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Comment by joegibbs | Hacker News Reader

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.

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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.

What OP is saying, I think, is that the argument that led us to believe that Boltzmann Brains are more likely than normal brains is itself product of the physics of the world we experience.

But then, if we conclude that we must be a BB, there is no reason for the physics of the universe in which this BB exists to be the same as the physics of the universe we experience. Hence, the argument breaks down, because BB are only very likely in the 'simulated universe', but have no reason to be in the 'real universe' (which has no reason to abide by the same laws of physics).

In other words, the assumption that we are a BB, because they are so much more likely, invalidates the argument that BBs are much more likely.

Whatever the physics of the parent universe are, they either prohibit BBs (and then that universe would be ours, which it presumably isn’t) or are unlikely to affect BBs in a way that disallows creating BBs that observe a similar universe. It’s akin to “why tf I’m a human on Earth 2024 of all planets and things” argument. Well, four reasons: you’re, a human, here, now.

Even if we assume that this universe we observe as BBs is as well the parent universe, it can produce not only human BBs obviously and not only coherent experiences. Complete nonsense is normal here too.

So if a universe allows for BBs (iow, spontaneous temporary observers with state that somehow produces the me-is-observing effect), it allows for all sorts of experiences, and given enough iterations could reconstruct itself and everything imaginable and unimaginable in a sequence of arbitrary length. “You’re certainly not”doesn’t follow here. It may be or it may be not. You’re a human, here, now.

Note: reasons to think something are not a constant over time or geography.

But if you can have a Boltzmann brain, then you can also have stable environment pop into existence. In a simulation, there's no guarantee the simulation follows the parent universe's rules. It could be a simulation with made-up rules. Maybe exploring alternate kinds of universes.

Why would there have to be consistency and rules?

That's exactly the point. There wouldn't.

Yet, I observe what appears to be consistency and rules. Randomness happening to manifest in a way that mimics consistency and rules is very very unlikely, probably more unlikely than there actually being consistency and rules.

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.

The part you said is falsifiable doesnt sound to me to be in the slightest bit falsifiable.

It's possible to run an experiment to see if a conscious entity could be convinced that a simulated reality was real. Hard to do ethically since consent would invalidate the illusion, but possible to demonstrate convincing virtual reality with computer generated sensory experiences.

Models like the holographic principle can be tested both mathematically and through experiment. Full tests are beyond our current capabilities but not unfalsifiable in theory.

>It's possible to run an experiment to see if a conscious entity could be convinced that a simulated reality was real.

This is like writing code to run a VM to detect if your code is being run inside a VM.

If the answer is no or yes it doesn't really say anything about whether the parent machine is running a VM with your code inside.

The results of the experiment wouldn't say anything about the simulation hypothesis.

This is a great example. You can prove that a VM can be just as capable as a bare metal OS. Then you connect to a random networked machine. Without any further information, would you guess that you chose bare metal or a VM (or container)? Knowing that virtualized OSs are both possible and heavily distributed, you would guess that any random machine you chose was probably virtualized.

The simulation hypothesis follows a similar logic with one less data point. Knowing that experienced reality could in theory be nested inside a superstructure but not knowing the actual deployment of such nested experiences, we would guess that our experienced laws of physics probably exist inside a superstructure.

What the properties of that superstructure are beyond the hypothesis itself because we don’t have the same knowledge of virtualization of physics as we do of OSs.

String theory is one attempt to describe that structure based on mathematical reasoning. The simulation hypothesis just states that physics is likely to be virtualized inside another system and that it’s worth exploring physics at its limits to understand the properties of that virtualization.

It’s falsifiable through the development of analytical methods that don’t fully exist yet but not theoretically unfalsifiable.

How "could in theory" suddenly became "likely"? The more contrived universe you imagine the less likely it is.

I think that's a misapplication of Occam's Razor. I'm not sure how exactly you're using contrived here, but the idea that complicated interactions like the ones we experience are likely to exist inside simpler systems is seeking the less contrived reason for existence. I'm saying that it's likely in the same way that virtual machines are likely to exist inside networks. Virtual machines might be more complicated than operating systems running on bare metal, but it's simpler and easier to create a thousand virtualized environments than one additional bare metal computer by orders of magnitude. In the same way, if it's possible to create nested experiencable universes, the total number of virtualized environments experienced is likely to be much greater than the number environments operating on the most bare, fundamental principles of existence alone.

This simulator's world is less likely, because it consumes more resources: needs to run thousand nested worlds, so their probabilities are reduced proportionally and further reduced by the virtual machine itself. Also bare metal is more efficient if virtual machine properly interprets instructions and doesn't merely forward them to processor.

Consuming more resources is a matter of perspective, not efficiency, because the scale of total phenomena would be much larger than what is experienced. Always bet against the comprehensiveness of your comprehension.

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.

> 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.

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.

I'm not sure. Quantum tunneling is a thing. Given the possibility of particles deciding to spontaneously just up and teleport to a nearby location, the available options increase significantly.

> particles deciding to spontaneously just up and teleport to a nearby location

that all but guarantees that it would never happen imo... and also shows that we have no clue how the universe actually works, and likely never will

Eternity is a LOT of time...

Actually no, it's -1/12 of a second

> 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.

"Infinity" is not the same thing as a "really long time". You can't use ordinary conceptions of probabilities on infinite time scales. If you wait a Graham's number of years, you still haven't even started a small fraction on the way to infinity.

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

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.

Belief in God implies some effect on one's behavior, unless you believe in a completely impersonal Prime Mover that retires thereafter.

The notion that one is a Boltzmann brain doesn't really change anything. If you are, there's absolutely nothing you can do about it. So the only sensible thing is to assume that you aren't, regardless of probabilities.

I've seen a paper (probably by Bostrom) deducing normative statements ("oughts") from the simulation hypothesis (purely descriptive, "is"). Namely: the grad students running these simulations are more likely to switch off boring simulations. Thus, if we want to keep living in this world, we should strive to make it interesting.

I must say, with Trump, Brexit, war, and more Trump: Well done, folks!

Our world is boring though, cf Boötes Void. Those transcendental extrauniversal aliens invented quantum physics, what do you expect them to believe? If their world can create such immense simulations, maybe it's because their world is too fabulous and they look for serenity.

I don't agree. A belief in a god/gods generally also includes beliefs about what that god(s) wants or does. A Boltzmann brain would have no special powers apart from what a (very) specific arrangement of particles would have. There's no hint of them operating outside physics at all.

Also, there is at least a connection to experimental physics in that we can measure "virtual" particles (e.g. Casimir effect) and can calculate their probabilities etc. There's no such underlying experiment for God(s) that I'm aware of.

I think BB is bigger than God. God still has specific ways, while BB can simulate all experiences given infinite time, in parallel. So the universe where God exists and he will burn us in hell for atheism and mastrubation is just a tiny subset of what BBs can do. Cause if BBs are possible, they can do things a human cannot imagine about any God. Imagine a cubic meter randomly enumerating all quantum states within it, forever, ignoring consciousless ones.

Well, a BB may well be bigger than our conception/imagining of God(s), but there's a fundamental difference - BBs are constrained by physics etc whereas God(s) are supernatural and not constrained by physics.

That’s an interesting idea I’m not sure I agree with, it’s hard to formulate why, but I’ll try.

God itself can be supernatural, but feels like it can only affect a limited part of any universe due to the limitations in observer’s mind. If we could expand BB size indefinitely up to the size where it stays coherent (light milliseconds?) then that would basically cover everything that a consciousness itself could experience. This makes God infiniteness sort of redundant and unclear why it would be needed to generate a universe.

This echoes with my vague idea that hypothetical FGH-sized beings are indistinguishable from God(s) whose infinite part could actually create more issues than it might solve.

Iow, we have to define some Continuum of reality for God of omega+ size to operate on, not to mention Proper Class sized God. Our ancestors really overkilled this idea, but little did they know. So maybe we should take its infiniteness as “anything imaginable by an arbitrarily-sized BB” rather than its naive infinite meaning.

I'm thinking that there's a difference between God(s) and the conception of God(s). Any BB will be limited by e.g. speed of light which will limit how big they can get and still have coherent thoughts. I suppose we could get a super-massive Borg type of BB collective, but they're still limited by location/speed etc. God(s) would presumably not be bound by such limitations. (Not that I happen to believe in God(s)).

It really depends what is meant by "the same instinct".

The reason I don't agree with the parent comment is because to truly believe in a Boltzmann brain would seem maximally nihilistic.

Many people truly believe in God/gods at their deepest level. While the Boltzmann brain is an interesting thought experiment, I don't think anyone really takes it to heart the same way a Christian believes in Jesus.

Even while I would probably give the Boltzman brain a far greater probability than most, people don't go around telling other people this is all just a momentary, random fluctuation.

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.

That's not true. The expansion of Pi is infinite, but that doesn't mean you can find every string of numbers in it, I believe that's still an open question. Just because you have an infinity, doesn't mean it contains everything an infinite amount of times. The Cantor set is a good example.

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.

The conclusion only holds if you assume that you yourself are not a BB. Yes, in our universe, the laws of physics predict that BBs are much more likely than normal brains, given you wait long enough.

However, the moment you assume that then it must mean that you yourself are a BB, the argument breaks down. Because the huge probability of BB applies only to the laws of physics of the universe you live in; if you are a BB, the laws of physics of your universe have no reason to be the same as the laws of physics in the actual universe, where the BB exists. Thus, you can make no prediction on the likelihood of a BB arising, since you don't know the physics of the actual universe.

I'm confused. We make predictions about things we don't fully understand all the time. And about things we cannot possibly perceive. We do so by recognizing patterns across things we can see, and probing the relationship to the things we cannot. (See could mean any perception).

It's not guaranteed we could do that, even in our universe it's not guaranteed, but it's also not ruled out.

I don't think that's actually a problem with the Boltzmann brain concept; I think it's just a reason why we don't want it to be the actual representation of reality.

I've chosen not to care; if I'm a BB, or even just a character in a simulation, my life and choices still have meaning to me -- whatever I actually am -- and that's what I've decided is important.

I mean the more interesting part to me is that probability comes into play: consider the age you live in. If you get to a historically conventional age for dying of old age, but then boom clinical immortality comes along, well that would feel technologically appropriate and yet be awfully convenient timing.

I'll be happy if it happens, but squint-eyes a little that it did.

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.

A Boltzmann brain can be identical to evolved brain, but it can also be different, because it's not constrained by evolution.

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.

The point of descarte is that you dont know anything about anything, and in my opinion, all of his bad arguments begin when he starts stating his certainties, except for his first one.

> It’s all unfalsifiable.

That might make it unscientific (in Popper's philosophy), but not impossible or implausible.

This is exactly what a Boltzmann Brain would say...

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