[HN Gopher] Boltzmann brain
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Boltzmann brain
Author : josephwegner
Score : 39 points
Date : 2024-12-10 05:22 UTC (17 hours ago)
(HTM) web link (en.wikipedia.org)
(TXT) w3m dump (en.wikipedia.org)
| rzzzwilson wrote:
| Clicked on the link hoping it was a wickedly funny parody but,
| alas, it's just title gore: *brain*.
| dang wrote:
| We fixed the title (it was originally "Boltzmann Brian")
| Vecr wrote:
| I think someone associated with Stephen Hawking once made
| that joke.
| joegibbs wrote:
| The problem with the Boltzmann brain, and the reason you're
| almost certainly not one, is that if you are one then your senses
| have no relation to reality - including the part of reality where
| you read about the Boltzmann brain concept, or any measurements
| you can make about the underlying reality that makes you think
| you could be one.
|
| This is the same with all solipsistic arguments, like simulation
| hypothesis. If the universe _is_ , in fact, an illusion, then how
| do you truly _know_ anything about the real world? Sure it could
| be a computer simulation, but there's no way to know for sure.
| The parent universe could actually follow different laws
| entirely. It could be creating a "simulation" through entirely
| different methods. Hell, for all you know it could be an evil
| demon using magic to trick us, because magic could be real in the
| parent universe. It's all unfalsifiable.
| CamperBob2 wrote:
| Also, any line of inquiry that applies probabilistic arguments
| to evolution-based questions is already off in the weeds. The
| brains in our bodies didn't arise as a result of pure random
| organization, but developed incrementally in a direction that
| maximized reproductive fitness. There is no reason to think
| that brains appearing in isolated space at random, complete
| with memories, would ever be a thing.
|
| So it's simply not meaningful to ask about the relative odds of
| these two positions.
| empath75 wrote:
| > There is no reason to think that brains appearing in
| isolated space at random, complete with memories, would ever
| be a thing.
|
| There are only a limited amount of physical states possible
| in a given volume and given an infinite amount of time and
| space, all of them will happen an infinite amount of times.
| wutwutwat wrote:
| I disagree. I once had someone say that if you were to
| smash an iphone into tiny tiny pieces and put it into a
| plastic bag and shake it, given enough time, it would
| reassemble itself into a working iphone, the pieces
| randomly ending up where they need to be in order to
| operate like it did originally.
|
| While it is technically possible for that to happen, the
| probability of the intricacies that make up the iphone's
| circuits and screen, the chemicals that make up the
| battery, etc, assembling themselves into a complete and
| working phone, even on an infinite timeline, is not that
| high. And it could, in theory, never actually happen, since
| if there is still time that you can move forward into,
| there's still the chance that the moment the iphone
| assembles itself into a working phone lies somewhere in the
| future, and always will. It could just never happen before
| the heat death of the universe.
|
| Possibility does not guarantee probability.
| roenxi wrote:
| That logic doesn't exactly hold. Consider Gardens of Eden
| in Game of Life [0]. We can suspect that reality is similar
| to GoL where there is an infinite space and time that
| evolves according to some ruleset. In that case it is
| plausible that there are conceivable states that will,
| nonetheless, not be assumed even if there are an infinite
| set of possible states that reality will assume and
| infinite time to explore them all.
|
| [0] https://conwaylife.com/wiki/Garden_of_Eden
| margalabargala wrote:
| I agree with your initial argument about why we aren't
| Boltzmann brains, but I don't think that the same argument
| follows regarding the simulation hypothesis. A simulation would
| imply a set of rules being set up, of which your senses, and
| the reality they experience, are an emergent property. That is,
| there are rules, and your senses are generally consistent with
| whatever they are.
|
| With a Boltzmann brain, there's no reason whatsoever to think
| that any senses are consistent from one moment to the next or
| that any action can predictably yield any reaction. It would
| all just be random.
| empath75 wrote:
| That's a good argument for why it's not worth spending a lot of
| time being concerned about your own ontological status, but
| it's not really an argument against the concept or the math
| behind it. It's a conclusion one could derive from some fairly
| non-controversial assumptions, and if we're agreeing that the
| conclusion is wrong, the problem with the chain of logic and
| math needs to be found.
| weare138 wrote:
| I think there's an even more interesting implication of
| Boltzmann brains. The non-local universe is infinite in both
| time and space and when you're dealing with infinities of time
| and space two axioms become true. Everything that can occur has
| to occur and nothing can occur only once. So if intelligent
| life was able to form in our local universe we would have to
| assume higher intelligence spontaneously arose, AKA Boltzmann
| brains, in the non-local universe and exists infinitely.
| egypturnash wrote:
| A lot of religions can be interpreted in such a way as to
| essentially say "the entire real world is just a very complex
| simulation being played out by the Divine"; there there _is_ no
| real world to know about, just thoughts in the Mind of God.
| sandgiant wrote:
| Well no, that's not the reason why we're not Boltzmann Brains.
| A Boltzmann Brain is perfectly capable of believing that it is
| sensing reality in exactly the same way that your brain
| believes so.
|
| It is worth reading the section "Modern reactions to the
| Boltzmann brain problem" in the article to understand why the
| Boltzmann Brain is a useful thought experiment.
| daseiner1 wrote:
| My chief complaint is that it's functionally equivalent to
| belief in God. It strikes me as fundamentally the same instinct
| but reinterpreted in a manner palatable to the "i'm very
| logical and rational" crowd.
| ewzimm wrote:
| The falsifiable part of something like the simulation
| hypothesis has to do with nested sets. If the reality we exist
| in is capable of producing everything that would be necessary
| for a conscious being to experience a convincing reality within
| its available resources and computational power, then the fact
| of consciousness is not sufficient to conclude that the reality
| in which we operate does not exist inside another reality with
| the same capability to produce an internal model of reality
| sufficient for supporting consciousness.
|
| As you said, it does not definitively tell us anything about
| the reality in which that simulation exists other than that it
| has the same property that we experience of being capable of
| hosting a nested reality sufficient for supporting
| consciousness.
|
| Although we can't specify particular aspects of that reality,
| we are capable of mathematically representing potential
| properties of universes that have the capability to host a
| nested simulation. None of this provides certainty, but it
| provides a basis of exploring possibilities, and actual
| understanding requires methods beyond the hypothesis of a
| larger reality.
|
| Physics provides us a lot of ideas about the potential for the
| nature of reality and methods for testing and falsifying them
| but is not in itself sufficient. We don't need to find all the
| answers in one line of inquiry. The holographic principle of
| string theory is one example of a type of simulation existing
| inside a larger reality but far from the only one.
| dang wrote:
| Related:
|
| _You do not need to worry about the argument that you are a
| Boltzmann brain_ - https://news.ycombinator.com/item?id=41031300
| - July 2024 (1 comment)
|
| _Boltzmann Brain_ -
| https://news.ycombinator.com/item?id=22079253 - Jan 2020 (149
| comments)
|
| _Boltzmann Brain_ -
| https://news.ycombinator.com/item?id=12152658 - July 2016 (17
| comments)
|
| _Boltzmann brain_ - https://news.ycombinator.com/item?id=6999074
| - Jan 2014 (18 comments)
| shagie wrote:
| Seven years ago, PBS Space time did an episode on Are You a
| Boltzmann Brain? https://youtu.be/nhy4Z_32kQo (this was also
| linked in the 2020 post
| https://news.ycombinator.com/item?id=22080393 )
| homebrewer wrote:
| See also this fantastic podcast (if I remember the episode
| correctly, although it doesn't matter much as they're all good
| and he talks about the subject frequently because it's tightly
| related to his day job)
|
| https://www.preposterousuniverse.com/podcast/2022/06/06/200-...
| unholiness wrote:
| The way I see it:
|
| The reasonable things that continue happening each day in our
| universe would be _extremely_ unlikely if we are just Boltzman
| brains. Every bit of sensible reality would be coincidental. The
| very continuance of that reality is an experiment constant
| proving the falsehood of Boltzman brains, at a rate of oh maybe
| millions of sigmas of confidence per second.
|
| Now, if you believe the universe came to an initial state due to
| pure thermodynamic coincidence, millions of sigmas per second is
| laughably small compared to the chance that a whole universe
| outside your brain popped into existence, so Boltzman brains are
| the most believable thing and you should believe in them.
|
| This completes a pretty direct argument: Believing the initial
| state of the universe was a thermodynamic coincidence forces you
| to believe in Boltzman brains, Boltzman brains force you to
| believe reality should collapse immediately, and reality does not
| collapse immediately. Therefore you simply can't believe the
| first assumption, that initial state of the universe was a
| thermodynamic coincidence.
|
| Accepting this is often called the "Past Hypothesis". It's spoken
| of in deferential terms and said that it can't ever be proven...
| But to me this is rock-solid proof, with more sigmas of evidence
| than any other scientific discovery and increasing by the second!
| Can't we just call it the Past Theorem already?
| yoru-sulfur wrote:
| I am mostly playing devil's advocate
|
| > and reality does not collapse immediately
|
| How do you know that reality does not collapse immediately? At
| any given instant you could be a fresh brain that just came
| into existence, all your previous memories which imply a life
| lived up to this point also formed in that same instant.
| smokedetector1 wrote:
| I dont need to logically disprove theories like this, because I
| experience myself in a way that you can't argue against. Trying
| to convince me my experience of myself is an illusion is, in my
| view, a horrible case of trying to fit reality to your model. Yet
| it's one that a surprising number of scientifically minded people
| enjoy doing, for some reason. Beats me.
| kempje wrote:
| Here's a different way of thinking about it. There are two
| things that are both very plausible: One - based on your direct
| personal experience - is that you are a non-boltzmann-brain-
| human living a normal life on earth. Two - based on well-
| accepted science - is that it is MUCH more likely for you to be
| a boltzmann brain than not.
|
| Great; these two things are seemingly inconsistent. Which means
| one must be false. But if either of these is false, it's
| surprising! Because one is based on our direct experience of
| ourselves, as you have pointed out, and the other is based on
| well-established science. So what's interesting about Boltzmann
| brain (and similar) is that it shows that one part of our body
| of knowledge must be false. And this ought to motivate us to
| investigate exactly what it is that we have wrong.
| kempje wrote:
| There is a widely circulated (amongst philosophers) argument
| against the Boltzmann brain hypothesis made on bayesian grounds.
| Technical, but very interesting. It's being published next year
| in what's generally regarded as the top academic journal for
| philosophy: https://philpapers.org/archive/DOGWIA-6.pdf
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