Comment by rcxdude

14 hours ago

Decoherence is how you get from "Maybe the wave function never collapses" to "Maybe there are many parallel 'universes' in QM.".

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rcxdude

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kgwgk  13 hours ago

Decoherence gets you a diagonal density matrix description of the world. It doesn't get you a single-state description of the world. Going from "There are many parallel universes" to "and we are in one of them" still takes a lot of handwaving.

  • mitthrowaway2  12 hours ago

    But we're not in one of them. We're in all of them. Yours is a misunderstanding of how it feels to be in a quantum superposition. There's no component of the wave function in which Schrodinger's cat experiences anything other than being alive or being dead. There's no component in which it feels like it's in some ghostly combination of both outcomes. Both components of the wave function exist in superposition, and to the extent that they are decoherent, they do not interact and do not even notice that they have company. I don't mean this only as an academic statement; it's also true of you and me, at this very moment.

    • monktastic1  3 hours ago

      It's a bit like:

      "Doc, I feel pain in my toe."

      "No, sorry, the math says you don't."

      "Okay, but like... I do."

      "Sorry, you're just not good at accepting math!"

      Not a perfect analogy, of course, but people have competing intuitions of what to do when the map fails to match the territory. MWI abandons the latter, most prefer the former.