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A comment on Many Lives in Many Worlds.

Re:Many Lives in Many Worlds by Xcelerate on Tuesday April 12, 2016 @08:10PM (#11484681)
The interpretation I prefer: the universal quantum state evolves unitarily at all times, and there are no parallel universes. Problem solved. Parallel universes are — by definition — unfalsifiable, so the best theory then is the simplest one, and that is a theory with one universe.

For similar reasoning used in a somewhat different scenario, see also http://plato.stanford.edu/entries/spacetime-holearg/

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Re:Many Lives in Many Worlds by ikeboy on Tuesday April 12, 2016 @09:02PM (#11484913)
It's not so obvious that a single universe is simpler.

See http://space.mit.edu/home/tegmark/PDF/multiverse_sciam.pdf and the excerpt quoted in https://en.wikipedia.org/wiki/Multiverse#Occam.27s_Razor

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Re:Many Lives in Many Worlds by pjdorrell on Wednesday April 13, 2016 @10:04PM (#11493844)
In the context of Many Worlds, a "universe" is an approximately classical wave function, where the degree of approximation is limited by the uncertainty principle.

Even if you start with an approximately classical wave function, it may evolve into a state where it is no longer approximately classical. However, it might now be equal to the sum of _two_ approximately classical wave functions. Ie, two "universes".

So, the universal wave function hasn't split, but the attempt to represent that wave function by approximately classical wave functions _has_ split.

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Re:Many Lives in Many Worlds by Xcelerate on Thursday April 14, 2016 @12:04AM (#11494224)
> but the attempt to represent that wave function by approximately classical wave functions _has_ split.

Exactly. The problem is that people keep trying to view quantum physics through a classical lens.

Decoherence is simply the fact that a quantum state evolves to a point where it can no longer be mathematically represented as a tensor product state. I don't lose any sleep over that.

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Re:Many Lives in Many Worlds by hammock on Tuesday April 12, 2016 @08:48PM (#11484859)
>the universal quantum state evolves unitarily at all times

What does that mean in layman's terms? Is that basically the Copenhagen interpretation (which has its own issues)

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