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Why light speed is constant? (please read)

  1. Sep 12, 2009 #1
    We'll know that the base of special relativity theory is "the light has a constant speed in vacuum".

    Time dilation and Lorentz contraction are consequences of the constance of light speed.

    If we excite photons, for example, its frequence increases (and the wavelength could decrease), but it happens for light speed continues constant. It's also an consequence of constance of light speed.

    Everything seems to be a consequence of constance of light speed.

    But, the question is: WHY light has a constant speed (in vacuum)?
    What about tachyons? (http://en.wikipedia.org/wiki/Tachyon" [Broken])

    Any discussions are welcome.
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Sep 12, 2009 #2


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    The question of 'Why?' is more philosophy than physics.
  4. Sep 12, 2009 #3


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    Anyway, the constant c would still be of great importance (and would still be measurable) even if there were no particles that moved that fast, assuming the laws of physics were still Lorentz-symmetric. For example, clocks moving at some v slower than light would still slow down by the factor of [tex]\sqrt{1 - v^2/c^2}[/tex].
  5. Sep 13, 2009 #4
    im not sure, but this is what i think:
    Hypothesis of why the speed of light is the speed of light:
    In the time of Big Bang when the first atoms were created, the matter and anti-matter destroyed eachother and made the photons. When they eliminated each other, photons were sent out, in the exact speed it was accelerated in. And as Newton’s laws says: “Nothing can be stoppep without friction”. And, as we all know, photons are massless particles and have no effect on gravity, and that’s why they never stop and always go in the same speed. :D PEACE!
  6. Sep 13, 2009 #5
    Trying to invoke cosmological arguments to explain a local phenomena doesn't seem a bit bizarre to you..?
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