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What happens to a photon wave packet when half out of a moving device?

  1. Sep 30, 2012 #1
    I was wondering if there has been a study done on what happens to a photon wave packet when half out of a device while the device emitting it is moved.

    If never done it would make an interesting scientific experiment to see where the influence of moving the device ends.

    I'd like to see or perform an experiment showing how much of the wave packet can exit the photon source, while the motion of the photon source will still influence the location where the photon impacts a photon detector.


    http://imageshack.us/a/img850/929/experimentz.png [Broken]
     
    Last edited by a moderator: May 6, 2017
  2. jcsd
  3. Oct 1, 2012 #2

    mfb

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    That model is not useful for your experiment. Photons are emitted or not emitted, but not "50% out of something".
     
  4. Oct 1, 2012 #3
    If the photon reaches the detector and its wave function collapses, obviously it was emitted.
    In order to be emitted, it must exit the source at some time prior to striking the detector, right?
     
  5. Oct 13, 2012 #4
    As others have mentioned, you would not be able to "catch" a photon half way out of an emitter.

    Think of it this way, the absolute fastest anything can move is the speed of light. This is the speed that photons move. The photon is also one of the smallest elementary particles. The smallest thing moving at the fastest speed is as close to instantaneous as it is possible to get.

    There's no chance, even with technology way beyond what we currently have, to catch a photon "half way out" of an emitter.

    Not to mention that a photon is a discrete packet size. There is nothing that exists which is a semi-photon. This is one of the fundamentals of the "quantumness" of our universe. Some things cannot be subdivided.

    This 'experiment' cannot be done.
     
  6. Oct 13, 2012 #5

    Drakkith

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    You are under a misconception that a photon is made of a wave packet. This is not true. The wave function describes the photon according to our own rules and math. It allows us to make predictions about photons, such as what the probability of a photon hitting a detector at a specific location is. The wave function, or wave packet, is not "something". It is a mathematical concept.
     
  7. Oct 14, 2012 #6
    "The wave function describes the photon according to our own rules and math. It allows us to make predictions about photons, such as what the probability of a photon hitting a detector at a specific location is. "
    So, how will the predictions about the locations of the photons hitting the screen be affected by the source being in motion?
    If the source is stationary, the distribution pattern of photons might like something like a bell curve.
    And if the source is in motion, and we normalize the location of the photons to direction the of the source, adjusting for the speed of light, will the bell curve get wider due only to experimental error? Or will the source motion have a widening effect on the distribution of photons even after normalizing for the source direction and experimental error?
     
  8. Oct 14, 2012 #7

    Drakkith

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    I'm not sure actually. I don't know how it would affect the direction of travel, wavelength, or what. If something is traveling at a high velocity in a direction perpendicular to your line of sight and emits light, what would happen to the light? Anyone know?
     
  9. Oct 14, 2012 #8

    AlephZero

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    The behaviour of the system is independent of the reference frame you use to observe it. So consider the situation in a frame where the light source is stationary and you are moving, then transform the result to whatever frame you want.
     
  10. Oct 14, 2012 #9

    Drakkith

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    Yes, that is what I am asking as I do not know what would happen in that case.
     
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