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Multi World Hypothesis and The Double Slit Experiment.

  1. Mar 14, 2012 #1

    From my last post, to this my understanding of QM has improved somewhat. (thanks mostly to these great forums).

    I was wondering how the Multi Universe Theory treats the observer effect in a basic Quantum Double Slit Experiment ???

    from howstuffworks.com :- "“When a physicist measures the object, the universe splits into two distinct universes to accommodate each of the possible outcomes.”"

    So does this mean, when we set up a detector to determine which slit the photon went through, in our universe the decoherence causes the photon to behave like a particle, but in an alternate universe, the photon could actually go anywhere and continue to to perhaps form an interference pattern?

    If my understanding is right, has anyone explored the nature of such an universe where observation has no effect on quantum events???
  2. jcsd
  3. Mar 16, 2012 #2
    No one? :( Sigh!
  4. Mar 20, 2012 #3


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    Presumably, when the photon hits the slit, the universe splits into infinite copies, where each copy the photon hits a different spot on the screen. There are more copies of the universe where the photon intensity is greater. Somehow, one universe is chosen and we see a spot on the screen. The many world hypothesis just adds some complexity and explains nothing in this scenario.
  5. Mar 20, 2012 #4
    As far as I know in the multiple worlds picture the wavefunction essentially gives you a 'list' of possible universes you might travel down.
    Tbh, I've seen nothing that makes the multiple world picture seem any different from the copenhagen except for the interchange of probability and universe

    In every case I've seen, copenhagen is a far more useful (well, intuative would be a better word, as I said before they seem equivelant) tool for thinking about the situation as well.

    In copenhagen you measure a particle, you get a probability for measuring it in a state.
    In MW you measure a particle, you get a probability for being in a universe where it's in a state.

    Reminds me of the Schrodinger vs Heisenberg picture
  6. Mar 20, 2012 #5
    No, there's a big difference between the two. In Copenhagen, after you do the measurement the wavefunction collapses into a delta function (Kronecker delta or Dirac delta depending on whether the observable is discrete or continuous), which is presumably a process not described by the Schrodinger equation. In Many Worlds the wave function just keeps evolving according to the Schrodinger equation and never collapses.
  7. Mar 21, 2012 #6
    Oh, it appears I have been misinformed then :redface:
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