[ExI] Boltzmann brains

[Stathis Papaioannou]

On Tue, 5 May 2020 at 15:55, Rafal Smigrodzki via extropy-chat <
extropy-chat at lists.extropy.org> wrote:

>
>
> On Sun, May 3, 2020 at 11:31 AM John Clark via extropy-chat <
> extropy-chat at lists.extropy.org> wrote:
>
>>
>> We have infinity to work with if Hugh Everett's Many Worlds
>> interpretation of Quantum Mechanics is correct, or if Eternal Inflation is
>> right, and if the inflationary model of the Big Bang is right then Eternal
>> Inflation probably is too. And even if none of that is true and the
>> universe is finite in the past dimension it could still have a infinite
>> eternal future.
>>
>
> ### For the Boltzmann brain idea to be a paradox you need to consider not
> so much the size of the universe (or multiverse), as the density of
> biological vs Boltzmann brains per unit of volume. Using a simplistic
> approach, biological brains that are a part of larger entities (such as
> galaxies) should be much less common per unit of volume, than Boltzmann
> brains, since the former require many more atoms to come together.
>
> As I mentioned elsewhere, the resolution of the paradox is that galaxies
> and biological brains (but not Boltzmann brains) are created by physical
> law, not randomly, so their density is dictated by physical law and cannot
> be easily simplistically deduced from the number of moving parts inside
> them.
>

It could be that, as you say, regular brains are more likely than Boltzmann
brains, but the problem is that in some cosmological models Boltzmann
brains are more likely. These cosmological models otherwise seem
reasonable; should they be rejected on the grounds that Boltzmann brains
are absurd?

> --
Stathis Papaioannou
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