Posted: Jun 11, 2011 10:21 pm
jamest wrote:Okay, thanks for the explanation. It appears that I've taken this 'many worlds' conception too literally. Anyway, if there are problems with the MWI I need to rethink them.
It depends what you mean by "too literally". What is important is that the "splitting" doesn't happen in any kind of (I don't even know what vocabulary I should use here) "ontologically profound" way. However, the theory does propose that these worlds do exist as far as we are concerned. If MWI is true, there will indeed be worlds in which the Nazis won World War II and a statue of Adolf Hitler is standing in London: the proportion of such worlds might be large or small depending on how lucky or not you think you Britain was during World War II. However, the only thing that makes these "other worlds" is the lack of interaction. To some being able to take a "Godseye" view of this, there would just be the wave function. This is the sense in which MWI is supposed to get rid of randomness. Randomness is still apparent to the inhabitants of a single world, but from the "Godseye" perspective, there is just the wave function, developing deterministically over time. To you, the randomness comes from having multiple futures at any time and continually being split as an observer.
Incidentally, a test for MWI was proposed, but I don't advise doing it.