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What enables light to go at such speeds?

  1. Feb 22, 2012 #1

    As I understand, light can travel at the fastest known speed.
    What enables it to do so? What prevents us, and other objects, from accelerating to such speeds?

  2. jcsd
  3. Feb 22, 2012 #2


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    Welcome to PF!

    Hello AbsoluteZer0! Welcome to PF! :wink:

    Because light has no rest-mass, and we have! :smile:
  4. Feb 22, 2012 #3

    I heard that when an object increases in speed, it's mass increases. Is this true?
    If it's true, does that mean that when light increases in speed it's mass at, for example 30 km/s, is less than that of another object at 30 km/s?
  5. Feb 22, 2012 #4
    Hi, AbsoluteZer0. Not sure if I understand your question about light being of less mass than another mass. However, yes. If an object goes really fast, its mass will increase. But light will always be lighter than any particle [pun intended] because it is a wave (Provable by diffraction, polarization, and Young's double slit experiment).

    I was wondering myself, if the measurements for the neutrino are accurate, couldn't that suggest that light actually does have mass and there is an even faster speed than what we know? Just wondering.
  6. Feb 22, 2012 #5


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    Yes: m = mo/√(1 - v2/c2).

    It gets more difficult to push ("heavier"), so that an infinite amount of pushing still won't get it quite up to the speed of light.
    It doesn't.

    Light always goes at exactly the speed of light (the clue's in the name! :wink:).

    (even in glass or water, light still goes at the same speed: it just gets delayed by a funny quantum effect)
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