Boltzmann brains and multiverse are logically distinct issues. A single universe with an eternal de Sitter future potentially has this problem. I regard any theory that predicts a Boltzmann brain majority as wrong, but it’s not clear how generic a prediction this is for eternal inflation, or even whether eternal inflation is the right cosmology (e.g. for the test case, Vasiliev gravity).
Boltzmann brains and multiverse are logically distinct issues. A single universe with an eternal de Sitter future potentially has this problem. I regard any theory that predicts a Boltzmann brain majority as wrong, but it’s not clear how generic a prediction this is for eternal inflation, or even whether eternal inflation is the right cosmology (e.g. for the test case, Vasiliev gravity).