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Quick clarification please

  1. Jun 19, 2012 #1
    Pardon the interruption, but I need some quick clarification.

    I was reading about decoherence, and QM, and trying to understand exactly what's going on, but I need to know if I have a grasp on the basic concept. In the double slit experiment, QM defines the probability that a particle will be found at a given location on the detector. But it is a misinterpretation of QM to say that the particle actually takes every path from emitter to detector. The wave function is a purely mathematical construct and not at all suggesting that the particle actually takes every path. Is this correct?

    There is nothing that can be said about what is actually occurring during the period when the particle is between the emitter and the detector. Is this correct?

    But there's another thing that I'm curious about. I assume then that String theory concerns the nature of the particle subsequent to the wave function collapse, and tells us nothing about the nature of any underlying structure. Is this correct?

    If I have misinterpreted something is there a simple way to illustrate the connection between QM and M-theory?

  2. jcsd
  3. Jun 19, 2012 #2

    Ken G

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    Gold Member

    That is a statement that I would agree with, but it is also something that is open to interpretation to say what that confounded particle is really doing. The Bohm interpretation says the particle definitely goes through one slit, but there is a "pilot wave" that goes through both, and coaxes the particle into an interference pattern. The many-worlds interpretation says the particle goes through both slits, but in different worlds, which partially overlap long enough to get the interference before our perceptions pick out one to observe. The Copenhagen approach says that there is no continuous existence of that particle, it is just a mental construct based on its performance in the complete experiment, so it doesn't make much sense to even talk about what it is doing in between. So you can see that different interpretations generate a different language about what is happening in there.
    That's a pretty standard interpretation, close to the Copenhagen approach. There isn't much consensus though, on which is the "best" way, and they all seem pretty equivalent.
    I don't know on that one.
  4. Jun 19, 2012 #3
    Thanks, Ken G, that was very helpful.
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