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Special relativity from the frame of refrence of photon

  1. Mar 6, 2013 #1
    we know that particle having rest mass cannot reach speed of light,c.
    but if we apply results of special relativity to a photon,then
    it seems that for a photon 1)there is no time
    and 2)length is contracted to zero.

    1) so does that mean photon is timeless & length dimension does not apply to a photon?
    2) only 2 dimensions exist for a photon?

    how can we explain this?
  2. jcsd
  3. Mar 6, 2013 #2


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    Staff: Mentor

    There's a FAQ on the rest frame of a photon at the top of the page: https://www.physicsforums.com/showthread.php?t=511170
  4. Mar 6, 2013 #3


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    Staff Emeritus
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    Education Advisor

    Please read the Relativity FAQ subforum.

  5. Mar 6, 2013 #4
  6. Mar 6, 2013 #5


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    Staff: Mentor

    Light traveling through a non-vacuum medium is a very different physical phenomenon that cannot be treated the same way as light in vacuum.

    The difference (warning - non-mathematical handwaving follows - this is an analogy not a rigorous explanation!) is that light traveling through a medium is constantly interacting with the atoms of the medium: It's being absorbed and re-emitted in different directions or even backwards. Thus, its effective speed through the medium may be much less than the speed with which it travels through the vacuum between the atoms.
  7. Mar 6, 2013 #6
    When they describe that the light is "stopped", they're giving the reader the impression that the photon has (for all intent and purposes) stopped propagating and is simply "there". They dont mention that it's absorbed by a particle and waiting to be released or that it's traveling in some kind of loop - back and forth in the medium.

    I realize this is a popular science article and all but how exactly are they "stopping" light? Is it simply being absorbed by a particle that cannot drop to a lower energy state and release it?
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