAxioms

Not quite. All motion can be specifed relative to a frame, specifically an inertial frame. Light speed is specified relative to (and is fixed only relative to) any inertial frame, so it isn’t an exception.

I think you've distorted the reality here noAxioms. An "inertial frame" is a theoretical derivative. It is derived from any situation with a body assumed to have uniform existence. Without the mass showing uniform existence there is no inertial frame. Therefore the body at uniform existence which provides for the inertial frame is prior to, and the defining feature of, any particular inertial frame. So there is at least one motion which is necessary and absolute to the inertial frame, therefore not relative to it.

Quoting noAxioms

You seem to see an exception when I don’t. Mathematically, how does this work?

As I said, the speed of light is relative to the passage of time, as is the inertial frame. By the basic principle of relativity (not special relativity) all frames employ the same passage of time, and their motions are relative. The inertial frame show no change over a duration of time. By special relativity, every frame is inertial relative to the motion of light, no change over a period of time, in relation to light. That is an absolute, hence the motion of light is exempt from the principle of relativity. Because of this exemption, the passage of time must be conceived of as unique to each frame. The mathematics is simple, the required length contraction and dilation of time. But the math gets more complicated when dealing with acceleration (general relativity).

Quoting noAxioms

You seem to see an exception when I don’t.

I've made my case. You insist otherwise, making claims supported only by equivocation. So I see no point in proceeding because you simply continue to insist on a perspective which cannot be supported.

Quoting noAxioms

It is exactly relative in that sense.

I explain how it is "absolute" and you say this is exactly how it is "relative". Yes, "relative" in that sense, but that is not the sense of the principle of relativity, which formulates all motion as equally relative. So when you say that the motion of light is always the same relative to any moving body, that claimed "relative" is an absolute, which is an exception to the principle of relativity.

Quoting noAxioms

Sounds like you’re now in denial of what an inertial frame is, perhaps suggesting that any inertial frame with something moving (or accelerating) in it isn’t a real one

An accelerating body cannot be the basis of an inertial frame the two are incompatible. The inertial frame is theory, therefore categorically distinct from any bodies. To speak of an inertial frame with something accelerating "in it" is just deception. The accelerating thing is not "in" the inertial frame, it is relative to it.

Quoting noAxioms

OK, this is pretty much rhetoric from the relativity denialist literature. You’re entitled to this opinion, but none of this is part of relativity theory.

You are clearly the one in denial. The characterization of simultaneity is the central aspect of special relativity. This is because both the "inertial frame" from the traditional principle of relativity, and "c" are grounded in the passage of time. This is how Einstein relates the motion of light to bodies involved in the relativity principle, by making stipulations about the passage of time and simultaneity. Rejecting facts simply because they are the facts reported in "relativity denialist literature" is not good academic practise.

Quoting noAxioms

OK, so where should light be at the rate of one hour per hour (just guessing at the rate)? IOW, what the heck does that statement even mean? What if time passed at one second per day? How would that affect where goes or what we see?

Your mind appears to be absolutely void in the conception of time. Do you agree that the passage of time is an essential aspect of the concept "inertial frame", a duration of time is necessarily implied by "inertial frame"? I think we'd better get agreement on this fundamental feature before we start to discuss whether that duration is a day, an hour, or a second, because we can go two ways toward determining the length of that duration, by relating that duration to the motion of bodies, or relating it to the motion of light.

Quoting Metaphysician Undercover

I would say any university with a good philosophy program, and adequate courses in metaphysics.

Amongst the myriad of courses in numerology, astrology, meditation, noetic sciences,chakras, auras, divination, spiritualism, angels, etc., I found an introductory course at Oxford that looks legit:

Introduction: what is metaphysics? An introduction to the distinctive character of metaphysical questions: the history of the idea of metaphysics, understood as the most general and abstract inquiry into the nature of reality.

Existence: what is existence? What is it to exist? People disagree about what exists; but how can we understand this disagreement? Are there things which do not exist?

Universals and particulars: in addition to particular objects and events, our world seems to contain general or universal features of things, like their colours and their shapes. Is this an illusion or does the world really contain such features, known as 'universals'?

Realism and idealism: does the world exist independently of our minds? Realism is the view that it does; idealism is the view that reality is mind-dependent. Are any features of the world mind-dependent?

The freedom of the will: we think our actions and decisions are free, or up to us, but this idea seems to be in conflict with the apparent fact that everything which happens is determined by what happens before it (this is known as 'determinism'). Does determinism imply that free will is an illusion, or are free will and determinism really compatible after all?

Cause and effect: what is it for one thing to cause another, or to make something happen? Is there more to cause and effect than the mere regularity of things happening after one another? If so, is causation a physical process, or is mental causation also possible?

The nature of time and space: what are time and space? Is there no more to them than the temporal and spatial relations which hold between events and objects? Or should they rather be conceived as the 'containers' in which things exist and events occur? Are the past, present and future genuine aspects of reality, or are they merely 'subjective' features of our experience of time?

We strongly recommend that you try to find a little time each week to engage in the online conversations (at times that are convenient to you) as the forums are an integral, and very rewarding, part of the course and the online learning experience.

I encourage any Q-physicist reading this post to consider enrolling in this course. :cool:

(or simply pull up all the threads on TPF relating to these subjects. Much profound stuff therein.)

Quoting jgill

I encourage any Q-physicist reading this post to consider enrolling in this course.

I would say, only if they are inclined to speculate about the true nature of reality. Otherwise they should be satisfied to carry on with the calculating.

Quoting jgill

I encourage any Q-physicist reading this post to consider enrolling in this course

If you mean this https://www.conted.ox.ac.uk/courses/reality-being-and-existence-an-introduction-to-metaphysics-online - I've had that course bookmarked a long while but have never found the time to enroll. But I agree, I think it looks a worthwhile undertaking.

[quote=noAxioms]... where all numbers are representable with finite states.[/quote]Quoting Andrew M

We may still be able to have a precise geometrical representation.

I can still express the length ?2 with two characters, a very finite state. Humans deal only with such representable numbers, and they’re countable. Actual numbers in nature (such as the ratio of the half lives of two specific isotopes) are not in this countable set. I have a hard time with a model of the universe that requires only the former sort of number, such as one would get in a simulation. Actual numbers are more analog, like ‘so big’ with your hands held apart.
[quote]Nature doesn't encode a digital representation of that number

Maybe it does, such as if our universe is digitally simulated. In this case, the amplitudes of the split beam would not be ?2, but close.
[quote]In a state-of-the-art 6-photon experiment, we realise this extended Wigner’s friend scenario, experimentally violating the associated Bell-type inequality by 5 standard deviations. If one holds fast to the assumptions of locality and free-choice, this result implies that quantum theory should be interpreted in an observer-dependent way.
— Experimental test of local observer-independence - Proietti, et al., 2019

Going to get back to you on this one. Interesting read, but the introduction is already full of interpretation dependent assumptions, such as counterfactual statements. I will look at it from my relational perspective which doesn’t make those assumptions, but thus far I’ve not read enough to really comment on it.

Quoting Agent Smith

I'm just surprised that the statement that describes the Schrödinger =n isn't that of ignorance (The cat may be dead or the cat may be alive, we don't know) but of knowledge (the cat is both dead and alive, we know).

There’s actually no empirical difference between those two cases. There is if there was a true superposition, but there isn’t in the cat case. It’s been demonstrated with macroscopic objects, but under conditions which would kill any cat (such as being in a vacuum and almost 0°K).

Quoting Metaphysician Undercover

An "inertial frame" is a theoretical derivative.

I guess so. I would have said it is an abstraction, an assignment of coordinates to events.

It is derived from any situation with a body assumed to have uniform existence.

This is nonsense. You have a reference to such a crazy definition from a consensus physics reference from the last century? What even is uniform existence? That a body must be the same everywhere? A carrot cannot taper? I presume you to be an absolutist and maybe get your definitions from the sites supporting such, but this is not the consensus definition as used by physicists.
[quote=noAxioms]perhaps suggesting that any inertial frame with something moving (or accelerating) in it isn’t a real one

To speak of an inertial frame with something accelerating "in it" is just deception.

Case in point.

Do you agree that the passage of time is an essential aspect of the concept "inertial frame", a duration of time is necessarily implied by "inertial frame"?

No, not at all. I can for example reference the inertial frame of Earth when referencing the twins scenario. No duration is specified or necessary when identifying that frame.

Quoting jgill

I encourage any Q-physicist reading this post to consider enrolling in this course. :cool:

There were lots of basic topics covered, down to interpretations of time near the bottom, but I didn’t see quantum interpretations mentioned at all, which requires probably a whole separate course.
The course description might devote an hour or three on each listed topic. Nice introduction, but you can get it just by reading each topic in places like Stanford philosophy.

Quoting noAxioms

There’s actually no empirical difference between those two cases. There is if there was a true superposition, but there isn’t in the cat case. It’s been demonstrated with macroscopic objects, but under conditions which would kill any cat (such as being in a vacuum and almost 0°K).

:brow:

Quoting noAxioms

This is nonsense. You have a reference to such a crazy definition from a consensus physics reference from the last century? What even is uniform existence? That a body must be the same everywhere? A carrot cannot taper? I presume you to be an absolutist and maybe get your definitions from the sites supporting such, but this is not the consensus definition as used by physicists.

"Uniform existence" is having an unchanging presence, as in not being acted upon by forces; what is described by Newton's first law, which is commonly referred to as "the law of inertia". Check the Stanford article I previously referenced:

[quote=https://plato.stanford.edu/entries/spacetime-iframes/#QuasInerFramNewtCoroV\ ]The laws of Newtonian dynamics provide a simple definition: an inertial frame is a reference-frame with a time-scale, relative to which the motion of a body not subject to forces is always rectilinear and uniform, accelerations are always proportional to and in the direction of applied forces, and applied forces are always met with equal and opposite reactions. [/quote]

Quoting noAxioms

No, not at all. I can for example reference the inertial frame of Earth when referencing the twins scenario. No duration is specified or necessary when identifying that frame.

That's a fictional "inertial frame", not properly formulated, so not an actual inertial frame. I could reference "the inertial frame of my right big toe", but unless it's properly formulated as an inertial frame, it's just fiction. Your terminology is not logically rigorous noAxioms. That's why I needed to point out your equivocation with "relative". Notice the above quote, "with a time scale". Any proposed inertial frame would be completely useless without a time scale.

Quoting noAxioms

There were lots of basic topics covered, down to interpretations of time near the bottom, but I didn’t see quantum interpretations mentioned at all, which requires probably a whole separate course

Might be hard to find a faculty member of a philosophy department capable of this. :cool:

I think that deep within the mathematical structure of QM is where superposition or assumed existence in two "separate" states simultaneously occurs, or a mixture of states. The process begins with Hilbert spaces and their inner products (in C these might be thought of as the power of combined vectors). States of a system are subspaces of these. A pure state is determined by a unit vector in the Hilbert space. Combining systems is interpreted as taking tensor products of two Hilbert spaces. The probability of a property when the system is in a pure state is given by the inner product.

It seems to be a mathematical thing and perhaps someday a different math approach will clarify this. Schrödinger's cat deserves a bowl of milk and gentle scratching around the ears.

Reply to jgill
But the issue is, what do these mathematical representations represent in the real material world? Or do we simply deny that there is a real material world? Perhaps our senses deceive us.

The problem with vectors is that they represent things (forces and movements) with one dimensional straight lines, when we know that in reality these things act in a multidimensional way. This produces a fundamental requirement of stacked vectors to represent a multitude of dimensions. Since the vector is a line segment, it fundamentally represents a relationship between points. However, through terms of usage which manipulate human thought, we come to believe that a vector represents properties at a point, forgetting that it really is a relationship between points.

So we get terms like "inner product' which appear to represent something which is internal to a point, when in reality it represents that point's relation to other points in a dimensional representation. Then there is a whole class of concepts such as "angular momentum" and "spin" which through the terminology used appear to represent something internal to a point, when in reality they are produced by relating that point to other points dimensionally.

The issue is, as I said at the beginning, the straight line of a vector does not accurately represent a multidimensional activity which has curves inherent within every infinitesimal point. So real movement from one infinitesimal space to the next is not accurately represented with straight vectors, and the longer the vectors are, the more the inaccuracy is magnified.

Quoting Metaphysician Undercover

The problem with vectors is that they represent things (forces and movements) with one dimensional straight lines, when we know that in reality these things act in a multidimensional way.

Quoting Metaphysician Undercover

The issue is, as I said at the beginning, the straight line of a vector does not accurately represent a multidimensional activity which has curves inherent within every infinitesimal point. So real movement from one infinitesimal space to the next is not accurately represented with straight vectors, and the longer the vectors are, the more the inaccuracy is magnified.

Oh my. This is dreadful, I fear. :gasp:

Whereas the simplest vector spaces (in R^2 or C) have vectors which can be represented by little arrows in the Euclidean or complex planes, most vectors in QM go far beyond this and cannot be so described. See Hilbert space. But, if I read between the lines you write I think what you may be getting at is the fact that linear maps are fundamental in applications.

Working with complicated functions in math one frequently tries to approximate little parts of these functions with linear functions, which are so much easier to work with. That's what happens, say, in finding a distance an object has traveled, D=Rt. If R is constant, we have R(t1+t2)=Rt1+Rt2. But if R varies we go to a definite integral, which, itself, consists of adding tiny parts of time with constant rates applied.

I've wondered about this linearity feature of QM and why it is so fundamental to the subject. But I am not a physicist. Here is a comment found in Wikipedia.

Quoting jgill

Oh my. Whereas the simplest vector spaces (in R^2 or C) have vectors which can be represented by little arrows in the Euclidean or complex planes, most vectors in QM go far beyond this and cannot be so described. See Hilbert space.

The basic principle of the vector remains the same, but the vector space described is more complicated. The complexity of these vector spaces is what gives rise to the idea of "inner products". The use of "inner" makes it sound like these are properties internal to the point. In reality they are how the point relates to other points (by means of vectors), therefore external relations.

Quoting noAxioms

I can still express the length ?2 with two characters, a very finite state. Humans deal only with such representable numbers, and they’re countable.

Yes, computable numbers.

Quoting noAxioms

Actual numbers in nature (such as the ratio of the half lives of two specific isotopes) are not in this countable set. I have a hard time with a model of the universe that requires only the former sort of number, such as one would get in a simulation. Actual numbers are more analog, like ‘so big’ with your hands held apart.

How would we know that such ratios aren't representable?

That question seems relevant to the physical Church-Turing thesis (Church-Turing-Deutsch principle) which says that any bounded physical system can be simulated by a Turing machine to any desired precision.

Quoting noAxioms

Going to get back to you on this one. Interesting read, but the introduction is already full of interpretation dependent assumptions, such as counterfactual statements. I will look at it from my relational perspective which doesn’t make those assumptions, but thus far I’ve not read enough to really comment on it.

The authors do list the assumptions of their experiment which they note can't jointly be true. Those assumptions are observer-independent facts (O), locality (L ) and free-choice (F). Also, they acknowledge the relational perspective in their conclusion:

Quoting Experimental test of local observer-independence - Proietti, et al., 2019

Another option is to give up observer independence completely by considering facts only relative to observers [24], or by adopting an interpretation such as QBism, where quantum mechanics is just a tool that captures an agent’s subjective prediction of future measurement outcomes [25].

Quoting Metaphysician Undercover

The use of "inner" makes it sound like these are properties internal to the point. In reality they are how the point relates to other points (by means of vectors), therefore external relations.

Inner product = input vectors into a form producing a real or complex number (scalar). Outer products are matrices or tensors. Word salad.

As soon as you get into the actual physics, then it's really better suited to Physics Forum. The question is not one about physics, it's one about meaning.

Quoting Wayfarer

The question is not one about physics, it's one about meaning.

Unfortunately, it may well be the meaning of the math as one follows that path to actualizations. When does that occur? Beyond me. The math is hard for me to follow. Not so young, anymore. :worry:

Reply to jgill
The issue is that you get dimensionless points (no volume of space occupied by the points), in space, which have properties, as point particles. Traditionally, a point could not be a body with properties, but its mass might be represented as a point, the centre of gravity. So the point became a very effect way to represent a body's mass for calculations in physics. The centre of gravity. You can see though, that the point does not provide a very truthful, or even accurate representation of a body, which really exists in the area around the point, though it provides a very useful representation of its mass for many practises.

But when we start to break bodies apart, getting down to smaller and smaller parts, the concept of "mass" breaks down as well, being a feature of a body's way of occupying space as a coherent whole. That's why "density" is an important concept in relation to "mass". So for instance, if you propose to break apart a massive particle, like a hadron (proton, neutron) into its composite quarks, it's mass cannot be accounted for. The mass is more like a property of the space that the combined quarks are existing in, as a coherent unity, and this is known as the strong force. So further particles, gluons, might proposed to account for the existence of this force, but these would be represented as points, therefore not properly representing the area.

You ought to be able to see that the strong force is a property of an area of space, the area within which the hadron exists. That area is responsible for the existence of the hadron and its mass. So when it comes down to the nitty gritty of providing a true and accurate representation of mass, the point, as the centre of gravity, fails badly. In reality, "mass" refers to how a body is extended in space, so when a physicist tries to break a massive hadron into its composite point particles, its mass cannot be adequately represented.

If the physicist does not respect this difference between theory (representing mass as a point), and practise (the experiments demonstrate that mass cannot exist at a point), then the physicist will continue into that theoretical fantasy land, a fictional world requiring the assumption of "virtual particles", in a pointless attempt to maintain the representation of mass at a point.

Quoting Metaphysician Undercover

then the physicist will continue into that theoretical fantasy land, a fictional world requiring the assumption of "virtual particles", in a pointless attempt to maintain the representation of mass at a point.

Lattice field theory avoids virtual particles, which are mathematical conveniences.

Quoting Metaphysician Undercover

the point does not provide a very truthful, or even accurate representation of a body, which really exists in the area around the point

I'm curious how you would express what you have said in the context of field theory.

Quoting jgill

Lattice field theory avoids virtual particles, which are mathematical conveniences.

Hmm, there seems to be an incommensurability between the lattice representation, and the continuum representation. Here's from Wikki' entry on lattice guage theory:

"When the size of the lattice is taken infinitely large and its sites infinitesimally close to each other, the continuum gauge theory is recovered...
...Such calculations are often extremely computationally intensive, and can require the use of the largest available supercomputers."

I think the issue with the lattice representation is that the designation of a quantum (discrete unit) of space is completely arbitrary, not based on any real attributes of space itself. Then it becomes just a matter of re-representing a spatial continuum as an infinity of spatial units. That an infinite number is required demonstrates the incommensurability. But when mass, forces, and motion are represented, there's probably no significant different from points and vectors, because it appears like they are just trying to reproduce this in a different form anyway.

Quoting jgill

I'm curious how you would express what you have said in the context of field theory.

I think that field theory gives properties to space itself, the electromagnetic field for example. But since the electromagnetic field is observed to react with massive objects like atoms, or even just electrons, through quanta, the tendency is to give the quantum of energy a particle-like existence, as a point. This is very similar to what I said above, that the object with mass is represented as a point (centre of gravity). It's a matter of simplicity, to interact with a particle with mass, which is represented as a point, the thing interacting is also represented as a point. As I said above, I believe this is inaccurate. So in as much as the representation of fields might in some way represent real spatial attributes, the points in the field, which are supposed to be particles are not adequate representations. But these points are needed to explain how the field interacts with mass which is represented as a point, a centre of gravity for the sake of simplicity. So what is needed is to get away from representing mass as a point. Then when the field interacts with mass in the way of quanta, it is not at a point in the field.

Consider the way that an electron interacts with a proton in an atom for example. The interaction does not occur simply between a point where the electron is, and a point where the proton is. The interaction is occurring everywhere within the orbital, so it is understood as the "electron cloud". It is not the case that at any moment, the electron is at some point in the cloud, it is the case that at every moment, the electron is everywhere in that cloud. This is because "the electron" does not exist as a particle at a point, that's just a representation which was made for simplicity sake, to show its mass as being at a point.

Quoting Metaphysician Undercover

I think the issue with the lattice representation is that the designation of a quantum (discrete unit) of space is completely arbitrary, not based on any real attributes of space itself

What are the "real" attributes of space?

[quote=Numerius Negedius]I'm not an observer, no, I'm definitely not.[/quote]

This is very confusing. :chin:

Does the observer have to be conscious or are there non-living "observers"?

Quoting Agent Smith

Does the observer have to be conscious or are there non-living "observers"?

First of all, why do you engage consciousness with living/non-living? There are livings who are not observes because they are not aware of anything. So, being alive does not imply being observer if I am not conscious enough around my scenario of reality, mind, ideas, persons, etc...

For example: A living dog is not conscious of metaphysical and philosophical enquiries, but at the same time, he is a living animal...

Reply to javi2541997 I find your views on the matter are relevant but ... (deliberately?) misses the point.

Reply to Agent Smith what am I missing then? If you can explain me, I would be so much appreciated.

Quoting javi2541997

what am I missing then? If you can explain me, I would be so much appreciated

You're exploring a vital aspect of the issue, but I would rather not go down that road. I'm bad at it and your precious time, mon ami, your ever so precious time.

Quoting jgill

What are the "real" attributes of space?

I wouldn't know the answer to that question, nor would anyone else, I believe. The point though is that we can represent space in two fundamentally different ways, as being a real thing with real properties (though unknown), or as completely abstract, being a conceptual tool to help us understand the existence of things. In the former, we are constrained by a desire to know the real properties of space, and produce models accordingly. In the latter, we are constrained only by arbitrary principles, pragmaticism, according to what serves the specific purpose. This is the basic difference between absolutism and relativity. Absolutism dictates that there is an absolute truth to the way that motions are modeled, while relativity dictates that differing models of motion are equal.

So, in the case of "the continuum", continuity is a principle based in the Aristotelian conception of "matter". Matter is how Aristotle accounts for the continuity of sameness as time passes, consistency in existence. Continuity is a temporal concept. So Newton gave matter a principal property, "mass", and mass is proposed as the means by which temporal continuity is maintained, the first law, inertia. That is supposed to represent a "truth" about time, the continuity of mass, as inertia. But geometric representations of space, perfect squares, perfect circles, perfect triangles, the number of degrees in a circle, the number of spatial dimensions, etc., derived as mathematical axioms, are not supposed to be "truths". They are abstractions created for practise, and mostly derived from practise, containing the arbitrariness which pragmatism relies on.

Special relativity takes the arbitrariness of spatial abstractions, and assigns it to our conception of time. Under this conceptual structure there is nothing real, no "truth", to ground the continuity of time. Continuity is now based in spatial conceptions, and the true basis for the conception of continuity, time, is left as obsolete. Since the conception of "space" has no real continuity, being arbitrary because of its base in pure abstraction, and "time" has been subsumed under "space", we are left with no principles for a real or true "continuum". Our lived experience of temporal continuity, and the only access we have toward an understanding of "true" continuity, is made no longer relevant, by denying its bearing on our concept of "time". The "continuum" now is just another arbitrary spatial concept, guided by pragmatism, and our real experience of continuity which is the continued existence of material objects as time passes, is not allowed to have any bearing on this conception of "the continuum". So our conceptions of mass must be manipulated to be consistent with the arbitrary conception of "the continuum", instead of altering the conception of "the continuum" to be consistent with our true observations of mass.

Reply to Metaphysician Undercover

Your replies are always entertaining, and frequently thought provoking. Continuous mappings, in the context of QM, can mean the topological definition applied to the Hilbert spaces of that subject. Inner products yield norms which give rise to metrics, within which continuity is defined. It's a long way from Aristotle.

I still think much of what is discussed in this forum concerning QM boils down to the problem of unitarity.

Quoting Andrew M

I can still express the length ?2 with two characters, a very finite state. Humans deal only with such representable numbers, and they’re countable.— noAxioms
Yes, computable numbers.

OK, maybe, but it’s a very different definition. Is there an example of something that isn’t in this set? Maybe my prior example of the half life of carbon 14. I called it a representable number, and I suppose that if you can represent it, you can compute it as per your definition, and if you can’t compute it, you also cannot represent it, except I think I just did in my example.
[quote=noAxioms]Do we know that "the ratio of the half lives of two specific isotopes" isn't representable?[/quote]I think I just represented it with such words, so I’ll answer my own question.
Quoting Andrew M

That question seems relevant to the physical Church-Turing thesis (Church-Turing-Deutsch principle) which says that any bounded physical system can be simulated by a Turing machine to any desired precision.

Does the statement above apply to non-classical physical systems? Can it simulate say a quantum computer to arbitrary precision? Another interesting note about the above statement is that a Turing machine cannot simulate itself, which is not a violation of the statement.


Quoting Andrew M

A related test has been carried out at a microscopic level (using photons instead of AI's) where it was shown that physical collapse does not occur.

OK, I said I’d get back on this one. I admittedly get lost in the complex examples, but I did at least want to comment on some of the assumptions the paper is making, assumptions which are very interpretation dependent. The topic here is about how MWI would handle it.
So commenting on specific things in the paper: https://arxiv.org/pdf/1902.05080.pdf

Quoting Agent Smith

Does the observer have to be conscious or are there non-living "observers"?

A.Smith, this is also relevant to your question. No, no experiment has demonstrated a living thing to have a special role.

The authors are Proietti, Pickston, Graffitti, Barrow, Kundys, Braniciard, Ringbauer, and Fedrizzi, so I’m going to refer to them as PPGBKBRF.
First of all, they put these little grey figures all over their diagrams, the observers. It makes it look like human interaction is somehow a critical step in a measurement, but no, near top of page 3 they define what these little guys are presumed to be:
[quote=PPGBKBRF]let us first clarify our notion of an observer. Formally, an observation is the act of extracting and storing information about an observed system. Accordingly, we define an observer as any physical system that can extract information from another system by means of some interaction, and store that information in a physical memory.[/quote]An observer is apparently a clerk, reacting to a measurement and putting into some non-volatile state. A digital camera for instance has a CCD (the measurement device) and an SD card (the persistent state) and a bit of circuitry (the observer) to move the data from the CCD to the SD card. This is nothing particularly special, but they give it a very special role in the paper:
[quote=PPGBKBRF]The observer’s role as final arbiter of universal facts [1] was imperilled by the advent of 20th century science.
…
in quantum theory, all physical processes are continuous and deterministic, except for observations, which are proclaimed to be instantaneous and probabilistic.[/quote]It seems that they’ve given this clerical role some special metaphysical status, that of arbiter of what is fact or not, and also the only physical process which is probabilistic instead of deterministic. I’m not sure if they’re asserting these things and strawman arguments to knock down or they’re actually pushing this.
They go on to a description of the Wigner’s friend thought experiment where they blatantly violate their own definition:
[quote=PPGBKBRF]According to quantum theory, the friend randomly observes one of the two possible outcomes in every run of the experiment. The friend’s record, h or v, can be stored in one of two possible orthogonal states of some physical memory, labeled either |“photon is h”> or |“photon is v”>, and constitutes a “fact” from the friend’s point of view. [/quote]This is suddenly a relational wording of the situation due to the addition of ‘from the friend’s PoV’. Suddenly the ‘observation’ doesn’t make anything a universal fact at all, as evidenced by Wigner’s measurement:
[quote=PPGBKBRF]Wigner can now perform an interference experiment in an entangled basis containing the states of Eq. (1) to verify that the photon and his friend’s record are indeed in a superposition—a “fact” from his point of view [/quote]
Rightly so. There are no facts, just points of view. The friend is measured to be in superposition of having recorded one fact and of having recorded a different fact, pretty much demonstrating a lack of universal facts. Establishment of those universal facts were the only apparent role of these observers, so with that neatly shot down, the observer plays no role at all.
This pretty much answers the topic title here, at least from that article’s description. Facts are relative to a system state, which makes it ‘observer dependent’ if you want to apply the label of ‘observer’ to a specific system state, but I see no point in the special label.



Quoting Metaphysician Undercover

"Uniform existence" is having an unchanging presence, as in not being acted upon by forces; what is described by Newton's first law, which is commonly referred to as "the law of inertia".

Thank you for the definitions. The article you referenced makes no mention of ‘uniform existence’, ‘unchanging presence’ so it helps to define these terms up front if you’re going to use them.

Check the Stanford article I previously referenced:
“an inertial frame is a reference-frame with a time-scale, relative to which the motion of a body not subject to forces is always rectilinear and uniform, accelerations are always proportional to and in the direction of applied forces, and applied forces are always met with equal and opposite reactions.”

A good definition, and it comes from the top of the article, not section 1.7 to which you linked. That section deals with pre-20th-century handling of what is now called accelerated reference frames. It even includes an early form of the equivalence principle as worded by Newton.

Quoting noAxioms

I can still express the length ?2 with two characters, a very finite state. Humans deal only with such representable numbers, and they’re countable.— noAxioms
Yes, computable numbers.
— Andrew M

OK, maybe, but it’s a very different definition. Is there an example of something that isn’t in this set?

Yes, one can use diagonalization to produce a number that isn't in the set. Another example is the probability that a randomly constructed computer program will halt (Chaitin's constant).

Quoting noAxioms

"That question seems relevant to the physical Church-Turing thesis (Church-Turing-Deutsch principle) which says that any bounded physical system can be simulated by a Turing machine to any desired precision."
— Andrew M

Does the statement above apply to non-classical physical systems? Can it simulate say a quantum computer to arbitrary precision?

Yes and yes (since a quantum computer is itself a physical system).

Quoting noAxioms

Another interesting note about the above statement is that a Turing machine cannot simulate itself, which is not a violation of the statement.

A universal Turing Machine can simulate itself by accepting, as input, a description of itself and running it. See Turing completeness.

Quoting noAxioms

OK, I said I’d get back on this one. I admittedly get lost in the complex examples, but I did at least want to comment on some of the assumptions the paper is making, assumptions which are very interpretation dependent. The topic here is about how MWI would handle it.

That's an easy one. The experiment matches the predictions of standard quantum mechanics, and thus also the predictions of MWI. So it doesn't challenge MWI on those grounds. But also, on an MWI view, it's disputable whether a measurement actually took place since no decoherence (and thus no world branching) occurred.

Quoting noAxioms

An observer is apparently a clerk, reacting to a measurement and putting into some non-volatile state. A digital camera for instance has a CCD (the measurement device) and an SD card (the persistent state) and a bit of circuitry (the observer) to move the data from the CCD to the SD card.

Yes, specifically the measurement information is stored in polarization states of the photons marked as ? and ? (per Figure 2). Also the detection of the photons marked as ?' and ?' provide a permanent record that a measurement (per the authors' definition) has occurred, though not what the measurement was.

Quoting noAxioms

This is nothing particularly special, but they give it a very special role in the paper:
The observer’s role as final arbiter of universal facts [1] was imperilled by the advent of 20th century science.
…
in quantum theory, all physical processes are continuous and deterministic, except for observations, which are proclaimed to be instantaneous and probabilistic.
— PPGBKBRF
It seems that they’ve given this clerical role some special metaphysical status, that of arbiter of what is fact or not, and also the only physical process which is probabilistic instead of deterministic. I’m not sure if they’re asserting these things and strawman arguments to knock down or they’re actually pushing this.

The authors have performed an experiment based on a no-go theorem by Brukner:

Quoting Experimental test of local observer-independence - Proietti, et al., 2019

for the no-go theorem we tested here [4] it is sufficient that [the observers] perform a measurement and record the outcome.

The experiment successfully demonstrates the violation of a Bell inequality as predicted by standard quantum mechanics. So, if one accepts the authors' definitions for an observer and measurement, then one of the assumptions of free choice, locality, and observer-independent facts must be false. As they say:

Quoting Experimental test of local observer-independence - Proietti, et al., 2019

Modulo the potential loopholes and accepting the photons’ status as observers, the violation of inequality (2) implies that at least one of the three assumptions of free choice, locality, and observer-independent facts must fail."

One may well reject their definitions for an observer and a measurement. But that is not a fault of their experiment. It just raises the question of what does count as an observer and a measurement, and what would be required to perform the equivalent experiment in that case. Which is why Deutsch's proposal to use an AI on a quantum computer would be an important and compelling experiment.

Quoting noAxioms

Wigner can now perform an interference experiment in an entangled basis containing the states of Eq. (1) to verify that the photon and his friend’s record are indeed in a superposition—a “fact” from his point of view
— PPGBKBRF
Rightly so. There are no facts, just points of view. The friend is measured to be in superposition of having recorded one fact and of having recorded a different fact, pretty much demonstrating a lack of universal facts. Establishment of those universal facts were the only apparent role of these observers, so with that neatly shot down, the observer plays no role at all.
This pretty much answers the topic title here, at least from that article’s description. Facts are relative to a system state, which makes it ‘observer dependent’ if you want to apply the label of ‘observer’ to a specific system state, but I see no point in the special label.

You're rejecting the "observer-independent facts" assumption, which is fine. Others may reject a different assumption or, alternatively, reject the authors' definitions for an observer and measurement.

In my view, the experiment has value because it has confirmed standard quantum mechanics for the simplest definition of an observer (or, at least, a prototype of an observer) in a Wigner's Friend scenario. Now presumably no-one expected it not to. So the next step would be to increase the scale of the physical systems involved in the experiment until it does test interpretations that people actually hold.

Reply to noAxioms
That's the exact definition I copied above:
Quoting Metaphysician Undercover

"Uniform existence" is having an unchanging presence, as in not being acted upon by forces; what is described by Newton's first law, which is commonly referred to as "the law of inertia". Check the Stanford article I previously referenced:

The laws of Newtonian dynamics provide a simple definition: an inertial frame is a reference-frame with a time-scale, relative to which the motion of a body not subject to forces is always rectilinear and uniform, accelerations are always proportional to and in the direction of applied forces, and applied forces are always met with equal and opposite reactions.
— https://plato.stanford.edu/entries/spacetime-iframes/#QuasInerFramNewtCoroV\

I think, "uniform existence" and "unchanging presence" are adequate descriptions. Notice that "uniform" is even used in the passage. "Motion" is taken for granted by me, for the reasons I gave already. Under the precept of the relativity principle any existing body is always in motion. "Existence" is how I described a body relative to a time-scale. The problem appears to be that you did not have a very good understanding of what an inertial frame is, so you did not recognize my description as a good one. You were trying to deny the importance of an essential aspect of the inertial frame, the time-scale.

So we have two features of the inertial frame. Firstly, what I called "uniform existence", which is the unchanging presence of a body not being acted upon by forces, and secondly, a time-scale relative to this body.

Would you agree that the inertial frame is just an ideal, and it does not actually represent anything real in the real world of physical, material bodies? In reality, whenever time is passing a body is subject to forces, and there is no body in the universe which is not subjected to forces at every moment of passing time. So the "inertial frame" is really just a convenient fiction, serving as a pragmatic principle to base mathematical calculations around. It really does not serve as a good representation of what is actually going on in the world. The use of "rectilinear" to describe the uniform motion which the inertial frame is based on, is a dead give away for revealing the fictitious nature of the concept. No true motion is really rectilinear, but this assumption supports the use of vectors (discussed above with jgill), in that fictitious misrepresentation of motion.

Rather a good series of 10 essays by Marcelo Gleiser on The Big Think about quantum physics and philosophy. Well-informed and level-headed.

https://bigthink.com/people/marcelo-gleiser/

So, coming back to this thread after many days away, Sean Carol has stated a solution to the Boltzmann Brain problem is that there won't be any observers in De Sitter space to cause decoherence under the MWI. Boltzmann Brains are thought to be the results of quantum fluctuations over an infinite amount of time after the heat death of he universe, but the wave function is deterministic, so as long as there are no decoherent branches, there's no sense of fluctuation.

It's still weird to me that the observer is a necessary component of making sense of MWI, since decohered branches are still in universal superposition, which is what infinite De sitter space will become, except without the decohered observers.

Quoting Marchesk

It's still weird to me that the observer is a necessary component of making sense of MWI, since decohered branches are still in universal superposition, which is what infinite De sitter space will become, except without the decohered observers.

Carroll defines what he means by "observation" and "observer" in comments here:

Quoting Squelching Boltzmann Brains (And Maybe Eternal Inflation) - Sean Carroll

... It has nothing to do with consciousness or intelligence (of course). An “observation” in quantum mechanics happens whenever any out-of-equilibrium macroscopic system becomes entangled with the quantum system being measured. It will then decohere (become entangled with the wider environment), which causes a splitting of the wave function into separate branches.

It’s key that the macroscopic device in question starts out far from equilibrium. Otherwise it would already be entangled with everything, and the measurement/splitting process couldn’t occur.

...

The informal notion of an “observer” requires a macroscopic system that is out of equilibrium. In de Sitter space, everything is in equilibrium.

In the main post he says:

Quoting Squelching Boltzmann Brains (And Maybe Eternal Inflation) - Sean Carroll

The standard story says that the inflaton field undergoes quantum fluctuations, which then get imprinted as fluctuations in density. What we’re saying is that the inflaton doesn’t actually “fluctuate,” it’s just in some calculable quantum state. But there’s nothing “observing” it, causing decoherence and branching of the wave function. At least, not while inflation is going on. But when inflation ends, the universe reheats into a hot plasma of matter and radiation. That actually does lead to decoherence and branching — the microscopic states of the plasma provide an environment that becomes entangled with the large-scale fluctuations of the inflaton, effectively measuring it and collapsing the wave function. So in our picture, all of the textbook predictions for inflation perturbations remain unchanged.

So in this case, the observer is the hot plasma of matter and radiation.

Quoting Squelching Boltzmann Brains (And Maybe Eternal Inflation) - Sean Carroll

It has nothing to do with consciousness or intelligence (of course). An “observation” in quantum mechanics happens whenever any out-of-equilibrium macroscopic system becomes entangled with the quantum system being measured

That is an a priori assertion, but which really could only ever be validated by observation.

Quoting Wayfarer

It has nothing to do with consciousness or intelligence (of course). An “observation” in quantum mechanics happens whenever any out-of-equilibrium macroscopic system becomes entangled with the quantum system being measured
— Squelching Boltzmann Brains (And Maybe Eternal Inflation) - Sean Carroll

That is an a priori assertion, but which really could only ever be validated by observation.

Touché!

As John Bell inquired, "Was the wave function waiting to jump for thousands of millions of years until a single-celled living creature appeared? Or did it have to wait a little longer for some highly qualified measurer—with a PhD?"

Quoting Andrew M

"Was the wave function waiting to jump for thousands of millions of years until a single-celled living creature appeared? Or did it have to wait a little longer for some highly qualified measurer—with a PhD?"

I have often addressed that question. Again it's a question of philosophy not physics. For practical purposes you can assume the world has been there all along, just as is. But that is a methodological assumption, not a metaphysical postuate. That is what I think Sean Carroll doesn't see.

Ever seen the Andrei Linde interview on Closer To Truth? He talks explicitly about the role of the observer.

Quoting Andrew M

OK, maybe, but it’s a very different definition. Is there an example of something that isn’t [a computable number]?
— noAxioms

Yes, one can use diagonalization to produce a number that isn't in the set. Another example is the probability that a randomly constructed computer program will halt (Chaitin's constant).

Both qualify as a computable number. The diagonalization method used with an ordered list of all rational numbers nicely produces a number that isn’t rational, but is very much computable by the definition on the site you linked. All one has to do to get n bits of precision is to list the first rational numbers and take a bit from each, a very finite task.
As for Chaitin’s constant, there is this from the site:
“Each Chaitin constant ? has the following properties:
• It is algorithmically random (also known as Martin-Löf random or 1-random). This means that the shortest program to output the first n bits of ? must be of size at least n ? O(1).“

The existence of an algorithm to output the first n bits seems make it a computable number since they say what it takes to compute it to some arbitrary finite precision. I say that, but then I linked over to a page on normal numbers and it says this: “For example, Chaitin’s constant is normal (and uncomputable).“ which means I’m reading that listed property above wrong. I think I’m missing the ‘at least’ part.

A universal Turing Machine can simulate itself by accepting, as input, a description of itself and running it. See Turing completeness.

The page seems to assume infinite memory and infinite machines states. The more memory you need to access, the more states you need, and a machine emulating something needs more memory/states than the thing being emulated. The page seems to assume for instance a generic language where say pointers are not of finite size. But I’ll accept the definitions used on the page and withdraw my statement.


Concerning the paper on the Wigner friend thing:

The experiment matches the predictions of standard quantum mechanics, and thus also the predictions of MWI.

I agree with that, but I wasn’t talking about predictions. I was talking about language describing things other than the results.

So it doesn't challenge MWI on those grounds. But also, on an MWI view, it's disputable whether a measurement actually took place since no decoherence (and thus no world branching) occurred.

Another reason why I don’t like the suggestion of actual metaphysical branching of worlds. Everett never suggested it, but DeWitt added that, coining the term ‘MWI’ in the process. I prefer Rovelli’s take on it where there is no ‘actual’ about any of the measurements, and observation serves only an epistemological purpose.

So, if one accepts the authors' definitions for an observer and measurement, then one of the assumptions of free choice, locality, and observer-independent facts must be false.

That just sounds like Bell’s theorem (old news). What in 2019 was added to that?

Which is why Deutsch's proposal to use an AI on a quantum computer would be an important and compelling experiment.

Sorry, but I don’t see what the AI adds that any simple device (like the circuit on the camera) doesn’t.

You're rejecting the "observer-independent facts" assumption, which is fine.

If I have to drop something, that one seems far preferrable to the others. I don’t reject it since it cannot be disproved.

Bottom line is that I haven’t understood the proposal enough to clarify how the different interpretations make different predictions for some experiment, hence offering a falsification test for a subset of them. Supposedly this might have already been done for counterfactuals, which would then be a very good reason to reject observer independent facts.

I like Carroll’s definition of observer, appropriate for something like MWI.
Quoting Andrew M

As John Bell inquired, "Was the wave function waiting to jump for thousands of millions of years until a single-celled living creature appeared? Or did it have to wait a little longer for some highly qualified measurer—with a PhD?"

This does not seem to reference that definition, but more of the dictionary definition of observer.



Quoting Metaphysician Undercover

Under the precept of the relativity principle any existing body is always in motion.

That sounds like an absolutist statement, which sort of violates PoR. PoR might be used to say that any body is in motion relative to certain frames. Without the frame reference, motion is undefined.

Would you agree that the inertial frame is just an ideal, and it does not actually represent anything real in the real world of physical, material bodies?

I’ve called it an abstraction, specifically an abstract assignment of coordinates to events. That’s true of any frame, inertial or not. So yes, an ideal as you call it.

there is no body in the universe which is not subjected to forces at every moment of passing time.

I’d have said ‘every moment of time’. I don’t see what the word ‘passing’ adds to that. That almost every body is subjected to nonzero net forces at any moment means that nothing exhibits inertial motion, but plenty of them exhibit good approximations of it to where the mathematics is very useful indeed.

Quoting noAxioms

That sounds like an absolutist statement, which sort of violates PoR. PoR might be used to say that any body is in motion relative to certain frames. Without the frame reference, motion is undefined.

It is not an absolutist statement, it is a deductive conclusion derived from two premises, the PoR, along with an inductive conclusion derived from empirical observation. It is observed that as time passes, there are always things moving. Along with the PoR we can conclude deductively that any existing body is always in motion.

You are reversing logical priority here. The concept "frame of reference" is derived from the principle of relativity, not vise versa. So motion was defined first, as relative (PoR), and then the concept "frame of reference" was developed as the means for measurement. The PoR discusses the motions of bodies relative to each other, and there is no need for a concept of frame of reference in this discussion.

Only when the intent is to put numbers to the motion, measure it, is the reference frame needed, due to what the PoR assumes. So the PoR gives one of the basic rules for constructing the frame. Also, we need a rule concerning the conceptions of space and time to be employed in the measurement. Newton employed a fixed, static backdrop of space, from which a coordinate system could be applied, along with an "absolute" time. Time is absolute in the sense of constant and continuous. Einstein proposed an alternative conception of space and time.

As per above, the conceptions of space and time are essential aspects of the conception of frame of reference. Also, Einstein used substantially different conceptions of space and time, from Newton. Therefore we can conclude that the substantially different conceptions of space and time employed by Einstein result in a substantially different form of "frame of reference".

Quoting noAxioms

I’d have said ‘every moment of time’. I don’t see what the word ‘passing’ adds to that.

There's a big difference in conception of "time" here, which we can apprehend through analysis. Some would posit "the present moment" as a moment which clearly and concisely separates the past time from the future time. No time passes at "the moment" in this conception because it is a precise, non-dimensional, division, similar to the way that a non-dimensional point divides two line segments. The past, along with the future, provide a complete representation of time, and the moment is an arbitrary (yet substantialized, and justified by "the present)") point in time. The abstracted point, removed from the assumed real point at the present, may be projected anywhere in time, to produce specific durations, like specific line segments.

So when I said "every moment of passing time", I implied that within any "moment" there is inherently some duration of time. This denies the reality of the abstracted "point", implying that instead of being a non-dimensional point, like a point which divides one line into two line segments, it is an infinitesimal point, such that there is some time within that point. Now there is not a clear and precise division between the two time segments past and future, as some time passes within the present moment. And since "the moment" is the dividing point by which time is measured, the time which inheres within the moment under this conception, evades measurement. It escapes from being measured. The measured durations are the line segments, yet some time inheres within the points which provide the boundaries to a segment, so that the boundary is somewhat vague, and this time within the point ends up as an unknown relative to the segments produced when a line is divided.

The first conception of "the moment" discussed above, is consistent with the Newtonian conception. The passage of time is constant and continuous and such consistency provides the basis for the assumption that we can posit points of division anywhere, just like what was done with traditional spatial conceptions. The second conception of "the moment" is consistent with the one employed by Einstein. This is understood as "the relativity of simultaneity". The moment in time which marks "now", as the divisor between past and present is not a clear and precise, non-dimensional point. Each frame of reference is allowed to have an independent and separate point which divides the two line segments, past from future. Within the frame of reference, the point is still supposed to provide a clear and precise non-dimensional divisor, but the vague boundary occurs when different frames, the basis from which measurements are made, are related to each other.

Under the Newtonian proposal, there is supposed to be an absolute divisor, "the present", which is substantiated or justified by human experience. This grounds all measurements of time as being consistent with each other, based in the experienced "present". Einstein removes this, saying that "the present" is relative to the frame of reference, rather than the human experience of a division between past and future. As a result, we have no basic principle to resolve any discrepancies in measurement which manifest as the result of the positioning of the divisor, the point which measured time segments are relative to, as measurements are made as time passes at the present. Resolutions would be arbitrary.

Simply put, Einstein recognized that human experience cannot provide a clear and precise non-dimensional division between one time period and the next, and he exploited this fact to employ the principle that there is no precise division between future and past. Consequently the Einsteinian observation perspective is based in this assumption, and all observations recorded from this perspective will demonstrate this feature, as conclusions reflect premises.

Quoting noAxioms

Both qualify as a computable number. The diagonalization method used...

The computable numbers are countable since they be put in a one-to-one correspondence with the natural numbers. However the real numbers are not countable per Cantor's diagonalization proof. Thus there are some real numbers that are not computable.

Quoting noAxioms

"So, if one accepts the authors' definitions for an observer and measurement, then one of the assumptions of free choice, locality, and observer-independent facts must be false."

That just sounds like Bell’s theorem (old news). What in 2019 was added to that?

The addition is that the experiment tests a Bell inequality for a Wigner's friend scenario (which the paper terms a Bell-Wigner test).

Specifically, there are two types of measurement that each Wigner (i.e., Alice and Bob) can perform. Alice can measure with her beam splitter removed (A[sub]0[/sub]) or present (A[sub]1[/sub]). Bob can similarly measure with his beam splitter removed (B[sub]0[/sub]) or present (B[sub]1[/sub]). When the beam splitter is removed, the Wigner measurement is the same as their friend's measurement. When the beam splitter is present, the Wigner measurement is in the {|+>,|->} basis.

So one of the A[sub]0[/sub] or A[sub]1[/sub] measurements and one of the B[sub]0[/sub] or B[sub]1[/sub] measurements are performed on each run of the experiment. Over multiple runs the measurements, on a classical explanation, must obey the CHSH inequality

[math]S = \langle A_1B_1 \rangle + \langle A_1B_0 \rangle + \langle A_0B_1 \rangle - \langle A_0B_0 \rangle <= 2[/math]

where Ax and By are the values -1 or +1, and is the averaged product over multiple runs.

Per the experiment, and as predicted by quantum mechanics, the CHSH inequality is violated.

Quoting noAxioms

Sorry, but I don’t see what the AI adds that any simple device (like the circuit on the camera) doesn’t.

It would be a macroscopic-scale experiment where the AI friends would exhibit human-level intelligence. It would thus be comparable to a human Wigner's friend experiment.

Quoting noAxioms

I like Carroll’s definition of observer, appropriate for something like MWI.

'As John Bell inquired, "Was the wave function waiting to jump for thousands of millions of years until a single-celled living creature appeared? Or did it have to wait a little longer for some highly qualified measurer—with a PhD?"'
— Andrew M

This does not seem to reference that definition, but more of the dictionary definition of observer.

Yes, which was part of Bell's point. It's well worth reading the full context of Bell's comment:

John Bell, Against 'Measurement':It would seem that the theory [quantum mechanics] is exclusively concerned about "results of measurement", and has nothing to say about anything else. What exactly qualifies some physical systems to play the role of "measurer"? Was the wavefunction of the world waiting to jump for thousands of millions of years until a single-celled living creature appeared? Or did it have to wait a little longer, for some better qualified system ... with a Ph.D.? If the theory is to apply to anything but highly idealized laboratory operations, are we not obliged to admit that more or less "measurement-like" processes are going on more or less all the time, more or less everywhere. Do we not have jumping then all the time?

The first charge against "measurement", in the fundamental axioms of quantum mechanics, is that it anchors the shifty split of the world into "system" and "apparatus". A second charge is that the word comes loaded with meaning from everyday life, meaning which is entirely inappropriate in the quantum context. When it is said that something is "measured" it is difficult not to think of the result as referring to some preexisting property of the object in question. This is to disregard Bohr's insistence that in quantum phenomena the apparatus as well as the system is essentially involved. If it were not so, how could we understand, for example, that "measurement" of a component of "angular momentum" ... in an arbitrarily chosen direction ... yields one of a discrete set of values? When one forgets the role of the apparatus, as the word "measurement" makes all too likely, one despairs of ordinary logic ... hence "quantum logic". When one remembers the role of the apparatus, ordinary logic is just fine.

In other contexts, physicists have been able to take words from ordinary language and use them as technical terms with no great harm done. Take for example the "strangeness", "charm", and "beauty" of elementary particle physics. No one is taken in by this "baby talk". ... Would that it were so with "measurement". But in fact the word has had such a damaging effect on the discussion, that I think it should now be banned altogether in quantum mechanics.

Quoting Wayfarer

Ever seen the Andrei Linde interview on Closer To Truth? He talks explicitly about the role of the observer.

Yes, we've discussed Linde's comments a few times before. See John Bell's comment above, where he says:

John Bell, Against 'Measurement':When one remembers the role of the apparatus, ordinary logic is just fine.

One could also say, "When one remembers the role of the observer, ordinary logic is just fine." Which is to say, there is logically no view from nowhere.

The key point for me, whether about observers or measurement apparatus, is that quantum mechanics predicts the result of the interaction between two systems (the observer and observed), not the pre-existing value of an isolated system (which Bell showed to be incoherent).

Quoting Andrew M

Which is to say, there is logically no view from nowhere.

You’ve said that before, and even though I obviously agree, I don’t think it’s as obvious, nor as insignificant, as you make it seem. As you might know, one of Thomas Nagel’s books is called ‘The View from Nowhere’. His point is to critique the widespread understanding that science provides a ‘view from nowhere’, meaning a view that is uncontaminated by anything we deem ‘subjective’, the aim being to arrive at a view which is at once universal and objective. Whereas to me, the lesson of quantum mechanics is that we cannot obtain such a view when it comes to the purported ‘ultimate constituents’ of existence (which is where, after all, such ultimate objectivity should be sought, you would think). The fact that observation has an unavoidably subjective dimension is the very thing that Einstein strenuously objected to - ‘does the moon continue to exist when nobody’s looking at it?’, he asked. He strongly believed that there was a reality that existed just so, independently of any act of observation, and it was science’s job to discern that. Insofar as it had to make concessions to ‘the method of observation’, then quantum mechanics was, to him, obviously incomplete. Wasn’t that the gist of the Einstein-Bohr debates?

Quoting Wayfarer

You’ve said that before, and even though I obviously agree, I don’t think it’s as obvious, nor as insignificant, as you make it seem. As you might know, one of Thomas Nagel’s books is called ‘The View from Nowhere’. His point is to critique the widespread understanding that science provides a ‘view from nowhere’, meaning a view that is uncontaminated by anything we deem ‘subjective’, the aim being to arrive at a view which is at once universal and objective.

I don't think it's either obvious or insignificant. Nagel critiques "the view from nowhere" but he doesn't reject it. He instead proposes an additional subjective dimension (per the usual Cartesian subject-object dichotomy) that just entrenches the error.

Quoting Wayfarer

The fact that observation has an unavoidably subjective dimension is the very thing that Einstein strenuously objected to - ‘does the moon continue to exist when nobody’s looking at it?’, he asked. He strongly believed that there was a reality that existed just so, independently of any act of observation, and it was science’s job to discern that. Insofar as it had to make concessions to ‘the method of observation’, then quantum mechanics was, to him, obviously incomplete. Wasn’t that the gist of the Einstein-Bohr debates?

Sure, but the debates have moved on. There have been subsequent discoveries that would have informed both their views, and have informed ours. For example, Bell's Theorem and decoherence, just to name two.

So there's no question that the moon is there when no-one's looking at it, not least because its effects are ever-present in the environment, such as in the ocean tides. Similarly, there's no question that dinosaurs once existed, even though no-one has ever observed them.

Quoting Andrew M

I don't think it's either obvious or insignificant. Nagel critiques "the view from nowhere" but he doesn't reject it. He instead proposes an additional subjective dimension (per the usual Cartesian subject-object dichotomy) that just entrenches the error.

I don’t agree that Nagel’s diagnosis is erroneous. I think he pinpoints something real and insidious.

And Bell's Theorem did nothing to validate Einstein's realist objections to 'spooky action at a distance'. Bell himself had this to say:

[quote=John Stewart Bell (1928-1990), quoted in Quantum Profiles, by Jeremy Bernstein (Princeton University Press, 1991, p. 84)]The discomfort that I feel is associated with the fact that the observed perfect quantum correlations seem to demand something like the "genetic" hypothesis. For me, it is so reasonable to assume that the photons in those experiments carry with them programs, which have been correlated in advance, telling them how to behave. This is so rational that I think that when Einstein saw that, and the others refused to see it, he was the rational man. The other people, although history has justified them, were burying their heads in the sand. I feel that Einstein's intellectual superiority over Bohr, in this instance, was enormous; a vast gulf between the man who saw clearly what was needed, and the obscurantist. So for me, it is a pity that Einstein's idea doesn't work. The reasonable thing just doesn't work.[/quote]

Quoting Wayfarer

I don’t agree that Nagel’s diagnosis is erroneous. I think he pinpoints something real and insidious.

Yes he does. I'm further saying that the view from nowhere should be rejected in its entirety, not supplemented by a further error (the Cartesian subject).

Quoting Wayfarer

And Bell's Theorem did nothing to validate Einstein's realist objections to 'spooky action at a distance'.

Yes, Bell showed that Einstein's idea didn't work. It doesn't follow that the moon isn't there when no-one looks at it.

Quoting Andrew M

It doesn't follow that the moon isn't there when no-one looks at it.

The moon (where 'moon' symbolises 'any object') does not exist outside your consciousness of it. However, neither does it not exist. The universe/world/moon/whatever is a featureless, undifferentiated and meaningless aggregation of matter-energy which is only differentiated into separate objects, with features and locations - which comes into being - in the mind of the observer.

Quoting Charles Pinter, Mind and the Cosmic Order

Let’s begin with a thought-experiment: Imagine that all life has vanished from the universe, but everything else is undisturbed. Matter is scattered about in space in the same way as it is now, there is sunlight, there are stars, planets and galaxies—but all of it is unseen. There is no human or animal eye to cast a glance at objects, hence nothing is discerned, recognized or even noticed. Objects in the unobserved universe have no shape, color or individual appearance, because shape and appearance are created by minds. Nor do they have features, because features correspond to categories of animal sensation. This is the way the early universe was before the emergence of life—and the way the present universe is outside the view of any observer.

Quoting Wayfarer

The moon (where 'moon' symbolises 'any object') does not exist outside your consciousness of it. However, neither does it not exist. The universe/world/moon/whatever is a featureless, undifferentiated and meaningless aggregation of matter-energy which is only differentiated into separate objects, with features and locations - which comes into being - in the mind of the observer.

One counter to this is that there is differentiation even without consciousness. True that there would be no conscious beings to conceptualize the universe, or out it into words and write about it on a forum. However structure would exist in how some parts of that universe can interact with others. This is the crux of the position that a conscious being is not needed to collapse a wavefunction - any interaction can do it.

Quoting PhilosophyRunner

True that there would be no conscious beings to conceptualize the universe, or out it into words and write about it on a forum.

‘There would be no objects with shape and appearance, because shape and appearance are created by minds’. But that is part of a larger argument. Context is important. From a naturalistic perspective of course it is true that objects exist independently of observation, but here we’re discussing the metaphysical issue suggested by ‘the observer problem’

Quoting Wayfarer

The universe/world/moon/whatever is a featureless, undifferentiated and meaningless aggregation of matter-energy which is only differentiated into separate objects, with features and locations - which comes into being - in the mind of the observer.

That's a more or less imaginable picture, but how do you know, how could you know, it captures the character of reality? How could we make sense of the idea that something utterly undifferentiated and featureless could give rise to the vast and complex universe we observe?

Quoting Squelching Boltzmann Brains (And Maybe Eternal Inflation) - Sean Carroll

But when inflation ends, the universe reheats into a hot plasma of matter and radiation. That actually does lead to decoherence and branching

That's informative and interesting. So once inflation ends, the multiverse begins, until De Sitter space, when there's nothing left to decohere and make observations. Then all is just superposition.

That sounds mostly reasonable, but the branching part based on something making observations still bothers me a bit. What is the branching mechanism? Perhaps I should have started with that question instead.

Quoting Janus

How could we make sense of the idea that something utterly undifferentiated and featureless could give rise to the vast and complex universe we observe?

Isn't that what we're all doing here? What I mean is, isn’t this one of the fundamental questions of philosophy? This is an approach that I think credibly addresses that question.

Quoting Marchesk

That sounds mostly reasonable

Pardon me for so saying, but you must have a very liberal definition of ‘reasonable’ ;-)

Quoting Marchesk

So once inflation ends, the multiverse begins, until De Sitter space, when there's nothing left to decohere and make observations. Then all is just superposition.

Physicists have coined words and expressions as conveniences as they work through the math, and we in the lay community have adopted them as if they really mean something. "Superposition" gets way overused, and frequently in a kind of mystical fashion. "Curved space" is right up there, too.

Once these words and expressions get into common usage philosophers begin using them as they explore metaphysical realms. It's quite a game. :chin:

Reply to Wayfarer Assuming that reality is non-dual I don't undertsand that to mean it is either one or many, which would entail that it is neither differentiated nor undifferentiated and that those dualistic categories do not apply.

Reply to Wayfarer Reasonable as in making sense within the MWI interpretation. MWI needs to be self-consistent and not have to introduce anything from outside the wave-function to make things works. So as long as observers and observation can be understand as parts of the universal wave-function, it's reasonable. I still have questions, though.

Reply to jgill That would be an anti-realist interpretation. Sean Carol is a realist about the wave-function, so he thinks there literally is a multiverse, at least from after inflation until heat death of the universe.

Quoting Wayfarer

‘There would be no objects with shape and appearance, because shape and appearance are created by minds’. But that is part of a larger argument. Context is important. From a naturalistic perspective of course it is true that objects exist independently of observation, but here we’re discussing the metaphysical issue suggested by ‘the observer problem’

My reply was very much to do with the context being discussed here.

In the context of the role of observers in the MWI, and the role of observers in quantum mechanics generally, there is no requirement for that observer to be a mind or have consciousness, or to be able to distinguish shapes or colors. The observer simply needs to be able to interact - something rocks, gasses, and moons can do. In the context of this discussion, even if all life in the universe was extinguished, the parts of the universe will continue to interact with other parts, and the lack of consciousness will make little difference.

That at least is the counter position to your previous argument.

Quoting Andrew M

The computable numbers are countable since they be put in a one-to-one correspondence with the natural numbers.

Not to disagree, but an assertion like that requires a demonstration that they’re countable.

However the real numbers are not countable per Cantor's diagonalization proof. Thus there are some real numbers that are not computable.

Interestingly, the real number generated by Cantor's diagonalization proof is a computable number, so I’m not sure if this counts as evidence that there are some real numbers not computable. Once again, not disagreeing with the conclusion, only with how it was reached.

That just sounds like Bell’s theorem (old news). What in 2019 was added to that?
— noAxioms
The addition is that the experiment tests a Bell inequality for a Wigner's friend scenario (which the paper terms a Bell-Wigner test).

OK, they managed to test something whose outcome (the CHSH inequality violation) was already predicted by quantum theory. It’s a new test, but not one that changed the theory or any of its interpretations in any way.
Thanks for the larger context Bell statement. I agree with it fully. What is ‘jumping’ in that quote? “Do we not have jumping then all the time?”.
Meanwhile, I still don’t see what the AI in the box will do. Bell’s statement is pretty clear that a real human in there wouldn’t serve any special role or purpose, so why would an AI be any different?



Quoting Metaphysician Undercover

You are reversing logical priority here. The concept "frame of reference" is derived from the principle of relativity, not vise versa.

Not sure where you get this idea. PoR is defined in a few places
[quote=wiki]In physics, the principle of relativity is the requirement that the equations describing the laws of physics have the same form in all admissible frames of reference.[/quote]
And from the special relativity paper itself:
[quote=Einstein,1905] They suggest rather that, as has already been shown to the first order of small quantities, the same laws of electrodynamics and optics will be valid for all frames of reference for which the equations of mechanics hold good. We will raise this conjecture (the purport of which will hereafter be called the “Principle of Relativity”) to the status of a postulate
…
1. The laws by which the states of physical systems undergo change are not
affected, whether these changes of state be referred to the one or the other of
two systems of co-ordinates in uniform translatory motion[/quote]
Each one of these definitions of the principle of relativity references ‘frames of reference’ or ‘systems of coordinates’. I would go so far as to say that the PoR is derived from frames of reference, but it certainly is defined using the concept. Thus the reference frame precedes the principle, else the definitions above would all be meaningless.
The definition of motion being relative to a reference makes no reference to the principle of relativity.

So when I said "every moment of passing time", I implied that within any "moment" there is inherently some duration of time.

That’s like asserting that a mathematical point or a location in space must have a size. Your choice I suppose. It seems to just complicate what is otherwise a simple thing.
Your presentist opinions are well known. They’re valid (there are alternatives to Einstein’s theories that deny both his SR premises), but they’re fringe alternatives. Your inability to demonstrate an understanding of the mainstream view seems baffling for somebody with in-depth interest in the subject.

Quoting Marchesk

Sean Carol is a realist about the wave-function

In quantum physics, a wave function is a mathematical description of the quantum state of an isolated quantum system. The wave function is a complex-valued probability amplitude, and the probabilities for the possible results of measurements made on the system can be derived from it.

Wikipedia

I can't see how this (a wave function) could be construed to be a physical reality, but some do. Perhaps my short-comings. :roll:

Quoting jgill

Perhaps my short-comings.

Not yours. Theirs. :rage:

Quoting PhilosophyRunner

The observer simply needs to be able to interact - something rocks, gasses, and moons can do. In the context of this discussion, even if all life in the universe was extinguished, the parts of the universe will continue to interact with other parts, and the lack of consciousness will make little difference.

You do notice the "realist" assumption lying behind this, when that is precisely what is at issue. In other words, it begs the question.

Quoting Wayfarer

You do notice the "realist" assumption lying behind this, when that is precisely what is at issue. In other words, it begs the question.

Absolutely, I made assumptions. But it no more begs the question than an idealist position or any other position on this issue, including the one you were arguing for.

However I want to add something. Realism in quantum mechanics does not always mean the same thing as in philosophy. We know almost for certain that local realism is not true. What is meant by realism here? It refers to there existing objects with certain defined properties separate to interacting with them - this does not seem to be true. But it is not at all clear that interaction requires consciousness, however too often I see people making that jump as if it were required and necessary based on quantum mechanics.

Reply to PhilosophyRunner But the realist attitude begs the question, insofar as the question is ‘does the object exist in the absence of any observer’? Whereas, the existence of objects for the observer is not in question. As idealist philosophers, such as Bernardo Kastrup, will argue, the fact of the experience of an objective domain is never at issue. What is at issue is the question as to whether that domain is really mind-independent. As Descartes said, we can doubt the veracity of any experience, but we can’t doubt that we are subjects of experience. And we can say that without begging any question whatever.

As far as local realism is concerned, that issue arises from the theoretical postulate of entanglement and its subsequent experimental validation, doesn’t it? Of course, much ink has been spilled on the implications of that, but I think it can be safely stated that it appears to violate the realist assumption that the world comprises objects separated by distance in space. We already discussed the QBist interpretation above, which others here don’t favour. But I want to try and home in on what, exactly, is at issue. The necessity of acknowledging the existence of the observer, who is outside the equation, so to speak, is telling us something about the nature of reality. And what it is telling us, is not necessarily something amenable to scientific analysis. I myself am accustomed to the ‘constructivist’ approach - that the reality which we naively take for granted as simply something given, something external and separate from us, is in some fundamental sense constructed by the mind - your mind, my mind.

From a naturalistic point of view, this is not considered - naturalism tends to assume the ‘reality of appearance’ so to speak. And as the mind is something that cannot be made subject to objective analysis, in that it’s not an object of perception, then its sits uneasily with the naturalist or objectivist framework. But that is what physics has called into question. Some interpretations can deal with that but others cannot. That is why I think there *is* a ‘many-worlds’ interpretation - specifically to avoid acknowledging the fact that reality itself, being itself, has a fundamentally subjective pole, which is intrinsic to it, but which is never disclosed directly through objective analysis. That’s the point at issue, as I see it.

Quoting noAxioms

Not sure where you get this idea. PoR is defined in a few places
In physics, the principle of relativity is the requirement that the equations describing the laws of physics have the same form in all admissible frames of reference.

Try this:

[quote=https://www.tau.ac.il/education/muse/museum/galileo/principle_relativity.html#:~:text=The%20principle%20of%20relativity%20states,moving%20and%20which%20is%20immobile.]Galileo formulated the principle of relativity in order to show that one cannot determine whether the earth revolves about the sun or the sun revolves about the earth. The principle of relativity states that there is no physical way to differentiate between a body moving at a constant speed and an immobile body. It is of course possible to determine that one body is moving relative to the other, but it is impossible to determine which of them is moving and which is immobile.[/quote]

Sorry noAxioms, but we're just too far apart in terminology to carry on any meaningful discussion. I spend all my time just having to show you that you don't know what you're talking about. First we spent forever on the meaning of "inertial frame", now we're stuck on the meaning of "the principle of relativity". It's pointless, we can't discuss anything significant.

Quoting Wayfarer

ut the realist attitude begs the question, insofar as the question is ‘does the object exist in the absence of any observer’? Whereas, the existence of objects for the observer is not in question. As idealist philosophers, such as Bernardo Kastrup, will argue, the fact of the experience of an objective domain is never at issue. What is at issue is the question as to whether that domain is really mind-independent. As Descartes said, we can doubt the veracity of any experience, but we can’t doubt that we are subjects of experience. And we can say that without begging any question whatever.

You are quite right that the existence of objects for the observer is not in question. But the original post I replied to a few days ago was going beyond that. It was suggesting that the objects do not exist if the observer is not observing. That is begging the question in that it is assuming that realism is wrong.

So saying that objects do not exist when you do not look at them, is begging the question just as much as saying that objects do exist when you do not look at them.

Quoting Wayfarer

The necessity of acknowledging the existence of the observer, who is outside the equation, so to speak, is telling us something about the nature of reality.

Yes
Quoting Wayfarer

And what it is telling us, is not necessarily something amenable to scientific analysis.

I am undecided on this. What it is telling me is that it is a fiendishly complicated issue at hand and I am not sure I have the correct tools to interrogate the problem. There are suggestions on how this may be interrogate using science, with quantum computers for example - I believe there is a post in this thread about the very thing. However I have not yet been able to wrap my head around this proposed experiment.

Quoting Wayfarer

I myself am accustomed to the ‘constructivist’ approach - that the reality which we naively take for granted as simply something given, something external and separate from us, is in some fundamental sense constructed by the mind - your mind, my mind.

I am not of this approach, partly because every time I explore it I find that the logical end to this approach is solipsism. The way i interact with you is no different to the way I interact with other physical objects. Thus without some form of realism, I have no reason to believe that the photons leaving my laptop screen in your posts, have anything to do with another consciousness. If I question whether the photons are real, then I should question whether wayfarer is real in the same way. It is only my consciousness that I inhabit differently, and so the natural conclusion down this path would be that I only exist. But I reject this. Perhaps this is a discussion for a different thread though.

Perhaps, just a wild guess, (the) mathematics (of quantum physics) is infected by (the) philosophy (of consciousness). :chin:

Quoting PhilosophyRunner

And what it is telling us, is not necessarily something amenable to scientific analysis.
— Wayfarer
I am undecided on this. What it is telling me is that it is a fiendishly complicated issue at hand

It's not that it's complicated, but that scientific analysis generally takes place on a different level - that of the scientific analysis of objects, forces and energy. The question of the role of the observer is not complicated in that sense, but it's also not an objective question. That's why it evades scientific analysis - not that it's complicated or remote, but that it's 'too near for us to grasp'.

Quoting PhilosophyRunner

The way i interact with you is no different to the way I interact with other physical objects.

When you interact with others on the forum, you are not interacting with physical objects, but with subjects and their ideas. It is vastly different to how you interact with physical objects.

Quoting PhilosophyRunner

So saying that objects do not exist when you do not look at them, is begging the question just as much as saying that objects do exist when you do not look at them.

The way I put it is that both existence and non-existence are mind-dependent. It's not as if the object literally ceases to exist apart from the mind, but that the sense in which it exists is inherently meaningless. I know it's a very tricky point to grasp. From the interview with Chris Fuchs about QBism:

It’s so ingrained in us to think about the world without thinking of ourselves in it. It reminds me of Einstein questioning space and time — these features of the world that seemed so absolute that no one even thought to question them.

It’s said that in earlier civilizations, people didn’t quite know how to distinguish between objective and subjective. But once the idea of separating the two gained a toehold, we were told that we have to do this, and that science is about the objective. And now that it’s done, it’s hard to turn back. I think the biggest fear people have of QBism is precisely this: that it’s anthropocentric. The feeling is, we got over that with Copernicus, and this has got to be a step backwards. But I think if we really want a universe that’s rife with possibility with no ultimate limits on it, this is exactly where you’ve got to go.

How does QBism get you around those limits?

One way to look at it is that the laws of physics aren’t about the stuff “out there.” Rather, they are our best expressions, our most inclusive statements, of what our own limitations are. When we say the speed of light is the ultimate speed limit, we’re saying that we can’t go beyond the speed of light. But just as our brains have gotten bigger through Darwinian evolution, one can imagine that eventually we’ll have evolved to a stage where we can take advantage of things that we can’t now. We might call those things “changes in the laws of physics.” Usually we think of the universe as this rigid thing that can’t be changed. Instead, methodologically we should assume just the opposite: that the universe is before us so that we can shape it, that it can be changed, and that it will push back on us. We’ll understand our limits by noticing how much it pushes back on us.

Quoting Wayfarer

It's not that it's complicated, but that scientific analysis generally takes place on a different level - that of the scientific analysis of objects, forces and energy. The question of the role of the observer is not complicated in that sense, but it's also not an objective question. That's why it evades scientific analysis - not that it's complicated or remote, but that it's 'too near for us to grasp'.

The role of the observer in the quantum mechanical sense is complicated. What you are doing is simplifying the question by making some assumptions about what an observer can be. To use your previous reply to me, it is begging the question, as those assumptions are not necessary.

Quoting Wayfarer

When you interact with others on the forum, you are not interacting with physical objects, but with subjects and their ideas. It is vastly different to how you interact with physical objects.

First of all I am interacting with light from my computer screen, I am also interacting with the plastic keyboard. Ideas are not flowing directly from your mind to mine. I cannot directly tap into your consciousness. The last bit is not a realist position on my part - I cannot inhabit your consciousness the way I do mine regardless.

However I am assuming that there the ideas in the post by wayfarer come from a conscious being. But there is no good reason for me to assume this if I question whether the screen before me is real, and the light coming from it is real. It seems to me that wayfarer is also not real, just a projection of my consciousness - my consciousness is the only one that I experience specially.

Quoting Marchesk

That sounds mostly reasonable, but the branching part based on something making observations still bothers me a bit. What is the branching mechanism? Perhaps I should have started with that question instead.

Per MWI, branching is the process of a system becoming entangled with the environment (of which the observer or measuring apparatus is a part) such that interference between the different parts of the wave function no longer occurs, i.e., decoherence. That process is, for all practical purposes, irreversible. Whereas the entanglement between two microscopic systems is reversible.

To give a classical analogy, suppose you knocked over an empty glass that you quickly stood up again. The action was reversible. But suppose the glass falls on the floor and shatters into a thousand pieces. For all practical purposes, that's an irreversible action.

Scott Aaronson has a good lecture on this:

Quoting Decoherence and Hidden Variables - Scott Aaronson

To see an interference pattern, you'd have to perform a joint measurement on the two qubits together. But what if the second qubit was a stray photon, which happened to pass through your experiment on its way to the Andromeda galaxy? Indeed, when you consider all the junk that might be entangling itself with your delicate experiment -- air molecules, cosmic rays, geothermal radiation ... well, whatever, I'm not an experimentalist -- it's as if the entire rest of the universe is constantly trying to "measure" your quantum state, and thereby force it to become classical! Sure, even if your quantum state does collapse (i.e. become entangled with the rest of the world), in principle you can still get the state back -- by gathering together all the particles in the universe that your state has become entangled with, and then reversing everything that's happened since the moment of collapse. That would be sort of like Pamela Anderson trying to regain her privacy, by tracking down every computer on Earth that might contain photos of her!

Quoting noAxioms

"The computable numbers are countable since they be put in a one-to-one correspondence with the natural numbers."
— Andrew M
Not to disagree, but an assertion like that requires a demonstration that they’re countable.

Here's one such demonstration, concluding with:

Quoting Alan Turing and the Countability of Computable Numbers - Adam A. Smith

The computable numbers are an infinite set. We have provided an injective function g that maps every computable number to a single natural number: a Godel number. Any set with such a function is countable, and therefore computable numbers are countable.

Quoting noAxioms

"However the real numbers are not countable per Cantor's diagonalization proof. Thus there are some real numbers that are not computable."
— Andrew M
Interestingly, the real number generated by Cantor's diagonalization proof is a computable number, so I’m not sure if this counts as evidence that there are some real numbers not computable. Once again, not disagreeing with the conclusion, only with how it was reached.

It isn't a computable number (though it is a real number) - see the section entitled "A counter proof?" at the above link.

Quoting noAxioms

OK, they managed to test something whose outcome (the CHSH inequality violation) was already predicted by quantum theory. It’s a new test, but not one that changed the theory or any of its interpretations in any way.

Yes, it would be big news if standard quantum theory were ever falsified.

Quoting noAxioms

Thanks for the larger context Bell statement. I agree with it fully. What is ‘jumping’ in that quote? “Do we not have jumping then all the time?”.

He's referring to the collapse of the wave function (i.e., a discontinuous change in the otherwise continuous time evolution of the Schrodinger equation).

Quoting noAxioms

Meanwhile, I still don’t see what the AI in the box will do. Bell’s statement is pretty clear that a real human in there wouldn’t serve any special role or purpose, so why would an AI be any different?

Presumably it wouldn't. But an AI (unlike a human) could be run on a quantum computer as part of a carefully controlled experiment, thus testing physical collapse theories that differ from standard quantum theory.

Quoting Wayfarer

"Let’s begin with a thought-experiment: Imagine that all life has vanished from the universe, but everything else is undisturbed. Matter is scattered about in space in the same way as it is now, there is sunlight, there are stars, planets and galaxies—but all of it is unseen. There is no human or animal eye to cast a glance at objects, hence nothing is discerned, recognized or even noticed."
— Charles Pinter, Mind and the Cosmic Order

So far, so good.

Quoting Wayfarer

"Objects in the unobserved universe have no shape, color or individual appearance, because shape and appearance are created by minds. Nor do they have features, because features correspond to categories of animal sensation. This is the way the early universe was before the emergence of life—and the way the present universe is outside the view of any observer."
— Charles Pinter, Mind and the Cosmic Order

Pinter's asserted view of "the way the present universe is outside the view of any observer" is a performative contradiction. That's the problem with the so-called view from nowhere in a nutshell.

My model is Aristotle's hylomorphism. We interact with nature in our capacity as natural creatures. That's the relational perspective. So the moon is round, orbits the Earth and pre-existed life on Earth from a human point-of-view.

Quoting Andrew M

Pinter's asserted view of "the way the present universe is outside the view of any observer" is a performative contradiction.

I don't see that. It's a statement based on his knowledge of neural modelling, and supported by an important vein in philosophy, not least Kant's.

Quoting Andrew M

. So the moon is round, orbits the Earth and pre-existed life on Earth from a human point-of-view.

I quite agree, but again I don't think you're coming to grips with the point at issue. I think the problem that is highlighted by these debates IS the pretence of science to arrive at a form of perfectly objective knowledge independent of the role of the observer. That is what Nagel is criticizing in his book of that name, he's not advocating it as any kind of ideal.

Quoting Andrew M

Pinter's asserted view of "the way the present universe is outside the view of any observer" is a performative contradiction. That's the problem with the so-called view from nowhere in a nutshell.

The real problem here is with the notion of "the present universe". What Einstein reveals with the relativity of simultaneity is that "the present" is frame dependent. So the whole idea that there is such a thing as "the present universe" is an unsound premise because "the present" is something created by the observational perspective.

When we realize that "the present" is purely subjective, and we try to imagine an objective universe, independent from any observer, we have no place to insert "the present", because this would be an artificial insertion, therefore the creation of an observational perspective. Then we cannot possibly imagine such a universe, without a designated temporal perspective, (a point in time of now), because all things would exist everywhere, without some way of determining a specific point in time in their motions.

Quoting Andrew M

Interestingly, the real number generated by Cantor's diagonalization proof is a computable number, so I’m not sure if this counts as evidence that there are some real numbers not computable. Once again, not disagreeing with the conclusion, only with how it was reached.
— noAxioms
It isn't a computable number (though it is a real number) - see the section entitled "A counter proof?" at the above link.

I pondered over this for several days trying to understand the arguments. I still hold to what I said. The section you mention nicely shows that the x generated from the list of computable numbers is not itself a computable number, but I was speaking of the x generated from Cantor’s original proof of some real not being a rational number. That x is computable, but not rational, and thus cannot be used as evidence that there are some real numbers not computable.
The page you linked does show other ways to demonstrate exactly this, but the diagonalization method is not one of them.

Back to the quantum business:

What is ‘jumping’ in that quote? “Do we not have jumping then all the time?”.
— noAxioms
He's referring to the collapse of the wave function (i.e., a discontinuous change in the otherwise continuous time evolution of the Schrodinger equation).

Collapse seems to be a choice of classical description of a quantum state, in other words, an interpretation-dependent thing. In interpretations with ‘jumping’, yes, it happens all the time, everywhere. In interpretations without it (such as Everett’s relative state formulation, pre DeWitt’s MWI), it’s just a classical effect, not anything physical that happens.

Presumably [the AI in the box] wouldn't. But an AI (unlike a human) could be run on a quantum computer as part of a carefully controlled experiment, thus testing physical collapse theories that differ from standard quantum theory.

I have serious doubts about that. It is a suggestion that there is an empirical difference between the interpretations, and yet I see not explicit prediction from any pair of interpretations that differ.

Quoting Metaphysician Undercover

Try this:[ tau.ac.il/education/muse/museum/galileo/principle_relativity.html ]

You had to reach to Tel Aviv university to find a page closer to your definition?
[quote=tau]Galileo formulated the principle of relativity in order to show that one cannot determine whether the earth revolves about the sun or the sun revolves about the earth.[/quote]This is blatantly wrong. For one, the appearance of the sun revolving around the Earth once a day is not explained by the Earth revolving around the sun once a day any more than we’re revolving around all those other objects (moon, stars, etc) once a day. Secondly, the sun revolving around the Earth (once a year) violates basic Newtonian physics (lacking a reaction for the action of the sun). Newton’s laws were not in place back then so Galileo wouldn’t have known that.
Anyway, his pitch of principle of relativity used a boat’s relation to the water as the example, not celestial mechanics. The idea was that one could not tell from inside the boat whether the boat was moving relative to the water or not.
[quote-tau]The principle of relativity states that there is no physical way to differentiate between a body moving at a constant speed and an immobile body.[/quote]This definition is still reasonable, despite lack of reference to something relative to which the motion is defined. In short, there’s no way to differentiate an observer’s motion relative to some X if the observer cannot measure X. X is typically implied to be the ground (or water in Galileo’s case) beneath the observer, but it can be anything.
I accept the definition since it is more or less possible to derive either definition from the other, presuming at least that the X is explicit. It is the lack of that explicit reference that makes the definition ambiguous.
[quote=tau]It is of course possible to determine that one body is moving relative to the other, but it is impossible to determine which of them is moving and which is immobile.[/quote]This statement is especially ambiguous. Which of them is moving/immobile relative to what exactly? Humans tend to imply the ground since that’s their lifelong reference, but the implication is begging in this context.

I spend all my time just having to show you that you don't know what you're talking about.

Maybe you should try to actually understand what I’m talking about instead. I’m referencing far more reputable sources than are you. I’m pointing out explicitly what’s wrong with the pages you choose to quote. I don’t see you doing that with my references.

I do agree that perhaps your inability to understand an alternative to this absolutist view prevents communication between you and the rest of the scientific community. One doesn't have to accept the view with which you don't agree, but to not even understand it just leaves you behind.

This Article is intriguing. At first I thought they had found a way to reverse time in the quantum world, but rather they rejuvenated a photon, taking it back to a previous state.

The mathematics involved is probably linear (much is in the quantum world), since most non-linear systems are not reversible. Who knows? :chin:

Quoting noAxioms

You had to reach to Tel Aviv university to find a page closer to your definition?

That's a hell of a lot better than Wikipedia.

Quoting noAxioms

This is blatantly wrong. For one, the appearance of the sun revolving around the Earth once a day is not explained by the Earth revolving around the sun once a day any more than we’re revolving around all those other objects (moon, stars, etc) once a day. Secondly, the sun revolving around the Earth (once a year) violates basic Newtonian physics (lacking a reaction for the action of the sun). Newton’s laws were not in place back then so Galileo wouldn’t have known that.
Anyway, his pitch of principle of relativity used a boat’s relation to the water as the example, not celestial mechanics. The idea was that one could not tell from inside the boat whether the boat was moving relative to the water or not.

You clearly have not read any of Galileo's material, and continue to demonstrate that you do not know what you are talking about.

Quoting noAxioms

This statement is especially ambiguous. Which of them is moving/immobile relative to what exactly?

One body relative to the other body, is what is being discussed. Obviously, each is moving and neither is immobile. That it is impossible to determine that either one is immobile, yet possible to say that each is moving, implies that neither is immobile. And of course this becomes more obvious when the number of objects considered relative to each other is increased.

Quoting noAxioms

Humans tend to imply the ground since that’s their lifelong reference, but the implication is begging in this context.

Why do you incessantly resist and deny the point of the principle of relativity? The basic principle is that nothing is immobile (nothing is at rest). The principle of relativity renders the concept of "at rest" as obsolete. That is what allowed Newton to apply his first law of motion. The traditional concept of "at rest" which implied that a body had to be acted upon to be moved, is replaced with "uniform motion" by Newton, because by the principle of relativity "at rest" is not a valid concept. Then through extension of Newton's first law, a rest frame, or inertial frame, can be derived from any body displaying uniform motion because "uniform motion" is the concept which has take the place of "at rest".

Quoting noAxioms

I’m referencing far more reputable sources than are you.

Yeah Wikipedia, great source.

Quoting noAxioms

I pondered over this for several days trying to understand the arguments. I still hold to what I said. The section you mention nicely shows that the x generated from the list of computable numbers is not itself a computable number, but I was speaking of the x generated from Cantor’s original proof of some real not being a rational number. That x is computable, but not rational, and thus cannot be used as evidence that there are some real numbers not computable.
The page you linked does show other ways to demonstrate exactly this, but the diagonalization method is not one of them.

Cantor's proof (by contradiction) shows that the set of real numbers is uncountable and thus can't be enumerated. Since the set of real numbers can't be enumerated, the diagonalized number therefore can't be computed. A similar point is made by Carl Mummert (a professor of computing and mathematics) on Mathematics Stack Exchange.

Quoting noAxioms

Collapse seems to be a choice of classical description of a quantum state, in other words, an interpretation-dependent thing. In interpretations with ‘jumping’, yes, it happens all the time, everywhere. In interpretations without it (such as Everett’s relative state formulation, pre DeWitt’s MWI), it’s just a classical effect, not anything physical that happens.

Yes. The interpretation provides an account for how a measurement operationally returns a definite state when the formalism describes an indefinite state.

Copenhagen-style interpretations also generally deny a physical collapse. So, in that sense, Copenhagen and Everett/MWI agree (and disagree with physical collapse theories such as GRW).

Quoting noAxioms

"Presumably [the AI in the box] wouldn't. But an AI (unlike a human) could be run on a quantum computer as part of a carefully controlled experiment, thus testing physical collapse theories that differ from standard quantum theory."

I have serious doubts about that. It is a suggestion that there is an empirical difference between the interpretations, and yet I see not explicit prediction from any pair of interpretations that differ.

The empirical difference is between physical collapse theories such as GRW, and non-physical collapse interpretations (such as MWI and Copenhagen). From Wikipedia:

Quoting Objective-collapse theory - Wikipedia

The fundamental idea is that the unitary evolution of the wave function describing the state of a quantum system is approximate. It works well for microscopic systems, but progressively loses its validity when the mass / complexity of the system increases.
...
Such deviations can potentially be detected in dedicated experiments, and efforts are increasing worldwide towards testing them.

Quoting jgill

This Article is intriguing. At first I thought they had found a way to reverse time in the quantum world, but rather they rejuvenated a photon, taking it back to a previous state.

The mathematics involved is probably linear (much is in the quantum world), since most non-linear systems are not reversible.

Yes, that's right. Here's the paper for anyone else interested.

Quoting Andrew M

Cantor's proof (by contradiction) shows that the set of real numbers is uncountable and thus can't be enumerated. Since the set of real numbers can't be enumerated, the diagonalized number therefore can't be computed. A similar point is made by Carl Mummert (a professor of computing and mathematics) on Mathematics Stack Exchange.

What do you think this means, to assume numbers which cannot be counted nor computed? To me it's a form of unintelligibility, to say that there are numbers which cannot be accessed by us, or used in any way. Supposing that such a conclusion would be a logical consequence of the axioms assumed, then why would we assume axioms which produce the conclusion that there are numbers which cannot be accessed by us? As real numbers, being implied by our mathematical axioms, this would indicate that there are aspects of reality which we cannot access, grasp. apprehend, or understand in any way, which correspond with these numbers which cannot be accessed.

Since axioms are produced by mathematicians who practise pure mathematics, and those people who apply mathematics have a choice as to which axioms are used, it would appear like we ought not use axioms like these, which necessitate that aspects of reality will be unintelligible to us. Instead, we ought to look for axioms which would render all of reality as intelligible.

Quoting Andrew M

Yes, that's right. Here's the paper for anyone else interested.

There was a member here, active a couple years ago, I can't remember the name, but a self-proclaimed physicist who was big on this time reversal stuff. I think the fact that processes at the quantum level might be understood as reversible is simply a reflection of a fundamental misrepresentation of mass.

Quoting Metaphysician Undercover

Since axioms are produced by mathematicians who practise pure mathematics, and those people who apply mathematics have a choice as to which axioms are used, it would appear like we ought not use axioms like these, which necessitate that aspects of reality will be unintelligible to us. Instead, we ought to look for axioms which would render all of reality as intelligible.

Those who apply mathematics normally are not deeply conversant with its axiomatic structure. Most mathematicians - in the pure realm - are not either. It's dreadful stuff, but some treasure it. :cool:

Quoting Metaphysician Undercover

There was a member here, active a couple years ago, I can't remember the name, but a self-proclaimed physicist who was big on this time reversal stuff.

@Kenosha Kid. He was a Q-physicist who left the profession to play his guitar, as he explained to me. He liked Transactional physics.

Brian May is an example.

Quoting Metaphysician Undercover

What do you think this means, to assume numbers which cannot be counted nor computed?

Cantor's diagonal argument assumes that the set of real numbers are countable and then shows that that assumption leads to a contradiction.

Quoting Metaphysician Undercover

Since axioms are produced by mathematicians who practise pure mathematics, and those people who apply mathematics have a choice as to which axioms are used, it would appear like we ought not use axioms like these, which necessitate that aspects of reality will be unintelligible to us. Instead, we ought to look for axioms which would render all of reality as intelligible.

You may find that with computable numbers (which are countable):

Quoting Computable numbers - Use in place of the reals - Wikipedia

The computable numbers include the specific real numbers which appear in practice, including all real algebraic numbers, as well as e, ?, and many other transcendental numbers. Though the computable reals exhaust those reals we can calculate or approximate, the assumption that all reals are computable leads to substantially different conclusions about the real numbers. The question naturally arises of whether it is possible to dispose of the full set of reals and use computable numbers for all of mathematics. This idea is appealing from a constructivist point of view, and has been pursued by what Errett Bishop and Fred Richman call the Russian school of constructive mathematics.

Also from physicist Max Tegmark:

Quoting Infinity Is a Beautiful Concept – And It’s Ruining Physics - Max Tegmark

I was seduced by infinity at an early age. Georg Cantor’s diagonality proof that some infinities are bigger than others mesmerized me, and his infinite hierarchy of infinities blew my mind. The assumption that something truly infinite exists in nature underlies every physics course I’ve ever taught at MIT — and, indeed, all of modern physics. But it’s an untested assumption, which begs the question: Is it actually true?

...

Yet real numbers, with their infinitely many decimals, have infested almost every nook and cranny of physics, from the strengths of electromagnetic fields to the wave functions of quantum mechanics. We describe even a single bit of quantum information (qubit) using two real numbers involving infinitely many decimals.

Not only do we lack evidence for the infinite but we don’t need the infinite to do physics. Our best computer simulations, accurately describing everything from the formation of galaxies to tomorrow’s weather to the masses of elementary particles, use only finite computer resources by treating everything as finite. So if we can do without infinity to figure out what happens next, surely nature can, too — in a way that’s more deep and elegant than the hacks we use for our computer simulations.

Our challenge as physicists is to discover this elegant way and the infinity-free equations describing it—the true laws of physics. To start this search in earnest, we need to question infinity. I’m betting that we also need to let go of it.

Reply to Andrew M
Thanks Andrew, I especially like this part:
Quoting Infinity Is a Beautiful Concept – And It’s Ruining Physics - Max Tegmark

The assumption that something truly infinite exists in nature underlies every physics course I’ve ever taught at MIT

This is completely opposed to what Aristotle presumed himself to have demonstrated, that it is impossible that anything actual is infinite. The closest he gets to an actual infinite, is "eternal", and he even proposes principles which demonstrate that anything eternal must be actual. This is interesting because it places "eternal" (actual) into a different category from "infinite" (potential). The result is that the conception of "eternal" which is derived from Aristotle's principles means roughly "outside of time", because the eternal thing cannot be infinite, being actual rather than potential. However, a commonly used meaning of "eternal" is "infinite time". This is incoherent by Aristotle's principles.

Quoting jgill

He was a Q-physicist who left the profession to play his guitar, as he explained to me.

So, why not do both? And participate here in his spare time.

Reply to Metaphysician Undercover His last participation was about a year ago. He had made some comment about pursuing a "Pot of Gold" with his guitar. :cool:

Quoting Infinity Is a Beautiful Concept – And It’s Ruining Physics - Max Tegmark

Our challenge as physicists is to discover this elegant way and the infinity-free equations describing it

Lots of mathematicians don't use the infinity symbol except in a limit sense. The idea of some entity called infinity existing doesn't normally crop up in classical analysis, for example. Tegmark cites the expression [math]\frac{\infty }{\infty }[/math], but elementary calculus shows ways around that (in very elementary settings), stating the expression is meaningless. If I were to say [math]\underset{n\to \infty }{\mathop{\lim }}\,f(n)=\infty [/math], I only mean that as n increases so does the function, with no upper bound. I don't mean it ultimately ends up at a magical point at infinity.

All this is very simple. I've read that Hilbert spaces used in QM must be infinite in order to preserve continuity and completeness in some circumstances. But there are ways of dealing with these concepts in constructive mathematics. I suspect the noise made by math foundationalists regarding cardinalities and "squeezing in" numbers in R by forcing and such things might make physicists uneasy - if they even care. I don't. :cool:

Reply to jgill Enough time spent with the guitar could lead to a resolution of the Fourier uncertainty.

Quoting jgill

I only mean that as n increases so does the function, with no upper bound. I don't mean it ultimately ends up at a magical point at infinity.

The problem as I understand it is if you posit the lower limit of zero, to a duration of time, this model negates as impossible, the possibility of a real quantum of time. Furthermore, in analyzing any change (force), relative to what is uniform (inertial), as we narrow down the duration of time, toward any supposed point in time, where the change begins, the magnitude of force required to produce the change approaches infinite. Time is inversely proportional to energy, so as the temporal duration assumed for the force becomes close to zero, the quantity of energy becomes close to infinite. Therefore placing a limit to time at the speed of light, inserts the infinite into calculations which relate mass to energy.

This problem was first expressed by Zeno, and though some mathematicians might claim that calculus resolved the problem with the use of limits, it just provided a practical work-around which was suitable for the practises of the time. In modern times engineers employ extremely short periods of time, so the problem naturally reappears despite the efforts of calculus. Another proposal by philosophers and mathematicians, has been to use infinitesimals. Infinitesimals allow that the apparent infinite change occurs within a non-zero duration of time (infinitesimal), but the actual change within that infinitesimal duration cannot be represented. In other words, each infinitesimal quantum of time may contain an unrepresentable change.

The problem though, is pretty much how Zeno represented it. The ideal (theoretical) representation of time and space is as continuous. However, our descriptions of how things move in real practise represent discrete units of space and time. So there is a fundamental incompatibility between how we describe our observations of things in practise, and how we explain or interpret our observations through mathematical theory. There has been some attempts to make the mathematical theory of continuity consistent with the observations of discrete units (quanta), but the proposals employed for mathematizing quanta are completely ideal, not based in any empirical principles of real discrete quanta of space or time. Until we take notice of the reality of how space and time are actually quantized in real discrete units, these attempts, such as limits and infinitesimals, will remain ideals of theory which do not adequately represent the quanta of reality.

For an analogy, consider how the ancient people modeled the orbits of the planets as eternal circular motions (perfect circles which by that perfection are eternal) which are described by Aristotle. This was the ideal which was employed, but it did not adequately represent reality. Within the practise of modeling the orbits, exceptions (retrogrades etc.) were incorporated to account for the fact that the reality was not as the ideal represented it. Until it is fully acknowledged, and recognized, that reality is not as the ideal (as indicated by the need for exceptions), people just do not get motivated to determine the real representation.

Intuitively, Smooth infinitesimal analysis can be interpreted as describing a world in which lines are made out of infinitesimally small segments, not out of points. These segments can be thought of as being long enough to have a definite direction, but not long enough to be curved.

Quoting Metaphysician Undercover

Until we take notice of the reality of how space and time are actually quantized in real discrete units, these attempts, such as limits and infinitesimals, will remain ideals of theory which do not adequately represent the quanta of reality.

Perhaps space and time are not "actually quantized in real discrete units".

Quoting Metaphysician Undercover

There was a member here, active a couple years ago, I can't remember the name, but a self-proclaimed physicist who was big on this time reversal stuff.

Maybe he’ll come back in the past. ;-)

Quoting Wayfarer

Maybe he’ll come back in the past. ;-)

I think I should revisit some old posts, and see if anything has mysteriously changed. If so, I'd be seriously spooked.

Quoting jgill

Perhaps space and time are not "actually quantized in real discrete units".

This is a respectable proposition, but the problems involved in applying mathematics (Zeno's to begin with) demonstrates otherwise. Let me explain, starting with some fundamental principles:

First principle, divisibility is very real, we can physically divide things, therefore division of space or time must be real.
Second principle, if space or time is divisible, and there is nothing real which restricts or limits the divisibility, then it is infinitely divisible.
Third principle, if there is something real which restricts or limits the divisibility of space or time, then these restrictions provide the basic premise for real quantized discrete units.

What has been evident ever since the time of Zeno (and probably even before this formalization, from Pythagoras), is that the second principle (stated above) is problematic. Representing our capacity to divide things with mathematics that provide for infinite divisibility creates various irrational ratios (Pythagoras), and paradoxes (Zeno). The mathematical axioms assume a continuity which is infinitely divisible. However, it can be demonstrated in theory (Pythagoras and Zeno), that these axioms will inevitably lead to problems in application. The conclusion we can draw, or which I would say we ought to draw, is that this idea, of infinite divisibility, is just an ideal which does not truly represent the nature of reality. And this is very intuitive too, because space and time are our fundamental representations for how the world really is, and if you think about it, it doesn't make sense to think that we could keep on dividing the real world, in the very same way, into smaller and smaller bits, forever. It's just not realistic, because this would imply no real substance to the world.

This is why the ancient Greeks proposed a fundamental indivisible base, "atoms", or "matter", to provide substance for our principles of divisibility. So this brings us to the third principle, "substance" is the real thing which limits and restricts our capacity for making divisions in the real world. The conclusion therefore is that we need to understand how "substance" limits and restricts our capacity for division, and formulate our axioms of mathematics to properly represent these restrictions. Then the numbering system which we employ will properly represent the world's real capacity for division.

For example, look at the principles for dividing the octave in music, the basic principles of "scale". Distinct tones, as specific frequencies, are supposed as the substance around which the divisions are made, and the scale is produced. But no tone is absolutely clean, crisp and clear, so there are complexities, overtones, timbre, etc.. Also, the scale of tones must be created so as to be useful in combination for the production of harmony, so "the scale" is intended to relate a multitude of octaves.

Now in dividing the octave into specific tones, to produce a scale, we must also consider what happens when we multiply, because this is how harmony is created, and that is just as important to the scale as the division into tones. Therefore proper, or true division, is not a straight forward act of dividing in any way that the physical world will allow, good proper division practises must be conditioned by the reality of what may be produced through the re-combination of the parts which are divided for. We could say that this is the role of "the good" in the practise of division, or analysis, that the things produced in division are a true representation of the actual parts which went into the production of the whole, rather than a random division. Like for example, cutting with a knife slices through the cells, providing a glimpse inside, but not providing a good principle of division.

So we divide the octave into parts, and produce a scale of individual tones or frequencies. But there is a possibility for random division here, and this would not produce a good scale. So we must keep in mind what will be created from those parts, harmonies, and we must create the scale accordingly. Basing "the scale" in good principles of harmony is what produces consistency in the production of a conceptual multi-leveled spatiotemporal reality. That is the need to represent how the various parts create a harmonic whole, as the reality of substance. In other words, "substance" in its real existence, is a multi-layered harmony through the micro/macro range, so that any production of a base scale must be consistent with intermediate scales, and upper scales, in the way of harmony, so that "substance" is properly formulated.

Quoting Metaphysician Undercover

The mathematical axioms assume a continuity which is infinitely divisible. However, it can be demonstrated in theory (Pythagoras and Zeno), that these axioms will inevitably lead to problems in application. The conclusion we can draw, or which I would say we ought to draw, is that this idea, of infinite divisibility, is just an ideal which does not truly represent the nature of reality.

I'm not sure what "problems in application" you refer to since in most applications - if not all - one works with rational or computable numbers. I can pretty much guarantee that Feynman's path integral is a computational problem.

However, you have written a compelling philosophical case for quanta time and space. I don't know about the set theory axioms that should be replaced. Beyond my sphere of interests. Wikipedia says this:

In mathematical physics, the concept of quantum spacetime is a generalization of the usual concept of spacetime in which some variables that ordinarily commute are assumed not to commute and form a different Lie algebra. The choice of that algebra still varies from theory to theory. As a result of this change some variables that are usually continuous may become discrete. Often only such discrete variables are called "quantized"; usage varies.

and

Physical spacetime is a quantum spacetime when in quantum mechanics position and momentum variables x , p x,p are already noncommutative, obey the Heisenberg uncertainty principle, and are continuous. Because of the Heisenberg uncertainty relations, greater energy is needed to probe smaller distances. Ultimately, according to gravity theory, the probing particles form black holes that destroy what was to be measured. The process cannot be repeated, so it cannot be counted as a measurement. This limited measurability led many to expect that our usual picture of continuous commutative spacetime breaks down at Planck scale distances, if not sooner.

It's a very technical subject that bears a slight resemblance to "not turtles all the way down".

Quoting Andrew M

Cantor's proof (by contradiction) shows that the set of real numbers is uncountable and thus can't be enumerated. Since the set of real numbers can't be enumerated, the diagonalized number therefore can't be computed.

But that number (from Cantor’s proof) is generated from a countable list of rationals, not an uncountable list of reals. So it can be computed. It doesn’t require the ordering of the reals. That was my point,.

Copenhagen-style interpretations also generally deny a physical collapse. So, in that sense, Copenhagen and Everett/MWI agree (and disagree with physical collapse theories such as GRW).

I am not really clear on what a formal statement of metaphysical Copenhagen interpretation would say. I’m more familiar of its roots as an epistemological interpretation where collapse (of what is known) very much does occur, but it is just a change in what is known about a system, not a physical change. They’ve since created a not-particularly well defined metaphysical interpretation under the same name, and if it doesn’t suggest physical collapse, I’d accept that statement.

The empirical difference is between physical collapse theories such as GRW, and non-physical collapse interpretations (such as MWI and Copenhagen). From Wikipedia:

[quote=wiki]Such deviations can potentially be detected in dedicated experiments, and efforts are increasing worldwide towards testing them.[/quote]Cool. Interesting to watch then. Thanks.

Quoting Metaphysician Undercover

One body relative to the other body, is what is being discussed. Obviously, each is moving and neither is immobile.

Totally agree with this, but it renders meaningless a statement about a single body in the absence of something relative to which motion can be defined.

The principle of relativity states that there is no physical way to differentiate between a body moving at a constant speed and an immobile body.

If there are two bodies with relative motion, then per the definition of motion, both are moving relative to the other, and the differentiation can easily be made by measurement. If there is but the one body, then motion isn’t defined at all.

Why do you incessantly resist and deny the point of the principle of relativity?

I don’t. I said in my prior post that I could accept it, despite the non-relative wording of it.

The basic principle is that nothing is immobile (nothing is at rest).

If what is being discussed is one body relative to the other body, your choice of wording leaves the second entity unspecified, merely implied, like there’s some embarrassment about it. So say it. Relative to what is nothing immobile?

The principle of relativity renders the concept of "at rest" as obsolete.

And here I thought it was the definition of motion that did that. The principle of relativity seems to still hold even if you discard the relative definition of motion, and Einstein’s theories along with it.

… because by the principle of relativity "at rest" is not a valid concept.

If the PoR makes the concept of ‘at rest’ invalid, why does it (or at least the version of PoR that you prefer) reference it?
My apologies for hanging on this point so much, but you seem to contradict yourself regularly, saying that the concept is invalid, but regularly referencing the invalid concept nonetheless. I personally don’t find the concept invalid at all. It’s just a totally different set of definitions with totally different physics than what Einstein proposes. I don’t prefer these alternate definitions, but I cannot prove them wrong.

Then through extension of Newton's first law, a rest frame, or inertial frame, can be derived from any body displaying uniform motion because "uniform motion" is the concept which has take the place of "at rest".

Anyway, I will accept this as well. You don’t seem to be pushing the alternate definitions. In Minkowskian spacetime, a rest frame can be any arbitrarily selected frame and the is the implied second object relative to which motion is defined. The selected frame is an inertial one if Newton’s laws of motion hold in it, but other frames (with different laws) are also allowed.
That said, I don’t know why nothing can be at rest in it. I do realize that I cannot name a single object which isn’t accelerating at least in the coordinate sense, so nothing seems to be stationary for any extended period of time. I say coordinate sense since an object in free fall (Earth say), except for spinning in place, is not particularly acted on by significant forces and thus is effectively stationary in its local inertial frame (it traces a geodesic through spacetime). This is a departure from Newton’s physics where gravity is a force and causes paths to curve.

Quoting Metaphysician Undercover

What do you think this means, to assume numbers which cannot be counted nor computed? To me it's a form of unintelligibility, to say that there are numbers which cannot be accessed by us, or used in any way.

I don’t find it unintelligible, but I do find fascinating the complete inaccessibility of such numbers to us. The vast majority of real values are these inexpressible values. I gave a few examples of them, especially ones that don’t require units which themselves are only approximately defined.
It seems that they can be measured to some precision, but those approximations are never the number itself. Hubble’s ‘constant’ (which unfortunately does have units) is one such number, and one that is known to not even an entire significant digit. I put ‘constant’ in quotes because the value changes over time.

Quoting noAxioms

Totally agree with this, but it renders meaningless a statement about a single body in the absence of something relative to which motion can be defined.

A statement about a single body is not completely "meaningless", because we can still state properties of the body itself, and this is meaningful. Predication is actually very meaningful. Now, you should consider the distinction between internal and external properties, a distinction which has been quite meaningful in classical philosophy. It seems like the science of physics has no real principles to distinguish these two, the difference between internal change (difference of properties) and external change (locomotion or change of place), and physics wants to reduce, and treat all change as change of place. Internal change would be change of place of internal parts.

The problem with this perspective arises when we get down to the fundamental parts. As I described above in a prior post, there must be base indivisible parts, or else the universe is fundamentally without substance. That's the principle employed by the ancient Greek atomists. If internal change is described exclusively through change of place to internal parts, then internal change to fundamental indivisible parts is ruled out as impossible. Yet if fundamental parts demonstrate internal change, such change is rendered as unintelligible, unless we allow for further division. Then fundamental parts cannot be found unless they are observed to be unchangeable.

Quoting noAxioms

If what is being discussed is one body relative to the other body, your choice of wording leaves the second entity unspecified, merely implied, like there’s some embarrassment about it. So say it. Relative to what is nothing immobile?

Relative to the principle of relativity, nothing is immobile. That is, if we take the principle of relativity as our primary premise, and add the observational premise that there are numerous bodies observed to be moving in different ways, we can conclude that noting is immobile. That is the fundamental conclusion, (assumption), which the principle of relativity give us, there is no such thing as "rest" in any truthful, grounded sense.

Quoting noAxioms

And here I thought it was the definition of motion that did that. The principle of relativity seems to still hold even if you discard the relative definition of motion, and Einstein’s theories along with it.

Yes, "motion" as defined by the principle of relativity is what renders the concept of "at rest" as obsolete, but only as defined by the principle of relativity. Prior to Galileo's development of the principle of relativity, "at rest" was a valid concept referring to one's position on earth, and motion was defined relative to any location on earth, the earth being "at rest". And, the locations on earth were supposed to be at rest relative to each other. The principle of relativity makes rest a property derived only from locations which are at rest relative to one another (lack of internal change), but these locations are not at rest in the wider context (external change, or change of place). So when motion is defined as change of place relative to what is external to a designated location (the principle of relativity), there is no such thing as "at rest".

Quoting noAxioms

If the PoR makes the concept of ‘at rest’ invalid, why does it (or at least the version of PoR that you prefer) reference it?

The principle of relativity creates an artificial, and arbitrary definition of "rest", as "the rest frame". It is not a real rest, because it is moving relative to its environment (external change). So we can designate a number of points, as locations, and say that they are not moving relative to each other (no internal change), and claim to have a rest frame. But this is not a true or real rest, as they move relative to external things. And, as the principles of Einstein's special relativity (time dilation, length contraction) demonstrate to us, there is not even any true internal rest here. We must overlook certain discrepancies to say that they are at rest relative to each other. The locations actually change relative to each other due to the effects of external change, acceleration. Therefore even the internal "rest", or lack of internal change, which is associated with the rest frame, is not a valid "rest".

Quoting noAxioms

My apologies for hanging on this point so much, but you seem to contradict yourself regularly, saying that the concept is invalid, but regularly referencing the invalid concept nonetheless. I personally don’t find the concept invalid at all. It’s just a totally different set of definitions with totally different physics than what Einstein proposes. I don’t prefer these alternate definitions, but I cannot prove them wrong.

If you can show me a valid concept of rest, lack of change, which can be maintained consistently along with the principle of relativity as well, I would appreciate the demonstration. Even if we accept locations to be "at rest" relative to each other in an internal way, and deny Einsteinian relativity, these locations are still not at rest in the wider (external) context. And when we start mapping the points which are supposed to be at rest relative to each other, in comparison with external things, we inevitably find minor inconsistencies which cannot be resolved, as demonstrated by Einstein's train example. So we do not have the evidence to adequately support any claim that any multitude of points of location in the material world are actually at rest relative to each other. The need for "spatial expansion" helps to demonstrate the reality of this point.

Quoting noAxioms

Cantor's proof (by contradiction) shows that the set of real numbers is uncountable and thus can't be enumerated. Since the set of real numbers can't be enumerated, the diagonalized number therefore can't be computed.
— Andrew M

But that number (from Cantor’s proof) is generated from a countable list of rationals, not an uncountable list of reals. So it can be computed. It doesn’t require the ordering of the reals. That was my point,.

Cantor's proof assumes an enumeration of the set of real numbers (any enumeration, not just an ordered one), and then proves that there can't be one. So it's therefore not possible to compute the diagonal for the set of real numbers. The specific diagonal that is computed as part of the construction is necessarily for a different set of numbers (say, the countable list of rationals).

If it were the diagonal for the set of real numbers, then it would appear somewhere on the list, say, the i[sup]th[/sup] index. But then to calculate the number at that index to the i[sup]th[/sup] digit would result in an infinite loop.

Quoting noAxioms

Copenhagen-style interpretations also generally deny a physical collapse. So, in that sense, Copenhagen and Everett/MWI agree (and disagree with physical collapse theories such as GRW).
— Andrew M

I am not really clear on what a formal statement of metaphysical Copenhagen interpretation would say. I’m more familiar of its roots as an epistemological interpretation where collapse (of what is known) very much does occur, but it is just a change in what is known about a system, not a physical change. They’ve since created a not-particularly well defined metaphysical interpretation under the same name, and if it doesn’t suggest physical collapse, I’d accept that statement.

:up:

Some quotes to that effect here.

Reply to Andrew M I'd be interested if you could see what I was driving at in this OP on Physics forum particularly #11 and #14. I was trying to argue that the probability wave is outside of space and time, although (probably predictably) the physicist who responded thought this 'gobbledegook' and preferred the (I think inane) dogma that 'particles interfere with themselves'. I don't know enough physics to really articulate the intuition I have about it.

Quoting Wayfarer

I was trying to argue that the probability wave is outside of space and time...

Space and time are conceptual. So "outside of space and time", simply means unable to be apprehended through our current conceptions of space and time. This issue is very much analogous to the discussion above, of numbers which our conception of numbers reveals to us as needed to be accounted for, but they lie outside of our capacity to apprehend them. What I argued above, is that this indicates a fundamental flaw in our conception of numbers, that this conception produces numbers which cannot be apprehended by us.

Reply to Wayfarer Yes I think I see what you're getting at.

So whether they're discharged one electron at a time, or at a faster (or is that 'higher'?) rate, then you still get the same pattern.

Yes, the pattern will be the same in both cases.

The fact that the effect can't be replicated by a physical (water) wave is, I think, due to the interference pattern not actually being 'waves' as such, but something for which the interference patterns of waves is just an analogy.

I think it's deeper than just an analogy. The wave dynamics are central to the math.

The argument that started this was about whether this means that time (being 'rate') is not a factor; which also that means that space (i.e. proximity of particles) is not a factor (as proximity is an aspect of space-time.) So, what is causing the interference pattern is outside, or not a function of, space-time.

Deux ex machina?

Reply to Andrew M Thanks for taking the time to look. I had the idea that the wave function literally is ‘the degrees of probability’. The reason that seems daft to many people is that there is no concept of ‘degrees of reality’ - usually it is assumed that nothing can be more or less real. But that is the point of [url= https://www.sciencenews.org/blog/context/quantum-mysteries-dissolve-if-possibilities-are-realities#:~:text=At%20its%20root%2C%20the%20new,objects%20or%20events%20in%20spacetime]this article.

This new ontological picture requires that we expand our concept of ‘what is real’ to include an extraspatiotemporal domain of quantum possibility,” write Ruth Kastner, Stuart Kauffman and Michael Epperson.

Considering potential things to be real is not exactly a new idea, as it was a central aspect of the philosophy of Aristotle, 24 centuries ago. An acorn has the potential to become a tree; a tree has the potential to become a wooden table. Even applying this idea to quantum physics isn’t new. Werner Heisenberg, the quantum pioneer famous for his uncertainty principle, considered his quantum math to describe potential outcomes of measurements of which one would become the actual result. The quantum concept of a “probability wave,” describing the likelihood of different possible outcomes of a measurement, was a quantitative version of Aristotle’s potential, Heisenberg wrote in his well-known 1958 book Physics and Philosophy. “It introduced something standing in the middle between the idea of an event and the actual event, a strange kind of physical reality just in the middle between possibility and reality.”

Reply to Wayfarer

Quoting Quantum mysteries dissolve if possibilities are realities - Tom Siegfried

This new ontological picture requires that we expand our concept of ‘what is real’ to include an extraspatiotemporal domain of quantum possibility,” write Ruth Kastner, Stuart Kauffman and Michael Epperson.

Considering potential things to be real is not exactly a new idea, as it was a central aspect of the philosophy of Aristotle, 24 centuries ago. An acorn has the potential to become a tree; a tree has the potential to become a wooden table.

Yes, an acorn has the potential to become a tree, as Aristotle would have correctly noted. That simply means that an acorn has the capability or possibility to develop into a tree under certain conditions.

That shouldn't suggest an "extraspatiotemporal" limbo world where tree potentialities exist and evolve until they are actualized as trees in our "spatiotemporal" world. Instead the world we inhabit just is where an acorn develops into a tree.

Similarly, under certain conditions, a series of particles in a dual-slit experiment will form an interference pattern. That is a true statement about the world that we can observe for ourselves.

The positing of an "extraspatiotemporal" domain as against a "spatiotemporal" domain is a variation of The Ghost in the Machine metaphor.

We don't live in a classical world supplemented by an extraclassical domain of existents, possibilities and processes. We live in a quantum world.

Quoting Andrew M

That shouldn't suggest an "extraspatiotemporal" limbo world where tree potentialities exist and evolve until they are actualized as trees in our "spatiotemporal" world.

As I thought had been established, the interference pattern in the double-slit experiments is independent of time and space (shown by its rate independence), thus indicating an extraspatiotemporal cause. It might be the same principle as an acorn becoming an oak, but on a far more pervasive and subtle level of existence. Put another way, the possibility equation really does describe 'degrees of reality' which are not actualised until a measurement is made. Hence the 'nothing exists until it is measured', of Neils Bohr.

Quoting Wayfarer

As I thought had been established, the interference pattern in the double-slit experiments is independent of time and space (shown by its rate independence), thus indicating an extraspatiotemporal cause.

No, I suggested that idea was a deux ex machina.

Everything follows quantum principles, whether acorns, water waves or particles.

Reply to Andrew M Show me a macroscopic entity existing in superposition.

Quoting Wayfarer

Show me a macroscopic entity existing in superposition.

A piezoelectric "tuning fork".

Quoting Quantum superposition - Wikipedia

A piezoelectric "tuning fork" has been constructed, which can be placed into a superposition of vibrating and non-vibrating states. The resonator comprises about 10 trillion atoms.

Quoting Macro-Weirdness: 'Quantum Microphone' Puts Naked-Eye Object in 2 Places at Once

Researchers have demonstrated a device that can pick up single quanta of mechanical vibration similar to those that shake molecules during chemical reactions, and have shown that the device itself, which is the width of a hair, acts as if it exists in two places at once—a "quantum weirdness" feat that so far had only been observed at the scale of molecules.

"This is a milestone," says Wojciech Zurek, a theorist at the Los Alamos National Laboratory in New Mexico. "It confirms what many of us believe, but some continue to resist—that our universe is 'quantum to the core'."

Reply to Wayfarer

I drive to Walmart to pick up my wife. She will either be standing at the door we agreed upon, or she will not (still shopping). When I get there, there she is - and the wave function has collapsed. Until I get there I do not know. She resides in that mystical state of superposition, being both there and not there. But I have calculated the probability and it has come out .7 in favor of her standing there and .3 her not.

Partial differential equations model quantum "realities". When you solve the equation there may be several possible solutions - that's just mathematics. Linear combinations of those solutions are also solutions. Until you actually perform the measurements you don't know which is correct. So, in the math, there is nothing weird going on. Mathematics is not a perfect model in would seem.

Reply to Andrew M Very clever experiments but I did notice

[quote=Macro-Weirdness: 'Quantum Microphone' Puts Naked-Eye Object in 2 Places at Once] As to how the day-to-day reality of objects that we observe, such as furniture and fruit, emerges from such a different and exotic quantum world, that remains a mystery.[/quote]

Quoting jgill

Until I get there I do not know. She resides in that mystical state of superposition, being both there and not there. But I have calculated the probability and it has come out .7 in favor of her standing there and .3 her not.

It's not a valid analogy, though. The strangeness of the observer problem in physics is that the act of observation itself is instrumental in determination of the outcome. The proper analogy would be that, prior to you seeing your wife, she didn't exist in any specific location at all, she's not simply in an unknown location.

The answer to the question as to where the particle is, prior to measuring its whereabouts, just IS the probability equation, it has no particular existence but only the probability of existence. That's the point.

Quoting Wayfarer

Very clever experiments but I did notice

"As to how the day-to-day reality of objects that we observe, such as furniture and fruit, emerges from such a different and exotic quantum world, that remains a mystery."
— Macro-Weirdness: Quantum Microphone Puts Naked-Eye Object in 2 Places at Once

OK. But as physicist Sidney Coleman says (via Peter Woit):

Quoting Quantum Mechanics in Your Face - Sidney Coleman (transcript and slides)

The problem is not the interpretation of quantum mechanics. That’s getting things just backwards. The problem is the interpretation of classical mechanics.

Which is to say, we view quantum mechanics through the lens of our classical concepts and intuitions. Coleman notes that, "The thing you want to do is not to interpret the new theory in terms of the old, but the old theory in terms of the new."

Quoting Quantum Mechanics in Your Face - Sidney Coleman (transcript and slides)

Now people say the reduction of the wave packet occurs because it looks like the reduction of the wave packet occurs, and that is indeed true. What I’m asking you in the second main part of this lecture is to consider seriously what it would look like if it were the other way around—if all that ever happened was causal evolution according to quantum mechanics. What I have tried to convince you is that what it looks like is ordinary everyday life.

To this, Peter Woit comments:

Quoting Peter Woit

While some might take this and claim Coleman as an Everettian, note that there’s zero mention anywhere of many-worlds. Likely he found that an empty idea that explains nothing, so not worth mentioning.

In the lecture, Coleman says, "The position I am going to advocate is associated with Hugh Everett in a classic paper" (referring to Everett's paper, '"Relative State" Formulation of Quantum Mechanics').

Then, from the Q&A:

Quoting Quantum Mechanics in Your Face - Sidney Coleman (video)

Question: You said in passing that you were a follower of Everett.

Coleman: Yeah, but that's a tricky thing to say. That's like saying you're a Christian. I mean, Everett wrote this one truly wonderful paper and then everyone got on their horse and rode off in all directions. The position I'm advocating is a position that, at least in my case, was certainly largely inspired by Everett's paper. Whether it's really Everett's position or not I would prefer not to discuss.

Which all leads to:

Quoting Wayfarer

It's not a valid analogy, though. The strangeness of the observer problem in physics is that the act of observation itself is instrumental in determination of the outcome. The proper analogy would be that, prior to you seeing your wife, she didn't exist in any specific location at all, she's not simply in an unknown location.

The proper analogy would be that @jgill observed interference effects until he and his wife met up and she pointed out that she had been standing there all the time.

Quoting Andrew M

That shouldn't suggest an "extraspatiotemporal" limbo world where tree potentialities exist and evolve until they are actualized as trees in our "spatiotemporal" world. Instead the world we inhabit just is where an acorn develops into a tree.

The problem though, is that with each passing moment the actual acorn, along with the potentialities, changes according to the conditions it is exposed to. Through chemistry we'd understand these changes as changes to the form, or actuality of the physical object, the acorn. But corresponding to these changes to the form, there are changes to the potential which cannot be directly understood simply through an understanding of the chemical changes to the form of the acorn. The potentialities really do evolve along with the changing actuality. We might apply premises from biology, which could state that X physical form is equivalent to Z potential, therefore destruction of X actuality is a destruction of Z potential. However, the theory of evolution, genetics and mutations, shows us that relating actualities to potentials is not so simple in reality. Actualities come and go, potentials change.

Actual forms don't directly correspond with potentials. The physical form is represented as one unity, an entity, or particular. Potential is related to the particular as a multitude of possibilities. Each possibility is itself represented (by us thinking humans) as a particular, to establish a direct relation to the actual, particular form. Thus a multitude of possibilities (possible actualities) is related to one actual form. So "potential" appears as a multitude of possible particulars, each of these particulars having a theoretical rather than a real spacetime representation. The theoretical spacetime representation, which is not a real spacetime representation (analogous to a counterfactual), constitutes what is known as a real possibility by modal logic.

But that is not a real representation of the real existence of "potential", it is only a representation of how potential relates to the actual. We create with our minds, a number of possible actualities which directly relate to the known actuality, and designate these as the real possibilities. But these are representation of actualities which are qualified as "possible", and these are supposed to relate the real potential to the real actual. We have no representation of real potential, only representations of real actualities. So to establish the relationship we represent potential as a multitude of possible actualities. But we also know that what we designate as real possibilities (possible actualities) cannot all be true without defying the laws of spacetime. Therefore we need to conclude that real potential, which is described in terms of incompatible spacetime actualities, is not describable by the laws of spacetime.

Quoting Andrew M

The proper analogy would be that jgill observed interference effects until he and his wife met up and she pointed out that she had been standing there all the time.

So we say that @jgill has extremely bad eyes, and all he sees until he's about three metres from his wife is a strange interference pattern? Suppose he's 50 metres away. How would he interpret the interference pattern as probabilities for the actual location of his wife? Consider that if this is a true analogy, the closer that he gets, he ought to be able to observe changes to the interference pattern which would increase his certainty.

Quoting jgill

But I have calculated the probability and it has come out .7 in favor of her standing there and .3 her not.

So? How did you interpret that interference pattern, to come up with these numbers? Ultimately, the way that you interpreted the pattern, to come up with accurate probabilities, says something very significant about what the wave interference which you are interpreting, really is.

Reply to Wayfarer ,Reply to Andrew M , Reply to Metaphysician Undercover

Oh well, and here I was trying to follow an important dictum of philosophical dialogue I have learned of on TPF: Wrong, but interesting. :smile:

Quoting Andrew M

Cantor's proof assumes an enumeration of the set of real numbers

OK, my mistake, since I was envisioning an enumeration of the rationals to prove that there are irrational numbers. But the proof of that is less complicated.

(any enumeration, not just an ordered one)

How can any enumeration not be ordered?



[quote=”Andrew M”]Copenhagen-style interpretations also generally deny a physical collapse.[/quote]Maybe. The list of interpretations on wiki says some of the Copenhagen interpretations say this. This implies at least that there’s more than one interpretation using this name. The reference they give on the ‘maybe’ talks about the epistemic view I mentioned, but then:
“By contrast, the Copenhagen interpretation has also been associated with an ontological view of the quantum state, in which the wave function somehow describes a real wave, and the collapse is a real physical process – presumably induced by the observer. This ontological view is usually attributed to von Neumann in his 1932 textbook exposition of quantum mechanics; … Thus, for Bohr, the wave function is a representation of a quantum system in a particular, classically described, experimental context. … When a measurement is performed (that is, when an irreversible recording has been made; see below), then the context changes, and hence the wave function changes. This can formally be seen as a "collapse" of the wave function, with the square quotes indicating that we are not talking about a physical process in which a real wave collapses.”
Square quotes? Should that say ‘scare quotes’? Anyway, that bit says we’re not talking about a physical collapse.
All this taken from https://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics
If collapse isn’t physical and isn’t epistemological, then what is it?


Quoting Metaphysician Undercover

A statement about a single body is not completely "meaningless", because we can still state properties of the body itself, and this is meaningful.

You know I’m talking about it’s property of motion, in complete absence of a second thing relative to which that motion (or lack of it) is meaningful.

That is, if we take the principle of relativity as our primary premise, and add the observational premise that there are numerous bodies observed to be moving in different ways, we can conclude that noting is immobile.

Non-sequitur. The principle (your chosen wording) seems only to say that there’s no way to tell, not that there cannot be an immobile one.
Anyway, I actually don’t wish to continue hammering this point, which just seems to be a different choice of wording the same thing.

If you can show me a valid concept of rest, lack of change, which can be maintained consistently along with the principle of relativity as well, I would appreciate the demonstration.

My chosen wording of the principle makes no mention of ‘at rest’ or ‘stationary’, nor does it make any mention of internal change, so it’s not mine to demonstrate.

Even if we accept locations to be "at rest" relative to each other in an internal way, and deny Einsteinian relativity, these locations are still not at rest in the wider (external) context. And when we start mapping the points which are supposed to be at rest relative to each other, in comparison with external things, we inevitably find minor inconsistencies which cannot be resolved, as demonstrated by Einstein's train example.

The train example presumes the premises listed. If you deny those premises, then the train example ceases to demonstrate any inconsistencies.
I always took you for somebody in denial of Einstein’s theory precisely because only in one frame (and not an inertial one either) are all the events in ‘the present’ simultaneous with each other. In all other frames, this is not so, so the laws of physics are different between this and that frame, in violation of the principle. This follows from your assertions, ones with which I do not agree.

Quoting noAxioms

You know I’m talking about it’s property of motion, in complete absence of a second thing relative to which that motion (or lack of it) is meaningful.

This is unintelligible to me. Motion is a concept. That is why I could give a definition of motion prior to the principle of relativity being produced, and also a definition of motion derived from the principle of relativity. That these differ indicates that the concept of motion has evolved.

That something is moving, or in motion, is a human judgement. This judgement requires a spatial temporal perspective, Kant's pure a priori intuitions. This means that there is necessarily an observer, and that observer is human, hence a "second thing". Therefore it's completely nonsensical to talk about the motion of a thing in the complete absence of a second thing.

Quoting noAxioms

Non-sequitur. The principle (your chosen wording) seems only to say that there’s no way to tell, not that there cannot be an immobile one.

No, it's a valid conclusion from the premises I stated. You are ignoring the other premise I stated. That premise is derived from empirical observation that there is a multitude of things. observed to be moving in different ways. From that empirical, observational premise, and the principle of relativity as the other premise, we can conclude that nothing is at rest.

I'm really surprised that you are arguing this point, because the absence of absolute rest is often cited as the basic epistemological principle which is derived from the principle of relativity, which is an ontological principle. So we take the principle of relativity (that the motion of a body is only determined relative to another body, and either one if the motion is observed as uniform, could equally be the rest frame), as the major premise. And this is an ontological theory. Then we add the observational data that there is always at least one body moving relative to any other, and this produces the conclusion that nothing is at rest. This principle serves as the epistemic base for the arbitrary application of the concept "rest frame". Since it is known by the logic above, that nothing is truly at rest, then the designation of "rest", or "rest frame" is necessarily completely arbitrary, therefore that designation is based in pragmatic principles, rather than an ontological principle. The ontological principle "relativity" renders "rest" as not true.

However, this puts "time" in a very odd situation. Our measurements of the passing of time are based in the ancient concept of motion within which, we as observers are assumed to be at rest. We observe motions relative to ourselves, assuming ourselves to be at rest, and produce temporal durations from these observations. Then we apply these temporal durations in measurement of other motions. Newton assumed that we ought to continue with "time" based in our rest frame. This is said to be an "absolute time". But it isn't really "absolute" time, it's just maintaining the old principle that we are at rest, and that observations of motions relative to us (as a sort of absolute rest) are the best suited for the measurement of time. You can see there is inconsistency because the principle of relativity denies that any perspective is true rest, but the "absolute time" perspective clings to our perspective as the true rest frame for producing temporal measurement. Einstein saw a way beyond this inconsistency by repealing the "absolute time" perspective.

Quoting noAxioms

The train example presumes the premises listed. If you deny those premises, then the train example ceases to demonstrate any inconsistencies.
I always took you for somebody in denial of Einstein’s theory precisely because only in one frame (and not an inertial one either) are all the events in ‘the present’ simultaneous with each other. In all other frames, this is not so, so the laws of physics are different between this and that frame, in violation of the principle. This follows from your assertions, ones with which I do not agree.

This is really confused. I haven't the foggiest idea of what you're trying to say. You seem to be employing the "absolute time" perspective to come up with "the present", yet also using "the relativity of simultaneity" to say that events in the present are not necessarily simultaneous. You cannot conflate these two in that way. They are completely different conceptions of time which are incommensurable. If you employ the relativity of simultaneity, you have no basis for a conception of "the present". And if you have the desire to base "the present" in your own observational perspective, or rest frame, as Newtonian "absolute time" does, this would just be an arbitrary designation, providing no true representation of "the present". This is why the principle of relativity puts "time" into an odd place. We can only measure time from our own perspective, yet relativity removes the validity of that perspective. Therefore we have no valid measurements of time.

Quoting Metaphysician Undercover

The proper analogy would be that jgill observed interference effects until he and his wife met up and she pointed out that she had been standing there all the time.
— Andrew M

So we say that jgill has extremely bad eyes, and all he sees until he's about three metres from his wife is a strange interference pattern? Suppose he's 50 metres away. How would he interpret the interference pattern as probabilities for the actual location of his wife? Consider that if this is a true analogy, the closer that he gets, he ought to be able to observe changes to the interference pattern which would increase his certainty.

It's the Wigner's friend thought experiment where the system in question (in this case Walmart rather than a laboratory) is isolated from the rest of the environment.

Per QM, the system could either be weakly measured (giving some information without destroying the superposition) or strongly measured resulting in rapid decoherence. Alternatively, the system could be transformed such that the probabilities change (including to certainty).

Quoting jgill

Wrong, but interesting. :smile:

Interesting, yes. See Wigner's friend.

Quoting noAxioms

"(any enumeration, not just an ordered one)"

How can any enumeration not be ordered?

I meant, "not just in order of smallest number to largest number."

Quoting noAxioms

If collapse isn’t physical and isn’t epistemological, then what is it?

Pragmatic. At some point it's necessary to ground a quantum mechanical description in a definite observation or measurement. So a Heisenberg cut is employed. As Heisenberg put it:

Quoting Heisenberg cut - Wikipedia

"The dividing line between the system to be observed and the measuring apparatus is immediately defined by the nature of the problem but it obviously signifies no discontinuity of the physical process. For this reason there must, within limits, exist complete freedom in choosing the position of the dividing line."

Neo-Copenhagen interpretations such as RQM, QBism and Consistent histories also employ this in their respective ways. All of these interpretations conform to the predictions of standard QM, including for Wigner's friend-style experiments. Whereas objective collapse theories are, in principle, experimentally differentiable from standard QM.

Quoting Andrew M

Per QM, the system could either be weakly measured (giving some information without destroying the superposition) or strongly measured resulting in rapid decoherence. Alternatively, the system could be transformed such that the probabilities change (including to certainty).

Can you elaborate these three, Andrew? What would be the act of a weak measurement? And, how could the probabilities involved with a specific system be changed to certainty without some form of measurement? To me, such a change would require a cause, and the cause would be a matter of "fixing" the system, like cheating if you're a gambler. But if "fixing" was possible then there would be no real mystery unless only the cheaters had figured it out.

Quoting Andrew M

It's the Wigner's friend thought experiment where the system in question (in this case Walmart rather than a laboratory) is isolated from the rest of the environment.

I've explained in other threads, that there is a potential problem with the application of systems theory towards real activity. Conventionally, there is a boundary defined which separates inside the system from outside the system. Any cause of change to the system (analogous to a force which changes the momentum of a body in Newtonian laws), must come from outside the boundary. However, this representation provides no place for what mystics and metaphysicians apprehend as a cause of change which comes from the inside.

So for example, gravity can be modeled as a cause of change (force) to a body's momentum, in the Newtonian way. It's modeled as an external force, acting on the body from the outside. But if gravity really acted on the body through the inside, this would require a completely different model for an accurate representation. And, that it may be the case that gravity acts through the inside is evidenced by the fact that the massive part of the atom is in the centre of the atom, and the massive parts interact directly through gravitation.

Allowing that causes of change which come from the inside are very real, and distinct from causes of change which come from the outside, forces the conclusion that systems theory does not provide an adequate representation. By classing all causes of change to the system which are not consistent with the system's inertial progression as "outside" the system, without distinguishing an inside boundary from the outside boundary, conflates these two distinct types of causation, potentially making some types of changes to the system impossible to understand.

Quoting Andrew M

The proper analogy would be that jgill observed interference effects until he and his wife met up and she pointed out that she had been standing there all the time.

Until Walmart opened its otherwise impervious doors. Contrary to most of the posts you’re getting, it has nothing to do with anybody actually looking at anything, with good or bad eyes.

How can any enumeration not be ordered?
— noAxioms
I meant, "not just in order of smallest number to largest number."

That’s just a different ordering, but any ordering can have a counting number assigned to each item in order. It’s still ordered.

If collapse isn’t physical and isn’t epistemological, then what is it?
— noAxioms
Pragmatic. At some point it's necessary to ground a quantum mechanical description in a definite observation or measurement.

OK, that seems to be a distinction between objective collapse and relational collapse, both of which are physical.

So a Heisenberg cut is employed.

A Heisenberg cut is a form of relational expression, that a system on one side of the cut is in some state (as represented by the wave function) relative to the system on the other side of the cut. Yes, the placement of the cut is arbitrary. The cut was first introduced as an epistemic cut (what one system knows about the other) but became a metaphysical one once the interpretation moved away from its epistemic roots.

Quoting Metaphysician Undercover

That something is moving, or in motion, is a human judgement.

I’m talking about the physics definition of motion, which does not require a human to be around deciding if it’s motion or not, even if it does require a human to have a human saying it’s motion.

Therefore it's completely nonsensical to talk about the motion of a thing in the complete absence of a second thing.

And yet again, your preferred wording of PoR does exactly that.

Then we add the observational data that there is always at least one body moving relative to any other, and this produces the conclusion that nothing is at rest.

I don’t see how that produces that conclusion.

The ontological principle "relativity" renders "rest" as not true.

It renders it meaningless, which is different than ‘not true’.

Our measurements of the passing of time are based in the ancient concept of motion within which, we as observers are assumed to be at rest.
[quote]Newton assumed that we ought to continue with "time" based in our rest frame. This is said to be an "absolute time".

Time wasn’t frame dependent back then, so it wasn’t based on any particular designated rest frame.

but the "absolute time" perspective clings to our perspective as the true rest frame for producing temporal measurement.

The absolute perspective has no dependency on the motion of any observer. Assignment of say Earth as the true rest frame is just arrogance and I’ve never seen a modern absolute interpretation that suggests it. Most of them suggest us moving at variable speed of around 350 km/sec and maybe twice that back when the T-rex was the local scary thing. This can be determined because spacetime isn’t Minkowskian, and the PoR only applies to Minkowskian spacetime.
But even those values are a local measurement of time since it varies based on gravitational potential as well, and we can’t know our absolute gravitational potential. So one ‘hour’ is not an actual hour, but a dilated one, even if measured by a stationary clock. So there are absolute theories out there, but even those cannot say how long an actual hour is.

Einstein saw a way beyond this inconsistency by repealing the "absolute time" perspective.

This is really confused. I haven't the foggiest idea of what you're trying to say.

Somehow I’m not surprised. Presentism requires a preferred frame. You don’t know this? Any other frame labels past and future events as simultaneous (ontologically different according to your assertions), which would be a contradiction. So presentism contradicts Einstein’s postulates and his theories along with them.

You seem to be employing the "absolute time" perspective to come up with "the present", yet also using "the relativity of simultaneity" to say that events in the present are not necessarily simultaneous.

Presentism says that all events in the present are necessarily simultaneous, does it not? Relativity of simultaneity is wrong in that case, something only derived from SR postulates, both of which are wrong under any form of absolute space and time.

Quoting noAxioms

I’m talking about the physics definition of motion, which does not require a human to be around deciding if it’s motion or not, even if it does require a human to have a human saying it’s motion.

You never provided any such definition, but if you think you can provide me with a definition of motion which does not require observation, be my guest, let's see it. Do you realize that motion is always a comparison? There are two factors, position and time. How do you suppose that motion could occur without a human to judge that time has passed?

Quoting noAxioms

The absolute perspective has no dependency on the motion of any observer.

Yes it does. The measurement of time is dependent on the observer's observations of motion. When motion is relative, the observer is necessarily moving if time is passing.

Quoting noAxioms

Somehow I’m not surprised. Presentism requires a preferred frame. You don’t know this? Any other frame labels past and future events as simultaneous (ontologically different according to your assertions), which would be a contradiction. So presentism contradicts Einstein’s postulates and his theories along with them.

You don't seem to understand how time is measured. As a result your response to my post doesn't make very much sense. You don't seem to actually address anything I said.

Quoting Metaphysician Undercover

Per QM, the system could either be weakly measured (giving some information without destroying the superposition) or strongly measured resulting in rapid decoherence. Alternatively, the system could be transformed such that the probabilities change (including to certainty).
— Andrew M

Can you elaborate these three, Andrew? What would be the act of a weak measurement? And, how could the probabilities involved with a specific system be changed to certainty without some form of measurement? To me, such a change would require a cause, and the cause would be a matter of "fixing" the system, like cheating if you're a gambler. But if "fixing" was possible then there would be no real mystery unless only the cheaters had figured it out.

Note that Wigner's friend is a thought experiment that is not practical (to say the least) with humans, but may one day be done using human-level AI's on a quantum computer.

With that said, suppose the friend's superposition state is:

|psi> = 0.6|here> + 0.8|there>

This means that there's a 36% chance of Wigner measuring the friend to be here as opposed to there (square the numbers to get the percentages).

To visualize the math, consider an XY axis where the |here> and |there> states are arrows (unit vectors) on the positive X and Y axes respectively and |psi> is an arrow from the origin to coordinates (0.6, 0.8).

If Wigner wants to test whether the friend really is in that superposition state, he can measure in the { |psi>, |-psi> } basis (where |-psi> is orthogonal to |psi>) and confirm that the result is |psi> (i.e., he sees +1 on his measurement dial rather than -1). Wigner can do this test multiple times and will always get the same result. This interaction is a weak measurement in the sense that information is extracted while leaving the friend in the initial superposition state.

Wigner can then measure her state in the { |here>, |there> } basis. This collapses |psi> to either |here> or |there>.

Alternatively, Wigner can rotate the friend's state onto one of the definite states, say, |here>. Wigner can then measure in the { |here>, |there> } basis which will confirm that she is here.

Quoting Metaphysician Undercover

Allowing that causes of change which come from the inside are very real, and distinct from causes of change which come from the outside, forces the conclusion that systems theory does not provide an adequate representation.

There's no problem with the friend acting inside the lab (e.g., moving here or there). However the subsequent measurement and/or rotation operations would be performed by Wigner from outside the lab.

Quoting noAxioms

Until Walmart opened its otherwise impervious doors. Contrary to most of the posts you’re getting, it has nothing to do with anybody actually looking at anything, with good or bad eyes.

Except maybe the measurement dials!

Quoting noAxioms

That’s just a different ordering, but any ordering can have a counting number assigned to each item in order. It’s still ordered.

:up:

Quoting noAxioms

A Heisenberg cut is a form of relational expression, that a system on one side of the cut is in some state (as represented by the wave function) relative to the system on the other side of the cut. Yes, the placement of the cut is arbitrary. The cut was first introduced as an epistemic cut (what one system knows about the other) but became a metaphysical one once the interpretation moved away from its epistemic roots.

:up:

Quoting Andrew M

Except maybe the measurement dials!

The entire quantum subject would be better served if "observer" were eliminated everywhere and replaced by "measurement". Then the casual physics dilettante could think, Yes, if I aim my flashlight at my keys on the table I don't disturb the keys, but if the keys were quantum size I might disturb them in the act of "observing" them. Just a comment.

Quoting jgill

The entire quantum subject would be better served if "observer" were eliminated everywhere and replaced by "measurement".

Can't have one without the other though. People often say, well measurement is any form of registration on any instrument, but we would never know that, save by checking. Long story short, science is an inextricably human undertaking, we can't perceive reality 'as it is in itself' as if were apart from our act of observing it. That's true all the time, but in quantum physics it becomes impossible to avoid.

Quoting jgill

The entire quantum subject would be better served if "observer" were eliminated everywhere and replaced by "measurement".

I think it's useful since we are observers. At any rate, since our understanding of quantum mechanics is incomplete, there's going to be differences of opinion on the best way to talk about it.

This is true even for experts in the field. For example, here's an argument I quoted earlier 'for observation'. And, in the other direction, here's John Bell's argument 'against measurement':

Quoting Against ‘measurement’ - John Bell, 1990

Here are some words which, however legitimate and necessary in application, have no place in a formulation with any pretension to physical precision: system, apparatus, environment, microscopic, macroscopic, reversible, irreversible, observable, information, measurement.

The concepts 'system', 'apparatus', 'environment', immediately imply an artificial division of the world, and an intention to neglect, or take only schematic account of, the interaction across the split. The notions of 'microscopic' and 'macroscopic' defy precise definition. So also do the notions of 'reversible' and 'irreversible'. Einstein said that it is theory which decides what is 'observable'. I think he was right - 'observation' is a complicated and theory-laden business. Then that notion should not appear in the formulation of fundamental theory. Information? Whose information? Information about what?

On this list of bad words from good books, the worst of all is 'measurement'. It must have a section to itself.

Against 'measurement'
...
The first charge against 'measurement', in the fundamental axioms of quantum mechanics, is that it anchors there the shifty split of the world into 'system' and 'apparatus'. A second charge is that the word comes loaded with meaning from everyday life, meaning which is entirely inappropriate in the quantum context. When it is said that something is 'measured' it is difficult not to think of the result as referring to some pre-existing property of the object in question.
...
In other contexts, physicists have been able to take words from everyday language and use them as technical terms with no great harm done. Take for example, the 'strangeness', 'charm', and 'beauty' of elementary particle physics.

No one is taken in by this 'baby talk', as Bruno Touschek called it. Would that it were so with 'measurement'. But in fact the word has had such a damaging effect on the discussion, that I think it should now be banned altogether in quantum mechanics.

The role of experiment
Even in a low-brow practical account, I think it would be good to replace the word 'measurement', in the formulation, by the word 'experiment'. For the latter word is altogether less misleading. However, the idea that quantum mechanics, our most fundamental physical theory, is exclusively even about the results of experiments would remain disappointing.

In the beginning natural philosophers tried to understand the world around them. Trying to do that they hit upon the great idea of contriving artificially simple situations in which the number of factors involved is reduced to a minimum. Divide and conquer. Experimental science was born. But experiment is a tool. The aim remains: to understand the world. To restrict quantum mechanics to be exclusively about piddling laboratory operations is to betray the great enterprise. A serious formulation will not exclude the big world outside the laboratory.

Quoting jgill

Then the casual physics dilettante could think, Yes, if I aim my flashlight at my keys on the table I don't disturb the keys, but if the keys were quantum size I might disturb them in the act of "observing" them. Just a comment.

If you do lose your quantum car keys, you can just call your local quantum mechanic.

Quoting Andrew M

you can just call your local quantum mechanic.

Who could be anywhere :lol:

Quoting Andrew M

Until Walmart opened its otherwise impervious doors. Contrary to most of the posts you’re getting, it has nothing to do with anybody actually looking at anything, with good or bad eyes.
— noAxioms
Except maybe the measurement dials!

Even looking at the measurement dials has no impact on the collapse or not. Of course, the descriptions you quote give a special role to an observer (writing down the reading of the dial say), but 1, it doesn’t take a human (or actual ‘observation’) to do that, and 2, it being written down isn’t what causes collapse. If the dial says |here>, then the wave function is collapsed whether or not anything (or person) reads that dial since the dial is not inside Walmart.

Quoting jgill

The entire quantum subject would be better served if "observer" were eliminated everywhere and replaced by "measurement".

Pretty much agree, but Andrew quotes a text that bashes even this word since it is still so open to common language interpretation, but I still agree and use the word in its proper context. Bell suggests ‘experiment’, but that loads the whole situation with intent that is meaningless. The dial unobserved seems not to be an experiment since nobody is recording what it says.
Quoting Wayfarer

Can't have one without the other though.

Nonsense. You can have measurement without observation such as the dial, reading |here>, but unnoticed by anybody.

People often say, well measurement is any form of registration on any instrument, but we would never know that, save by checking.

That’s an epistemological issue, not a metaphysical one. Measurement results a physical fact (in interpretations with physical collapse), and observation results in knowledge of that fact. The far side of the moon is still there when nobody looks at it since looking at it isn’t what makes it there.

Quoting Metaphysician Undercover

I’m talking about the physics definition of motion, which does not require a human to be around deciding if it’s motion or not, even if it does require a human to have a human saying it’s motion.
— noAxioms
You never provided any such definition, but if you think you can provide me with a definition of motion which does not require observation, be my guest, let's see it.

Well I googled ‘motion definition in physics’ and get a britannica one saying “change with time of the position or orientation of a body.“ which makes no mention of a requirement for observation (human or otherwise) to be involved. You seem to be attempting to worm in the definition of ‘measurement of motion’ or ‘human concept of motion’ or some other obfuscation hiding behind the line between map and territory.
Admittedly the definition that first comes up makes an implicit reference to a coordinate system without which the position or orientation of the object in question is not meaningful.
Wiki says something similar but adds “with respect to time”.
UW-Madison (a university, so must be far better than wiki per your post above) says unhelpfully: “Motion is the area of physics that studies how things move” which is just a self reference, useless without the definition of ‘move’. It also attempts to define the ‘study of motion’ which is quite different than the definition of motion itself.

Do you realize that motion is always a comparison?

It is a difference of position states at two different times. It is still motion even if those two positions are not compared by anything.

How do you suppose that motion could occur without a human to judge that time has passed?

That’s a pretty idealistic assertion. Are you one of those people that suggest that nothing happened before humans came along? I think that position can be driven to solipsism, which means motion cannot occur without you specifically to judge that time has passed, and that’s assuming that time is something that passes, something else with which I don’t agree, and which none of the definitions above require.

The absolute perspective has no dependency on the motion of any observer.
— noAxioms
Yes it does. The measurement of time is dependent on the observer's observations of motion.

I wasn’t speaking of measurement. Absolute time has no dependency on its being measured. If it flows, the rate (and direction) at which it does so is entirely independent of anything’s perception or measurement of it. You seem to keep attempting to make everything about your knowledge of something, about the map and not about the territory.

When motion is relative, the observer is necessarily moving if time is passing.

Apologies for ragging on every word, but you seem to be going out of your way with the weird suggestions this time. This statement here is no exception. If I’m here now and here later, that seems to be not-moving relative to ‘here’. OK, one might express that as motion at velocity (relative to here) of zero, which is arguably still motion. I would accept that.

You don't seem to understand how time is measured.

Again, I’m talking about time, not about how it is measured, so I’ve given no demonstration of my understanding of how time is measured or my lack thereof.

Quoting noAxioms

The far side of the moon is still there when nobody looks at it since looking at it isn’t what makes it there

You do recall the anecdote that Einstein once exclaimed, when walking with one of his friends, 'surely the moon still exists when no-one is looking at it!' This was in relation to the very assumption you're making, and he said it because of the challenge that quantum mechanics poses to scientific realism. In fact it's what this whole debate is about. When it comes to the denizens of quantum physics - purportedly the most fundamental constituents of physical existence - Bohr said 'no elementary phenomenon is a phenomenon until it is observed'.

Quoting Wayfarer

Can't have one without the other though.

What if the purely "mechanical" act of measurement produces a numerical result that goes automatically into a computer file and is never "observed" as it sits there and rots? :smile:

Quoting Andrew M

I think it's useful since we are observers. At any rate, since our understanding of quantum mechanics is incomplete, there's going to be differences of opinion on the best way to talk about it.

Thanks for your thoughtful reply.

Quoting Andrew M

If you do lose your quantum car keys, you can just call your local quantum mechanic.

Quoting Wayfarer

Who could be anywhere :lol:

Having imbibed a bit too much at the local pub he enters a state of superposition, thoroughly confused, an unknowing victim of a partial differential equation.

Quoting noAxioms

Measurement results a physical fact (in interpretations with physical collapse), and observation results in knowledge of that fact.

:up: :cool:

Quoting jgill

What if the purely "mechanical" act of measurement produces a numerical result that goes automatically into a computer file and is never "observed" as it sits there and rots?

As I said - through inductive reasoning, we can expect that the measurement is taken, that the data exists on that system unobserved. But you won't empirically verify that inductive step without observing the result. And isn't this very much at the heart of the whole issue? The realist attitude is, well all these processes simply occur, whether we're observing or not. But if that were so, then we wouldn't even be having this discussion!

Reply to jgill Just noticed the mechanic... :lol:

Quoting Wayfarer

The far side of the moon is still there when nobody looks at it since looking at it isn’t what makes it there
— noAxioms

You do recall the anecdote that Einstein once exclaimed, when walking with one of his friends, 'surely the moon still exists when no-one is looking at it!'

That comment was what made the moon the thing to exist (or not) based on watching it, sort of like the cat became the classic thing in the box.

This was in relation to the very assumption you're making

But I'm not making the assumption you probably think I am. I suspect the principle of counterfactual definiteness (scientific realism) is false. I'm pretty public about that. I take more a relational view.
First of all, 'looking at it' has nothing to do with anything. It is impossible for any human (dead or alive) to not be continuously measuring the moon.
Secondly, since the moon had been measured, it cannot suddenly jump into a nonexistent state. It's not a solution to the moon's wave function, or at least not one with a probability of zero to more digits than you can imagine. That's what I mean by the moon still being there when nobody looks at it. The moon has been measured and cannot be unmeasured.

he said it because of the challenge that quantum mechanics poses to scientific realism.

Which is why I'm not such a realist. If I say the moon exists, I mean that I've measured it, which doesn't involve looking or any other conscious function.

Bohr said 'no elementary phenomenon is a phenomenon until it is observed'.

But that's true classically. A human phenomenon by definition involves a human observation. Quantum collapse doesn't. It involves an interaction between two systems. Andrew M quoted Bohr on this distinction just a few posts above in the part labeled 'Against measurement'.

Quoting jgill

What if the purely "mechanical" act of measurement produces a numerical result that goes automatically into a computer file and is never "observed" as it sits there and rots?

It was observed in that scenario, so it makes no sense to say it was subsequently not observed. The statement attempts to use the dictionary definition of observation.
Quoting Wayfarer

As I said - through inductive reasoning, we can expect that the measurement is taken, that the data exists on that system unobserved.

You seem to do likewise. Conscious observation plays zero role except epistemic.
Quoting Wayfarer

But you won't empirically verify that inductive step without observing the result. And isn't this very much at the heart of the whole issue?

No, that's just an epistemic effect that has nothing to do with whether the result took place or not.

The realist attitude is, well all these processes simply occur, whether we're observing or not.

No, not at all. The realist attitude is that these things (objectively?) occur whether or not there is interaction with some other system. It has nothing to do with observation as you seem to be using the word: an action that a human does and a rock doesn't. Being forced to choose, I chose to discard objective realism of this sort, and for this reason.

Quoting noAxioms

since the moon had been measured, it cannot suddenly jump into a nonexistent state. It's not a solution to the moon's wave function, or at least not one with a probability of zero to more digits than you can imagine. That's what I mean by the moon still being there when nobody looks at it. The moon has been measured and cannot be unmeasured.

I think there's a deeper underlying issue. Despite your professed scepticism about scientific realism, I think your philosophical framework is still committed to a form of realism. This is an opportunity to explore the implications of that.

It is often said by way of objection to philosophical idealism, that idealism must mean that things go into or pass out of existence depending on whether they're being observed. After all that appears to be the implication of Berkeley's 'esse est percipe' - 'to be is to be perceived'.

But I don't think this is what philosophical idealism means - not, at least, as I understand it. This has to do with the nature of the objects of perception. Realism posits that the existence of those objects is independent of our perception or experience. They exist just so - in the case of the moon for billions of years. So it is preposterous to claim that they could cease to exist simply because nobody is looking at them. Yet this is what idealism seems to claim.

And I think this was the point of Einstein's rhetorical question. Realism expects that all such objects are really existent, independently of any mind or anyone's perception. That is, after all, the very definition of realism. This is the gist of Einstein's well-known declaration that he 'cannot seriously believe in [the quantum theory] because it cannot be reconciled with the idea that physics should represent a reality in time and space, free from spooky actions at a distance.'

But an alternative is to acknowledge that the existence of sensable objects is contingent and not absolute. This not to assert that objects exist in any absolute sense, on the one hand, but neither is it to claim that they cease to exist when they're not observed, on the other. It is to acknowledge that judgement concerning the reality of objects is a function of human sensory perception and reason, and that it is therefore not absolute. From the human point of view, all such objects exist - you'd better believe it! - but their existence is contingent and not absolute.

So this attitude does call realism into question but without falling into a caricature of idealism that it is easily taken to imply. I think it teaches us to respect that science is a human undertaking and that it's not a revelation of what is truly the case independently of any observer.

Or, put another way, that physics alone cannot constitute the totality of our experience.

Quoting noAxioms

Bell suggests ‘experiment’, but that loads the whole situation with intent that is meaningless.

It's not meaningless to point out the intent which is inherent within observation, measurement, etc.. And the intent is much more evident with the word "experiment". It's a fundamental fact that experiments are designed, and this points to the theory-laden nature of measurements and observations.

In general, the fact that experiments are designed is a very good feature of the scientific method. It allows us to control for specifics. However, design under defective theories, defective premises, etc., can also allow us to be drawn down long paths of misunderstanding.

The fact that the apparatus, rather than the human senses, does the observing, is something which the implications of, needs to be considered. The apparatus has the position of being a medium between the thing observed, and the human observer. Because of this, it is essential to know exactly what the apparatus is doing in this position, as necessary to an accurate interpretation of the observations. In the case of quantum experiments, the issue of exactly what the apparatus is doing, is where the experiments are very theory-laden.

To understand what I am saying, consider making observations through a magnifying glass. The magnifying glass is the medium between the observer and the thing observed, it's the apparatus. When interpreting your observations it is essential to know what the magnifying glass is doing in this position, because it could produce some sort of interference which would not be there naturally, (like the way it can focus light on the object to burn it) and you might interpret this interference as a natural part of the thing you are observing. The magnifying glass is a very simple thing, but it can have a strong causal effect on the observed thing, as the burning example shows. As we move toward more and more complicated observational apparatus, the microscope, the electron microscope, the need to understand the theory involved, and the soundness of the theory, in making interpretations becomes more and more important.

Quoting noAxioms

Well I googled ‘motion definition in physics’ and get a britannica one saying “change with time of the position or orientation of a body.“ which makes no mention of a requirement for observation (human or otherwise) to be involved.

I told you, time requires observation, it is the outcome of observation. So "change with time of the position..." does require observation. Time is part of the map. And, once you realize this, you'll see that "position" also is part of the map. It is a human designation of where a thing is in relation to other things. "Position" also requires observation. This is Kant's point when he says that space and time are fundamental "intuitions". They exist as part of the human being's observational apparatus, as intuitional theory, not as part of the thing being observed.

Quoting noAxioms

That’s a pretty idealistic assertion. Are you one of those people that suggest that nothing happened before humans came along?

I think there was no descriptions derived from human observations (of which "motion" is one), before humans came along.

Quoting noAxioms

Absolute time has no dependency on its being measured. If it flows, the rate (and direction) at which it does so is entirely independent of anything’s perception or measurement of it. You seem to keep attempting to make everything about your knowledge of something, about the map and not about the territory.

"Absolute time" is a misnomer. I told you this already. What is referred to as the perspective of "absolute time", is the assumption that one's position on the earth is the grounding point, as the position of rest, from which all passage of time is assumed to be relative to. Any measurement of time passing, the "flow" you refer to is done from this rest frame. It is said to be "absolute" because it serves as the grounding for the measurement of time for all frames of reference, unlike special relativity which allows the measurement of time to be frame specific.

Nevertheless, what is referred to as "absolute time" is a theoretical proposal, a condition of the observational perspective. It does not refer to something independent of the perspective, but it is a definitional feature of the perspective. So in the map analogy it is part of the "key", or "legend", which i necessary for interpreting and using the map. Therefore it is part of the map rather than the territory.

Quoting noAxioms

If I’m here now and here later, that seems to be not-moving relative to ‘here’.

Come on Axioms, your pretense of naivety is overwhelming me. This statement is so filled with problems that it is actually bordering on ridiculous. First, what the hell does "here" refer to? The term gives no positional reference. It's just a matter of you stipulating I am "here", and the place I call "here" at one time is the same place I call "here" at another time. Even if we could assume that "here" refers to the exact same position in "here now", as it refers to in "here later", thus creating the appearance that you have not moved, there's nothing to exclude the possibility that you flew around the whole universe in the meantime. So your sense of "seems to be not-moving" is not at all a logical conclusion, and is just as much an illusion as it is a case of you simply stipulating "I am here therefore I am not moving".

Quoting noAxioms

Even looking at the measurement dials has no impact on the collapse or not. Of course, the descriptions you quote give a special role to an observer (writing down the reading of the dial say), but 1, it doesn’t take a human (or actual ‘observation’) to do that, and 2, it being written down isn’t what causes collapse. If the dial says |here>, then the wave function is collapsed whether or not anything (or person) reads that dial since the dial is not inside Walmart.

Yes, decoherence doesn't depend on whether anyone looks or not.

Nonetheless the observer - or, even better, agent or person - closes the loop in the sense that it is human experience that grounds quantum theory and the quantities that can be measured.

A further point is that you won't ever find a contradiction when comparing what has been observed. It's the assumptions about what hasn't been observed that can lead to trouble as Bell's Theorem shows. Sometimes it's not even clear what should count as a measurement. For example, consider this passage from Sidney Coleman's lecture:

Quoting Quantum Mechanics in Your Face - Sidney Coleman

Neville Mott worried way back in 1929 about cloud chambers. He said: “Look, an atom releases an ionizing particle at the center of a cloud chamber in an s-wave. And it makes a straight line track.

Why should it make a straight line track? If I think about an s-wave, it is spherically symmetric. Why do they not get some spherically symmetric random distribution of sprinkles? Why should the track be a straight line?

One possible answer is that the cloud chamber is making a rapid series of measurements that constrain the particle to a straight line. Mott's answer (now the generally accepted answer) is that the cloud chamber is also a quantum system which evolves together with the particle and the potential paths not on the straight line cancel out. So nothing clearly qualifies as a measurement here.

Quoting jgill

Having imbibed a bit too much at the local pub he enters a state of superposition, thoroughly confused, an unknowing victim of a partial differential equation.

You might enjoy this excerpt from Coleman's lecture:

Quoting Quantum Mechanics in Your Face - Sidney Coleman

Now I will give an argument due to David Albert[21] with respect to Zurek’s question. Zurek asked: “Why do I always have the perception that I have observed a definite outcome?” To answer this question, no cheating: we can’t assume Zurek is some vitalistic spirit loaded with élan vital unobeying the laws of quantum mechanics. We have to say the observer—well I don’t want to make it Zurek, that would be using him without his permission, I’ll make it me, Sidney—has some Hilbert space of states, and some condition in Sidney’s consciousness corresponds to the perception that he has observed a definite outcome, so there is some projection operator on it, the definiteness operator. If you want, we could give it an operational definition: the state where the definiteness operator is +1 is one where a hypothetical polite interrogator asks Sidney: “Have you observed a definite outcome?”, and he says: “Yes”. In the orthogonal states he would say: “No, gee, I was looking someplace else when that sign flashed” or “I forgot” or “Don’t bother me, man, I’m stoned out of my mind” or, you know, any of those things.

In Coleman's account, these are all potential paths that can interfere.

Quoting Andrew M

Nonetheless the observer - or, even better, agent or person - closes the loop in the sense that it is human experience that grounds quantum theory and the quantities that can be measured.

That also seems true of say Newtonian theory. Is there some way in which human agency or observation makes a difference in (grounds) QT in a way that it doesn’t in NT? That would be a pretty incredible claim, that physics (and not just human theories/knowledge of physics) is different in the presence of humans than it is in a universe absent them.


Quoting Wayfarer

But I don't think this is what philosophical idealism means - not, at least, as I understand it. This has to do with the nature of the objects of perception. Realism posits that the existence of those objects is independent of our perception or experience.

But the converse is not true. It being independent of perception doesn’t necessitate a stance of realism. My ontology has nothing to do with perception, and yet I don’t suggest things ‘are real’ in any objective sense.

They exist just so - in the case of the moon for billions of years.

For instance, I wouldn’t make statements like that, but a realist would.

So it is preposterous to claim that they could cease to exist simply because nobody is looking at them. Yet this is what idealism seems to claim.

OK, but I’m not claiming idealism as you describe it. That’s about perception as you say.

And I think this was the point of Einstein's rhetorical question. Realism expects that all such objects are really existent, independently of any mind or anyone's perception. That is, after all, the very definition of realism. This is the gist of Einstein's well-known declaration that he 'cannot seriously believe in [the quantum theory] because it cannot be reconciled with the idea that physics should represent a reality in time and space, free from spooky actions at a distance.'

I don’t think quantum theory suggests idealism. Perhaps there was a suspicion way back then. People were just coming to terms with the new implications, watching all their classical assumptions getting trampled. The conversation by Einstein was part of that realization that the classical assumptions cannot all be correct. Bell went on later to prove that, saying that either realism or locality had to go. I think Einstein would have had a much harder time letting go of locality since all his relativity theory rests on premises that assume it.

But an alternative is to acknowledge that the existence of sensable objects is contingent and not absolute. This not to assert that objects exist in any absolute sense, on the one hand, but neither is it to claim that they cease to exist when they're not observed, on the other. It is to acknowledge that judgement concerning the reality of objects is a function of human sensory perception and reason, and that it is therefore not absolute. From the human point of view, all such objects exist - you'd better believe it! - but their existence is contingent and not absolute.

Don’t think any of that contradicts what I’m saying. Reality itself is neither absolute nor a function of perception, but judgment of it is a function of perception.

I think it teaches us to respect that science is a human undertaking and that it's not a revelation of what is truly the case independently of any observer.

I don’t see how that follows, sorry.


Quoting Metaphysician Undercover

It's not meaningless to point out the intent which is inherent within observation, measurement, etc.. And the intent is much more evident with the word "experiment". It's a fundamental fact that experiments are designed, and this points to the theory-laden nature of measurements and observations.

Usage of the word implies that quantum effects only occur when there is intent behind the measurements. There’s no evidence for that and heavy evidence against it. I’m not saying there’s anything wrong with intent in scientific experiments. That’s the point after all.

The magnifying glass is the medium between the observer and the thing observed, it's the apparatus.

Poor example I think since a magnifying glass doesn’t usually qualify as a measurement. They’re used in multiple places in typical laser experiments and they don’t collapse wave functions in them, else the experiments would fail. They’re not detectors, only refractors, and refraction wouldn’t work (wouldn’t bend light) at all if it constituted a measurement.

I told you, time requires observation, it is the outcome of observation.

How very idealistic of you. See Wayfarer’s post above about if perception is required for the reality of something.

I think there was no descriptions derived from human observations (of which "motion" is one), before humans came along.

But I wasn’t asking about descriptions. You say time requires observation. You didn’t say a description of time requires observation. I’d have agreed to that. So you’re evading the question instead by answering a different one.

First, what the hell does "here" refer to?

The origin of the coordinate system defined by the series of events at which I am present.

The term gives no positional reference.

Don’t be silly. You know it does. It is the location of that which said ‘here’.

there's nothing to exclude the possibility that you flew around the whole universe in the meantime.

But you said that being stationary was not possible, so you seem to exclude the possibility that you didn’t go anywhere during that interval. And as for my statement, had I indeed flown all around during that interval, at no time would I not be where I am, thus I’d always still be ‘here’. I’d simply not be inertial, so the coordinate system in which I am perpetually at the origin would not be an inertial coordinate system.

Quoting noAxioms

I don’t see how that follows, sorry.

That’s quite alright. Thanks for your feedback.

Quoting noAxioms

Nonetheless the observer - or, even better, agent or person - closes the loop in the sense that it is human experience that grounds quantum theory and the quantities that can be measured.
— Andrew M

That also seems true of say Newtonian theory.

Yes. Though, of course, we've found through observation that Newtonian theory is incorrect. Also, the "action-at-a-distance" aspect was suspect to Newton from the outset.

Quoting noAxioms

Is there some way in which human agency or observation makes a difference in (grounds) QT in a way that it doesn’t in NT? That would be a pretty incredible claim, that physics (and not just human theories/knowledge of physics) is different in the presence of humans than it is in a universe absent them.

No, my point is that quantum theory is constructed abductively from what we observe. As far as we know, it applies universally.

Quoting noAxioms

My ontology has nothing to do with perception..

Consider the old saying, "you see what you want to see". There are principles of interpretation inherent within, built into, and therefore affecting the way that you perceive things. What you believe about reality (your ontology) has a very real affect on the way that you perceive things.

And that is just the tip of the iceberg, what we have access toward understanding, through sciences like psychology. Underneath, in the subconscious, there are all sorts of similar factors affecting the way you perceive things. If your ontology is the conscious manifestation of your attitude toward the reality of the things you are sensing, then underneath there is all sorts of intuitions and innate tendencies which feed your ontology, but also have an immense affect on the way things are perceived by you.

Quoting noAxioms

Usage of the word implies that quantum effects only occur when there is intent behind the measurements. There’s no evidence for that and heavy evidence against it.

There is always intent behind human actions, therefore intent behind measurements. If you removed it the acts would be random. I don't know on what basis you say there is no evidence of intent behind measurements.

Quoting noAxioms

Poor example I think since a magnifying glass doesn’t usually qualify as a measurement. They’re used in multiple places in typical laser experiments and they don’t collapse wave functions in them, else the experiments would fail. They’re not detectors, only refractors, and refraction wouldn’t work (wouldn’t bend light) at all if it constituted a measurement.

The magnifying glass was an analogous example, to demonstrate how the tool of observation (apparatus arranged for observational purposes) affects the observations, and why there is a need to have very good theory, and understand the theory, behind the use of the tool which is used.

In no way was I saying that a magnifying glass is used to make quantum measurements. I really cannot understand your mode of interpretation noAxioms. Have you no experience with reading examples or analogies?

Quoting noAxioms

But I wasn’t asking about descriptions. You say time requires observation. You didn’t say a description of time requires observation. I’d have agreed to that. So you’re evading the question instead by answering a different one.

No Axioms, "time" is a descriptive term, just like "space" is a descriptive term. The point is that you cannot use these descriptive terms to refer to anything other than something which is observational, because observation is inherent within, as "implied by", being an essential feature of, what the terms refer to.

So, what "time" refers to is something derivative from the observation of motions. What "space" refers to is something derivative from the observation of bodies. There is no such thing as time without observation, or space without observation, because these words refer to concepts which are derived from observation, having the observation data inherent within, as an essential aspect of the concept. If you remove the essential aspect of the concept (observation in this case), the concept referred to by the word is annihilated.

I am not evading the question, you are evading the reality. You say that's "idealistic", and your ontological attitude is to deny idealism, so you deny the reality because it doesn't jive with your ontology. Instead of recognizing that observation is inherent in, as an essential part of what "time" means, and realizing that you need to change your ontology because your ontology is inconsistent with this, your recourse is to deny the reality, that observation is necessary to the meaning of "time". That is an unreasonable response, to deny the evidence because it is inconsistent with your belief.

Quoting noAxioms

Don’t be silly. You know it does. It is the location of that which said ‘here’.

I have no idea where you are, and therefore no idea where "here" is when you say it. Imagine two people in a dark space, one says "here", the other hears "here". Ten seconds later this is repeated. Then the person who said "here" insists "I haven't moved because both times when I said "here" I was truthfully "here". That's how ridiculous your claim was, that because you were "here" now, and "here" later, you hadn't moved.

If I was being silly, it was because I was laughing at the ridiculousness of your claim.

Quoting noAxioms

But you said that being stationary was not possible, so you seem to exclude the possibility that you didn’t go anywhere during that interval. And as for my statement, had I indeed flown all around during that interval, at no time would I not be where I am, thus I’d always still be ‘here’. I’d simply not be inertial, so the coordinate system in which I am perpetually at the origin would not be an inertial coordinate system.

Please, stop with the ridiculousness No Axioms! However, I will oblige you with your solipsistic example if it will make you feel better.

Wherever you are is "here", and all the time you are always here, and "here" always refers to the same place, the place where you are, therefore you are never moving. Anything else in the world is totally irrelevant to you because in your solipsistic reality, nothing is ever changing places relative to you, which might make you think that you are actually moving.

Now, you said "If I’m here now and here later, that seems to be not-moving relative to ‘here’. OK, one might express that as motion at velocity (relative to here) of zero, which is arguably still motion." What in the world are you referring to when you say "not-moving relative to 'here'"?

To me, "here" signifies the place where you are, therefore it's obvious that you cannot be moving relative to here, because that would be contradictory. "Here", by the definition in the example, is always where you are. Do you agree, that this sort of tautology, or self-evident truth, that you are never moving relative to yourself, says absolutely nothing about whether or not you are "moving"? That is because 'you moving relative to yourself', or the more precise account, 'you moving relative to the place where you are', is a nonsensical thing to say, and to make it into something sensible would require a different definition of "moving".

To make sense of "I am moving relative to the place where I am' would require a completely different definition of "moving". This would be a definition which is completely inconsistent and incoherent in relation to any conventional definition of "moving", allowing that a thing is moving relative to the place where it is. So your claim of "not-moving relative to 'here'" is completely nonsensical without changing the definition of "moving" to something inconsistent and incoherent in relation with conventional definitions.

Therefore your example using "here" says absolutely nothing about motion as we understand motion. All you are saying is that "motion" in this nonsensical way, of myself moving in relation to the place where I am, is inconsistent with how "motion" is used in any conventional way. And your example says absolutely nothing about "motion" as used in any conventional way.

Quoting Andrew M

No, my point is that quantum theory is constructed abductively from what we observe. As far as we know, it applies universally.

My point was that this abductive construction isn’t in any way something unique to quantum theory. That’s not what make it different, and it certainly doesn’t indicate that physical processes require the presence of humans. Sure, the human knowledge of physics requires humans, but that knowledge isn’t necessary for trees to fall in the forest when nobody is around.

Quoting Wayfarer

I don’t see how that follows, sorry.
— noAxioms
That’s quite alright.

You choose not to defend it. That’s alright too I guess. I will instead offer a counterargument.
Consider a Wigner’s friend scenario. The friend is in a box, takes a measurement, and based on that measurement, either drinks a hot tea or eats ice cream. To Wigner, the friend is in a superposition of consuming tea and of eating ice cream. This superposition can be demonstrated. Wigner opens the box to find the ice cream case. My question is, what is it like to be the tea-drinking friend?
Different interpretations say different things. MWI and relational might say that the tea drinking friend is observed by a different Wigner or is real only to that other Wigner. The objective collapse interpretations are hard to figure. Does the experience of the tea-drinker just suddenly cease? Does the tea drinker not actually have any experience of it? Is there more than one identity of the friend, one hot and one cold, or are somehow both states experienced by the same friend, but only one remembered? How would you reply to something like that?

Quoting Metaphysician Undercover

There is always intent behind human actions, therefore intent behind measurements.

You seem to be using the street definition of ‘measurement’ instead of the definition relevant to quantum theory. Please see the Bell quote in Andrew M’s post a few back which addresses exactly this naive mistake and the common misconceptions that result from such assumptions.

your ontological attitude is to deny idealism, so you deny the reality because it doesn't jive with your ontology

I’m not denying idealism, I’m merely not talking about it. Sure, under idealism, you (and nobody else) causes wave function collapse.

I have no idea where you are, and therefore no idea where "here" is when you say it.

That’s right. My coordinate system has no need for you to know where its origin is. But you can do it for yourself.

That's how ridiculous your claim was, that because you were "here" now, and "here" later, you hadn't moved.

That would be ridiculous since the frame reference was omitted from the assertion of not having moved, rendering it meaningless at best.

Anything else in the world is totally irrelevant to you because in your solipsistic reality, nothing is ever changing places relative to you

Where did I ever imply that? If you want to take my argument apart, surely you can do it without dragging in strawman stuff like that. So far, all I’ve seen is you applying the appeal to ridicule fallacy.

What in the world are you referring to when you say "not-moving relative to 'here'"?

Given a coordinate system in which some object is always at the origin, that object always at location zero and thus not moving relative to that coordinate system. This is tautologically true. That coordinate system would be an inertial coordinate system only if no external forces were acting on the object in question. Given the comment below, you seem to already know this.

Do you agree, that this sort of tautology, or self-evident truth, that you are never moving relative to yourself, says absolutely nothing about whether or not you are "moving"?

The bolded part of that statement gives no frame reference, so I would agree that nothing was said about that ambiguous statement. I will also say that something’s lack of motion relative to one frame does not imply lack of motion relative to a different frame, had an alternate one been specified.

To make sense of "I am moving relative to the place where I am' would require a completely different definition of "moving".

That depends on what the first definition (the one you apparently reject) was.

And your example says absolutely nothing about "motion" as used in any conventional way.

Agreed, but I’m not using conversational definitions of just about anything. I’m using physics definitions.

Quoting noAxioms

I’m using physics definitions.

Don't you see a problem with that?

Physical definitions don't have to have any meaning either in conversational or in a philosophical sentence. Even in physics meaning is convenient but superfluous as long as the formulas invented/derived describe to a point of prediction of possible phenomena. Physical definitions relate hypothetical mathematical objects of pure intellect. When explored philosophically, which is really unnecessary except to aid students in bridging to a physical mode of thinking, physical objects, such as energy and so on become Platonic conditional abstractions.

Quoting noAxioms

You seem to be using the street definition of ‘measurement’ instead of the definition relevant to quantum theory

Ha, ha, "street definition", that's funny. Is that the definition of "measurement" which the cop with the radar gun uses to prosecute in court? "I calibrated my machine in the lab according to...so that it would be accurate to within... on the street". On the street we don't really use definitions noAxioms.

Face it no Axioms, there's alwaya intent behind "measurement" no matter how you use the word. There must be or else there'd be no measurement. It determines what will be measured, when, how, all those decisions,

Quoting noAxioms

That would be ridiculous since the frame reference was omitted from the assertion of not having moved, rendering it meaningless at best.

Yes, and that was your assertion, that's why I said you were being ridiculous. "If I’m here now and here later, that seems to be not-moving relative to ‘here’." "Here" does not constitute a frame of reference. We went over that already. You are not adhering to proper definitions, as we discussed, and slipping back into street talk. You blabber on about "coordinate systems", then you assume that "here" constitutes one. The point of course, is that no frame of reference can use just one point, location must be established relative to another point. "Here" means nothing on its own. That's why I called your example solipsistic.

Quoting noAxioms

Given a coordinate system in which some object is always at the origin, that object always at location zero and thus not moving relative to that coordinate system. This is tautologically true. That coordinate system would be an inertial coordinate system only if no external forces were acting on the object in question. Given the comment below, you seem to already know this.

Are you proposing that you could map motion with a spatial representation that employs a coordinate system with only one locational point, a point zero, without any other points? How would that work? Let's see, object is always at point zero therefore object is never moving. What defines point zero? The place where the object is. Hmm, object never moves because object is always at point zero, 'here', and point zero is defined as "the location of that which said ‘here’". My spidey sense is tingling.

Quoting magritte

Don't you see a problem with that?

Quoting Metaphysician Undercover

Don't you see a problem with that? — magritte

You're taking that out of its context. It was only meant to help unravel an attempt at a correct subjectivist philosophy. Not only psychology but also some physics can only be seen that way. But how?

Quoting noAxioms

My point was that this abductive construction isn’t in any way something unique to quantum theory. That’s not what make it different, and it certainly doesn’t indicate that physical processes require the presence of humans. Sure, the human knowledge of physics requires humans, but that knowledge isn’t necessary for trees to fall in the forest when nobody is around.

I agree. Trees have a separate existence and evolution to us. Nonetheless the idea of trees falling only has meaning in the context of human experience. We can point to a tree and to something falling and say that this is what is meant. That relational connection grounds our language.

Quoting noAxioms

Please see the Bohr quote in Andrew M’s post a few back

I think you meant the John Bell quote.

Here's the current installment from the excellent Matt O'Dowd of PBS Spacetime on the reality of space and time (hey he's been working up to this title for a long while!) It is queued to a passage about Leibniz' view that space (and by implication time) are grounded, in some sense, in subjective perception rather than a truly mind-independent reality. Starts with 'Leibniz had another controversial idea...'



[quote=Matt O'Dowd]Leibniz felt that whatever it is that's out there that behaves like space only gains the subjective feeling of depth, breadth, height, and distance when our brains try to organise objects that are separated by an altogether more abstract property. [/quote]

Although I would comment that it's not that it's abstract, simply that, because it is a fundamental constituent of conscious awareness, it's not something we can be aware of. It is, as Kant would later say, a pre-condition of conscious experience.

Quoting Andrew M

Nonetheless the idea of trees falling only has meaning in the context of human experience.

This seems to be a point of contention because I’m not in any way talking about the meaning of the word trees or the human experience of one falling or lack thereof. I was referring to the tree itself falling in the total absence of human anything. It pains me to have to use human language to express that, but I’m not talking about the language, the expression, the concept, the fact that the tree happens to be my very distant cousin, or whatever. I’m talking about the tree.
It is me that nobody seems to get that? I’m not saying that the alternative (that noumena supervenes on human phenomena or human language) is necessarily wrong, but that such a stance utterly destroys any hope of acquisition of knowledge

I think you meant the John Bell quote.

Thx, fixed that. One 4-letter B-word is the same as another, no?

Quoting Metaphysician Undercover

Ha, ha, "street definition", that's funny. Is that the definition of "measurement" which the cop with the radar gun uses to prosecute in court? "I calibrated my machine in the lab according to...so that it would be accurate to within... on the street". On the street we don't really use definitions noAxioms.
Face it no Axioms, there's alwaya intent behind "measurement" no matter how you use the word. There must be or else there'd be no measurement.

This is all using the common definition. It seems appropriate that one should use the quantum theory definition of ‘measurement’ when discussing quantum theory. So rather than admitting this obvious thing, you resort again to ridicule in attempt to salvage your assertions.
If I’m wrong to use that definition, then tell me why. Once again, see Bell’s quote above discussing why quantum theory should never have used the word ‘observer’ or ‘measurement’ for precisely the reason you are demonstrating: I leads the naive reader to suspect that humans are somehow necessary for physics to work, that the universe supervenes on you and not the other way around. Yes, it’s a solipsistic stance you seem to be taking.

"Here" does not constitute a frame of reference.

No, it doesn’t. I had specified the frame in which I was stationary.

The point of course, is that no frame of reference can use just one point, location must be established relative to another point.

Just a velocity reference is enough, which is usually defined by the object referenced in establishment of that frame. So I can say ‘the local inertial frame of the sun’ which defines the velocities of everything around it but not any particular coordinate system. To generate a coordinate system, with numbers assigned to every nearby event, would require specification of an origin and of the orientation of the spatial axes. Saying ‘the inertial frame of the sun’ implies the sun at the origin, but only specifies the orientation of one axis, not the other three. So from just that, I cannot specify say the coordinates of Earth at a particular moment in time. I need to know where the axes are, and for that, more than one additional reference must be given. The plane of the ecliptic might define one of those, but still not the other two. A distant reference (Betelgeuse say) might suffice to anchor the other two.
So your statement would be correct about a coordinate system, but a ‘frame’ does not require additional references.

Are you proposing that you could map motion with a spatial representation that employs a coordinate system with only one locational point, a point zero, without any other points?

As per the above, a specification of only the origin defines a frame but does not assign coordinates to events not at that origin. So I could for instance have a frame of a rocket with the origin at the nose, the very ‘front’. That point will always be at the origin no matter what the rocket does, but we need two more points to make a coordinate system of it. So say the rear-most point is on the x axis, and some feature on the side defines the y axis. The z is just orthogonal to the other two and requires no additional reference. Now it’s a coordinate system, and the ‘abort’ button is always (nearly) stationary in this coordinate system regardless of what the rocket does. The astronaut knows where the button is despite the motion of the rocket because he’s using that coordinate system when needing to hit that button. I say ‘nearly stationary’ because vibration and other stresses will move that button a mm or two now and then due to strain on the vehicle.

Let's see, object is always at point zero therefore object is never moving. What defines point zero? The place where the object is.

Very good, The latter half even constitutes the frame reference, which you almost always omit.

Quoting noAxioms

Does the experience of the tea-drinker just suddenly cease? Does the tea drinker not actually have any experience of it? Is there more than one identity of the friend, one hot and one cold, or are somehow both states experienced by the same friend, but only one remembered? How would you reply to something like that?

I don't understand the point you're trying to illustrate. Nothing on the macroscopic level really exists in anything like the mathematical superposition of states that describe subatomic particles. It seems a version of the 'Schrodinger's cat' idea.

Quoting noAxioms

It pains me to have to use human language to express that, but I’m not talking about the language, the expression, the concept, the fact that the tree happens to be my very distant cousin, or whatever. I’m talking about the tree.

But you've already said:

Quoting noAxioms

I don’t suggest things ‘are real’ in any objective sense.

Yet in another place, you say

Quoting noAxioms

The far side of the moon is still there when nobody looks at it since looking at it isn’t what makes it there.

And also that:

Quoting noAxioms

If I say the moon exists, I mean that I've measured it, which doesn't involve looking or any other conscious function.

So, what do you mean, really? Because it seems to me, despite your claims to the contrary, that your view is realist, i.e. that trees, the moon, the proverbial table or proverbial apple, are all quite real, independently of anyone's knowledge or experience of them. Isn't that the point at issue?

Quoting noAxioms

It is me that nobody seems to get that? I’m not saying that the alternative (that noumena supervenes on human phenomena or human language) is necessarily wrong, but that such a stance utterly destroys any hope of acquisition of knowledge

I'm not saying anything like that. It seems to me obvious that without ordinary, everyday human experience we wouldn't be talking about trees falling in the forest, or quantum theory, or anything else. I'm not therefore saying that trees somehow depend on human experience. Obviously they don't.

Quoting noAxioms

I think you meant the John Bell quote.
Thx, fixed that. One 4-letter B-word is the same as another, no?

In this case ... no. ;-)

Quoting Andrew M

I'm not therefore saying that trees somehow depend on human experience.

Well good then. I was beginning to wonder since all the conversation kept turning to human discourse on physics and not the actual physics.

Obviously they don't.

Not even obviously. Many times things that are obvious are also wrong. As my username implies, I don’t assume anything.
In the end, a few premises are needed though, and I explicitly list that one (that humans are not special, and reality doesn’t supervene on my experience). I even attempt a logical demonstration of it, but I don’t think it constitutes a proof.


Quoting Wayfarer

I don't understand the point you're trying to illustrate.

I’m asking what it must be like to be the person who doesn’t win the wave function collapse.

Nothing on the macroscopic level really exists in anything like the mathematical superposition of states that describe subatomic particles. It seems a version of the 'Schrodinger's cat' idea.

Just because it is hard to do doesn’t mean the theory doesn’t support it. And it’s the Wigner’s friend idea, an extension of the cat idea. It works with the cat as well as long as you’re allowed to ask what it’s like to be the cat, which some deny.
And yes, I very much think that I undergo collapse like I describe since my choice of interpretation supports it. The experience is quite normal I assure you.

"I don’t suggest things ‘are real’ in any objective sense." — noAxioms

Yet in another place, you say "The far side of the moon is still there when nobody looks at it since looking at it isn’t what makes it there."

Translation: it is there relative to any person. Sorry that you found a case where I wasn’t explicit about the relation. I do not suggest that the moon is objectively real or even real relative to the universe.

And also that: "If I say the moon exists, I mean that I've measured it, which doesn't involve looking or any other conscious function."

Yes, there I am more explicit about the relationship and the nature of that relationship.

Quoting Wayfarer

So, what do you mean, really? Because it seems to me, despite your claims to the contrary, that your view is realist, i.e. that trees, the moon, the proverbial table or proverbial apple, are all quite real, independently of anyone's knowledge or experience of them.

Independent of knowledge and experience, yes, but not independent of measurement (quantum definition, since everybody seems to presume otherwise). A rock measures the moon as much as I do, and so the moon exists to the rock. The relationship has absolutely nothing to do with one part of the relation being something living or perceiving or having any sensory apparatus.

Quoting noAxioms

the moon exists to the rock

Only if they interact. Otherwise neither exists to the other.

The point is to look at what it means to 'exist' objectively, publicly, subject independently and time&space independently, as against exist subjectively with reason.

Subjectively the rock is the center of its universe without denying the possibility of the subjective universe of others. Without interaction nothing can exist.

Solipsism is an extreme scenario that denies other universes.

Quoting noAxioms

A rock measures the moon as much as I do, and so the moon exists to the rock.

Inanimate objects don't measure anything. And measurement is a conscious process. The 'moon exists to the rock' is a meaningless statement.

'Imagine that all life has vanished from the universe, but everything else is undisturbed. Matter is scattered about in space in the same way as it is now, there is sunlight, there are stars, planets and galaxies—but all of it is unseen. There is no human or animal eye to cast a glance at objects, hence nothing is discerned, recognized or even noticed. Objects in the unobserved universe have no shape, color or individual appearance, because shape and appearance are created by minds. Nor do they have features, because features correspond to categories of animal sensation. This is the way the early universe was before the emergence of life—and the way the present universe is outside the view of any observer' ~ Charles Pinter, Mind and the Cosmic Order.

So - the observer creates the reality. This is not a figurative expression or a thought-experiment. It is actually happening moment-by-moment.

Quoting Wayfarer

the observer creates the reality.

Questionable in my opinion Wayfarer, the observer observes reality, and even as far as the observer has the ability to affect reality. Whether the observer CREATES reality runs into the problem of reality CREATING the observer.

Quoting magritte

the moon exists to the rock
— noAxioms
Only if they interact. Otherwise neither exists to the other.

That's the relational view, yes.

The point is to look at what it means to 'exist' objectively, publicly, subject independently and time&space independently, as against exist subjectively with reason.

I didn't get that whole list. To exist is a matter of definition. Objectively seems to be in the absence of measurement. "There is a universe with 4 spatial and 2 time dimensions". That seems to be an objective statement of reality.
Publicly I suppose means that the rock and the water both measure the moon and each other. I didn't get the rest.

Subjectively the rock is the center of its universe without denying the possibility of the subjective universe of others. Without interaction nothing can exist.

The word 'subjectively' implies the rock has experience. I selected it because it doesn't.


Quoting Wayfarer

So, realist.

No. Realist is counterfactual definiteness, existence in absence of measurement. Existence due to measurement is not that.

Quoting Wayfarer

Inanimate objects don't measure anything. And measurement is a conscious process.

I expect such statements from @Metaphysician Undercover, but you also seem to fail to use the quantum theory definition of 'measurement' in a topic discussing quantum theory. Hence the rise (and fall) of the Wigner interpretation which, due to that language ambiguity, gave rise to the proposal that consciousness causes wave function collapse, an interpretation abandoned by Wigner himself due to it being driven to solipsism.

The 'moon exists to the rock' is a meaningless statement.

Thank you for you time then.

Charles Pinter, Mind and the Cosmic Order:'This is the way the early universe was before the emergence of life—and the way the present universe is outside the view of any observer'

I disagree with Charles here. Words were used by Pinter to describe this counterfactual reality. I agree that there'd be nothing to put words to the features of things, or to designate certain arrangements of matter as a 'thing' in the first place. But none of that stops physics from happening. It only stops physics from being meaningfully described by anything in that universe.

While I'm disagreeing with him, I'm also on record for stating that absence of life doesn't imply the necessary absence of language, as the quote suggests.

Quoting noAxioms

But none of that stops physics from happening.

Physics is a human undertaking. Who is doing the measuring is just as much part of it as the object of measurement. The mistake is to believe that physics describes a universe as if there were no humans. All measures are made by humans. All that's happened throughout all this is that quantum physics has now made that obvious.

Quoting noAxioms

Realist is counterfactual definiteness, existence in absence of measurement.

Just for the sake of clarity:

[quote=ChatGPT]In physics, counter-factual definiteness is a concept related to the measurement problem in quantum mechanics. It refers to the idea that physical systems have definite properties, even if they are not measured or observed.

According to counter-factual definiteness, if a measurement had been made on a quantum system, it would have had a definite outcome, even if that outcome was not actually observed. In other words, the properties of a system exist independently of any measurements or observations made on it.[/quote]

Quoting noAxioms

Existence due to measurement is not that.

So, you're still 'realist', but you are outsourcing measurement to everything that exists:

Quoting noAxioms

The relationship has absolutely nothing to do with one part of the relation being something living or perceiving or having any sensory apparatus.

So, 'measurement', for you, occupies the place that 'God' does, for Berkeley, i.e. it keeps everything in existence when not being observed, as Berkeley's God keeps everything in existence even while not being perceived.

Quoting noAxioms

Once again, see Bell’s quote above discussing why quantum theory should never have used the word ‘observer’ or ‘measurement’ for precisely the reason you are demonstrating:

I read that. It in no way indicates that there is not intent behind measurement in quantum physics. The article suggests replacing "measurement" with "experiment". The use of "experiment" simply enforces the fact that there is intent. And I really do not see how you can conceive of any sort of measurement (experiment) without intent. I explained already why I think measurement without intent is impossible, now it's your turn to explain how you think there could be such a thing.

To begin with, do you recognize that a system is an artificial thing, a human creation, whether it is a theoretical system, with boundaries imposed by theory, or a mechanical system, with created physical boundaries? And, artificial things are created with intent.

Quoting noAxioms

A rock measures the moon as much as I do, and so the moon exists to the rock.

All you are saying here, is that you've never measured the moon, because the rock sure hasn't, by any definition of "measure", measured the moon.

Quoting noAxioms

Realist is counterfactual definiteness, existence in absence of measurement. Existence due to measurement is not that.

How are you using "measurement" here? If to interact is to measure and be measured, as you seem to think (which is a ridiculous definition of "measure" not consistent with any actual usage), then by what principle do you assume that there is any sort of "existence in absence of measurement"? That would mean you are assuming something which interacts with nothing.

Quoting noAxioms

I expect such statements from Metaphysician Undercover, but you also seem to fail to use the quantum theory definition of 'measurement' in a topic discussing quantum theory. Hence the rise (and fall) of the Wigner interpretation which, due to that language ambiguity, gave rise to the proposal that consciousness causes wave function collapse, an interpretation abandoned by Wigner himself due to it being driven to solipsism.

You are not paying attention to the article which you requested that I read. The article suggests reasons why "measurement" should not be used, because "measurement" to most people implies some real existing aspect of the universe which is measured, like when we count something we assume that there is an existing quantity which can be counted and it has some real existence as that quantity, prior to being counted. This is what Bell says is misleading in quantum mechanics. What is being "measured" has no real existence prior to the measurement. And so he suggest that "measurement" be replaced with "experiment".

Quoting noAxioms

I leads the naive reader to suspect that humans are somehow necessary for physics to work, that the universe supervenes on you and not the other way around.

The issue is not the relation between human beings and the universe, it is the relation between human beings and the "measurement". In order to make a measurement there are constraints placed on the universe. These controls are necessary in order that the measurement measures what it is supposed to measure. The form of an "experiment" for example is to follow a specific procedure. It is necessary to follow the procedure in order to fulfil the intent of the experiment, which is to test an hypothesis.

Humans are necessary for the measurement. But when you represent the measurement (being the confines of the experiment) as the universe, you step way outside the boundaries of the measurement. The measurement is not measuring the universe, it is measuring whatever is being controlled for, which is dictated by the intent behind the experiment.

Quoting noAxioms

No, it doesn’t. I had specified the frame in which I was stationary.

You did not specify a frame, you said "here".

Quoting noAxioms

Just a velocity reference is enough,

"Here" does not provide a velocity reference. And you've got things backward anyway. A frame of reference, with multiple location points is required to make a velocity reference, not vise versa.

.Quoting noAxioms

but a ‘frame’ does not require additional references.

Yes it does, and you've misrepresent "frame" as a point. A point is not a frame.

Quoting noAxioms

As per the above, a specification of only the origin defines a frame...

No, a point does not constitute a frame. You seem to have no technical understanding of this matter, insisting that the coordinate system is derived from the frame, rather than that the frame is a derivative of the coordinate system. You need to straighten out your logical priority. "Frame" implies "coordinate system". There is no frame without a coordinate system as you seem to believe.

Quoting noAxioms

So I could for instance have a frame of a rocket with the origin at the nose, the very ‘front’. That point will always be at the origin no matter what the rocket does, but we need two more points to make a coordinate system of it. So say the rear-most point is on the x axis, and some feature on the side defines the y axis. The z is just orthogonal to the other two and requires no additional reference. Now it’s a coordinate system, and the ‘abort’ button is always (nearly) stationary in this coordinate system regardless of what the rocket does. The astronaut knows where the button is despite the motion of the rocket because he’s using that coordinate system when needing to hit that button. I say ‘nearly stationary’ because vibration and other stresses will move that button a mm or two now and then due to strain on the vehicle.

Your "frame" in this example is a coordinate system which maps the rocket, not one point such as "here". And if you say that the rocket is one point, "here", this is a misrepresentation, because the rocket is mapped as a frame of reference, consisting of a coordinate system with multiple locational points.

Quoting noAxioms

Very good, The latter half even constitutes the frame reference, which you almost always omit.

This clearly demonstrates your misunderstanding. a point cannot constitute the frame of reference.

Quoting noAxioms

In the end, a few premises are needed though, and I explicitly list that one (that humans are not special, and reality doesn’t supervene on my experience). I even attempt a logical demonstration of it, but I don’t think it constitutes a proof.

Per "reality doesn’t supervene on my experience", it seems to me that that is how me ordinarily use language. It works well, while other uses are problematic.

I only skimmed this thread, but has the Born Rule problem really not come up?

To bring up the example before, it is like someone's spouse is either in spot A with probability 30% or spot B with probability 70%, except, get this, she is also in BOTH spots with probability 100%. Explaining that satisfactorily is going to be a doozy, and I don't think Dutch Book arguments really solve the problem.

There is also the issue of worlds existing where large systems, perhaps the whole universe, decrease in entropy over time. I can see why, if you're committed to reduction, it is tempting to kick the Second Law out to the status of "initial conditions," but I have never seen a satisfactory explanation of why we should find ourselves in the world that has increasing entropy, except in an appeal to the anthropic principle. This is a weak appeal though, as it is hard to show conclusively how sentient observers are only likely to exist in worlds with increasing global entropy.


Reply to Metaphysician Undercover

The real problem here is with the notion of "the present universe". What Einstein reveals with the relativity of simultaneity is that "the present" is frame dependent. So the whole idea that there is such a thing as "the present universe" is an unsound premise because "the present" is something created by the observational perspective.

When we realize that "the present" is purely subjective, and we try to imagine an objective universe, independent from any observer, we have no place to insert "the present", because this would be an artificial insertion, therefore the creation of an observational perspective. Then we cannot possibly imagine such a universe, without a designated temporal perspective, (a point in time of now), because all things would exist everywhere, without some way of determining a specific point in time in their motions.

Relativity shows simultaneity is local, not that it is somehow arbitrary. It is not the case that relativity in any way prescribes eternalism, although this has not stopped popular science authors from making this claim (or others from continually coming along to debunk it; I have not seen the debunking debunked in turn however, and it convinced me).

No one present is privileged, but you can have a "many fingered time," with multiple time variables.

Not sure if that's what you meant by "subjective," but that is certainly a common misconception. That there are issues with positing the world as it is sans observers is quite true, but it is true even ignoring SR/GR.

Quoting Count Timothy von Icarus

I only skimmed this thread, but has the Born Rule problem really not come up?

To bring up the example before, it is like someone's spouse is either in spot A with probability 30% or spot B with probability 70%, except, get this, she is also in BOTH spots with probability 100%. Explaining that satisfactorily is going to be a doozy, and I don't think Dutch Book arguments really solve the problem.

See the brief discussion earlier in the thread (with a link to Sean Carroll's solution).

Reply to Andrew M

I see it now. Yes, I am aware of that solution, and while clever, it doesn't seem satisfactory. The whole Sleeping Beauty problem class seems to be misused in a lot of physics scenarios, IMO, in part because rational agent based models aren't reversible. For example, this is where Tegmark's first book (mentioned ITT) begins to start going off the rails. He starts talking about the Doomsday Problem, and "what are the chances that you would randomly be the nth member of X sentient species ," in terms of frequencies.

This is an area where frequentism starts to become incoherent if you apply it this way. MWI is deterministic. The person you are and the time you exist in history isn't random or independent, it is entirely determined in MWI. You can apply frequentism in plenty of physics cases and get away with it, but using it here in the context of cosmic inflation or MWI makes absolutely no sense.

In the Doomsday Scenario for instance, any early human would have been just as justified in thinking humanity will die out before even 5 billion people are born as Tegmark is today worrying about humanity going extinct before 250 billion people. But obviously, when one lives is not i.i.d. He's obviously a smart guy, and I enjoyed most of the book, but this and some Born Rule explanations could be part of a public awareness campaign called "this is your brain on frequentism. Just say no! (to calling probability and frequency identical)"

You can turn the Born Rule into an argument about which bets a person should place, but that doesn't answer why those bets are likely to be good ones except in terms of empiricism when the derivations of the Born Rule are circular (e.g. when using axioms originally added just for the Born Rule). It becomes a sort of hybrid frequentist-QBism in some solutions, which I don't even think is coherent if it is unpacked.

Or, to let someone else say it:

From these axioms they conclude that rational agents should bet on the outcomes of a quantum experiment with probabilities given by the Born rule. Who cares? Should we really believe that the statistics of an experiment will be constrained by rationality axioms? And conversely, if you can show that the statistics of a quantum experiment follow the Born rule, doesn’t it become obvious that rational agents should bet that they do, making the whole decision-theoretic argument superfluous? It’s worth noting that this same criticism applies to my derivation, as it is just a cleaned up version of the Deutsch-Wallace argument...

Let’s move on to Vaidman, Carroll, and Sebens. Their derivations differ on several important points, but I’m interested here in their common point: they passionately argue that probability is about uncertainty, that a genuine source of uncertainty in Many-Worlds is self-locating uncertainty, and that locality implies that your self-locating uncertainty must be given by the Born rule. Arguing about whether probability is uncertainty is a waste of time4, but their second point is well-taken: after a measurement has been done and before you know the outcome, you are genuinely uncertain about in which branch of the wavefunction you are. I just don’t see how could this be of fundamental relevance. I can very well do the experiment with my eyes glued to the screen of the computer, so that I’m at first aware that all possible outcomes will happen, and then aware of what the outcome in my branch is, without ever passing through a moment of uncertainty in between. Decoherence does work fast enough for that to happen.5 What now? No probability anymore? And then it appears when I close my eyes for a few seconds? That makes sense if probability is only in my head, but then you’re not talking about how Nature works, and I don’t care about your notion of probability.

https://mateusaraujo.info/2021/03/12/why-i-am-unhappy-about-all-derivations-of-the-born-rule-including-mine/

I don't have these same concerns, but I think it is important than many proponents of MWI do list similar concerns about other theories in quantum foundations.

I like MWI for itself elegance; no ad hoc collapse. But there is a problem where theory is elevated above empirical results (i.e. the observation of apparent collapse), but then a crucial element of collapse, is then explained in terms of epistemology. Why prefer shifting the [I] squishy [/I] part of the theory from one place to another?

This is also the issue of "splitting" versions of MWI. In these, there isn't one universal wave function that we see part of, but instead the universe actually "splits," during measurement. The problem is that, while physics is time asymmetrical as a whole, parts under consideration are not, making the "causal" relationship between measurement and "splitting" another thing that begs explanation (and this is true even if you argue "cause" is just another name for description). Splitting then seems as ad-hoc as collapse, whereas a seeming benefit of non-splitting versions is that such collapse/splitting is only an appearance.

Furthermore, because MWI is fully deterministic, it seems like we should have a block universe. But do we have a growing block universe where splits occur in the direction of time's passage? That is what the splitting versions of MWI seems to suggest. But if each world is its own four dimensional object then it seems we need a new, fifth, "time" dimension for the multiverse in which splitting occurs, this being true even if we take an eternalist view of such splits as having already occured/existing eternally. There is a state of the multiverse M1 before a split occurs where it has fewer branches than M2, the multiverse at a later time, but this change cannot occur across the same time dimension as the time dimension that each individual universe has, since a split is necessarily the spawning of a new, complete four dimensional object.

Then we have to consider that, if we have an eternalist view of things, why is it that, by reversing the direction of time, we have a universe where many universes begin to merge into a smaller number of universes? Is the direction of splitting the true arrow of time? If so, why (and why are there so many physicists who embrace eternalism, claim physics is ultimately reversible, and embrace MWI?) If the physics in question is reversible, why do we posit a splitting universe instead of a merging one, aside from the fact that having it split in both directions (forwards and backwards in time) is incoherent?

Perhaps whenever we make a measurement we merge universes, such that we progress by such merges to one of many potential end points, final conditions, of the universe, assuming ad hoc that it has an end? This might work, but it blows up the rational-agent based derivations of the Born Rule. Rational agent models are not reversible, we don't say, "given what I observe now, what must have happened in the future, what endpoint must I be most likely to be converging on?"

The problem might be worse, since splits occur vis-á-vis a parent, such that we can arbitrarily pick any starting point and then see a family tree descending from that current universe. If we have two such family trees, does it work to say that splitting in both occurs across the same dimension? I'm not sure it does, given the "multi-fingered" nature of time in our one observable universe, in which case you need even more time dimensions.

Quoting Count Timothy von Icarus

Relativity shows simultaneity is local, not that it is somehow arbitrary. It is not the case that relativity in any way prescribes eternalism, although this has not stopped popular science authors from making this claim (or others from continually coming along to debunk it; I have not seen the debunking debunked in turn however, and it convinced me).

What I said in the quoted passage is that the idea that there is a present state of the universe, is shown to be unsound by special relativity, as a premise which is inconsistent with special relativity. This is consistent with "simultaneity is local". I wasn't talking about eternalism.

Quoting Count Timothy von Icarus

No one present is privileged, but you can have a "many fingered time," with multiple time variables.

Sure, but this presents a problem toward understanding any causal relations between "one present" and another present. The present is local, but there is still interaction between far away places, as the travel of light indicates.

Quoting Count Timothy von Icarus

That there are issues with positing the world as it is sans observers is quite true, but it is true even ignoring SR/GR.

I certainly agree with this. However, as a person who is a temporal realist, it is easy for me to see SR/GR as taking advantage of the fact that there are issues with positing the world as it is sans observers.

The issue is that knowing how the world would have been without observers is not a realistic counterfactual to entertain. This is because even if we could theoretically produce a "without observers" perspective, any sort of "knowing" which is derived from this perspective still implies observers, as "knowledge" has an observational aspect.

So the first thing that I notice, if I try to produce an observer-free perspective in theory, is that the "here" of "here and now" (here and now being the defining features of the observational perspective), could be anywhere, and the universe would maintain intelligibility. However, the now, since "now" must be restricted to a specific duration of time to make the universe intelligible, does admit to that freedom. If "now" were an infinite duration of time, the universe would be unintelligible because everything would be everywhere, now. The conclusion therefore, is that how we understand "now" determines which aspects of the universe will be intelligible to us.

So let me relate this to why I say SR/GR takes advantage of the problem with positing a world without observers. To understand the universe in its totality requires that we have a conception of "now", which accurately accounts for all the restrictions imposed by the reality of what now is. But SR/GR provides no real principles to account for the reality of now, thus allowing "now" to be defined by other principles. As explained above, this will render aspects of the universe (where the restrictions imposed by theory are not representative of the restrictions imposed in reality) as unintelligible.

Quoting Wayfarer

Physics is a human undertaking.
...
All measures are made by humans.

Fine. I googled ‘what is measurement in quantum mechanics’ and got this [quote=”Wiki: Measurement in quantum mechanics”]In quantum physics, a measurement is the testing or manipulation of a physical system to yield a numerical result. [/quote]This seems more a classical physics definition of measurement, but I concede the point that there is implied intent going on.
I don’t have a different word to use. Therefore we lack for vocabulary since ‘measurement’ and ‘physics’ are both human undertakings and apparently cannot be used for interactions not involving humans.
What do you call the actual mechanisms of the universe, as opposed to ‘physics’, the human undertaking to describe it? What would you call an interaction between systems of which humans are completely unaware, say where one system (some radioactive atom) emits an alpha particle which alters a second system (some molecule somewhere) by altering its molecular structure (and probably heating up the material of which the molecule is part). It isn’t a measurement because there’s no intent and no numerical result yielded, so what word describes this exchange between the atom and the molecule?
Bell complained of ‘measurement’ as well, saying it comes loaded with meaning from everyday life, meaning which is entirely inappropriate in the quantum context. This is exactly what I’ve been trying to convey.
Give me another word that you find acceptable that describes that which makes the state of system B collapse relative to system A. 'Interaction' seems a plausible candidate, but not all interactions constitute the state of B causing an alteration the state of A.

That of which I am speaking is the measurement in the quantum measurement problem, which has a different wiki page.[quote=”Wiki: Measurement problem]In quantum mechanics, the measurement problem is the problem of how, or whether, wave function collapse occurs. The inability to observe such a collapse directly has given rise to different interpretations of quantum mechanics and poses a key set of questions that each interpretation must answer.
The wave function in quantum mechanics evolves deterministically according to the Schrödinger equation as a linear superposition of different states. However, actual measurements always find the physical system in a definite state. Any future evolution of the wave function is based on the state the system was discovered to be in when the measurement was made, meaning that the measurement "did something" to the system that is not obviously a consequence of Schrödinger evolution. The measurement problem is describing what that "something" is, how a superposition of many possible values becomes a single measured value.[/quote]
This is what I am talking about. What precisely physically ‘does something’ to a system that makes its [past] state change, I say physically because I’m not talking about somebody’s mere knowledge or description of a system. I assure you it isn’t the determination of a numerical value by a conscious entity that changes the target system.
Now one can certainly posit that the universe supervenes on humans, and that physical systems collapse into a real state only when a human consciousness tests or manipulates a laboratory system in such a way to yield a numerical result. Such an idealistic interpretation does not concern me, but it is listed as one of the obscure interpretations.
There are various other interpretations. A counterfactual one (e.g. Bohmian mechanics) would say that the wave function never collapses and all systems are in one state, measured or not. Superpositions are an illusion, and apparent interference is due to something other than a system being in more than one state.
MWI would also say no collapse, and an interaction from B to A would simply entangle A with B’s superposition of different states, all of which are instantiated in various worlds. MWI is a realist interpretation that denies counterfactual definiteness, so that principle is not equivalent to a stance realism.
Others call out an arbitrary divide between A and B, or ‘system’ and ‘aparatus’ as Bell puts it. This wording implies again that quantum effects only occur when intentional apparatus is involved, but the interpretations do not suggest this. In Copenhagen, the Heisenberg cut delimits measurer and measured. It can be assigned arbitrarily and is entirely abstract. Actual physical systems have no meaningful boundaries of objects or systems.
A relational view is similar, where an arbitrarily defined system’s state relative to a different system changes upon some kind of interaction from one to the other.



Quoting Wayfarer

[Counter-factual definiteness] refers to the idea that physical systems have definite properties, even if they are not measured or observed.

Given your definitions, this seems to translate to a system having properties despite the absence of humans, which is impossible since ‘system’ and ‘property’ are human terms, not meaningful in the absence of humans.
Alternatively, you perhaps suggest an epistemological definition of counter-factual definiteness, where in the absence of human measurement/observation, humans would not know of the thing, and existence is defined by human knowledge of it. Hence, again, by definition, nothing can exist in the absence of humans since no human could know of it. Counter-factual definiteness is therefore false either way.
Correct me where I’ve misinterpreted what you’ve been trying to tell me.

So, you're still 'realist', but you are outsourcing measurement to everything that exists

No, because ‘everything that exists’, lacking a relation, is meaningless in a view requiring such a relation. It’s worded as an objective statement. Only a realist gives meaning to such a phrase.

So, 'measurement', for you, occupies the place that 'God' does, for Berkeley, i.e. it keeps everything in existence when not being measured, as Berkeley's God keeps everything in existence even while not observed.

No. That’s still a cheap attempt to put objective existence on things, like it was a property instead of a relation. I also don’t see how a god (or anything not part of the quantum structure) could measure a closed quantum system.
Why do you find it so difficult to let go of your realist assumptions when being asked to consider an alternative? You seem only determined to pin the realist label on me, listing one strawman argument after another.
I think a god watching (if that is even meaningful) would put categorize things into ‘that which this god watches’, as distinct from that which it doesn’t, which would still be a relation with the god. It would only be realism if the god was real (sans relation).


Quoting Metaphysician Undercover

do you recognize that a system is an artificial thing, a human creation, whether it is a theoretical system, with boundaries imposed by theory, or a mechanical system, with created physical boundaries?

I was going to agree with this until the last bit about physical boundaries. A system’s boundaries are an arbitrary abstraction, nothing physical about it. But the arbitrary designations are needed for description, not for the actual processes to work.

then by what principle do you assume that there is any sort of "existence in absence of measurement"?

Given this intentional definition of ‘measurement’, I cannot answer this question since I don’t define existence in terms of it, but it sounds like a version of the principle of counterfactual definiteness. I personally choose to deny that principle.

because "measurement" to most people implies some real existing aspect of the universe which is measured, like when we count something we assume that there is an existing quantity which can be counted and it has some real existence as that quantity, prior to being counted.

That’s pretty pragmatic to assume that, yes. It’s also pretty pragmatic to assume that I cannot choose to alter some event in the past, but it’s been demonstrated that one of those assumptions (if not both) are wrong.

You did not specify a frame, you said "here".

That one word was not where the frame was specified.

but a ‘frame’ does not require additional references.
— noAxioms
Yes it does, and you've misrepresent "frame" as a point. A point is not a frame.

I didn’t say a frame was a point. I can say ‘the frame of the sun’, and that defines a frame relative to which the velocity of things (Earth say) can be expressed. An additional reference is not needed to determine that Earth at a particular moment moves at about 30 km/sec relative to that frame. The statement does not assert that a frame is a point. The frame happens to be a velocity reference. It is limited. I cannot, given just that, specify the x y and z coordinates of Earth at a given moment. More definition is needed for that to be done.
If you disagree with that, then do you deny that Earth moves at about 30 km/sec relative to the sun? What additional references are required before that statement can be made?

As per the above, a specification of only the origin defines a frame...
— noAxioms
No, a point does not constitute a frame.

I didn’t specify a point, and I didn’t say it constituted the frame. The sun for instance is a worldline, not a point. A point would be an event, and an event indeed does not define a frame. A worldline defines a frame. An unaccelerated worldline defines an inertial frame. So before I said ‘my frame’ which is a frame defined by my worldline, and relative to that worldline, ‘here’ is always at the same location, and no, that worldline does not constitute the frame, it only defines it.

"Frame" implies "coordinate system".

It does not. For instance, there is the cosmological frame, an expanding metric that foliates most of the universe. The CMB appears isotropic to anything stationary relative to that frame. But coordinate system implies coordinates. One can measure the sun’s current velocity relative to that frame (not quite 400 km/sec in the direction of Leo), but one cannot specify the current coordinates of the sun relative to it. That would require a coordinate system. Hence a frame and a coordinate system are different things. The former is a velocity reference, but the latter assigns numbers (coordinates) to all events.

There is no frame without a coordinate system as you seem to believe.

I just gave multiple examples of them. If you disagree, then tell me the current coordinates of our sun (a number for x, y, and z, your choice of units). Remember, the only reference is the CMB here, not a worldline this time, but enough.

Your "frame" in this example is a coordinate system which maps the rocket, not one point such as "here"

No, because I didn’t define it relative to that which says ‘here’. I chose a different origin, which was the nose of the rocket. In fact, I never used the word ‘here’ in releation to the frame of the rocket.

And if you say that the rocket is one point

I never said that, so no worries. I referred to the very tip was a point where I assigned the origin. The rest of the rocket is not located at the tip, and so not at the origin. Other parts of the rocket have nonzero coordinates relative to the coordinate system described.

”Wiki: Measurement problem:The wave function in quantum mechanics evolves deterministically according to the Schrödinger equation as a linear superposition of different states. However, actual measurements always find the physical system in a definite state. Any future evolution of the wave function is based on the state the system was discovered to be in when the measurement was made, meaning that the measurement "did something" to the system that is not obviously a consequence of Schrödinger evolution

This will probably turn out to be really dumb, a lesson not to mess in physics when one is not a practitioner, but nevertheless: Here is a stripped down version of the Schrödinger equation, showing its simple solution. Note that the solution is originally dependent upon a constant, [math]{{C}_{0}}[/math]. This is the measurement at time t=0. Whatever value this constant assumes will then determine the time evolution of the (wave) function.

There are an infinite number of solutions depending upon that constant (measurement) - a superposition. Then the measurement takes place and a "collapse" occurs giving a particular solution. Did the measurement "do something" to the system, or does one simply experiment to find the appropriate value of the constant? Where is the magic?

Being dumb in QM, I am missing some subtlety, I admit. :chin:

[math]\frac{d\psi }{dt}=ik\psi \text{ }\Rightarrow \text{ }\frac{d\psi }{\psi }=ikdt\text{ }\Rightarrow \text{ }\ln \psi =ikt+C\text{ }\Rightarrow \text{ }\psi (t)={{e}^{C}}{{e}^{ikt}}={{C}_{0}}{{e}^{ikt}}[/math]

[math]{{C}_{0}}=\psi (0)[/math]

Quoting Count Timothy von Icarus

I have never seen a satisfactory explanation of why we should find ourselves in the world that has increasing entropy

As opposed to what? A world at thermodynamic equilibrium?

And what do you mean by explanation here? We are bound to find ourselves in one world or another. How could you explain the fact that the world that we find ourselves in is this one? Explain in terms of what?

Reply to SophistiCat

Yes. Since there are more ways to be high entropy than low entropy we should have more worlds with high entropy than low. So why are we in a low entropy world if it is very statistically unlikely?

Some version of the past hypothesis, right? But then seeing a world where the past hypothesis is true is vanishingly unlikely, even if it occurs with probability 1, according to MWI derivations of the Born Rule.

Weyl curvature arguments are ok here, but both MWI and Cosmic Inflation tend to go for the Anthropic Principle to explain this.

"All possible worlds exist. Obviously we exist and our world is possible. And we can only exist in some narrow band of worlds in terms of initial conditions."

The obvious problem here is that this makes explanations from physics trivial. "Anything observed is physically possible and anything possible occurs so of course you see x even if x is a 1 in quadrillion event," is just "if you see it, it is possible, so it is."

All explanations about how stars, planets, life, etc. evolved in our particular history, the how and why of science, gets fobbed off onto "initial conditions, all of which are true."

Obviously, some cosmologists find this answer very deep, hence the popularity. However, it essentially reduces to "if it's possible it happens and if you see it, it is possible." This isn't a real answer. The answer we want in non-multiverse theories isn't actually addressed, which reformulated for an "all possibilities exist multiverse," is the question "why did our particular history occur such that we see x."

Also, apparently you should be bothered by extremely unlikely events in your experiments if you believe in MWI, since you should care about the Born Rule... except when it comes to identifying that you are in an incredibly low probability universe. Then, when doing cosmology, it is ok to jettison probabilities when making explanations and resort to "everything has to happen with p = 1."

If you follow the epistemological logic used for cosmology at the individual level, you shouldn't be surprised when jumping in front of a train doesn't kill you or standing in front of a firing machine gun leaves you unscathed (ala Tegmark's quantum suicide set up). If you were dead, you wouldn't see anything. Even if being alive is incredibly unlikely, that's all you're going to see, and so the anthropic principle, applied on the individual level, says there is nothing at all notable about throwing yourself into a volcano and surviving, etc.

It seems to me that either low probability events should always be surprising and make us ask questions or they never should, not a too cute mix of both. Just bite the bullet and say the Born Rule is meaningless, a total illusion, in that case.

Quoting noAxioms

What would you call an interaction between systems of which humans are completely unaware, say where one system (some radioactive atom) emits an alpha particle which alters a second system (some molecule somewhere) by altering its molecular structure (and probably heating up the material of which the molecule is part). It isn’t a measurement because there’s no intent and no numerical result yielded, so what word describes this exchange between the atom and the molecule?

It's all descriptive. There's no way around it. That's why it becomes "the hard problem" for those who do not accept the reality that there's an unbridgeable gap between the map and the territory. And, the problem is that the description is completely different depending on the perspective one takes. That's the importance of understanding the true nature of relativity theory.

We can take "relativity" in two ways. 1) The world appears different to us, depending on the perspective we take. 2) The world is different from different points of view. The former is realist, as assuming a true way that things are, independent of the various perspectives. The latter assumes no such independent "real" point of view. And the problem is that to apply relativity theory, and make it work for us, we need to assume the latter. Since that position is adopted for the purpose of applying relativity theory, we cannot make the results derived from the application of relativity theory compatible with the realist assumption of a real independent world. We must recognize and respect this fact, that whatever results are produced from the application of relativity theory, these are fundamentally incompatible with that form of realism.

Consider "an apple hanging from a tree". That's one way of describing the scenario, it's a static scenario, though "hanging" is still a verb. But we could also describe it as a whole bunch of different molecules with atoms interacting, and the gravity of the earth interacting with the massive molecules, putting immense force on the stem, until with ripeness, the atomic and molecular interactions change considerably, and the apple falls.

Notice, the former is a very simple description, as a static state, it takes no account of the passing of time, except for the word "hanging". The latter description makes an attempt to account for the effects of time passing, by describing the scenario in terms of activity.

Quoting noAxioms

This is what I am talking about. What precisely physically ‘does something’ to a system that makes its [past] state change, I say physically because I’m not talking about somebody’s mere knowledge or description of a system. I assure you it isn’t the determination of a numerical value by a conscious entity that changes the target system.

This question is answered with "the passing of time". The passing of time "does something" to the system, and we have only the vaguest idea of what it does. Sometimes it's named by "entropy". But what the passing of time really does, is understood much better through terms other than "entropy". You see, we understand the future in terms of possibilities, what may or may not happen, and the past we understand in terms of actualities, what has actually happened. This leaves "the present" with a peculiar temporal position, as the time when possibilities are selected for as the ones which will be actualized. And this actualization of possibilities we observe as the activity which occurs at the present.

The significant and important thing to consider here is that when a vast multitude (even approaching infinity) of possibilities for the future is related to a single, or at least a very restricted number of actualities in the past, there is a need to assume a process of "selection". The determinist wants to describe the selection process as completely determined, while the free willie understands final cause as a type of causation which is not determined in that way. So the free willie concludes that if there is a way that the conscious human being can pick and choose from possibilities, as to which ones will be actualized, in an undeterministic way, so it must be in the greater universe in general, that something (traditionally "God") picks and chooses from the possibilities in an undeterministic way.

”Wiki: Measurement problem:The wave function in quantum mechanics evolves deterministically according to the Schrödinger equation as a linear superposition of different states.

This "deterministic" evolution of the wave function is completely a feature of the type of description employed. It is described so as to be deterministic, when in reality, this description, the "superposition of different states", violates the law of noncontradiction, showing that this deterministic description is actually very faulty.

We can say, "the apple hanging on the tree" is a determinist description, and by Newton's laws that hanging apple will continue to hang, as an equilibrium, in its deterministic way, until a force causes it to fall. The deterministic wave function is analogous with the apple hanging, and we could place bets concerning the collapse, the fall. The deterministic bettor would look for the upcoming forces which would cause the fall. The undeterministic bettor would look at the passing of time itself, and the selective process which inheres within the passing of time itself (the Will of God), as a force which could potentially act on the apple. But the laws of physics, from the foundations of Newton's first law, which provides the basis for the deterministic perspective, do not have the required provisions for looking at the passing of time as a selective force. As Newton himself said, his first law takes the Will of God for granted. So if this implied selective process (as the Will of God) which is active at the micro scale, as time passes, actually makes selections, our determinist laws of physics have no way to account for these selections.

Quoting noAxioms

I was going to agree with this until the last bit about physical boundaries. A system’s boundaries are an arbitrary abstraction, nothing physical about it. But the arbitrary designations are needed for description, not for the actual processes to work.

You are not following the distinction I made between a system in theory, and an engineered system. The latter being a designed physically existing system created for the purpose of doing work. It has a physical boundary, and the energy lost to the system as entropy, may or may not escape somehow through this boundary, because where the energy which is lost to entropy actually goes to, is an unknown.

Quoting noAxioms

That’s pretty pragmatic to assume that, yes. It’s also pretty pragmatic to assume that I cannot choose to alter some event in the past, but it’s been demonstrated that one of those assumptions (if not both) are wrong.

Huh? I don't see how this follows at all. I don't think you understood what I said. I was taking that from the reference from Bell which you provided. I don't think you understand that quote very well. Here's the part:
Quoting Against ‘measurement’ - John Bell, 1990

When it is said that something is 'measured' it is difficult not to think of the result as referring to some pre-existing property of the object in question.

I discussed this principle in another thread with a number of participants. Suppose there is a jar with marbles in it. The marbles can be counted and this will determine the quantity. The others argued that the quantity is already determined, prior to the counting. The quantity is a "pre-existing property". But "quantity" is a human determination produced by the act of counting, and cannot exist prior to the counting. This idea, that the quantity determined by the act of measuring exists prior to the act of measuring, is what Bell is referring to here as a problematic way of looking at QM.

This faulty way of looking at reality is pervasive in the modern intellect. It seems to have been propagated by Platonism in mathematical axioms, which would imply that there is "a number" for the potential count, already in existence, and all we need to do is somehow find that number. The problem manifests deeply when the axioms deal with infinities, and assume that a "countable number" has some type of actual existence in the same way as a counted number.

Quoting noAxioms

I didn’t say a frame was a point.

This discussion is pointless (please excuse the pun, it just came out that way). You were arguing that "here" constitutes a frame. If you still can't admit to the fault in this, I really don't see the point to continuing.

Quoting noAxioms

If you disagree with that, then do you deny that Earth moves at about 30 km/sec relative to the sun? What additional references are required before that statement can be made?

Do you not see, that "the earth" and "the sun" involves two distinct places, unlike "here"?

Quoting noAxioms

It does not. For instance, there is the cosmological frame, an expanding metric that foliates most of the universe.

And "metric" doesn't imply "coordinate system" to you, in this context, such that a coordinate system is a logical necessity for a metric?

Quoting noAxioms

No, because I didn’t define it relative to that which says ‘here’. I chose a different origin, which was the nose of the rocket. In fact, I never used the word ‘here’ in releation to the frame of the rocket.

This is exactly the point. What we were discussing is the meaning of "here" in your previous example, and the ridiculousness of that example. Now you want to replace "here" with "the nose of the rocket", but you admit right here (excuse the pun again), that the two are not analogous.

Quoting SophistiCat

As opposed to what? A world at thermodynamic equilibrium?

Quoting Count Timothy von Icarus

Yes. Since there are more ways to be high entropy than low entropy we should have more worlds with high entropy than low. So why are we in a low entropy world if it is very statistically unlikely?

Some version of the past hypothesis, right? But then seeing a world where the past hypothesis is true is vanishingly unlikely, even if it occurs with probability 1, according to MWI derivations of the Born Rule.

I am surprised that you went for this explanation, given what you said above about frequentist explanations. This is a textbook case where statistics does not apply because it simply does not exist.

Your reasoning applies to an ergodic system that has been evolving for a long time, or an equivalent ensemble. But the early universe is nothing like that. If there is no explanation for the past hypothesis (we don't have a good theory of the universe's origin), then it makes no sense to talk about how likely or unlikely it is, because the universe was and still is far from ergodic, it hadn't been evolving for a long time (ex hypothesi), and we don't have an ensemble (unless some kind of a multiverse theory is true, but that is still very speculative, so we can't take it as given).

Quoting Count Timothy von Icarus

It seems to me that either low probability events should always be surprising and make us ask questions or they never should, not a too cute mix of both. Just bite the bullet and say the Born Rule is meaningless, a total illusion, in that case.

Eh, surprise is a tricky thing. There have been some detailed analyses of surprise in the literature, both from the purely epistemological standpoint and specifically in the context of issues like the multiverse and fine-tuning. But I find that in the latter case the arguments get too far afield. They start from some careless analogies (e.g. Leslie's firing squad) and then get bogged down in the arguments over the analogies. Given that our everyday intuitions are not trained for such exotic scenarios as multiverses, we probably shouldn't put too much stock in them.

Reply to SophistiCat

I am surprised that you went for this explanation, given what you said above about frequentist explanations. This is a textbook case where statistics does not apply because it simply does not exist.

Frequentism seems fine in some contexts, or at the very least, it is at times much easier to explain things in that frame when it doesn't make a material difference. A closer look would indeed show problems with my example. If you accept determinism at all levels of reality, then of course there is only one way a system can evolve, the very way it does evolve, and entropy has to be framed as somehow subjective, or at least relational. The problem with frequentism IMO is that it is generally the only way of understanding probability theory that is taught, and is incoherent when applied to some situations.

Your reasoning applies to an ergodic system that has been evolving for a long time, or an equivalent ensemble. But the early universe is nothing like that. If there is no explanation for the past hypothesis (we don't have a good theory of the universe's origin), then it makes no sense to talk about how likely or unlikely it is, because the universe was and still is far from ergodic, it hadn't been evolving for a long time (ex hypothesi), and we don't have an ensemble (unless some kind of a multiverse theory is true, but that is still very speculative, so we can't take it as given).

You are correct about the nature of the Past Hypothesis; that's a fine answer, but it isn't the argument I get frustrated with. By definition, there are more ways to be in a high entropy state than a low entropy state. Perhaps there is indeed a mechanism at work in the early universe that makes a later low entropy state counterintuitively more likely than a high entropy one. But, barring support for that fact, we are left with the principal of indifference, and this suggests that we weight all options equally, combinatorially if there are a finite number of states. That is, giving equal likelihood to all potential universes of X mass energy existing in an early state with all possible levels of entropy, the high entropy universes outnumber the low entropy ones, barring some other sort of explanation. Appeals to the Anthropic Principle don't address this. The same issue comes up with the Fine Tuning Problem; if we don't know the likelihood of values for constants, indifference should prevail.

If this is the case, then it remains that high entropy states outnumber low entropy ones, and remain more likely.

Positing some as of yet not understood mechanism by which this is not the case is fine, after all, we have empirical evidence that the entropy of the early universe was low (counterintuitively despite being near equilibrium, wrapping your head around negative heat is a doozy). The problem I was addressing is using the Anthropic Principle to address this rather than any appeals to the probability of any observation of the state of the early universe. This is where the problem of triviality comes up.

I think this is a similar problem to that of claims that "everything is explainable in terms of fundemental physics," and then appealing to the black box, brute facts of initial conditions as the origin of many of the most interesting things we'd like the natural sciences to explain. I think the proper response here is: "yes, but we want to know how the particular initial conditions in our past led to X and Y, etc. historically, and if this cannot be explained without appeals to brute facts for a vast array of all natural phenomena, then nature does not reduce to fundemental physics in terms of explanations."

Quoting noAxioms

we lack for vocabulary since ‘measurement’ and ‘physics’ are both human undertakings and apparently cannot be used for interactions not involving humans.
What do you call the actual mechanisms of the universe, as opposed to ‘physics’, the human undertaking to describe it? What would you call an interaction between systems of which humans are completely unaware, say where one system (some radioactive atom) emits an alpha particle which alters a second system (some molecule somewhere) by altering its molecular structure (and probably heating up the material of which the molecule is part). It isn’t a measurement because there’s no intent and no numerical result yielded, so what word describes this exchange between the atom and the molecule?

You’re asking for a description of the world that is not described by physics. Such an undertaking would fall under the general heading of metaphysics, wouldn't it?

Quoting noAxioms

Given your definitions...

The definition of counter-factual definiteness I provided was generated by ChatGPT. Granted, ChatGPT is no all-knowing oracle, but I felt it to be a reasonable summary.

Quoting noAxioms

Alternatively, you perhaps suggest an epistemological definition of counter-factual definiteness, where in the absence of human measurement/observation, humans would not know of the thing, and existence is defined by human knowledge of it. Hence, again, by definition, nothing can exist in the absence of humans since no human could know of it. Counter-factual definiteness is therefore false either way.

Correct me where I’ve misinterpreted what you’ve been trying to tell me.

Grappling with the distinctions you're providing between various types of interpretation is quite a challenge - not that there's anything wrong with them, but there's a lot to take in, and I think you're better read in them than I am. But there is probably more detail in those diverse interpretations than is required by the broadly idealist view that I'm trying to advocate. Which is that - whatever we construe existence to be, it contains a mental or subjective pole or aspect, which is not in itself disclosed amongst the objects of scientific analysis. From a naturalistic perspective, it is perfectly sound to presume that the laws and objects of physics obtain independently of any observer, but the lesson of quantum physics is that this is not ultimately so, but that the observer retains a central role. And why this is, is not itself a scientific question, but a metaphysical one.

One of the text books I've been consulting on this is Nature Loves to Hide, Shimon Malin. He advocates an idealist interpretation which he says is consistent with Western philosophy (unlike the other authors on this subject who appeal to Eastern philosophy. You can find a profile of Malin here).

Quoting jgill

Then the measurement takes place and a "collapse" occurs giving a particular solution. Did the measurement "do something" to the system, or does one simply experiment to find the appropriate value of the constant? Where is the magic?

That is indeed the measurement problem in a nutshell. The act of observation is not described by the equations but appears central to the outcome. That is what the many-worlds interpretation seeks to explain away. But nobody has a definitive or unanimous solution - hence the debate!

Quoting Wayfarer

You’re asking for a description of the world that is not described by physics.

No, I’m asking for vocabulary that you would accept in describing parts of the world that are not in a laboratory or anywhere else where attention is being paid by some human.

Given your definitions...
— noAxioms
The definition of counter-factual definiteness I provided was generated by ChatGPT. Granted, ChatGPT is no all-knowing oracle, but I felt it to be a reasonable summary.

I found it quite reasonable. I wasn’t speaking of that, I was speaking of your definition of ‘measurement’, ‘physics’ and such, all those words that you refuse to apply to a case where a human isn’t involved.

Counter-factual definiteness is therefore false either way.

There are valid interpretations that hold to the principle. It has never been falsified, but of course neither has it been proven.

From a naturalistic perspective, it is perfectly sound to presume that the laws and objects of physics obtain independently of any observer

This statement contradicts your assertion that the word ‘physics’ implies a human endeavor and thus cannot ‘obtain independently of any observer’. It seems that you use the word that way, but refuse to let me do it.

One of the text books I've been consulting on this is Nature Loves to Hide, Shimon Malin. He advocates an idealist interpretation which he says is consistent with Western philosophy (unlike the other authors on this subject who appeal to Eastern philosophy. You can find a profile of Malin here).

There is undeniably an element of idealism in a relational view. I might find a copy of this worth reading, but cannot accept anything where the operation of the universe is different for humans than it is for anything else. I doubt it goes there.

The act of observation is not described by the equations but appears central to the outcome. That is what the many-worlds interpretation seeks to explain away.

I think that’s what all the interpretations try to explain, or ‘explain away’ if you happen to disapprove of the way it was explained.


Quoting Metaphysician Undercover

1) The world appears different to us, depending on the perspective we take.
2) The world is different from different points of view.

Kindly give examples of each so I get a clue as to what you’re attempting to convey. The second one seems pretty obvious. The stop sign appears red from the front, but from the rear (a different point of view) it isn’t. From a realist position, the stop sign is not different due only to this difference of perspective, but it appears different. I don’t know what you mean by the first one, a different perspective that isn’t a different point of view, hence my request for an example. OK, I think maybe the apple thing below is such an example, but unclear if it illustrates point 1 or 2.

The former is realist, as assuming a true way that things are, independent of the various perspectives.

OK, maybe I’m confusing your usage of both, and my stop sign example was a difference of perspective, in which case I need an example of a different PoV that isn’t a different perspective. Point of view usually means appearance from some specific location in space, but you seem to be using the term differently.
None of this seems to have anything to do with relativity theory.

And the problem is that to apply relativity theory, and make it work for us, we need to assume the latter. Since that position is adopted for the purpose of applying relativity theory, we cannot make the results derived from the application of relativity theory compatible with the realist assumption of a real independent world.

You seem to be attempting to mix theories of two very different things. Relativity theory isn’t different depending on one’s realism stance on quantum theory and works pretty much the same either way.

Consider "an apple hanging from a tree". That's one way of describing the scenario, it's a static scenario, though "hanging" is still a verb. But we could also describe it as a whole bunch of different molecules with atoms interacting, and the gravity of the earth interacting with the massive molecules, putting immense force on the stem, until with ripeness, the atomic and molecular interactions change considerably, and the apple falls.
Notice, the former is a very simple description, as a static state, it takes no account of the passing of time, except for the word "hanging". The latter description makes an attempt to account for the effects of time passing, by describing the scenario in terms of activity.
This is what I am talking about.

OK, but it wasn’t what I was talking about. Is there a point then? The apple is open to different descriptions. I don’t disagree with any of it, but it’s all still just descriptions. The actual physical system isn’t any different due to your choice of description, unless I suppose if you’re proposing some sort of reality that supervenes on language. Anyway, is this what you mean by ‘different point of view’?
There’s nothing quantum about your example. The apple isn’t in superpostiion of states in your description.

This question is answered with "the passing of time".

No. A system in isolation will remain in superposition indefinitely, so it isn’t time that ‘does something’.

The wave function in quantum mechanics evolves deterministically according to the Schrödinger equation as a linear superposition of different states.
— ”Wiki: Measurement problem
This "deterministic" evolution of the wave function is completely a feature of the type of description employed. It is described so as to be deterministic, when in reality, this description, the "superposition of different states", violates the law of noncontradiction, showing that this deterministic description is actually very faulty.

There’s no violation. MWI essentially posits exactly that: that the wave function evolves deterministically and there is no collapse, and no contradiction.

I discussed this principle in another thread with a number of participants. Suppose there is a jar with marbles in it. The marbles can be counted and this will determine the quantity. The others argued that the quantity is already determined, prior to the counting. The quantity is a "pre-existing property".

Marbles in a jar is a classical system, and yes, the count of them is fixed before they’ve been counted. At the quantum level, which is what Bell was talking about, these things are not necessarily true.

You were arguing that "here" constitutes a frame. If you still can't admit to the fault in this, I really don't see the point to continuing.

If I said that, it would be faulty, yes. You should include my quote then.

And "metric" doesn't imply "coordinate system" to you, in this context, such that a coordinate system is a logical necessity for a metric?

No coordinate system was specified, so one isn’t necessary when specifying a metric as I did, one relative to which the velocity of anything can be expressed, despite the lack of coordinates.

Quoting noAxioms

I’m asking for vocabulary that you would accept in describing parts of the world that are not in a laboratory or anywhere else where attention is being paid by some human.

And I'm saying, it's not a matter of vocabulary. The question is one of metaphysics.

Quoting noAxioms

From a naturalistic perspective, it is perfectly sound to presume that the laws and objects of physics obtain independently of any observer - Wayfarer
This statement contradicts your assertion that the word ‘physics’ implies a human endeavor and thus cannot ‘obtain independently of any observer’. It seems that you use the word that way, but refuse to let me do it.

What I'm saying is, that from the perspective of natural philosophy, it is perfectly sound to presume....etc. What I'm arguing is that naturalism presumes that the world would exist, just as it appears to us, even without there being an observer - and that, for pragmatic purposes, this is a sound assumption. But quantum physics challenges that assumption because it calls the purported mind-independent nature of reality into question. That's what the debate is about!

Quoting noAxioms

I...cannot accept anything where the operation of the universe is different for humans than it is for anything else.

You still require that we can arrive at a description of a truly mind-independent reality.

Reply to Count Timothy von Icarus

Lots of interesting comments there. I'll focus on the Born rule for the moment.

Quoting Count Timothy von Icarus

https://mateusaraujo.info/2021/03/12/why-i-am-unhappy-about-all-derivations-of-the-born-rule-including-mine/

I don't have these same concerns, but I think it is important than many proponents of MWI do list similar concerns about other theories in quantum foundations.

Yes, fair point.

MWI aside, the puzzle is whether the observed probabilities can be derived without positing the Born rule. The basic approach (borrowing from Carroll and Sebens, Zurek, and others) is to use two alternative rules.

1. The indifference rule: If the amplitudes for the terms in a quantum state are equal, assign the same probability to each term such that they sum to 1.
2. The reduction rule: If the amplitudes are unequal, reduce the state to terms with equal amplitudes. Then apply the indifference rule.

Now those rules may be thought to be equivalent to positing the Born rule. However they aren't mysterious in the way that the Born rule seems to be.

For example, consider a qubit in the state:

[math]|\psi\rangle = \sqrt{\frac{1}{3}}|0\rangle + \sqrt{\frac{2}{3}}|1\rangle[/math]

Since the amplitudes are unequal, the reduction rule is applied. The reduced state is:

[math]|\psi_r\rangle = \sqrt{\frac{1}{3}}|0\rangle + \sqrt{\frac{1}{2}}(\sqrt{\frac{2}{3}}|1_a\rangle + \sqrt{\frac{2}{3}}|1_b\rangle) = \sqrt{\frac{1}{3}}|0\rangle + \sqrt{\frac{1}{3}}|1_a\rangle + \sqrt{\frac{1}{3}}|1_b\rangle[/math]

Since the amplitudes are now equal, the indifference rule is applied. There are three states, so the probability for each state is 1/3 which gives 1/3 for the [math]|0\rangle[/math] state and a total of 2/3 for the reduced [math]|1\rangle[/math] states, which matches the Born rule when applied to [math]|\psi\rangle[/math].

That's an operational derivation that bypasses issues about uncertainty, what probabilities "really are", and any reference to MWI.

Quoting Count Timothy von Icarus

If the physics in question is reversible, why do we posit a splitting universe instead of a merging one, aside from the fact that having it split in both directions (forwards and backwards in time) is incoherent?

Perhaps whenever we make a measurement we merge universes, such that we progress by such merges to one of many potential end points, final conditions, of the universe, assuming ad hoc that it has an end? This might work, but it blows up the rational-agent based derivations of the Born Rule. Rational agent models are not reversible, we don't say, "given what I observe now, what must have happened in the future, what endpoint must I be most likely to be converging on?"

As it happens, David Deutsch describes both splitting and merging in his version of the Wigner's friend thought experiment (for which reversibility is relevant). See an earlier thread here.

The principle is really just an extrapolation from what is observed on the microscopic scale. Cast in quantum computing terms, qubits and quantum logic gates are reversible. Applying a Hadamard gate to a computational basis state splits it into an equal superposition state, and applying a Hadamard gate again merges the superposition back to the original state. So the question is whether that process scales up to the everyday, macroscopic level. And, if so, whether or how that should affect our reasoning.

Quoting jgill

The wave function in quantum mechanics evolves deterministically according to the Schrödinger equation as a linear superposition of different states. However, actual measurements always find the physical system in a definite state. Any future evolution of the wave function is based on the state the system was discovered to be in when the measurement was made, meaning that the measurement "did something" to the system that is not obviously a consequence of Schrödinger evolution
— ”Wiki: Measurement problem

...

There are an infinite number of solutions depending upon that constant (measurement) - a superposition. Then the measurement takes place and a "collapse" occurs giving a particular solution. Did the measurement "do something" to the system, or does one simply experiment to find the appropriate value of the constant? Where is the magic?

To apply your example, consider the double-slit experiment. When there is no measurement at either slit, the originally emitted particles build up an interference pattern on the back screen. That pattern can be described by a linear superposition of each particle going through the left slit plus each particle going through the right slit, i.e.:

[math]|\psi\rangle = \frac{1}{\sqrt{2}}(|left\rangle + |right\rangle)[/math]

Suppose, instead, that there is a measurement at the slits. The originally emitted (and measured) particles no longer build up an interference pattern. The particles measured at each slit subsequently end up on the back screen as described by the [math]|left\rangle[/math] and the [math]|right\rangle[/math] terms independently, and not as described by [math]|\psi\rangle[/math].

That outcome is not obviously a consequence of (continuous) Schrödinger evolution. So it seems that the measurements "did something" to the system.

Compare to an ocean wave that might be described as a linear superposition of simpler waves. In that case, observing or measuring the wave doesn't affect the system.

Reply to Count Timothy von Icarus I didn't want to further detail the thread, so I started a new discussion: The Past Hypothesis: Why did the universe start in a low-entropy state?

Quoting noAxioms

No, I’m asking for vocabulary that you would accept in describing parts of the world that are not in a laboratory or anywhere else where attention is being paid by some human.

Describing something requires paying attention to it. How do you think that someone could describe a part of the world which has no one paying attention to it? You are asking for the impossible, what is excluded by contradiction.

Quoting noAxioms

OK, maybe I’m confusing your usage of both, and my stop sign example was a difference of perspective, in which case I need an example of a different PoV that isn’t a different perspective. Point of view usually means appearance from some specific location in space, but you seem to be using the term differently.
None of this seems to have anything to do with relativity theory.

Yes, you seem very confused as to what I was trying to say. I did not express it very well, so we better forget about that. It's very apparent that you have a completely different idea about what relativity theory says from what I do.

Quoting noAxioms

Relativity theory isn’t different depending on one’s realism stance on quantum theory and works pretty much the same either way.

It isn't the case that relativity theory is different depending on one's realism stance, but it is the case that a true realism cannot be maintained in the application of relativity theory.

Consider that within any system of formal logic, one must maintain consistency with the axioms. Any premise not consistent with the axioms cannot be employed because it would cause contradiction and incoherency. Take what you said above for example. Axiom: to be described requires that the thing described be observed. If we now proceed with the premise that we can describe something which has not been observed, we'll run into some incoherency.

Realism is not consistent with relativity. Refer back to Galileo's initial development of relativity theory. His point was to show that the orbits of the planets could equally be represented by the geocentric model, or the heliocentric model. By relativity theory each model is equally correct, there is no such thing as the "real" representation. That each representation, or description, is equally correct, and they are contradictory to each other, is the reason why relativity is not consistent with realism. Are you familiar with "model-dependent realism". This is an attempt to make relativity theory consistent with realism, but it isn't a form of realism at all. It just borrows the word "realism", assuming itself to be the closest thing to realism which we can get under the precepts of relativity theory.

Quoting noAxioms

The actual physical system isn’t any different due to your choice of description...

Yes it is different. The actual physical system is as described, and the descriptions differ. That's the point. There is no axiom which allows us to say that the physical system is different from what is described, because that would imply that the description is wrong. And, the descriptions differ according to one's choice of description. Therefore the actual physical system is different depending on one's choice of description. For more information read about model-dependent realism.

If you are a hard core realist, there is an escape from this trap. The escape is to realize that relativity theory is not truthful. What it says about the world is a falsity, and we just use it as a useful tool, but the tool is not a truth. Then we can reject model-dependent realism as just a manifestation of relativity theory, and we can maintain a true realism.

Quoting noAxioms

Marbles in a jar is a classical system, and yes, the count of them is fixed before they’ve been counted. At the quantum level, which is what Bell was talking about, these things are not necessarily true.

What Bell is saying, is that this idea, that the number of marbles in the jar is fixed, prior to the count is a misleading idea. The quantity of marbles, the number which corresponds with the physical situation, is only determined through a judgement. So the idea, that the number is fixed, prior to the count is a false idea.

Think about this. If the number is fixed, prior to the count, then it is necessary that nothing changes in the meantime, the time between the fixing and the count. If it is even possible that something could change, then we cannot say that the number is fixed. So we tend to think along the lines of Newton's law of inertia, and we figure that a force would be required to change things, so if the jar is watched in the meantime, we'd see if a marble was added or removed. Therefore if we exclude all the ways that we deem are possible ways that the quantity could change, then we can say that the number is fixed. But what if we do not apprehend all the possible ways, and there's other ways, what a physicalist might call "magic" or something like that. The proper conclusion therefore, is to recognize that the number is not actually fixed prior to the count, because there is always some logically possible way that it could change in the meantime. The idea that the number is fixed prior to the count, is just another useful tool that is not the truth about the situation.

Quoting Andrew M

Suppose, instead, that there is a measurement at the slits

Does this measurement physically affect a photon on its way to the far screen?

Quoting Wayfarer

And I'm saying, it's not a matter of vocabulary.

It is a matter of vocabulary. You denied my saying that the moon existed relative to a rock because I used words you feel can only be used for human intentful actions. I cannot discuss a metaphysical view that isn’t based on human intent.

What I'm arguing is that naturalism presumes that the world would exist, just as it appears to us, even without there being an observer and for pragmatic purposes, it is a sound assumption.

I mostly agree with that. But firstly, naturalism does not necessarily imply objective realism even though most of the time it does. Your comment was worded using the language of realism.
More importantly, while the world may exist, absent an observer, it wouldn’t ‘appear’ at all. It can be described, but it wouldn’t have an appearance. I think you cover this point with the pragmatic bit. I am for instance attempting a pragmatic description of a quantum interaction between a radioactive nucleus and some molecule a ways off. I attempt to leave off descriptions of how they would appear.

But quantum physics challenges that assumption.

I don’t see how it does anymore than say Newtonian physics which equally wasn’t different when human intent or observation was involved than when not.

You still require that we can arrive at a description of a truly mind-independent reality.

Yes, but that’s pretty easy. It gets tricky (not impossible) when you attempt a truly mind-independent description of reality, but I suppose you would deny it being possible by the anthropocentric restrictions you place on vocabulary, where any description made by something not human is by definition not a description, even when discussing non-anthropocentric metaphysics.


Quoting Metaphysician Undercover

It isn't the case that relativity theory is different depending on one's realism stance, but it is the case that a true realism cannot be maintained in the application of relativity theory

What is ‘true realism’ as distinct from realism? Does it mean something more significant than ‘my personal opinion’?
.

Take what you said above for example. Axiom: to be described requires that the thing described be observed.

I didn’t say any such thing. For instance, I described a stop sign, all without either of us observing it. Had you never seen a stop sign, perhaps the description would have needed to be more thorough, but no reason it cannot be done.

[Galileo's i] point was to show that the orbits of the planets could equally be represented by the geocentric model, or the heliocentric model. By relativity theory each model is equally correct

Both correct, but not equally. The physics of a rotating accelerating frame is not the same as a different kind of frame, so they’re not equal. The frames are abstractions. The abstractions are different (not equal), but both refer to the exact same reality, so they’re not wrong in that sense.

That each representation, or description, is equally correct, and they are contradictory to each other, is the reason why relativity is not consistent with realism.

That one abstract system describes my baguette as about 61 cm and another as about 2 feet is not a contradiction, just a different abstraction. I think the physics community would have noticed by now if there were contradictions between different abstractions of the exact same thing.
I can even take different perspectives and notice that the baguette had a longish silhouette but from the end the same thing appears circular, a contradiction you say. You’ve actually been pushing that fallacious example for years. No actual contradiction has been identified.

Are you familiar with "model-dependent realism".

It seems a form of reality supervening on models instead of the other way around. The baguette is skinny and long. The baguette is circular. Both are equally valid. Something like that.

There is no axiom which allows us to say that the physical system is different from what is described, because that would imply that the description is wrong.

But the baguette being circular and skinny-long are not wrong descriptions, but neither are they complete. Neither fully describes the thing. Models are inherently simplifications. I’m not sure how model-dependent reality deals with that part.

Think about this. If the number is fixed, prior to the count, then it is necessary that nothing changes in the meantime, the time between the fixing and the count. If it is even possible that something could change, then we cannot say that the number is fixed.

Right. It was fixed, but then before they were counted, somebody goes and adds a handful more. It has changed, so it was a mistake to say the first time that it was fixed. Where’s the controversy? The actual number of marbles in the jar has nothing to do with somebody’s knowledge of the count. The latter is epistemology, and the judgement only serves epistemology. Watching it doesn’t make it stay fixed or not. Watching it only makes it somewhat more likely that the watcher knows if the number is changing or not, all of which is irrelevant to the actual count. Point still is, it’s a classical system that does not exhibit quantum behavior. None of your comment seem to suggest otherwise.

But what if we do not apprehend all the possible ways, and there's other ways, what a physicalist might call "magic" or something like that. The proper conclusion therefore, is to recognize that the number is not actually fixed prior to the count

It does not matter what is counted. What matters is how many marbles are in there. I’m discussing metaphysics, not acquisition of information. The number is what it is, and if by some means marbles are added or removed, then that number changes. At no point is the jar in superposition of having different numbers in it. That’s why it’s a classical system.

because there is always some logically possible way that it could change in the meantime.

I never denied that marbles can be added or removed. There’s no particularly logical necessity that such changes can’t happen. It happens frequently to a typical cookie jar.

Quoting jgill

Does this measurement physically affect a photon on its way to the far screen?

All measurements of anything physically affect the thing measured.

The which-slit detection need not actually convey which-slit information. They put polarizing filters at the slits and this can destroy the superposition (it constitutes a measurement) without actually conveying to anything which actual path the photon took. The vanishing of the interference pattern is the effect. And one photon cannot create a pattern. Only repeated iterations do.

Reply to jgill [quote=Brian Greene, The Fabric of the Cosmos] The explanation of uncertainty as arising through the unavoidable disturbance caused by the measurement process has provided physicists with a useful intuitive guide as well as a powerful explanatory framework in certain specific situations. However, it can also be misleading. It may give the impressions that uncertainly only arises when we lumbering experimenters meddle with things. This is not true. Uncertainty is built into the wave structure of quantum mechanics and exists whether or not we carry out some clumsy measurement. ...Since the wave is uniformly spread throughout space, there is no way for us to say the electron is here or there. ...And this conclusion does not depend on our disturbing the particle. We never touched it. Instead it relies on a basic feature of waves - they can be spread out.[/quote]

Quoting noAxioms

You denied my saying that the moon existed relative to a rock because I used words you feel can only be used for human intentful actions.

It's not the words you used, but their meaning, which I'm disputing. What you actually said was

A rock measures the moon as much as I do, and so the moon exists to the rock.

and I disputed the idea that rock measures anything, and also that the expression that 'the moon exists to the rock' is meaningless. //Both 'measurement' and 'existing for' imply intentionality, which both the moon and the rock are devoid of. Why they're devoid of intentionality is not a matter of vocabulary but of metaphysics (or more specifically of ontology).

Quoting noAxioms

But firstly, naturalism does not necessarily imply objective realism even though most of the time it does.

It certainly does. Objectivity is the touchstone for naturalism, what is objectively the case, what is truly so irrespective of what anyone thinks. Again, the whole problem here is that this is what has been called into question. Otherwise there would no 'problem of interpretation.'

Quoting noAxioms

For instance, I described a stop sign, all without either of us observing it.

To describe a type of thing, a stop sign for example, is not the same as describing a particular thing, like a particular stop sign.

Quoting noAxioms

It seems a form of reality supervening on models instead of the other way around. The baguette is skinny and long. The baguette is circular. Both are equally valid. Something like that.

It's not that they are equally valid, but they are equally true, "true" meaning corresponding with reality.

Quoting noAxioms

But the baguette being circular and skinny-long are not wrong descriptions, but neither are they complete. Neither fully describes the thing.

If you do not think that "long and skinny" is inconsistent with "circular", then so be it. I don't think that's something I can convince you of.

Quoting noAxioms

It was fixed, but then before they were counted, somebody goes and adds a handful more.

You are not grasping the point which Bell is making. The number is not fixed, because no one has determined the quantity. The quantity is not fixed until someone determines it. How could it be? Do you have an explanation as to how a specific numbered could be associated with the objects, unless someone counts them? Does God establish that relationship between the number and the container? If not, who does, if no one counts them?

Quoting noAxioms

It does not matter what is counted. What matters is how many marbles are in there.

Obviously, it does matter. If they are not counted there is no number which correlates. Tell me how there could be one specific number which represents how many marbles are in there, if they have not been counted. Who would designate which number that is? And if no one designates the number, how can you say that there is a number which represents how many marbles are there?

Would you also argue that the winning number for a lottery is already designated before the draw is made?

Quoting Wayfarer

It's not the words you used, but their meaning, which I'm disputing.

Only because you will not accept how I mean the words. I say ‘measurement’, I mean that to which the ‘measurement problem’ refers. If you think that means human intended action with a numeric result, then you don’t know quantum theory at all.

What you actually said was
A rock measures the moon as much as I do, and so the moon exists to the rock.
and I disputed the idea that rock measures anything

Yea, because you insist on using your human-intent definition of the word. Being unable to get around that, I asked for a different word to describe the interaction between the moon and rock, but none was offered. ‘Interaction’ seems reasonable, and I’ve tried to use that since. Hence:
The rock interacts (a one-way interaction) with the moon as much as I do, and so the moon exists to the rock.

and also that the expression that 'the moon exists to the rock' is meaningless

despite my defining its meaning. The whole relational ontology is based on it, instead of being based on realism.

Both 'measurement' and 'existing for' imply intentionality, which both the moon and the rock are devoid of.

There you go again, insisting on using your definitions of those words. Hence my request for alternate vocabulary since existence supervening on intentionality is not what I’m trying to convey.
We’re going in circles. You’re still making all the same mistakes despite my pointing out how I’m using all these terms.

But firstly, naturalism does not necessarily imply objective realism even though most of the time it does.
— noAxioms
It certainly does. Objectivity is the touchstone for naturalism

Nonsense. Objectivity is the touchstone for realism. Naturalism is just not-supernaturalism. No woo. One can be a realist but not a naturalist, or one can be a naturalist but not a realist, such as the relational view.


Quoting Metaphysician Undercover

For instance, I described a stop sign, all without either of us observing it.
— noAxioms
To describe a type of thing, a stop sign for example, is not the same as describing a particular thing, like a particular stop sign.

Wow, something I agree with. Good thing I didn’t specify a particular stop sign. You said “Axiom: to be described requires that the thing described be observed“. That statement didn’t mention that the axiom only applies to particular things. I also question the statement since ‘observed’ is not defined. You tend to take the common definitions of words (at least when it suits your purpose), which would imply that a blind man couldn’t possibly describe anything particular since he cannot observe.

[/quote]It's not that they are equally valid, but they are equally true, "true" meaning corresponding with reality.
…
If you do not think that "long and skinny" is inconsistent with "circular", then so be it. I don't think that's something I can convince you of.[/quote]You say they’re equally true, and then you say that it’s inconsistent to say so. They’re just different perspectives of the exact same physical object, so yes, it’s not inconsistent to use either word to describe the baguette. They’re both valid 2D projections (or shadows) of the exact same 3D baguette shape, and an appearance to a human is a 2D projection after all.

You are not grasping the point which Bell is making.

I know Bell’s point, but the marble thing is classical and thus doesn’t illustrate the point at all.

The number is not fixed, because no one has determined the quantity.

That’s a pretty idealistic statement. Not being one, I deny this. Knowledge of the count has nothing to do with how many marbles are in there. It’s not a wave function that is yet to collapse. Perhaps you mean a mental concept of a number, but for that, no measurement is necessary. A number can be assigned without consulting the jar. The number is then fixed, regardless of the number chosen.

If they are not counted there is no number which correlates.

Correlates to what?

Quoting noAxioms

I asked for a different word to describe the interaction between the moon and rock, but none was offered. ‘Interaction’ seems reasonable, and I’ve tried to use that since. Hence:
The rock interacts (a one-way interaction) with the moon as much as I do, and so the moon exists to the rock.

The relationship between two such masses is defined solely in terms of gravitational attraction. The way sentient beings interact with the moon is through the mind and the senses, which rocks don't possess. So it's not a valid analogy.

What I'm arguing is that there is no existence without mind and that the nature of the universe outside any mind is unintelligible and unknowable. That's why I keep referring to the book Mind and the Cosmic Order, which is not a philosophy book, but a book about neural modelling. If you simply scan the chapter abstracts you'll see the point, which is actually rather simple, but requires something of a gestalt shift.

If we're going around in circles, it's because you continue to insist that, no, there is a universe that would exist, even if there was no mind at all to behold it. And I don't think that's an unreasonable thing to believe, in fact most people would agree with you. However, I don't agree with it, for the reasons I have been stating.

Anyway, I appreciate your patience, and also the opportunity to have had this discussion. :pray:

Quoting noAxioms

Good thing I didn’t specify a particular stop sign.

In your question you asked about describing "parts of the world". This implies particular stop signs. So it just means that your example was not relevant to what you asked for.

Quoting noAxioms

I know Bell’s point, but the marble thing is classical and thus doesn’t illustrate the point at all.

You are not grasping the fact that an act of measurement is essentially the same whether it is classical or quantum. There is an act, "measurement" and there is a result produced from the act of measurement, which is "the measurement". The idea that the result, the measurement, exists prior to the act of measurement in a classical measurement, is a fundamental misunderstanding of the act, which is misleading you into thinking that there is a difference in this matter, between classical and quantum measurement.

We could use the map/terrain analogy. The act of measurement is part of the act of making the map, and the resultant measurement is part of the map. The idea that "the quantity" is actually part of the thing measured (terrain), instead of a product of the measurement (part of the map) is a basic misunderstanding of the act of measuring.

In the example, the thing measured is called "the jar of marbles". The parameter is "the quantity of marbles in the jar". To describe the thing (jar of marbles) in terms of parameters requires parametrization which is a human act of defining boundaries. In this respect there is no difference between a classical measurement and a quantum measurement. The "quantity" is the result, posterior to the act of measurement, as derived from and posterior to parameterization. These are human acts which are necessarily prior to the existence of the quantity. This principle is validated by the nature of description in general, as "the property" is representative of the quale, so a property is part of the map, not the terrain.

What Bell is pointing out is that the vulgar way of understanding "measurement" misleads us because we commonly think that the quantity is what is measured, not what we assign to the thing after we measure it. The vulgar way confuses map and terrain. In mundane measurements this mistaken view is inconsequential, therefore it has propagated. But this view misleads us when we consider quantum measurements. It is not the case that quantum measurements differ in this respect, as you propose, it is the case that the vulgar way of understanding "measurement" is mistaken, and misleads us.

Quoting noAxioms

That’s a pretty idealistic statement. Not being one, I deny this.

It appears like your anti-idealist attitude is making it difficult for you to understand the nature of the act of measurement.

Quoting Wayfarer

What I'm arguing is that there is no existence without mind and that the nature of the universe outside any mind is unintelligible and unknowable. That's why I keep referring to the book Mind and the Cosmic Order, which is not a philosophy book, but a book about neural modelling

At age 91, Dr Pinter is still intellectually active it seems. But he made his mark in mathematics, not metaphysics or neurology. His speculations about why we see multiple objects simultaneously and not isolated single objects is perhaps of interest to some. But to stretch this to imply "there is no existence without mind" seems a tad sketchy. :roll:

Quoting jgill

But to stretch this to imply "there is no existence without mind" seems a tad sketchy.

I agree my way of putting it seems pretty blunt, but I've read the book thoroughly, and he makes the case quite convincingly, in my view (although I'll acknowledge he doesn't make that exact statement). But there are physicists who do - among them a Richard Conn Henry, 'Academy Professor of Physics and Astronomy at Johns Hopkins University, author of one book and over 200 publications on the topics of astrophysics and various forms of astronomy including optical, radio, ultraviolet, and X-ray.' He arrived at an idealist point of view through his own reflection on, and knowledge of, physics, as he spells out in his 2005 editorial, The Mental Universe ( Nature). And there are others.

Of course, I understand that a lot of people will see this as a form of madness (and I think I even understand why they would see it that way.) But that is why I said there's necessary shift of perspective involved. It doesn't mean what most people think that it actually means.

I will add, what is meant by 'mind' is something much greater than simply the contents of an individual's conscious thought. Conscious thought and internal mentation are the merest sliver on top of the biological, physical and psychological complex which constitutes the human being. So I don't mean that the world is like an image in the individual mind or a product of the individual's imagination. Nothing like that. We are intelligent beings whose minds synthesise and incorporate information from a huge range of sources perceptual, sensational, and rational (which is why we are designated 'beings'). From this, the mind generates the unified whole which comprises reality for us, and all of science takes place against that background of unified perceptive and rational experience. Whatever judgement we make about objects of experience is made against that background - but that background, 'the mind' in the deepest sense, is not itself amongst those objects.

Quoting jgill

Suppose, instead, that there is a measurement at the slits
— Andrew M

Does this measurement physically affect a photon on its way to the far screen?

Generally, yes. One exception is where a detector is placed at only one slit. The detector will not interact with the photons going through the other slit. See also interaction-free measurements.

It's also possible to use polarizers to remove and/or restore the interference pattern:

Quoting Young's double-slit experiment with single photons and quantum eraser - Rueckner, Peidle

For single photons, the double-slit interference pattern can be made to disappear by using a marker.
...
The which-path marker consists of two, mutually perpendicular, polarizing filters.
...
When either the vertical or the horizontal filter covers both slits, the double-slit interference pattern is preserved, albeit at a reduced intensity compared to no filter. When the vertical filter covers one slit and the horizontal filter covers the other, the double-slit pattern disappears completely. Two superimposed single-slit patterns are all that remain. This new arrangement changes the setup into a which-path experiment in the sense that it is now (in principle) possible to know which slit the photon passed through; this destroys the quantum interference.

Introducing a third polarizing filter, the quantum eraser, between the marker and the detector thwarts the which-path experiment if it is oriented 45° with respect to the marker filters. Every photon reaching the detector is now polarized in the direction of the third polarizer and it is no longer possible to know which slit each photon passes through; as a result, the interference phenomenon is restored.

Quoting Wayfarer

The relationship between two such masses is defined solely in terms of gravitational attraction.

I gave no such definition. Just for example, one mass might be larger than the other. That’s a relation that isn’t gravity related. It’s also not the relation of which I speak, which is one about A existing relative to B.
And the rock might be affected by a photon emitted by the moon. That’s a fairly trivial and direct interaction. In fact, it is nearly impossible to keep two nearby objects from interacting, which is why putting a macroscopic object into superposition of states requires it to be in the total darkness and cooled to nearly absolute zero, and even then the interaction is prevented for only a microsecond or so.

The way sentient beings interact with the moon is through the mind and the senses, which rocks don't possess. So it's not a valid analogy.

The way sentience affects the interaction of things is irrelevant to an ontology not based on sentience. The analogy is spot on if you would just stop interjecting assumptions from different views. I’m really surprised that you can’t do that, let go of your biases for a moment to consider a different view. You can’t falsify it if you presume alternate views to do the falsification.

What I'm arguing is that there is no existence without mind

Not in a view that doesn’t define existence based on epistemology. This is exactly what I mean about your inability to set aside this bias long enough to consider something that doesn’t assume this.

If we're going around in circles, it's because you continue to insist that, no, there is a universe that would exist, even if there was no mind at all to behold it.

I said no such thing. That’s realism, a valid view in itself even if it contradicts your biases. But I’m not talking about that view either, and I didn’t suggest that there is a universe that would exist even if there was no mind at all to behold it. And yes, we’re going in circles because almost all my responses are pointing out where you put in your assumptions in a view that doesn’t posit them, or you insisting on realist assumptions in a view that isn’t realist.

And I don't think that's an unreasonable thing to believe, in fact most people would agree with you.

You mean most people agree with realism. But I’m describing something else. Realism seems to have problems, but not the problems you see which is only an incompatibility with your views.

However, I don't agree with it, for the reasons I have been stating.

That’s fine. I’ve never asked you to agree with anything, realism or otherwise. I don’t think you’ve shot down realism since various realist interpretations (MWI, the subject of this topic, being one of them) are still considered valid interpretations by the physics community.


Quoting Metaphysician Undercover

Good thing I didn’t specify a particular stop sign.
— noAxioms
In your question you asked about describing "parts of the world". This implies particular stop signs.

If you think I described a particular stop sign, then surely you can inform me which one was specified.
The sign thing was simply my attempt to figure out how you distinguish ‘perspective’ from ‘point of view’, something you’ve not clarified.

It appears like your anti-idealist attitude is making it difficult for you to understand the nature of the act of measurement.

I’m not anti-idealist, but the premises of idealism shouldn’t be asserted when discussing a non-idealistic view.

Quoting Metaphysician Undercover

If they are not counted there is no number which correlates.

You did not answer my question about this, and it’s important. Correlates to what?

Quoting noAxioms

If you think I described a particular stop sign, then surely you can inform me which one was specified.
The sign thing was simply my attempt to figure out how you distinguish ‘perspective’ from ‘point of view’, something you’ve not clarified.

I didn't see that either of us was trying to distinguish 'perspective' from 'point of view'. What would be the point of making such a distinction?

Quoting noAxioms

You did not answer my question about this, and it’s important. Correlates to what?

The number which correlates with the defined parameter. I went though that already. There's an object described as a jar full of marbles. The defined parameter is 'how many marbles are in the jar?'. There is no specific number which correlates with this parameter until someone counts the marbles and establishes that relation. You can say that someone estimates, guesses, or assigns a random number, these are all different modes of counting, and the mode of "counting" is not relevant. The point is that there is no answer to the question of "how many marbles are in the jar?" until someone answers it.

Quoting noAxioms

set aside this bias...

My trying to explain a philosophical view to you is not 'bias'. It's a philosophical view.

Quoting noAxioms

The way sentience affects the interaction of things is irrelevant to an ontology not based on sentience.

So, an ontology not based on sentience is described as what? Where in the philosophy text books or science textbooks do you find a description of such an ontology?

Quoting Wayfarer

My trying to explain a philosophical view to you is not 'bias'.

It's a bias if you apply the assumptions of that view to all other view.


Quoting Metaphysician Undercover

I didn't see that either of us was trying to distinguish 'perspective' from 'point of view'. What would be the point of making such a distinction?
You said the following, suggesting two different ways to 'take' relativity, seemingly differing only in the words 'perspective' or 'point of view'.

Metaphysician Undercover;790029:We can take "relativity" in two ways. 1) The world appears different to us, depending on the perspective we take. 2) The world is different from different points of view.

Not knowing how you distinguish those, I don't see the two ways. I think you're speaking of relativity theory, but not sure about that either.

Quoting Metaphysician Undercover

Correlates to what?
— noAxioms

The number which correlates with the defined parameter. The defined parameter is 'how many marbles are in the jar?'

But you defined the latter as the same as the former. 'How many marbles are in the jar' is a mental quantity in your mind, which tautologically is going to correlate to count, also the mental quantity in your mind, no matter which number you choose. Interaction with the jar (counting) seem unnecessary for this.

[quote]The point is that there is no answer to the question of "how many marbles are in the jar?" until someone answers it.

This seems to agree with my assessment just above.

You seem to suffer from the same problem as Wayfarer, which is insistence on applying the premises and definitions of idealism to falsify a view that isn't idealism, which is a begging fallacy.'

Quoting noAxioms

But you defined the latter as the same as the former. 'How many marbles are in the jar' is a mental quantity in your mind, which tautologically is going to correlate to count, also the mental quantity in your mind, no matter which number you choose. Interaction with the jar (counting) seem unnecessary for this.

Right, that's the way ontology works, we make definitions which accord with the way that we understand reality, and we proceed from those principles. If you think that you have a better ontological understanding of this matter, (perhaps you think that God always counts how many marbles are in the jar, or something like that), then propose your better definition.

Quoting noAxioms

You seem to suffer from the same problem as Wayfarer, which is insistence on applying the premises and definitions of idealism to falsify a view that isn't idealism, which is a begging fallacy.'

This is obviously because idealist premises are the one which best correspond with the reality of the situation. You haven't provided any reasons why you think that they are not the best premises, only the attitude of 'those are idealist therefore reject them'.