Boltzmann brains are a problem even if you’re a 50 percenter. Many fixed models of physics produce lots of BB. Maybe you can solve this with a complexity prior, that BB are less real because they’re hard to locate. But having done this, it’s not clear to me how this interacts with Sleeping Beauty. It may well be that such a prior also favors worlds with fewer BB, that is, worlds with fewer observers, but more properly weighted observers.
(ETA: I read the post backwards, so that was a non sequitur, but I do think the application of anthropics to BB is not at all clear. I agree with Eliezer that it looks like it helps, but it might well make it worse.)
Boltzmann brains are a problem even if you’re a 50 percenter. Many fixed models of physics produce lots of BB. Maybe you can solve this with a complexity prior, that BB are less real because they’re hard to locate. But having done this, it’s not clear to me how this interacts with Sleeping Beauty. It may well be that such a prior also favors worlds with fewer BB, that is, worlds with fewer observers, but more properly weighted observers.
(ETA: I read the post backwards, so that was a non sequitur, but I do think the application of anthropics to BB is not at all clear. I agree with Eliezer that it looks like it helps, but it might well make it worse.)