Here is an
interesting paper by David Wallace. It may be wrong because the author is talking about
Max Tegmark's Level 3 parallel universes, which may not exist because of P.W. Anderson's "
More is different," i.e. the classical world is emergent from post-inflation macro-quantum vacuum coherence with a new set of local non-unitary rules that supercede micro-quantum theory's nonlocal unitary rules.