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Does Electromagnetic radiation travel faster than the speed of light?

  1. Sep 29, 2012 #1
    Please feel free to move this to the correct forum.

    After doing some reading, I've found that Electromagnetic radiation travels at the speed of light in a vacuum. EMR also travels in the path of a wave. Whereas, light and/or light photons travel in the path of a straight line.

    Having said that, the path of the wave will have a greater distance of travel from point A to point B than would a straight line. Therefore, I have to conclude that Electromagnetic radiation actually travels faster than the speed of light, at least in a vacuum.

    Would this be true..?
  2. jcsd
  3. Sep 29, 2012 #2


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    Light IS electromagnetic radiation...how can the two travel at different speeds?
  4. Sep 29, 2012 #3
    Matterwave is correct, however I believe your misunderstanding comes from a deeper problem with the way you are looking at this.

    Light as a wave is not a wave like the circular waves on a pond, it is a condensed area which exhibits wave behavior (my terminology here is sloppy, wikipedia 'wave packet' for a better understanding), waves (and wave packets) would not travel a greater distance than a straight line, why would they?
  5. Sep 30, 2012 #4


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    You seem to think radiation follows a "wavy path" rather than a "straight path". It doesn't. The wave is the radiation, and the wave moves in a straight line in empty space.

    You do know, don't you, that "light" is just the name we give to electromagnetic radiation within a particular range of frequencies and that all forms of electromagnetic radiation are composed of photons?
  6. Sep 30, 2012 #5
    Is it correct to say that the "wave" part is not moving in the direction of flight at all? They are fields at right angles to one another which alternately express the energy of the photon in its electric field and magnetic field perpendicular to the direction of flight (alternating at a frequency proportional to the energy).

    Or is that too much of a classical view?
  7. Sep 30, 2012 #6


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    And they (or, alternatively, their positions) move with the speed of light.
  8. Sep 30, 2012 #7


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    This is not correct. The energy does not alternate back and forth between the electric and magnetic fields. The electric and magnetic fields in a light wave are in phase, reaching their peak value at the same time, and simultaneously falling to zero at a later time.
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