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Is relativity Uncertain

  1. Jan 21, 2005 #1
    [SOLVED] Is relativity Uncertain

    Simple question: -
    If a photon does not experience time how does it know how many times to
    wiggle as it crosses space.
  2. jcsd
  3. Jan 21, 2005 #2


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    It oscillates (wiggles) because of its energy, its frequency can decrease or increase to keep propagating at c through any field. But a photon doesnt know to die or better yet decay. A photon emmited during the big bang is still here today at 0 years old. It is emmited at a certain frequency and wavelenght and travels its path. A photon doesnt experience time because it travels at c. Anything traveling at c will have a zero variation world line. But of course nothing with mass can travel at c as Einstein prooved.
  4. Jan 27, 2005 #3
    Hi DB

    Your answer really does not address the problem. To say the photon oscillates at a given rate because of its energy is merely referring to Planck’s equation. Planck himself never attempted to explain the mechanism behind the formula.

    It is true at a superficial level the photo-electric effect and the Compton effect seem to substantiate the idea of the photon but at a deeper level we find that it is inconsistent with the theory of relativity and also some aspects of quantum mechanics. Special relativity denies it the time for it to come into being and quantum mechanics demands that it be in all places at the same time. I admire your confidence in attempting to answer my question but I think a little more is required.
    Last edited by a moderator: Jan 27, 2005
  5. Jan 27, 2005 #4

    Hans de Vries

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    A light wave doesn't wiggle in time. It's shape stays constant (in vacuum)
    and just shifts along with the speed of c. At the most it can spread because
    not all parts move exactly in the same direction. The EM components at the
    head or the tail of the light pulse stay always directed in the same direction.

    Regards, Hans
  6. Jan 27, 2005 #5
    Hi Hans

    Does this mean relative to its own frame of reference the light has an infinite wave length?

    Regards, NL
    Last edited by a moderator: Jan 27, 2005
  7. Jan 27, 2005 #6

    Hans de Vries

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    Yes, it's frequency is zero in it's own reference frame. It's maximally Red shifted:

    [tex]f' \ \ = \ \ \sqrt{\frac{c-v}{c+v}} \ f[/tex]

    Regards, Hans
  8. Jan 27, 2005 #7

    Hans de Vries

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    A few tips to understand what's going on:

    You can draw a Minkovsky diagram. The light phases are bands at 45
    degrees in parallel with the x' and t' axis.

    You'll see that the frequency over the t' axis is zero.

    And this one: The 'head' of a photon can never see it's own tail since
    this would need propagation > c. The "head" can only see it's own phase,
    (=> 0 Hz) The other parts of the photon are all mapped on it's light cone.

    (What we call photon is spatially extended on the x-axis)

    Regards, Hans
  9. Jan 28, 2005 #8
    In that case when a photon interacts with an absorber system, the photon will see the absorber system as having infinite mass and a Debroglie frequency that is also infinite. The photon could never be fully absorbed because the universe would have grown old and died long before the process could be completed.
  10. Jan 28, 2005 #9


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    A photon doesn't have a valid reference frame, because you get infinities if you try to apply the Lorentz transformations using v=c. You can consider the limit as v approaches c, but this gives you weird answers, like that a photon would experience its entire path throughout history as a single point in space which takes zero time to traverse.
  11. Jan 31, 2005 #10
    So what's that telling us about the nature of the photon and its relationship with relativity?

    Why is not possible to have theory which is free from these infinitives and we can apply mathematics to it in a self consistent way?
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