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Gravity waves

  1. Oct 28, 2005 #1


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    I read that one of the most accepted proofs that gravity waves have energy is Richard Feymann's : imagine beads on a rod, gravity waves can move the beads creating friction and heat so they must have energy.

    Why does the heat creation make this such a great proof? Isn't it obvious that if they can accelerate mass than they must at least have potantial energy? I know that I must be missing something here. Can someone please explain?
  2. jcsd
  3. Oct 28, 2005 #2


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    One might otherwise argue that the passing of a GW will not alter the rod permanently and therefore the GW doesn´t lose energy. Or so.
  4. Oct 28, 2005 #3
    How can it not be altered permanently if it's giving off heat?
  5. Oct 29, 2005 #4


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    Is that why the heat is so important?
  6. Nov 1, 2005 #5
    It is important since it is thermodynamically impossible to convert all work to heat, so if a gravity wave does some work W for some time T, then does no more work, and an amount of heat Q is given off, the entropy of the rod has increased.
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