Expanding universe and the Boltzmann brain problem

[analyst5]

Because you got sarcastic and personal, and I don't think that allows a reasonable discussion.

You're right, my bad. I agree that this disallows a reasonable discussion. I apologize.

If you're okay with the fact that I would like to continue the discussion, I hope that you can write your opinion because I respect it despite occasional disagreements.

 

[Chronos]

I agree with MFB, never say never, although IMO Boltzmann brains, Boltzmann unicorns, etc., are so egregiously improbable they never have nor will occur within the lifetime of the observable universe.

 

[Stavros Kiri]

Boltzmann brains, Boltzmann unicorns, etc., are so egregiously improbable they never have nor will occur within the lifetime of the observable universe

How do we know that God isn't a Boltzmann brain?
[[But] In that case He was created by the Universe, and not vice versa ... (?)]

 

[Chronos]

There is at least a miniscule probability some things will remain forever unknown.

 

[analyst5]

Where is the unexplainable position? In a universe that produces some "normal" brains and then Boltzmann brains later, the normal brains should not rule out that they live in such a universe, because they would be wrong.

There is also the probability that you are a Boltzmann brain.

Especially if both the number of normal and Boltzmann brains is infinite, probabilistic considerations stop making sense.

This is what is obviously wrong, and not only in my opinion but in opinion of many who have studied the subject precisely.

If there are infinite BBs in the future, normal brains would have no logical reason to believe their observations because each normal observation would be vastly outnumbered by a BB observation of the same kind. There would be only an infinitesimal chance that that they are correct to rule out that they are not BBs.

 

[windy miller]

The Botlzman brian problem assumes that a single brain is more likely to fluctuate into existence than a single universe , as a single universe ( which contains brains) is less likely than a single brain.
But I think inflation and Darwin have undermined this claim. Inflation implies a sub atomic sized seed of inflationary matter is all you need to make an entire universe this universe can then evolve and over millions of years and with Darwinian evolution brains are created form other simple beginnings. The seed and the Darwinian process are not necessarily less likely than the Boltzmann brain and therefore I don't see who the BB is a well posed problem.

 

[durant35]

They should be possible. Assuming I am not a Boltzmann brain, the universe is so young that regular brains should be much more common, but in the very distant future Boltzmann brains could dominate. Most of them will have weird inconsistent memories, but some will have a brain like we have. This is incredibly unlikely for a given place and time, but if you have a finite chance for it and infinite time and/or infinite space, it wil happen.

https://arxiv.org/abs/1702.00850 [Sean Carroll - Why Boltzmann Brains are bad]

Read this.

 

[nikkkom]

then eventually there will be an infinite number of such brains, regardless of how absurdly rare they are.

Not true. A Boltzmann brain is not indestructible. In fact, its destruction due to a random quantum event (a change which makes it non-operational, just a lump of dead machinery) is very, very much more likely event than creation.

IOW: Boltzmann brains "decay" and have some "half-life". Since they are created astoundingly rarely, ones which _are_ created eventually break down. Every individual brain is unlikely to ever see even just one another (functioning) brain.

 

[Chalnoth]

Not true. A Boltzmann brain is not indestructible. In fact, its destruction due to a random quantum event (a change which makes it non-operational, just a lump of dead machinery) is very, very much more likely event than creation.

They should be destroyed as quickly as they're created. I don't mean an infinite number at once, but rather an infinite number created in total.

 

[rootone]

I think I understand why Boltzmann gave it up now.
The issue is not that the existence of such observers is ruled out by data, but that the theories that predict them are cognitively unstable: they cannot simultaneously be true and justifiably believed.