[unholiness]

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]

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.

[XorNot]

Indeed the bigger issue as I see it is that the only "sensible reality" that can exist is the one you subjectively experience. Since that one is the only sensible one, it's the only one you perceptually would be able to hang around for - even if it's actually a conincidental series of flickers of sapience across trillions and trillions of years.

i.e. a time stepped simulation, absent external reference, doesn't know how long it's been between the actual steps - could be seconds, could be hours, could be years.

EDIT: Like the real issue with "death" is that it's not "eons on darkness" - which is why I think people get afraid of it (or one of the reasons) - but that actual, literal non-existence is inconceivable even though we all did it - 13 billion years of not-existing in the universe, then suddenly you.

So after you die the same problem re-emerges: the conscious experience of "you" ends...but then from the subjective blink of an eye if something happens to restart that information process just right, suddenly again, you - and it has to be you, and no one else, because if it wasn't then well, it would be someone else - i.e. why am I me, and not my wife or son for example?

[matthewdgreen]

What if it was someone who just happened to be extremely similar to you? There's a decent probability that someone extremely similar to you will come into existence during the finite lifespan of the universe. Would that person be likely to be "you"? By comparison, would they be more "you" than a version of yourself that woke up with brain damage?

[gpderetta]

Reminds me of the dust theory from Permutation City.

[danparsonson]

The point is that you, dear reader, could be the Boltzmann Brain, and that would mean that all your memories spontaneously came into being, giving you the illusion of a past history, and it would also mean that you will dissipate again shortly after; there is no continuity, and we're not all BBs. 'We' are all just figments of your imaginary imagination, conjured momentarily into memory and then lost again.

For a Boltzmann brain there is no real past or future - your reality does indeed collapse immediately and you'll never know it; the idea that 'reality doesn't collapse immediately' is not a verifiable fact, because the only evidence you have to the contrary is encoded in and perceived by your brain...

[ajuc]

If you are a Boltzman brain then you are born with memories you have (that haven't really happened) and you have no future (because the next moment you'll collapse).

You could even live kind of a "life" by randomly popping into existence once every million years in some differrent galaxy, experiencing one planck time and collapsing (and the only thing that connects the instances to each other is that the next instance by random chance has memories consistent with the previous instance).

They could even appear in non-chronological order.

I don't think it's likely, but it's more likely than having the one randomly generated brain experience stuff "in real time".