Sean Carroll

You just fluctuated into existence.

So I think that's the important lesson of the Boltzmann fluctuation thing.

You're not going to get out of it by thinking hard about what is required for a Boltzmann brain.

The other thing to emphasize is that the fluctuations are not that quick, right?

Like short-lived.

I mean, it depends what you mean by short-lived.

But remember the whole point is

of the Boltzmann brain is that we're looking for trajectories through phase space that are the most likely ones given some boundary conditions on whatever macroscopic features you want your brain to have.

So there's no like sneaky internal correlations that you might have in the real world because like in the real world, we all come from a lower entropy past.

So what that means is that very roughly the future evolution of the Boltzmann brain, so like you fluctuate into existence and then what happens?

If it's just out there, maybe it would freeze.

Maybe it would like freeze into a rock and only very, very slowly decay, like whatever it actually you think would happen.

The assembly process of the Boltzmann brain is exactly like that but played backward in time.

There's an absolute symmetry between the future of the Boltzmann brain.

At whatever moment you have installed your conditions that I want the brain to look like this, the future and past will look statistically the same.

So that might take a very long time for the Boltzmann brain to fluctuate into existence.

At least it might take, you know, years or millions of years or whatever.

But that's very, very short compared to the lifetime of an eternal universe.

Alex Dubrow says, in your recent interview with Christian List, the intentional stance was discussed mainly in terms of interpretation from the perspective of an observer.

But Daniel Dennett's framework also included the design stance, which wasn't discussed by List.