[richardlong]

Given the internal and logical consistency apparent in this life, it stands to reason the Boltzmann brain would have to be simulating the entire thing -- the thought processes of other people, countries, wildlife, the movement of the stars, and so on.

Absent some calculation cost, which Boltzmann brains don't seem to provide, there's no reason everything wouldn't be fully rendered inside the Boltzmann brain.

At some point you just have a God, and are right back at old-timey religion, not that there's anything wrong with that.