Boltzmann brains: In an infinite duration we are more likely to be a disembodied brain

Down The Rabbit Hole May 11, 2023 at 22:10 10750 views 99 comments
The Boltzmann brain paradox effectively says, in an infinite duration, we are more likely to be a disembodied brain with false memories than existing as persons within the complexities of our universe.

https://www.youtube.com/watch?v=OpohbXB_JZU

How can we defeat the Boltzmann brain paradox?

In an infinite duration, aren't all possible outcomes equally likely to occur?

Comments (99)

noAxioms May 11, 2023 at 23:18 #807371
Sean Carroll put out a paper explaining why Boltzmann brains are bad
https://arxiv.org/pdf/1702.00850.pdf

The gist is: "the theories that predict them are “cognitively unstable: they cannot simultaneously be true and justifiably believed.

Therefore only theories that predict low probabilities of them can be justifyably believed. The OP makes it sound like the universe must produce these more probably than a standard brain given enough time, which is false. Only under certain theories is this true, and it is a real problem if the theory that is the right one happens to be one of them.

Quoting Down The Rabbit Hole
How can we defeat the Boltzmann brain paradox?

I suppose by choosing a theory that doesn't predict a significant probability of them.

Quoting Down The Rabbit Hole
In an infinite duration, aren't all possible outcomes equally likely to occur?
No, that doesn't follow at all. I cannot think of a theory that has equal ratio of regular humans to BB's.

PS: I didn't watch the video.
SophistiCat May 12, 2023 at 20:18 #807547
Quoting Down The Rabbit Hole
https://www.youtube.com/watch?v=OpohbXB_JZU

How can we defeat the Boltzmann brain paradox?

In an infinite duration, aren't all possible outcomes equally likely to occur?


The clip doesn't say that last bit. That said, it is more confusing than anything else. I only got what it was hinting and gesturing at because I've already read more about this topic. If you are interested, I would advise you to do the same.
RogueAI May 12, 2023 at 21:46 #807562
Countable infinities are equal, so the infinite set of worlds where we're Boltzmann brains is equal to the infinite set of worlds where we're not. It's a 50/50 chance, epistemically speaking. Given an infinitely large multiverse, of course.
Down The Rabbit Hole May 12, 2023 at 22:01 #807567
Reply to RogueAI

Quoting RogueAI
Countable infinities are equal, so the infinite set of worlds where we're Boltzmann brains is equal to the infinite set of worlds where we're not. It's a 50/50 chance, epistemically speaking. Given an infinitely large multiverse, of course.


That's what I was thinking! Thoughts @noAxioms?
Down The Rabbit Hole May 12, 2023 at 22:27 #807578
Reply to RogueAI

Yes, the part about all outcomes being equally likely within infinity, is my challenge to the paradox.

It would be good to have your thoughts. I have been impressed with many of the regulars knowledge on infinities.
noAxioms May 12, 2023 at 23:12 #807590
Quoting RogueAI
Countable infinities are equal
Tosh

If that were true, if I pick a random whole number of at least 10 digits, odds are even that it would be prime because there are countably infinite numbers that large that are prime, and countably infinite numbers that are not.

Did the you-tube link make a claim of that nature? If so, it would validate my policy to not get my facts from you tube.

Quoting Down The Rabbit Hole
Thoughts noAxioms?
Post what you think the video is claiming. If your thoughts are aligned to the bit above, you're on your own.

What exactly are we counting here anyway? The point is not how many universes in the multiverse (which is not countable no matter what kind of multiverse you're talking about), but rather the probability of the physics of this universe being such that BB's are more probable than regular brains. There is no equal probability in any of that.
It seems that neither normal nor BB's are countable in any reasonable manner, especially since empirical measurement is questionable.

RogueAI May 12, 2023 at 23:27 #807595
Reply to noAxioms I'm not a math major by any means. I'm going by stuff like this:

https://math.stackexchange.com/questions/760553/are-all-uncountable-infinities-greater-than-all-countable-infinities-are-some-u#:~:text=(b)%20No%2C%20all%20countable,numbers%2C%20than%20%CE%B1%3E%CE%B2.
RogueAI May 12, 2023 at 23:27 #807596
Reply to Down The Rabbit Hole I think we can defeat the Boltzmann Brain problem by adopting idealism. The idea that consciousness and mind can come from non-conscious mindless stuff leads to all sorts of problems.
noAxioms May 13, 2023 at 01:18 #807616
Quoting RogueAI
I'm going by stuff like this:

The answer there says that the cardinalities of two countable infinities are equal.
That's very different than the statement that two countable infinities are equal, which sort of suggests that there are numbers representing its sizes and those numbers are the same, which is just silly since there can be no such number.

Again I repeat, why is this relevant? Who is comparing two countable infinities? The conclusion of 'equally likely probability' is invalid from a comparison of the cardinalities, as the prime-number example illustrates.
Patterner May 13, 2023 at 01:19 #807617
The video says:
[B]"But if the universe exists over an infinitely long time, extremely unlikely events [I]will[/I] happen."[/B]
I'm sure some will. But there are an infinite number of unlikely events. No reason to think [I]all[/I] of them [I]will[/I] happen. There are an infinite number of things those infinite monkeys on infinite typewriters could type. There are an infinite number of things they could type that do not contain the letter E.
noAxioms May 13, 2023 at 01:32 #807618
Quoting Patterner
"But if the universe exists over an infinitely long time, extremely unlikely events will happen."

Since the universe is infinite in size, it doesn't even take a significant amount of time for extremely unlikely events to occur. I think a comparison of how likely it is to occur within say a given volume of space would help express things better.
I'm sure some will. But there are an infinite number of unlikely events. No reason to think all of them will happen.
Questionable. Some occurrences get less probable over time. They happen because of the infinite size, but if the probability of something drops in half with each passing century, it probably will never happen in a given volume even given infinite time. It all has to do with the area under the probability curve. Is it finite or not? Some infinite series approach infinity and some do not.

There are an infinite number of things those infinite monkeys on infinite typewriters could type. There are an infinite number of things they could type that do not contain the letter E.
But you didn't mention something that they cannot type (pi to full precision is a nice example), and how about anything larger than one monkey can type in its lifetime? The monkeys are not immortal, so the probability of something getting typed drops off sharply after the life expectancy of one. Sure, one monkey lives long enough to hammer out all of Shakespeare. That's why we have a lot of monkeys, which represents infinite space. Immortal monkeys represents infinite time. A single immortal monkey who never stops outputting random characters is all that is needed to eventually put out any finite work of literature, buried of course with gibberish on either side.

RogueAI May 13, 2023 at 01:41 #807619
Quoting noAxioms
Who is comparing two countable infinities?


If the universe is infinite, then there are infinitely many Boltzmann brains and infinitely many non-Boltzmann brains. Since the two sets are equal, the subjective probability that one is a member of either set is 50/50. What else could it be? What do you think the probability that you're not a Boltzmann brain is? And how do you arrive at that value?
SophistiCat May 13, 2023 at 08:32 #807656
Quoting RogueAI
If the universe is infinite, then there are infinitely many Boltzmann brains and infinitely many non-Boltzmann brains. Since the two sets are equal, the subjective probability that one is a member of either set is 50/50.




See the problem here? Probabilities don't work like that.

In any case, this is not relevant to the OP video, which was comparing the probabilities of a "Boltzmann Brain" fluctuation and a "Boltzmann Big Bang" fluctuation. You don't need an infinite domain with its measure problems to do that.
universeness May 13, 2023 at 09:27 #807658
From wiki:
The Boltzmann brain thought experiment suggests that it might be more likely for a single brain to spontaneously form in a void (complete with a memory of having existed in our universe) rather than for the entire universe to come about in the manner cosmologists think it actually did. Physicists use the Boltzmann brain thought experiment as a reductio ad absurdum argument for evaluating competing scientific theories.

My question becomes a rather simple one. If Boltzmann brains exist, then why have we never found one?
They seem as hidden as gods.
Patterner May 13, 2023 at 12:16 #807665
Quoting noAxioms
A single immortal monkey who never stops outputting random characters is all that is needed to eventually put out any finite work of literature, buried of course with gibberish on either side.
Anything's possible. But with an infinite number of possibilities that are not works of literature, including an infinite amount of gibberish; an incomprehensibly large number of combinations of the same number of letters, punctuation, and spaces as Shakespeare's works that are [I]not[/I] Shakespeare's works; and a rather large number of works of literature that are not Shakespeare's works... I'd bet against it.
RogueAI May 13, 2023 at 13:51 #807673
Reply to SophistiCat I'm not sure you're right, so let me ask you the same question I asked Axiom:
What do you think the probability that you're not a Boltzmann brain is? And how do you arrive at that value?

RogueAI May 13, 2023 at 13:52 #807674
Quoting SophistiCat
f the universe is infinite, then there are infinitely many Down The Rabbit Hole brains and infinitely many non-@Down The Rabbit Hole brains. So for any given brain, there is a 50% probability that it is a @Down The Rabbit Hole brain.


We were talking about subjective probabilities, not actual probabilities, and it's already known by me that I don't have "Down the Rabbit Hole"'s brain, so this "If the universe is infinite, then any given brain is either a @RogueAI or a @Down The Rabbit Hole brain." is false. I already know that my own given brain cannot be Rabbit Hole's brain.
noAxioms May 13, 2023 at 14:23 #807679
Quoting universeness
From wiki:
The Boltzmann brain thought experiment suggests that it might be more likely for a single brain to spontaneously form in a void (complete with a memory of having existed in our universe) rather than for the entire universe to come about in the manner cosmologists think it actually did.
That's a horrible wording of the problem. What is 'the void' here? Is it that from which the universe sprang, or is it our universe, mostly nearing infinite time and space? Our universe contains an infinite number of real brains, so comparing that to the more probable BB's in 'the void' is still not comparing real to BBs. One improbable roll times infinity is questionably more than the more probable roll.

Physicists use the Boltzmann brain thought experiment as a reductio ad absurdum argument for evaluating competing scientific theories.
Something like that. The Carroll paper I liked states the problem far more clearly than does wiki.

[quote=universeness]My question become a rather simple one. If Boltzmann brains exist, then why have we never found one?[/quote]The odds of one existing exactly on our past light code is zero to an incredible number of digits. If one by super freak chance happens to exist exactly on our past light cone, the odds that we'd notice it there is zero to a whole bunch more digits. We can't even see a rock that size if its further away than the moon, let alone on the far side of the visible universe.
Other answer: Maybe you are one, in which case you've technically found one.

A BB need not be a 3 dimensional thing, or in any way resembling a human brain. It just needs to be something functioning as one in enough ways.

Quoting RogueAI
If the universe is infinite, then there are infinitely many Boltzmann brains and infinitely many non-Boltzmann brains. Since the two sets are equal, the subjective probability that one is a member of either set is 50/50. What else could it be?

You say you're not a math major, ask a question, then ignore the answer (given by several posters).
The two sets are not equal. To say they are equal is to say that every Boltzmann brain is also a normal non-Boltzmann brain. The two sets would be the same set. This is a contradiction.

"Subjective probability" is a meaningless term. Probability refers to the odds of one thing relative to another, or the odds of something being true or not.

Quoting Patterner
But with an infinite number of possibilities that are not works of literature, including an infinite amount of gibberish; an incomprehensibly large number of combinations of the same number of letters, punctuation, and spaces as Shakespeare's works that are not Shakespeare's works; and a rather large number of works of literature that are not Shakespeare's works... I'd bet against it.

So given a die with 10[sup]10000000[/sup] sides, one of those sides corresponds to the complete works of Shakespeare, and the rest other things, mostly gibberish. You're betting that if this die is rolled an unlimited number of times, most of those other sides will come up an infinite number of times, but the one side in question will not come up even once.
You're not a math major either I take it. Neither am I, but I can do simple arithmetic at least.
universeness May 13, 2023 at 15:00 #807683
Quoting noAxioms
The odds of one existing exactly on our past light code is zero to an incredible number of digits. If one by super freak chance happens to exist exactly on our past light cone, the odds that we'd notice it there is zero to a whole bunch more digits. We can't even see a rock that size if its further away than the moon, let alone on the far side of the visible universe.
Other answer: Maybe you are one, in which case you've technically found one.


If the Universe can manifest Boltzman brains, then surely they would at least be a numerous as planets or neutrinos. What would restrict their number?

The wiki article goes no to say:
Over a sufficiently long time, random fluctuations could cause particles to spontaneously form literally any structure of any degree of complexity, including a functioning human brain. The scenario initially involved only a single brain with false memories, but physicist Sean Carroll pointed out that, in a fluctuating universe, the scenario works just as well with entire bodies, even entire galaxies.

and

Sean Carroll states "We're not arguing that Boltzmann Brains exist—we're trying to avoid them." Carroll has stated that the hypothesis of being a Boltzmann brain results in "cognitive instability". Because, he argues, it would take longer than the current age of the universe for a brain to form, and yet it thinks that it observes that it exists in a younger universe, this shows that memories and reasoning processes would be untrustworthy if it were indeed a Boltzmann brain. Seth Lloyd has stated, "They fail the Monty Python test: Stop that! That's too silly!" A New Scientist journalist summarizes that "The starting point for our understanding of the universe and its behavior is that humans, not disembodied brains, are typical observers.

I underlined some of the words from the new scientist journalist, as I always perceived Boltzmann brains, as posited by Boltzmann, to be 'disembodied' notions of a thinking agent, so how could I have or be one?
Perhaps I missed something about the various descriptions I have read about Boltzmann's work.
Definitely a genius scientist but he had a very bad time by all accounts.

In 1906, Boltzmann's deteriorating mental condition, forced him to resign his position, and his symptoms indicate he experienced what would today be diagnosed as bipolar disorder. Four months later he died by suicide on 5 September 1906, by hanging himself while on vacation with his wife and daughter in Duino, near Trieste (then Austria).
Patterner May 13, 2023 at 15:34 #807693
Quoting noAxioms
But with an infinite number of possibilities that are not works of literature, including an infinite amount of gibberish; an incomprehensibly large number of combinations of the same number of letters, punctuation, and spaces as Shakespeare's works that are not Shakespeare's works; and a rather large number of works of literature that are not Shakespeare's works... I'd bet against it.
— Patterner
So given a die with 1010000000 sides, one of those sides corresponds to the complete works of Shakespeare, and the rest other things, mostly gibberish. You're betting that if this die is rolled an unlimited number of times, most of those other sides will come up an infinite number of times, but the one side in question will not come up even once.
You're not a math major either I take it. Neither am I, but I can do simple arithmetic at least.
The die has an infinite number of sides. Not the finite number that the one you postulate has. It's not simple arithmetic. You could roll this die an infinite number of times, and you would never see every side. There are an infinite number of sides you would never see.

noAxioms May 13, 2023 at 16:42 #807708
Quoting universeness
If the Universe can manifest Boltzman brains, then surely they would at least be a numerous as planets or neutrinos. What would restrict their number?
I don't know what you mean by 'their number'. Things which occur an unlimited number of times don't have a number to restrict, and thus has no bearing on the likelihood of finding one. See the example about the primes in my post above.

The wiki article goes no to say:
Over a sufficiently long time, random fluctuations could cause particles to spontaneously form literally any structure of any degree of complexity, including a functioning human brain.
Or a functioning entity that thinks it's a human brain.

I underlined some of the words from Seth Lloyd as I always perceived Boltzmann brains as posited by Boltzmann to be 'disembodied' notions, so how could I have or be one?
They're subjectively indistinguishable from a regular one, at least for a moment. BBs don't last but for a moment usually, unless a life-support system also springs into existence along with it.



Quoting Patterner
The die has an infinite number of sides.
Finite sides. It represents about 5 million random keystrokes, enough to write the complete works of Shakespeare.
You suggest the number is not finite. How can you justify that? Is there a finite probability of the letter 'T' being typed first? If so, is it infinitely unllkely that a 'h' would follow? Exactly at what character (out of the 5 million) does the next correct keystroke suddenly become infinitely improbable? There are about 65 characters from which to choose. Perhaps you are suggesting that the product of 5 million of of these nonzero numbers is zero, and not just a really small number with only about 10 million leading zeros.

RogueAI May 14, 2023 at 00:13 #807762
Quoting noAxioms
The two sets are not equal.


Your claim is then that the two countable infinite sets (Boltzmann brains and non-Boltzmann brains) are not equal? Any math people want to comment on that? It's my understanding all infinite countable sets are equal.

[i]With these definitions, here are the answers (without proofs):

(a) Yes, every uncountable infinity is greater than every countable infinity.

(b) No, all countable infinities are the same: if A and B are both countable and infinite, then ?=?[/i]
.
https://www.google.com/search?q=%22countable+infinities+are+equal%22&rlz=1C1CHBH_enUS956US956&oq=%22countable+infinities+are+equal%22&aqs=chrome..69i57j33i160l2.10534j0j4&sourceid=chrome&ie=UTF-8
Patterner May 14, 2023 at 11:44 #807841
I wonder how many Boltzmann brains think they are Martians. And how many think they are from sentient stars. And how many think they are in a universe with entirely different laws of physics than those in the universe I think I am from. And how many think they are God. And how many think they are…. Well, anything else we can imagine, as well as any number of things we don’t get around to imagining.

Is there any reason any of these things couldn’t happen?
universeness May 14, 2023 at 11:48 #807843
Quoting noAxioms
I don't know what you mean by 'their number'. Things which occur an unlimited number of times don't have a number to restrict, and thus has no bearing on the likelihood of finding one. See the example about the primes in my post above.


I don't assign much value to notions such as infinity or 'an infinite number of possibilities,' etc.
A notional number like a googolplex, cannot be written out as 1 followed by the number of zero's required, as there is not enough space in the universe to do so. A googolpex is as far from infinity as the number 1. If there were a googolplex of boltzmann brains in the universe then every coordinate in the universe would contain one and we would know what the universe was 'made of.'
If I wandered freely in the universe, the chances of me encountering a galaxy, a star and a planet are quite good, given an adequate amount of time. So, based on Boltzmann's description of a Boltzmann Brain, I think we would have encountered them by now, if they existed, regardless of any probability arguments you have offered regarding primes.

Quoting noAxioms
if I pick a random whole number of at least 10 digits, odds are even that it would be prime because there are countably infinite numbers that large that are prime, and countably infinite numbers that are not.


The term 'countable infinity,' has little value imo. I don't know what a maths expert such as @jgill would comment, on the 'usefulness' of terms such as 'countable and uncountable infinities,' perhaps he will offer us his view.

The maths stack exchange has:
A countable infinite set is a set where you can list the elements one-by-one, but your list is infinitely long. Some examples are the natural numbers, integers, and rationals.

It's not possible to count all possible members of the list of integers, sure, you can start to count them, and I suppose that's why such a list is called 'countable,' but, the concept is 'over burdened,' as it is self-defeating to suggest that a list of items is 'countable' and then demonstrate that you can start the count, but the heat death of the universe will complete before the counting process completes, so 'countable infinity' is about as useful a notion as a permanently hidden deist god.

The points I have been making SUPPORT your (and Sean Carroll's ) proposal that we need not consider that in 'an infinite duration we are more likely to be a disembodied brain,' as there is NO such duration, as an infinite duration, so there is NO possibility that we are in REALITY, some disembodied brain.

I appreciate that I am a maths child, in comparison with someone who merits the title maths prof.
I cannot see any particular usefulness for the notion of 'different types of infinity' based on notions such as cardinality and bijective/injective functions, but perhaps someone like @jgill could explain why such notions are essential and support the notion of Boltzmann brains.
noAxioms May 14, 2023 at 14:30 #807869
Quoting universeness
I don't assign much value to notions such as infinity or 'an infinite number of possibilities,' etc.

Infinity just means essentially 'without bound', or more literally, not finite. "An infinite number" is a contradiction. There is no number that is infinite.

Y'all are missing the point. It hasn't anything to do with infinity. It all has to do with one's theory of choice and not with the actual universe. Any theory that produces BB at a higher probability cannot be justified by empirical means or any other means. That's the point.

A notional number like a googolplex, cannot be written out as 1 followed by the number of zero's required, as there is not enough space in the universe to do so.
Lack of ability to write a number down doesn't make it a not-number. People have expressed numbers an awful lot higher than a googleplex.

A googolpex is as far from infinity as the number 1.
No. There is no 'distance' to infinity since it isn't a number.

If there were a googolplex of boltzmann brains in the universe then every coordinate in the universe would contain one and we would know what the universe was 'made of.'
Not so, and there are probably more than that many BBs in our universe, and hopefully more regular brains than that.

If I wandered freely in the universe, the chances of me encountering a galaxy, a star and a planet are quite good, given an adequate amount of time. So, based on Boltzmann's description of a Boltzmann Brain, I think we would have encountered them by now, if they existed, regardless of any probability arguments you have offered regarding primes.
Non-sequitur. Stars and planets are pretty persistent; BB's are not. Stars and planets are readily visible,. BBs are not. The sun has wandered freely for about a third the age of the universe and hasn't encountered a star yet, so I suppose I can deny the first assertion as well. A random walk through the universe will probably not hit an object as large as a planet before those objects have long since gone cold and dead. You will on the other hand encounter small things like dust once in a while, but not often enough to say doom a spacecraft like Voyager before it stops talking to us.

Nobody is claiming that BB's are popping up constantly around every corner. They're incredibly unlikely things, but then you multiply that super-low probability by unlimited 'time', if 'time' is a meaningful concept outside of our own posited spacetime.

The term 'countable infinity,' has little value imo.
There's an awful lot of literature about such sets, and their relation to sets of higher cardinality.

I don't know what a maths expert such as jgill would comment, on the 'usefulness' of terms such as 'countable and uncountable infinities,' perhaps he will offer us his view.

It's not possible to count all possible members of the list of integers
Of course not. Each integer (and each rational number for that matter) can be assigned a unique position in the list. That's the mathematical definition if it being countable. So for instance, the integer 75 is probably 150th on the list of integers by the simplest method of counting. Since there is no integer that cannot be assigned such a position, the list is deemed countable. You're definition seems to be "can be counted". If it could be counted, it would be by definition finite.

as there is NO such duration as an infinite duration
That's like saying that the spatial extent of the universe must be finite. There is nothing precluding unbounded time, and my condolences if you cannot handle it.

Quoting RogueAI
Your claim is then that the two countable infinite sets (Boltzmann brains and non-Boltzmann brains) are not equal?
You just endlessly repeat the same claim, without backing and without addressing any of the counter arguments. The links you supplied do not support your case.

For two numbers to be equal, they would need to be the same number. Similarly, for two sets to be equal, they'd need to be the same set. Maybe you're working from a different definition of what it means for two things to be equal, but you've not provided that.
There's been plenty of counterexamples to your assertion and you've not found fault with any of them.

As for your claim of my claim above, that too is false since it is possible for both sets to be empty, and therefore equal.
RogueAI May 14, 2023 at 16:03 #807886
Quoting noAxioms
You just endlessly repeat the same claim, without backing and without addressing any of the counter arguments. The links you supplied do not support your case.


Sure they do. If A and B are both countably infinite, A=B. Do you dispute this? Is the link I proved wrong? You also haven't provided any links to back up your point. Can you do so? Do you want to say they're the same size instead of being equal? That's fine with me.

ETA:
In the late 19th century, the German mathematician Georg Cantor captured the spirit of this matching strategy in the formal language of mathematics. He proved that two sets have the same size, or “cardinality,” when they can be put into one-to-one correspondence with each other — when there is exactly one driver for every car. Perhaps more surprisingly, he showed that this approach works for infinitely large sets as well.
https://www.quantamagazine.org/mathematicians-measure-infinities-find-theyre-equal-20170912/
universeness May 14, 2023 at 17:06 #807901
Quoting noAxioms
If there were a googolplex of boltzmann brains in the universe then every coordinate in the universe would contain one and we would know what the universe was 'made of.'
Not so, and there are probably more than that many BBs in our universe, and hopefully more regular brains than that.


I think your statement above is nonsense, based in the definition of a googolplex.

Quoting noAxioms
That's like saying that the spatial extent of the universe must be finite. There is nothing precluding unbounded time, and my condolences if you cannot handle it.

Thank you for your unrequested, unrequired and impudent condolences.

The geometry of the universe is currently considered flat, and unbounded, not infinite. It could seem flat to us based on its actual size. It could be an expanding sphere shape, but not expanding into anything as it IS everything. I think this train of thought is why Carl Sagan liked the idea that this universe may be like an atom, and every atom in this universe, being a universe. An unlikely but more plausible idea, than the existence of boltzmann brains imo.
I agree with Seth.
Quoting universeness
Seth Lloyd has stated, "They fail the Monty Python test: Stop that! That's too silly!"
RogueAI May 14, 2023 at 18:00 #807914
Reply to universeness Can you address my reply to you about subjective probabilties?
universeness May 14, 2023 at 19:29 #807931
Reply to RogueAI
Have you replied to the wrong poster here? You did not reply to me asking about subjective probabilities,
you directed that towards noAxioms and sophistiCat. For what it's worth, you posted this reply to SophistiCat

Quoting RogueAI
We were talking about subjective probabilities, not actual probabilities, and it's already known by me that I don't have "Down the Rabbit Hole"'s brain, so this "If the universe is infinite, then any given brain is either a RogueAI or a @Down The Rabbit Hole brain." is false. I already know that my own given brain cannot be Rabbit Hole's brain.


My response would be:
I think 'subjective probability,' defined as:
Subjective probability is a probability that reflects an individual's personal judgment or own experience about the likelihood of an event. It is not based on formal calculations, data, or theory. It may vary among different people and situations. It is sometimes used when more objective methods are not available or feasible.

Is at best, a limited way to offer credible evidence of a proposal, and as your subjective probability is further based on a complete unknown, such as 'is the universe infinite?' then this does not add to my confidence level that Boltzmann brains are possible.
RogueAI May 14, 2023 at 19:36 #807932
Reply to universeness Quoting universeness
Is at best, a limited way to offer credible evidence of a proposal, and as your subjective probability is further based on a complete unknown, such as 'is the universe infinite?' then this does not add to my confidence level that Boltzmann brains are possible.


Yes, I confused you with another poster, sorry about that.

Assuming that the universe is infinite, what do you think the probability is that you're a Boltzmann brain?
noAxioms May 14, 2023 at 19:59 #807938
Quoting RogueAI
The links you supplied do not support your case.
— noAxioms
Sure they do. If A and B are both countably infinite, A=B.
The mathexchange link never says A=B. It says their cardinalities are the same, with which I fully agree. That means that neither can be said to be more numerous than the other since there's a 1-1 mapping between members of the two sets.

The reply in that article does say about A and B that "they're the same", refering to their cardinality, but is not an assertion that both sets contain the same members.

Do you dispute this?
I dispute that the sets contain the same members (that they're actually the same), or that (to take my first counterexample) a large random positive number is as likely to be prime as not prime, despite the fact that all non-prime whole numbers can indeed be mapped 1-1 with prime numbers. You are drawing invalid probabilistic conclusions from sets based only on their identical cardinality.

Is the link I proved wrong?
I have no problem with it. The primes and non-primes are clearly not the same set, else any member of one would be a member of the other.

You also haven't provided any links to back up your point.
What point? That a large random number is probably not prime? No, I didn't provide a link for that. Do you dispute it?

Do you want to say they're the same size instead of being equal? That's fine with me.
There is a 1-1 mapping between the two sets. It therefore cannot be argued that one set is more numerous than the other. That's 'the same size' when speaking of infinities.

Another example is the set of whole numbers and the set of 1, 10, 100, 1000 ....
In that case the set of whole numbers clearly contains members not in the 2nd set, but the 2nd set is entirely contained in the first set. Nevertheless, they have the same cardinality and neither set can be asserted as having a greater size than the other. The mapping between the two sets is trivial in this case, in either direction.

About the quanta magazine article. There are several errors in it typical of a pop article, but the gist seems to be proving if the real numbers had the next cardinality up from 'countable' or if there was a cardinality in between. Cohen comes along about 60 years ago and proves that the question could not be answered within the framework of set theory. M&S came along in 2016 and proved that there wasn't.

I may have read that wrong. Thanks for the link. I was unaware of the work.


Quoting RogueAI
Assuming that the universe is infinite, what do you think the probability is that you're a Boltzmann brain?

It isn't a function of the size of the universe. It is a function of the theory that describes the workings (or the origin) of the universe. Given that, you get a ratio of BB's vs real brains. That ratio should be incredibly close to zero or some huge number. The size of the universe has no impact on that ratio. The odds of the ratio being something else (like say 1) is too small to consider. It's a matter of sorting the theories into two heaps: empiricallly justifiable or not.



Quoting universeness
I think your statement above is nonsense, based in the definition of a googolplex.

However large, a googolplex is a finite number. If a finite number of things are spread out evenly in an infinite volume, there would be infinite distance between them on average. You find this nonsense? Perhaps you assume a finite size universe, in which case the question reduces to how finite? It becomes a simple division problem between two finite numbers to get the nonzero density of BBs, but given infinite space, any finite number of objects contained in that volume would have zero density.

The geometry of the universe is currently considered flat, and unbounded, not infinite.
Reference? Those three seem mutually contradictory. Any two, fine, but all three? Perhaps this is our disconnect.

universeness May 14, 2023 at 20:40 #807943
Quoting RogueAI
Assuming that the universe is infinite, what do you think the probability is that you're a Boltzmann brain?

I thought I had already answered that question with the suggestion that using my own subjective probability, I think that the universe is NOT infinite.
universeness May 14, 2023 at 20:48 #807944
Quoting noAxioms
However large, a googolplex is a finite number. If a finite number of things are spread out evenly in an infinite volume, there would be infinite distance between them on average. You find this nonsense? Perhaps you assume a finite size universe, in which case the question reduces to how finite? It becomes a simple division problem between two finite numbers to get the nonzero density of BBs, but given infinite space, any finite number of objects contained in that volume would have zero density.


You have already agreed that all 'numbers' are finite and in my opinion, there is no infinite volume.
YES, I am suggesting the universe is spatially finite. You can call something unbounded to indicate that it SEEMS to go on forever, and a 2d creature living in flatverse might even think its universe is totally linear, especially, if all of its scientific instrumentation supports that proposal. BUT, it will still accept the possibility that its flatverse is in fact circular but it's so vast that from it's 'light cone' it seems to be linearly unbounded.
jgill May 14, 2023 at 21:22 #807946
Quoting RogueAI
Countable infinities are equal, so the infinite set of worlds where we're Boltzmann brains is equal to the infinite set of worlds where we're not. It's a 50/50 chance, epistemically speaking. Given an infinitely large multiverse, of course.


Prime Number Theorem
Janus May 14, 2023 at 22:16 #807952
Quoting Down The Rabbit Hole
The Boltzmann brain paradox effectively says, in an infinite duration, we are more likely to be a disembodied brain with false memories than existing as persons within the complexities of our universe.


This seems self-refuting: if we were disembodied brains with false memories there would seem to be no rational justification for believing that we could be such, since the hypothesis that we are more likely to be Boltzmann brains relies on accepted mathematical and physical understandings which are reliant on the assumption that our memories are accurate (enough).
Patterner May 14, 2023 at 22:33 #807956
Just because we might expect it in an infinite duration, doesn’t mean we have reason to expect it now.
Down The Rabbit Hole May 14, 2023 at 23:25 #807963
Reply to Janus

Quoting Janus
This seems self-refuting: if we were disembodied brains with false memories there would seem to be no rational justification for believing that we could be such, since the hypothesis that we are more likely to be Boltzmann brains relies on accepted mathematical and physical understandings which are reliant on the assumption that our memories are accurate (enough).


Yes, I think this is the point raised by Sean Carroll. And it is the same kind of paradox that faces epistemological nihilism - if we can't know things, we can't know that we can't know things.

We can only be completely agnostic on the question of if we are a Boltzmann Brain?
Janus May 14, 2023 at 23:58 #807970
Quoting Down The Rabbit Hole
We can only be completely agnostic on the question of if we are a Boltzmann Brain?


Either that, or the idea is groundless and/ or incoherent. I don't know what to think about it.
Wayfarer May 15, 2023 at 01:09 #807983
Quoting Down The Rabbit Hole
In an infinite duration, aren't all possible outcomes equally likely to occur?


In an infinite duration, and as all possible existents are of finite duration, then everything would have happened already.
RogueAI May 15, 2023 at 03:29 #808004
Quoting Janus
Either that, or the idea is groundless and/ or incoherent. I don't know what to think about it.


If the idea that minds can emerge from mindless stuff is incoherent, this problem goes away. As does simulation theory.
Patterner May 15, 2023 at 03:43 #808005
Quoting Wayfarer
In an infinite duration, and as all possible existents are of finite duration, then everything would have happened already.
I don’t understand. Has there already been an infinite duration?
Wayfarer May 15, 2023 at 03:46 #808006
Reply to Patterner Not according to the cosmological model popularly known as the 'big bang'. According to that model the Universe emerged from the singularity approximately 13.8 billion years ago.
Patterner May 15, 2023 at 03:48 #808007
Reply to WayfarerThen why would everything have happened already?
jgill May 15, 2023 at 04:22 #808012
Quoting Wayfarer
In an infinite duration, and as all possible existents are of finite duration, then everything would have happened already.


Why is that?
Wayfarer May 15, 2023 at 04:35 #808014
Reply to jgill Doesn't it stand to reason that, if the Universe was of infinite duration, and all events in the Universe are of finite duration, then all events would already have occurred? Isn't that deductively valid? (It also seems to map against the idea of the heat death of the universe, which is a hypothesis that the universe will evolve to a state of no thermodynamic free energy, and will therefore be unable to sustain processes that increase entropy.)
Janus May 15, 2023 at 04:54 #808016
Quoting Wayfarer
Doesn't it stand to reason that, if the Universe was of infinite duration, and all events in the Universe are of finite duration, then all events would already have occurred? Isn't that deductively valid? (It also seems to map against the idea of the heat death of the universe, which is a hypothesis that the universe will evolve to a state of no thermodynamic free energy, and will therefore be unable to sustain processes that increase entropy.)


That would only seem to hold if the Universe was of finite extent, that is contained a finite number of microphysical constituents. If we consider Nietzsche's 'eternal return' to be more than just a thought-experiment to test for life-affirmation, then this is the physical basis of his idea.

The astrophysicists at the time postulated that if the Universe was of infinite duration and extent, then the night sky should be ablaze with light, given that there would be an infinite number of stars and an infinite amount of time for the light to reach us, and the conclusion was that the Universe must be of finite extent, and it was unclear whether it had been of infinite duration.
Wayfarer May 15, 2023 at 06:46 #808022
Reply to Janus I looked it up. The argument is known as the "Eternal Recurrence" and was proposed by various ancient philosophers including Pythagoras, Empedocles, and Heraclitus. The argument is based on the assumption that time is infinite and that the number of possible events that can occur in time is also infinite. If the universe is eternal, then it follows that every possible event will occur an infinite number of times. It was picked up by Nietszche. Where I had misunderstood it was to mean that, if all events are of finite duration, and the Universe is infinitely old, then everything that could occur would have already occurred, because no number of finite events could ever occupy an infinite expanse of time. But I'm not going to press the point!
Patterner May 15, 2023 at 10:36 #808057
Reply to WayfarerAh. I didn’t realize the idea is that the universe is infinitely old.
universeness May 15, 2023 at 10:38 #808059
Reply to jgill
From a mathematical pov, does prime number theorem support or act against the Boltzmann brain proposal?
Down The Rabbit Hole May 15, 2023 at 10:55 #808063
Reply to Wayfarer

Quoting Wayfarer
If the universe is eternal, then it follows that every possible event will occur an infinite number of times.


This is the basis for my suggestion that Boltzmann brains and human-life are equally likely to occur. Despite the latter's pattern being more complex.

Other posters have cast doubt on this suggestion. It would be appreciated if @jgill put us straight.
Down The Rabbit Hole May 15, 2023 at 11:16 #808066
Reply to RogueAI

Quoting RogueAI
If the idea that minds can emerge from mindless stuff is incoherent, this problem goes away. As does simulation theory.


I don't see how we will be able to prove what gives rise to consciousness.

You're not suggesting substance-dualism are you?
noAxioms May 15, 2023 at 14:00 #808098
Quoting Janus
This seems self-refuting: if we were disembodied brains with false memories there would seem to be no rational justification for believing that we could be such, since the hypothesis that we are more likely to be Boltzmann brains relies on accepted mathematical and physical understandings which are reliant on the assumption that our memories are accurate (enough).

That it is circular like that doesn't result in the conclusion that we're not BBs. It only yields the conclusion that our hypothesis is unjustifiable.
So if you are in fact a BB (there is no 'we' about that, it would be a solipsistic existence), then there is zero evidence of your own nature. If you by freak chance happen to be in a state of suspicion about being a BB, that is just coincidence, completely unrelated to the fact that it happens to be true in this case.
If you are in fact an evolved thing (living in a non-Boltzmann galaxy, if there is such a thing), then you have access to empirical evidence, but you have no way of telling the difference. So you come up with a plausible hypothesis (the BB cannot 'come up with' anything) about the nature of your universe and if the hypothesis predicts that you're more likely to be a BB than not, then there cannot be justification for that hypothesis.

I think that's the summary of the argument.

Quoting Down The Rabbit Hole
We can only be completely agnostic on the question of if we are a Boltzmann Brain?

We can do more than that. We can restrict our hypotheses to ones that predict normal existence. If the actual 'way that things are' happens not to correspond to such a hypothesis, then the truth of reality is not something that can be reasonably guessed at.

Quoting Wayfarer
In an infinite duration, and as all possible existents are of finite duration, then everything would have happened already.

To use the tense 'would have happened' presumes that there is a present time, and that that present time is after all events (is at the end of infinite time, a contradiction).

Quoting RogueAI
If the idea that minds can emerge from mindless stuff is incoherent, this problem goes away. As does simulation theory.

I think that if such is your hypothesis, then like the BB scenario, empirical evidence cannot be trusted, and once again, the result is a completely unjustifiable hypothesis.

Quoting Wayfarer
Not according to the cosmological model popularly known as the 'big bang'. According to that model the Universe emerged from the singularity approximately 13.8 billion years ago.
That figure presumes that we can trust empirical evidence, which hasn't been established if we don't start with a hypothesis that allows us to make that assumption.

Quoting Janus
The astrophysicists at the time postulated that if the Universe was of infinite duration and extent, then the night sky should be ablaze with light,

This assumes a steady-state hypothesis. It was one of the earliest arguments that our universe is of finite age.

Quoting universeness
From a mathematical pov, does prime number theorem support or act against the Boltzmann brain proposal?

I don't see how it is relevant at all, since the BB idea isn't dependent on infinities or primes. It does however illustrate that just because two countable infinities (primes and not-primes say) can be given a 1-1 correspondence, it doesn't follow that random numbers have equally probability of being prime or not. So the following for instance is a non-sequitur:
Quoting Down The Rabbit Hole
This is the basis for my suggestion that Boltzmann brains and human-life are equally likely to occur.

I know of no hypothesis where normal minds and BBs have probabilities within a hundred orders of magnitude of each other, let alone equal.

RogueAI May 15, 2023 at 14:02 #808099
Quoting Down The Rabbit Hole
I don't see how we will be able to prove what gives rise to consciousness.


I think you can arrive at a proof via a reductio ad absurdum: the idea that consciousness and mind can from matter leads to absurdities like the following:
https://xkcd.com/505/
SophistiCat May 15, 2023 at 20:05 #808174
Quoting RogueAI
We were talking about subjective probabilities, not actual probabilities


Any probability has to obey additivity and normalization axioms, otherwise it's not a probability. If you find that your subjective probabilities add up to more than 100%, then you are being inconsistent.

Quoting Down The Rabbit Hole
This is the basis for my suggestion that Boltzmann brains and human-life are equally likely to occur. Despite the latter's pattern being more complex.


You need to be careful about what exactly "equally likely to occur" means in this context. The way cosmologists might pose this question is: "Given an observer, is it more likely to be a regular observer (a human or a similarly evolved creature) or a freak observer like a Boltzmann Brain?" This is a tricky epistemological question involving concepts like reference class, self-location and self-selection.

And yes, infinite, or just very big worlds seem to present a general challenge to observations:

Quoting Nick Bostrom
Big World theories, popular in contemporary cosmology, engender a peculiar methodological problem: because they say the world is very big and somewhat stochastic, they imply (or make it highly probable) that every possible human observation is made. The difficulty is that it is unclear how we could ever have empirical reasons for preferring one such theory to another, since they all seem to fit equally well with whatever we observe.


Intuitively though it seems that simply adding "more of the same" to the world (more space or more time or more observers) should not make a difference to a generic observation made by a particular observer at a particular place at a particular time, so the challenge to epistemologists is to explain just how this challenge is only a seeming one. (Bostrom purports to meet it with his Self-Sampling Assumption, which he also uses elsewhere to analyze puzzles like Boltzmann Brains.)
RogueAI May 15, 2023 at 20:09 #808176
Quoting SophistiCat
Any probability has to obey additivity and normalization axioms, otherwise it's not a probability.


Yes, but subjective probabilities are different than objective probabilities.
jgill May 15, 2023 at 22:05 #808195
Quoting universeness
?jgill

From a mathematical pov, does prime number theorem support or act against the Boltzmann brain proposal?


It was a counter to the number of primes being 50%.

Quoting Down The Rabbit Hole
In an infinite duration, aren't all possible outcomes equally likely to occur?


An infinite duration could include an infinite number of stages, the possibilities of something happening in a particular stage might not exist in other stages. In other words, its all babble. :smile:


Janus May 15, 2023 at 22:25 #808198
Quoting Wayfarer
Where I had misunderstood it was to mean that, if all events are of finite duration, and the Universe is infinitely old, then everything that could occur would have already occurred, because no number of finite events could ever occupy an infinite expanse of time.


Even if all events were of finite duration, and the Universe were infinitely old, that all events that could occur would already have occurred would rely on the Universe being of finite extent; that is the salient point.

I don't know exactly what you are thinking is entailed by "no number of finite events could ever occupy and infinite expanse of time" in this context. That sounds like the standard argument against the possibility of an actual infinite duration.

You could have said, which would have been clearer I think, "no finite number of events could ever occupy an infinite expanse of time", and that, if true, would show that either the Universe has not been of infinite duration or that, if it were, then an infinite number of events would have occurred, with recurrence if the extent of the Universe were finite, but not necessarily if not. That events are finite is a given.

Quoting noAxioms
So you come up with a plausible hypothesis (the BB cannot 'come up with' anything) about the nature of your universe and if the hypothesis predicts that you're more likely to be a BB than not, then there cannot be justification for that hypothesis.

I think that's the summary of the argument.


Yes, that's pretty much what I was thinking. Sure, we might be Boltzmann in any case, but if we were then we would have no rational justification for thinking that we are or even might be.
Down The Rabbit Hole May 16, 2023 at 00:10 #808219
Reply to SophistiCat

Quoting SophistiCat
You need to be careful about what exactly "equally likely to occur" means in this context. The way cosmologists might pose this question is: "Given an observer, is it more likely to be a regular observer (a human or a similarly evolved creature) or a freak observer like a Boltzmann Brain?" This is a tricky epistemological question involving concepts like reference class, self-location and self-selection.


Quoting SophistiCat
Intuitively though it seems that simply adding "more of the same" to the world (more space or more time or more observers) should not make a difference to a generic observation made by a particular observer at a particular place at a particular time, so the challenge to epistemologists is to explain just how this challenge is only a seeming one. (Bostrom purports to meet it with his Self-Sampling Assumption, which he also uses elsewhere to analyze puzzles like Boltzmann Brains.)


Yes, I think our meaning of "equally likely to occur" is pivotal. A more agreeable meaning may be from The Principle of Indifference: "A rule for assigning epistemic probabilities. It assumes that if you have multiple plausible scenarios, you should assume each is equally likely till you have evidence otherwise".
Patterner May 16, 2023 at 04:36 #808239
Hey, I call dibs on the first Boltzmann USS Enterprise when it pops up!!!
Down The Rabbit Hole May 16, 2023 at 09:54 #808262
Reply to Patterner

You'll have to fight @universeness for it.
universeness May 16, 2023 at 10:14 #808264
Reply to Down The Rabbit Hole
Absafragginlootly! and WHEN I gain full possession, the first things I will do, is drop 'Boltzmann' from the name, and go looking for a qualified Captain who looks a little bit like William Shatner or, if I am pushed, Scott Bakula or maybe even Avery Brooks :chin:
Down The Rabbit Hole May 16, 2023 at 10:23 #808266
Reply to universeness

Well, Shatner's a classic, but Patick Stewart is my favourite captain of all time.

Have you finished the new Star Trek: Picard? I've still got two episodes to go.
Patterner May 16, 2023 at 10:30 #808267
Have you people no respect for dibs?!? Barbarians!
universeness May 16, 2023 at 11:11 #808272
Reply to Patterner
My dibs are bigger that your dibs :lol: The neverending claim of all historical and current gangsters/heros/nations and so called, attempts at human civilisations.
Sorry, I am experiencing some cognitive crossover between this thread and the other that I am posting on right now, 'Culture is Critical.'
universeness May 16, 2023 at 11:22 #808273
Reply to Down The Rabbit Hole
Picard or 'Patrick Stewart' is just too 'Shakespearian' for me. I still love TNG of course.
I have finished watching Picard season 2, and Discovery season 4 and I have started watching Strange new worlds, season 1. I don't buy the cartoon ones such as 'below decks.' I only buy the DVD sets when they become available. I cant be bothered watching a series, in a episodic style, as they come on-line.
I prefer to play catch up, and watch the DVD's under my terms, rather than under the terms imposed by some broadcaster. The Picard arc is a bit bizarre here and there. I am not too keen on the Borg storyline and the 'pop up' moment of 'Wesley Crusher' that seems to have been pointless.
Addition: I also hated Picard's 'reincarnation' after he was killed!
I am happy to enjoy this divergence from the OP in this thread, as it's your thread, but the mods may insist such 'chat' style exchanges, be moved to the shoutbox or the lounge.
Addition 2: The 'Discovery' series storylines have been ok, but the amount of teary eyed exchanges and 'breathy' emotional exchanges between the characters, has almost totally destroyed the impact of the show imo.
Patterner May 16, 2023 at 11:52 #808277
it may be divergence, but it is also entirely legit. OK, maybe there couldn’t be such a thing as a functioning Enterprise, Boltzmann or otherwise, for reasons of how the technology works. But my point, aside from the fun, is that there will be an infinite number of Boltzmann Enterprises. As well as Defiants, Voyagers, etc. And all of these, but with each other's names. And each, but named USS Boltzmann. And my favorite, the USS Tao, for which I'm willing to give up the Enterpris. As well as an infinite number of Death Stars, Godzillas, Green Destiny swords, Enola Gays (both laden and not), levers big enough to move the world levers big enough to move the world (Archimedes has dibs, I believe), and every other damn thing we can think of, and those we cannot think of. There’s no reason the process that brings about a brain wouldn’t bring about anything and everything else.
Down The Rabbit Hole May 16, 2023 at 12:20 #808280
Reply to universeness

I enjoyed TNG the most, followed by Voyager I think. I was just getting into Discovery and Netflix took it off :sad: I won't spoil Picard Season 3 for you, but it gets a lot better. There's some nice surprises.

Blame @Patterner for setting me off. That said, better my thread than @Bartricks'.
universeness May 16, 2023 at 12:28 #808283
Quoting Patterner
But my point, aside from the fun, is that there will be an infinite number of Boltzmann Enterprises


How do you account for 'paradox' in your 'every possibility that can happen, will happen in time.'
If I state 'The only true existent regarding Boltzmann brains is that they have no true existent.'
Is that statement true given a very large or even infinite duration of time?
universeness May 16, 2023 at 12:33 #808286
Quoting Down The Rabbit Hole
That said, better my thread than Bartricks'.

Again, absafragginlootly! I think I maybe over-using that colloquialism.
Patterner May 16, 2023 at 13:08 #808290
Quoting universeness
But my point, aside from the fun, is that there will be an infinite number of Boltzmann Enterprises
— Patterner

How do you account for 'paradox' in your 'every possibility that can happen, will happen in time.'
If I state 'The only true existent regarding Boltzmann brains is that they have no true existent.'
Is that statement true given a very large or even infinite duration of time?

I don't account for it. Although it's fun, I think this whole topic is nonsense.


Quoting Down The Rabbit Hole
I enjoyed TNG the most, followed by Voyager I think. I was just getting into Discovery and Netflix took it off :sad: I won't spoil Picard Season 3 for you, but it gets a lot better. There's some nice surprises.
I grew up on TOS. I know a lot of people find it unwatchable because of the effects, but it and TNG are my favorites. Then Voyager.

Down The Rabbit Hole May 16, 2023 at 15:04 #808302
Reply to Patterner

Quoting Patterner
I grew up on TOS. I know a lot of people find it unwatchable because of the effects, but it and TNG are my favorites. Then Voyager.


I'm not of that generation, but I can respect the nostalgia.

As your tastes are similar to mine, you must be a Stargate fan. SG1 if my favourite Sci-fi series.

Reply to universeness

Quoting universeness
How do you account for 'paradox' in your 'every possibility that can happen, will happen in time.'
If I state 'The only true existent regarding Boltzmann brains is that they have no true existent.'
Is that statement true given a very large or even infinite duration of time?


(Unless all of this suddenly appeared from literally nothing, was created by god/s, or is an illusion) we know that patterns are spat out from something, like a QRF, or infinite universe/s (whether cyclical or a multiverse). Provided it's possible for Boltzmann brains to form, in an objective sense, they will almost certainly exist.

The question is how likely are we to be a Boltzmann brain. The Sean Carroll objection, that other posters have picked up on, suggests we cannot sensibly measure. As by doing so would be from the assumption that we are not a Boltzmann brain with false memories. I think @noAxioms is suggesting that our theory of how patterns form is more important than the fact there has been an infinite duration. And @RogueAI is saying from the view that material cannot naturally give rise to consciousness, Boltzmann brains cannot exist in any event.
Patterner May 16, 2023 at 15:28 #808311
Quoting Down The Rabbit Hole
I'm not of that generation, but I can respect the nostalgia.

As your tastes are similar to mine, you must be a Stargate fan. SG1 if my favourite Sci-fi series.
Oddly, I never much watched it. No particular reason. I only saw a few scattered episodes. I'd like to. Guess I'll see if it's available on one channel or other.


Quoting Down The Rabbit Hole
And RogueAI is saying from the view that material cannot naturally give rise to consciousness, Boltzmann brains cannot exist in any event.
Are we not material? Or did our consciousness arise unnaturally?

universeness May 16, 2023 at 16:32 #808324
Reply to Down The Rabbit Hole
Yeah, I think I get at least the main jist, of all the points made.
I only cited paradox just to exemplify the notion of 'we just cant currently know.'
This is probably all we can say for sure, regarding the existence of Boltzmann Brains.
In science, no theory can go further than the theory stage! No scientific theory can be declared FACT.
No matter how good the evidence, because exhaustive testing is impossible.
Patterner May 16, 2023 at 17:17 #808337
If Boltzmann Objects could exist, if the universe was infinitely old, we'd see billions of odd things floating around. So either they can't exist, or the universe is not infinitely old.

Still, if they could exist, isn't the universe old enough that we'd see SOME odd things floating around? Any of an infinite number of possible things might come into being at any given moment. Surely, something would have come along in our neighborhood my now. No? A replica of the Empire State Building crashes into Mars. Something that looks like an alien ship floats around near Jupiter. Action Comics #1 falls in my lap. Or the telescopes see something farther away that doesn't seem explainable in any non-Boltzmann way. Infinite possibilities in 13.8 billion years didn't produce anything that left a trace?
Down The Rabbit Hole May 18, 2023 at 22:22 #808898
Reply to Patterner

Quoting Patterner
Are we not material? Or did our consciousness arise unnaturally?


I think consciousness is most likely either a property of matter or arises from it. Some people believe there is a non-material substance (such as a soul) that combines with the material to make consciousness.

Quoting Patterner
If Boltzmann Objects could exist, if the universe was infinitely old, we'd see billions of odd things floating around. So either they can't exist, or the universe is not infinitely old.


Science suggests this bubble was started by a big bang about 14 billion years ago. Boltzmann Brains could have existed before our big bang, either in previous bubbles or from a quantum fluctuation. Or if there is a multiverse, there could be infinite Boltzmann Brains existing right now. We wouldn't see them from our bubble.
RogueAI May 18, 2023 at 22:52 #808908
How would you calculate density for a infinite number of things (e.g., Boltzmann brains) in an infinitely large space?
Patterner May 19, 2023 at 21:14 #809069
Quoting Down The Rabbit Hole
Science suggests this bubble was started by a big bang about 14 billion years ago. Boltzmann Brains could have existed before our big bang, either in previous bubbles or from a quantum fluctuation. Or if there is a multiverse, there could be infinite Boltzmann Brains existing right now. We wouldn't see them from our bubble.
I guess you can't argue with that. But I am skeptical. :D We also wouldn't see them if there weren't any. While not seeing any is not proof that there aren’t any, neither is it proof that there are. And our ability to list any number of reasons why we might not expect to find evidence of them is not evidence of them.

I doubt they are possible. If you take an airtight bag - or, rather, a hydrogentight bag - fill it with hydrogen and oxygen, and shake the hell out of it, will you maker water? I don't think a functioning brain will come into being if the right particles happen to bump into each other. I suspect they only work when they grow in the manner, and the order, that our brains grew.
wonderer1 May 20, 2023 at 12:30 #809163
If you take an airtight bag - or, rather, a hydrogentight bag - fill it with hydrogen and oxygen, and shake the hell out of it, will you maker water?
Reply to Patterner

I don't know about shaking the hell *out* of it. But shaking the hell *into* it makes water.

I just applied a chunk of burning sulfur to my big bag of hydrogen and oxygen... ...and hell!!!

Patterner May 20, 2023 at 15:01 #809184
Quoting wonderer1
I don't know about shaking the hell *out* of it. But shaking the hell *into* it makes water.

I just applied a chunk of burning sulfur to my big bag of hydrogen and oxygen... ...and hell!!!
Yes. The elements don't join together simply by bumping into each other. You need a little burst of energy. How many of these little bursts will we need to make all the water in a brain?

There are almost a couple hundred billion cells in the brain, and they can't be free floating cells and still be viable when they all bump into each other. So we need the constituent parts of all the cells to be in exactly the right places at the right time. But they won't form cells simply but bumping into each other, any more than hydrogen and oxygen will form water. What energy/reactions are needed for every joining at every level?

And will all of these joinings succeed when they are all as tightly packed as they'd need to be, with all these energy bursts and reactions going off all around them? We can eliminate the bursts needed for the formation of all the needed water by having free-floating water molecules. They couldn't be free-floating in groups, or they'd be useless ice. But I guess individual molecules would be fine. So that's some billions fewer of energy bursts to screw with the other formations. But it's not enough to make this scenario at all possible.
Down The Rabbit Hole May 22, 2023 at 22:41 #809936
Reply to RogueAI

Quoting RogueAI
How would you calculate density for a infinite number of things (e.g., Boltzmann brains) in an infinitely large space?


Good question. It may be that density has no meaning within infinity.
GRWelsh May 26, 2023 at 19:33 #810909
How can you even prove that disembodied brains are possible? The only examples of brains that we have are as parts of bodies. I can't see how anyone could argue that they are more likely without first establishing that they are possible, and so far I don't think anyone has done that.
Down The Rabbit Hole May 29, 2023 at 21:39 #811582
Reply to GRWelsh

Quoting GRWelsh
How can you even prove that disembodied brains are possible? The only examples of brains that we have are as parts of bodies. I can't see how anyone could argue that they are more likely without first establishing that they are possible, and so far I don't think anyone has done that.


Yes, that's a strong objection.

Disembodied brains can exist, but they don't last long. I think I read that upon decapitation consciousness lasts for up to 10 seconds, and brain death occurs within 3-6 minutes.

Say viable brains with false memories appear as a result of quantum fluctuations - they only need to last momentarily for you to be having the experience you are having now. As your memories could be false, you don't know that you existed before this moment.
Patterner May 29, 2023 at 23:07 #811624
A brain isn’t a bunch of pieces that can be put together like a puzzle. Even if all the necessary particles happened to bump into each other at the exact same instant, they would not be a working brain for even that instant.
RogueAI May 30, 2023 at 01:12 #811655
Reply to Down The Rabbit Hole
Reply to Patterner If a working brain could assemble itself randomly, then a working brain with life-support equipment would also be possible. The Boltzmann argument would have to work that way, because I'm not passing out due to lack of oxygen.
Patterner May 30, 2023 at 03:49 #811677
Reply to RogueAIThe issue isn't life-support for the brain. It's the assembly. It's not a simple matter of assembling the pieces. The particles that make up a brain can't be assembled like a jigsaw puzzle. Put all of the (good lord, how's many?) atoms exactly where they would be in a functioning brain, and you would not have a functioning brain. They don't simply bond to all of those they need to bond to because they are touching.
RogueAI May 30, 2023 at 05:43 #811685
Reply to Patterner I don't anything about that part of it. You're saying Boltzmann is wrong?
Patterner May 30, 2023 at 09:01 #811707
Reply to RogueAI
I am. You can't put the hundred trillion atoms that would be needed to make a single living cell right next to each other, and get a living cell. Just as you can't place two pieces of wood end to end, and have one long piece of wood. That's not how long pieces of wood come about. And it's not how brain cells come about, much less entire brains.
noAxioms May 30, 2023 at 16:04 #811769
Quoting Patterner
If Boltzmann Objects could exist, if the universe was infinitely old, we'd see billions of odd things floating around.

This is flat out wrong. If BBs are more likely, then you probably are one.

Regardless, if we're not one, we do not expect to see one. Far more likely is space filled with Boltzmann 100 euro notes, and we don't see those either. One must understand the sheer improbability of these things, which become likely only when multiplied by the idiot amount of time given for them to occur.

If you are a BB, then we don't 'see' anything. It is a solipsistic existence. One cannot measure the age of the universe (have you ever personally done it?), and since there's nobody else to do it, there's no way to know.

No model predicts that anything (BB or not) actually sees something like this.

Quoting GRWelsh
How can you even prove that disembodied brains are possible?

Not a matter of proof. It's a function of the model behind which one chooses to stand. If the model (not reality) predicts a greater likelihood of being a BB, then the model cannot be justified. It is simply a method of discarding not wrong models, but the unjustifiable ones. If reality happens to actually correspond to something like that, then the nature of reality literally cannot be known.

Quoting RogueAI
f a working brain could assemble itself randomly, then a working brain with life-support equipment would also be possible.
Exactly. Given said life support (a far more improbable thing), then the BB would persist long enough to actually think (as opposed to just be in a mental state), and to perhaps sense things (presuming the life support included sensory organs).

Quoting Patterner
A brain isn’t a bunch of pieces that can be put together like a puzzle. Even if all the necessary particles happened to bump into each other at the exact same instant, they would not be a working brain for even that instant.

Can you back that assertion? It sure looks an awful lot like a collection of matter to me. And no, an BB would be these particles 'bumping into each other', which would give them momentum and such that a brain doesn't have. So the thing just appears by sheer chance, and yet, it is in a certain mental state at that moment. The next moment consciousness is gone because disembodied brains don't do so well in a vacuum, but a Boltzmann-Earth does fine in a vacuum and the inhabitants might take whole seconds to notice something wrong.
I'm admittedly not sure of how relativity deals with mass (of a brain, planet, galaxy or 'universe') suddenly appearing out of nowhere. It violates all sorts of conservation laws, but lacking a unified theory, I don't think we can dismiss the conjecture at this point.

Quoting Patterner
Just as you can't place two pieces of wood end to end, and have one long piece of wood.

You can, but it's super improbable.


GRWelsh May 30, 2023 at 16:20 #811770
Reply to noAxioms
Not a matter of proof. It's a function of the model behind which one chooses to stand. If the model (not reality) predicts a greater likelihood of being a BB, then the model cannot be justified. It is simply a method of discarding not wrong models, but the unjustifiable ones. If reality happens to actually correspond to something like that, then the nature of reality literally cannot be known.


The claim is "in an infinite duration we are more likely to be a disembodied brain." I am questioning why we should accept that claim of probability? And especially why should we accept it when it hasn't even been established that a disembodied brain -- simply appearing in space and time with false memories and lacking any sense organs -- is possible. If no support is offered to support this claim, why should I accept it? In other words, I don't see why, given an infinite duration, we should accept that we are more likely to be Boltzmann Brains than what we think we are (embodied brains living on earth). Shouldn't it first have to be established that Boltzmann Brains are possible? Where is the argument and evidence for that?
noAxioms May 30, 2023 at 18:24 #811801
Quoting GRWelsh
The claim is "in an infinite duration we are more likely to be a disembodied brain."
Who made that claim? Boltzmann? Carroll? Some poster above?
I don't see how it even makes syntactic sense.

I am questioning why we should accept that claim of probability?
I think you shouldn't, so I'm probably with you on it. To make such a claim is to totally misunderstand the BB issue.

And especially why should we accept it when it hasn't even been established that a disembodied brain -- simply appearing in space and time with false memories and lacking any sense organs -- is possible.
Now you're the one making a claim. Has it been established to be impossible? If not, what's left?
GRWelsh May 30, 2023 at 20:14 #811832
Quoting noAxioms

Now you're the one making a claim. Has it been established to be impossible? If not, what's left?


I'm not saying it has been established to be impossible, but that it hasn't been established to be possible. It hasn't to my knowledge. But, I'll just stick to asking a question: has this been established as possible? What is the argument and evidence to back up that claim?
Patterner May 30, 2023 at 21:00 #811849
Quoting noAxioms
Can you back that assertion? It sure looks an awful lot like a collection of matter to me.
It is. But it didn't come into that arrangement when a quintillion (whatever) particles all happened to bump into each other in the exact right arrangement. You can shake a bag of hydrogen and oxygen, but you won't make water. Something more than their physical contact is needed. You can't shake a bag of protein and fatty substances, and pull out meylin sheath. You can't add iron, proteins, and lipids to a bowl, stir, and have a bowl of blood. Physics and Chemistry can tell us how X and Y can be joined together in any given case.

Dr. Manhattan can say, "Thermodynamic miracles... events with odds against so astronomical they're effectively impossible, like oxygen spontaneously becoming gold." If there was a way to prove it, I'd bet the ends of two pieces of wood have never fused together simply by being touched together. Some help is needed. The assertion that needs backing is that an incomprehensibly large number of the exact right mixture of particles can happen to come together in exactly the right arrangement, and fuse together in ways such particles are not known to fuse together, and become a living brain. "A lot can happen in a really long time" is not supporting evidence.


Quoting GRWelsh
And especially why should we accept it when it hasn't even been established that a disembodied brain -- simply appearing in space and time with false memories and lacking any sense organs -- is possible.
Quoting noAxioms
Now you're the one making a claim. Has it been established to be impossible? If not, what's left?
I don't see that Gar is making a claim. GR is asking how's it had been established that such a thing can be possible. And that cannot be established. As for "What's left"! A universe in which life came came about on Earth, and we evolved.
noAxioms May 31, 2023 at 03:49 #811942
Quoting GRWelsh
has this been established as possible?

No model has been specified, and in cases such as this, the model must precede the establishment of any facts such as the possibility of BBs. It's kind of backwards from the usual situation where the observations precede the model.
Quoting GRWelsh
What is the argument and evidence to back up that claim?
Again, the model precedes the evidence. Given the wrong model, there can be no evidence.

Case in point:
Quoting Patterner
But it didn't come into that arrangement when a quintillion (whatever) particles all happened to bump into each other in the exact right arrangement.
There we go. You have a model of pre-existing particles bumping into each other by chance. It's not the usual model, but a workable one.
Quoting Patterner
You can shake a bag of hydrogen and oxygen, but you won't make water.
Actually, that's pretty much how most of the water gets made, so I very much beg to differ.

Quoting Patterner
Dr. Manhattan can say, "Thermodynamic miracles... events with odds against so astronomical they're effectively impossible,
Astronomical odds are still finite, so when multiplied by infinite time, they become not just probable, but certain. I don't think you realize the size of the numbers they talk about when discussing these sorts of probabilities. They are astronomical indeed, and they don't need to be a human brain (or even a 3-dimensional construct). It just needs to be something in a state believing it is a 3d human, and believing in theory X.
jgill May 31, 2023 at 04:03 #811945
Quoting noAxioms
Astronomical odds are still finite, so when multiplied by infinite time, they become not just probable, but certain


?? Reference, please.
Patterner May 31, 2023 at 10:28 #812014
Quoting noAxioms
You can shake a bag of hydrogen and oxygen, but you won't make water.
— Patterner
Actually, that's pretty much how most of the water gets made, so I very much beg to differ.
That is not how any water was made. Simple physical contact does not combine the atoms. A Google search will bring up any number of sites about it. Energy is required. A spark.

Quoting noAxioms
Dr. Manhattan can say, "Thermodynamic miracles... events with odds against so astronomical they're effectively impossible,
— Patterner
Astronomical odds are still finite, so when multiplied by infinite time, they become not just probable, but certain. I don't think you realize the size of the numbers they talk about when discussing these sorts of probabilities.
What are the odds, and how are they determined? How is it known that it is [I]effectively[/I] impossible, rather than impossible?
noAxioms May 31, 2023 at 16:59 #812092
Quoting Patterner
Energy is required. A spark.

A sack of hydrogen and oxygen has no energy? What does more energy do other than increase the rate at which they hit each other hard enough? A sack full of room temperature molecules will occasionally impart enough speed to some of the particles that they will react/combine. It's just slower.

Quoting Patterner
What are the odds, and how are they determined?

I think that's the right question. Dr Manhattan is perhaps assuming a model that yields sufficiently low probabilities (like ones that drop off over time so an infinite series of them converges to a low number). That's what makes it 'sufficiently unlikely'.

Quoting jgill
?? Reference, please.

For what? That 0.00[an awful lot of zeros]06 * 100[an unlimited number of zeros] yields something large? You require a reference for that or are you contesting something else?
RogueAI May 31, 2023 at 17:11 #812094
Is a Boltzmann hydrogen bomb possible?
jgill May 31, 2023 at 20:56 #812139
Quoting noAxioms
?? Reference, please. — jgill

For what?


Perhaps I misinterpret what you said. It sounds like you are saying that it is certain those monkeys will type out Shakespeare.
Patterner September 05, 2023 at 22:41 #835844
Quoting RogueAI
How would you calculate density for a infinite number of things (e.g., Boltzmann brains) in an infinitely large space?
Excellent question. I hadn’t thought of it that way. That being the case, how can we calculate the odds that all of the particles needed to form a BB would ever be near each other?