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Is an electron everywhere at once?

  1. Dec 25, 2003 #1
    Is an electron everywhere at once within a waveform?
     
  2. jcsd
  3. Dec 25, 2003 #2
    and what about a photon?
     
  4. Dec 25, 2003 #3
    it's probablity dictates the electron to be in other places rather than the one observed by the experiment, the experiment affects the state of an electron (which is in a superposition).
     
  5. Dec 25, 2003 #4
    cheers loop
     
  6. Dec 25, 2003 #5

    Tom Mattson

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    That cannot be said with any certainty. It is just one untestable interpretation of quantum theory, and I for one am inclined to think it is false.

    Check out this thread by loop quantum gravity:

    https://www.physicsforums.com/showthread.php?s=&threadid=9661
     
  7. Dec 25, 2003 #6

    dlgoff

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    When bound in an atom their location can be narrowed to a probability density distribution depending on its energy state. However, within the distributions, HUP still applies.

    Corrections encourged.
     
  8. Dec 25, 2003 #7

    Tom Mattson

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    The probability distributions are infinite in extent, so saying that the HUP applies "within the distributions" is just another way of saying that the HUP applies everywhere.
     
  9. Dec 26, 2003 #8
    Isn't this related to Schrödinger's cat mystery?
     
  10. Dec 26, 2003 #9

    dlgoff

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    Tom,

    So even as part of an atom, the electrons probability distribution is everywhere? What about the wave equation solutions for the hydrogen atom for example. I thought that they described various symetrical distribution patterns that are localized (i.e. depending on the its quantum numbers).
     
  11. Dec 26, 2003 #10

    Tom Mattson

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    Yes.

    Take a look at the solutions. They only go to zero asymptotically, at infinity. That means they are nonzero everywhere.

    You probably got that impression from looking at those famous 3d polar plots of atomic orbitals, that seem to have definite cutoff points. The thing is, those pictures are generated by imposing a cutoff. That is, they determine the orbital which contains, say, the innermost 90-95% of the probability density, and draw that. To go to 100% would require an infinite amount of space.

    The atomic electrons are "localized" only in the sense that their probability densities approach zero as r approaches infinity. The only way to truly localize a particle to a finite region of space is to confine it in a potential well whose walls are infinitely high (on the energy axis). This, of course, is not physically realizable.
     
  12. Dec 26, 2003 #11

    Tom Mattson

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    Yes. The idea is that you do not know exactly where the electron is until you measure it. Since you can only know the result of a measurement, it leaves open the (untestable) interpretation that, inbetween measurements, the electron can be in more than one place at a time, though it does not imply that. The absurdity of such a position was highlighted by Schrodinger with a "quantum cat" that was at once, both dead and alive.
     
  13. Dec 27, 2003 #12
    I read an article a few months ago about this "riddle". Sir Roger Penrose wanted to prove that Schrödinger was right. That an electron can be in two places at once. To me however, this sounds more like a metaphysical idea.
     
  14. Dec 27, 2003 #13

    dlgoff

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    Thanks Tom. I should have thought before asking. But I'm glad I did since you have explained very well whats going on.

    Thanks again,
     
  15. Dec 27, 2003 #14
    Maybe Penrose looks for such explanation to prove some of his metaphysical ideas. It shows that measurement problems of an (egocentrical) observer influences his general perception of the reality of the world. The same absurdity is like some people say that the tree that falls in the wood without an observer doesn't makes a sound.
     
  16. Dec 28, 2003 #15
    That sounds more like surrealistic poetry:smile:
     
  17. Jan 5, 2004 #16
    Penrose misinterprets the frequency of the particle with the particle itself. Notwithstanding any logic to the contrary.
     
  18. Jan 5, 2004 #17

    DrChinese

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    Doesn't seem all that absurd, really. No different really than the Aspect experiments. I.e. assuming that quantum particles have discrete values when not being watched, which we now know cannot be demonstrated. I would call that the equivalent of the tree in the forest, what would you call it?
     
  19. Jan 7, 2004 #18
    A moon-sized asteroid crashing into an earth-like planet 100 million light years away makes a hell-of-a huge sound in that local environment, regardless of whether or not anyone observes it.
    Prove that wrong.
     
  20. Jan 7, 2004 #19
    I suppose it depends on how you define sound.

    Webster's Definition:

    1 a : a particular auditory impression : TONE b : the sensation perceived by the sense of hearing c : mechanical radiant energy that is transmitted by longitudinal pressure waves in a material medium (as air) and is the objective cause of hearing


    Definitions a and b depend on an observer for a sound to exist whereas definition c differentiates sound and hearing.

    Definition c is a physical description so I suppose in this sense a sound would exist if no listener were present.
     
  21. Jan 7, 2004 #20
    Sure. It was not a moon-sized asteroid but still a serious one. Indeed it made a serious sound. Result: end of the dino's. Not human observers but animal. But they noticed and felt the effects!
     
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