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Experimentally probing the photon's reference frame

  1. Aug 8, 2010 #1
    Hi All,

    Suppose a photon is approaching the origin of set of three cartesian axes, along the negative part of the z axis.

    If we put a slit, geometrically defined as:
    1a) half plane z = 0 and x >= epsilon
    2a) half plane z = 0 and x <= -1 * epsilon

    Note that the slit width is 2 * epsilon.

    After the photon has passed through it a diffraction pattern can be seen. We know it.

    Now suppose this photon approaches the origin with a different structure put in its way.

    Let this structure be defined as follows:
    1b) half plane z = 0 and x >= epsilon
    2b) half plane z = 1 and x <= -1 * epsilon

    If the limiting case of Lorentz Transfomation to a c moving reference frame applies, the diffraction pattern should be the same in these two cases, for the photon would "see" the longitudinal dimension of our world condensed in one point, and so, both constructions would be the same to this photon.

    Does this line of thought seem to be correct?

    Best wishes

  2. jcsd
  3. Aug 9, 2010 #2
    Please clarify what exactly you mean by a photon's 'frame of reference' , as the photon has a probabilistic distribution in keeping with its wavefunction.
  4. Aug 9, 2010 #3
    The view I am trying to sustain here is that of a photon as a wave packet, whose peak travels at vectorial velocity (0, 0, c) and which comes from a source located at some large negative value of z axis.

    Near the origin there are two options of apparatus, the first one being a regular slit of width 2 * epsilon. The second apparatus is also a slit in a certain sense, but one of its walls has been shifted 1 meter ahead in positive z direction.

    If the behavior (interference behavior) is the same for these two setups then we have a point in favor of the statement that for the photon the longitudinal direction is collapsed and it experiences only two dimensions.

    Of course, to see the interference behavior we will need a large ammount of such photons, identically prepared.

    I hope this have been of use.

    Best Regards,

  5. Aug 9, 2010 #4


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    If I've imagined your apparatus correctly, then the diffraction patterns will be different. When light interacts with matter it does so in normal 3D space. As for what light 'experiences', I don't think it is testable and so not interesting scientifically.
  6. Aug 9, 2010 #5
    It is possible that Albert Einstein have been worried with not so interesting scientifically questions. I agree the word "experiences" humanizes the photon and so seems to be an irregular move on science game.
    But my point here is that, using Lorentz Transformation in the limiting case where v tends to c, one is tempted to state that whatever moves together with such limiting reference frames, it will experience a lot of Lorentz contraction in its logitudinal dimension and no contraction at all in the other two, not to mention its time perspective. So we are led to the conclusion that, following the tendency of this limiting operation, photons have no longitudinal dimension, living in a projected 2D world.

    And if this projection is true, then there are a class of equivalent apparatus, all similar to one slit, which yield the same diffraction pattern.

    Best Regards,

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