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Sound at the Speed of Light?

  1. Aug 9, 2004 #1
    If man were able to travel the speed of light - what would it sound like to this man? Would it be a mad deafening roar? Or would it be complete silence? What does the speed of light sound like?
  2. jcsd
  3. Aug 9, 2004 #2
    If he was traveling in a craft, sound for him would not change from the way it is in our everyday world. If we were watching him pass by, he would burn up from the friction in the sound medium (air). Then you would hear the sound from the blast about 1 second later for every mile distance from the explosion.
  4. Aug 9, 2004 #3
    It he were traveling in space in the absense of matter then at speeds near light speed (you can't go at light speed) he wouldn't notice anything unless he was looking out the window. This is because its impossible to even speak of moving unless you've stated what your moving with respect to. Right now you are moving at near the speed of light with respect to some frames of reference.

    If he were moving near c with respect to the average rest frame of matter in the universe (locally) then he'd notice nothing as welll unless he looked out the window. Then, because he's traveling at near the speed of light with respect to the cosmic background radiation (locaal zero momentum frame) then he'd see gamma rays in the direction of motion and super lw frequency rays when he looked out his rear window.

  5. Aug 9, 2004 #4


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    I'm travelling at almost the speed of light right now (as I imagine everyone on this forum likewise is doing). Note that such a statement in no way contradicts the perspective that I am also at rest.
  6. Aug 11, 2004 #5
    exackly. all of us are travelling at imencelly high speeds right now (space expansion), but because we are in an internal frame, this has no effect on us and we cannot notice it.
  7. Aug 13, 2004 #6


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    It has nothing to do with space expansion. It is the issue that velocity is a relative quantity.

    What's an "internal frame?"
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