"If the exact physical state is underdetermined by the problem description, then there will be separate branches of the wavefunction for each possible state, although they might have diverged arbitrarily long ago. So, yes."

Are you seriously proposing that *my* use of ambiguous _language_ splits the universe? This is unbelievable. I understand how incoherency would split the universe, but how can ambiguous language do that? How about false information -- if my bank tells me that my paycheck came in, is there an alternate world where my paycheck in fact DIDN'T come in?

I just don't buy this. I think I get the quantum MW model; it makes a certain kind of sense. What I don't get is how it enables you to claim that there are any number of worlds that you want! I think you can only claim a quantum split where there is actually decoherence, and that the splits will contain only events which had a nonzero "quantum probability" in that decoherence.

There may be a world in which my paycheck didn't actually come in to my bank -- but the explanation for that lack is NOT "because I just imagined it", or "because it's the negation of something that did happen"; rather, it's because of some specific quantum decoherence which could eventually result EITHER in my paycheck arriving or NOT arriving.

What am I missing?