View Single Post
Delta Kilo
Aug25-11, 03:04 AM
P: 273
Quote Quote by mitchell porter View Post
Well, presumably there is a non-"arbitrary" part of the multiverse which actually corresponds to me-here-now, having the specific experience I seem to be having?
Well, yes and no. I'd say there is a whole bunch of you in the multiverse, having all sorts of experiences simultaneously. I would say that your experiences are macroscopic and the boundaries between them, between you-here-now and another-you-there-then are kind of fuzzy.

At every moment, all sorts of quantum superpositions get decohered around you one way or the other. Say if a photon just landed on your forehead, it won't matter that much to you whether it was horizontally or vertically polarized, your experiences will not be affected and you-here-now branch will include both alternatives. On the other hand if a stray cosmic ray hit a cell in a DRAM chip and crashed your computer, one of you would never read this message so you-here-now branch would split and diverge at that point. But between these two extremes there would be a gray area where it would be very hard to tell whether your experiences are sufficiently different to count it as a split.

Quote Quote by mitchell porter View Post
And that is what we are trying to establish - whether MWI can show that branches which, empirically, ought to be more frequent, are actually more frequent in MWI, according to whatever recipe it provides for parsing the mathematical wavefunction of the universe as a physical multiverse of coexisting branches or worlds.
Yes, I agree, this is a very good question to ask. I also admit that current answer is not entirely satisfactory: some people dismiss it by saying since it is the same old formalism it produces the same answers and doesn't require a separate proof, other people say they have proved it and yet other people say that all those proofs rely on circular arguments and are therefore invalid. I tried to follow these arguments and got seriously bogged down, so I don't have an opinion one way or the other but my gut feeling is that such proof should be possible.