I am aware that matter with mass experiences dilation and photon is massless. there is no inertial frame where photon is at rest. However, wave form of light has momentum and energy. Blue light wave has higher energy and shorter wavelength than red light. So, in specific time, blue light will have more oscillation cycles than red light.

can we say blue light has slower clock time than red light due to short wavelength and higher energy? (my assumption: blue light covers short distance before cycle repeats so if it's clock run slow then c maintains constancy. opposite applies for the case of red light)

  • $\begingroup$ In special relativity, one cannot have slower clock time. You have to mention slower w.r.t. whom? Someone's own clock cannot be slower( Proper time). And immediately you see the problem. $\endgroup$ – Ari Nov 25 '15 at 5:03
  • $\begingroup$ How about w.r.t. each other? is it possible? $\endgroup$ – James Nov 25 '15 at 5:09
  • $\begingroup$ No. Because to get a time dilation you require the two frames to move in different velocities, which is impossible for light as all frequencies move in same velocity. $\endgroup$ – Ari Nov 25 '15 at 5:12
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    $\begingroup$ You are asking whether the blue light's clock runs slower (as measured in some frame) than the red light's clock. But light does not have a clock. $\endgroup$ – WillO Nov 25 '15 at 5:23
  • $\begingroup$ anything with energy should be subjected to time dilation, shouldn't it? $\endgroup$ – James Nov 25 '15 at 5:39

No. Photons do not experience the passage of time, as they are traveling at the speed of light. Remember when they discovered that neutrinos must have mass? Originally it was thought that neutrinos traveled at the speed of light, but then it was discovered that neutrinos change their flavors over time, which means that time must pass for neutrinos, which means that neutrinos must have mass and be traveling slower than the speed of light.

You might think that red-shifting is the results of photons changing over time, but that would be incorrect; it's just that our reference frame is different from the reference frame where the photons were created. Had we no velocity relative to the source galaxies, we wouldn't see any red-shifting. It has nothing to do with time acting upon the photons.


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