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What Term must be used for this formalism?

  1. Feb 6, 2016 #1
    I noticed something especially in Physicsforums. It seems we have cornered quantum stuff to attain classical attributes.What I mean is this. You have the 3 main interpretations

    Many Worlds
    Bohmian
    Copenhagen

    In all 3 versions. there are either classical worlds branching or particle with trajectories or subjective Bayesian views. What happens to the idea about wave function of an electron being also present elsewhere.. or in the absence of measurement to determine a particle properties.. the particles has no definite particles? What I'm asking is.. what interpretation should it be called.. this idea wave function being real? There should be a name of it especially when you can't falsify it so it should be a valid interpretation too.
     
  2. jcsd
  3. Feb 6, 2016 #2

    vanhees71

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    I'd call it esoterics ;-)).
     
  4. Feb 6, 2016 #3
    Or let me ask about this question of localization. Quantum system like the electrons in atoms are delocalized.. upon measurement, it localizes. But the 3 main interpretations can't model this localization. In Many Worlds.. the electrons before measurement has a world of each own? or are they delocalized? In Bohmian.. it has trajectories as all time meaning before measurements.. the electrons in atoms have trajectories.. in Copenhagen.. the wave function is just tools or subjective (but then in Copenhagen what happens to the electrons in the atoms?)
     
  5. Feb 7, 2016 #4

    vanhees71

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    What do you mean by localization? You measure the position of, say an electron. That means the electron has interacted with some device like a photoplate leaving a track which lets you read off the position at an accuracy given by the apparatus's resolution. If you know the quantum-theoretical state, you can know only the probability for where the electron will be found, and nothing else. What happens to the electron after the measurement depends on the apparatus. In the case of a photoplate it gets absorbed.

    For your electron in an atomic state you can use some scattering experiment, e.g., shooting with another electron or photons on the atom and measure the electromagnetic form factor of the atom, from which you can get an idea of the charge-density distribution of the electrons within the atom. Usually then you excite the atom or even kick out one or more electrons. You can calculate the various transition properties from the initial (usually the ground state) to another atomic state (including scattering states, where you are left with an ionized atom and one or more free electrons) from quantum scattering theory.
     
  6. Feb 7, 2016 #5
    What I meant was.. before measurement.. the electron are not localized.. they don't have physical locations. They are just state vectors. Is this also the idea of Many worlds.. where before measurement.. the electrons are not really electrons but just wave function?
     
  7. Feb 7, 2016 #6

    vanhees71

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    Electrons "are" not the wave function, but the wave function describes the probability distribution of their location. A point particle in classical physics "is" also not a column of six position-momentum vectors.
     
  8. Feb 7, 2016 #7
    But without being observed.. there are only wave functions... Bill just wrote in the other thread that "QM is silent on what's going on when not observed." Perhaps you believe it is not silent? Pls. elaborate on whether photons/particles exist in all possible states simultaneously before measurement or others you have in mind.
     
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