> infinite parallel universes That's a pretty uncharitable interpretation of it. If you look at the actual physics, MWI is incredibly simple: the wavefunction

> infinite parallel universes That's a pretty uncharitable interpretation of it. If you look at the actual physics, MWI is incredibly simple: the wavefunction just evolves as the wavefunction evolves. That's it. There's some amplitude over here, and there's some amplitude over there, and this possibility and that possibility are mutually exclusive etc (with some "weird" quantum correlations, of course.) The Copenhagen interpretation's "wavefunction collapse" is just like a Bayesian update -- the wavefunction you're left with is like a conditional probability. Maybe it makes you happy to throw away the "other universe" bits of the wavefunction and normalise probabilities on your own branch, but you obviously don't have to, and any discussion of when the collapse happens (or worse, whether it's a physical process that propagates across the universe faster than light) is obviously very silly business.