| I just mean like this: http://www.preposterousuniverse.com/blog/2014/06/30/why-the-... "We wouldn’t think of our pre-measurement state (1) as describing two different worlds; it’s just one world, in which the particle is in a superposition. But (2) has two worlds in it. The difference is that we can imagine undoing the superposition in (1) by carefully manipulating the particle, but in (2) the difference between the two branches has diffused into the environment and is lost there forever." (State 1 is when the particle is in a superposition by itself and state 2 is when it's entangled with a macroscopic apparatus.) My issue is that he uses words like "forever" and "impossible." These convey a sense of finality, but the decision of where to draw the boundary is subjective. The worlds can in principle (and under certain cosmological models, must) recohere. See, for example: https://arxiv.org/abs/1105.3796 "Decoherence - the modern version of wave-function collapse - is subjective in that it depends on the choice of a set of unmonitored degrees of freedom, the "environment"." See in particular Section 3.2 (Failure to irreversibly decohere: A limitation of finite systems) (Edit: I should mention that I am not a physicist, by a long shot. Just a curious amateur.) |