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Effect of gravitational waves

  1. Sep 23, 2009 #1
    What effect would a train of gravitational waves have when it hits a solid sphere of mass?
    We know about its expected effect on a dust sphere where it is ellipsed alternately in x and y direction. I would like to know how would an isolated solid sphere be affected when it is hit by a train of gravitational waves?

    Would appreciate if the regular professionals respond - no speculating amateurs please!

    Thanks.
     
  2. jcsd
  3. Sep 24, 2009 #2
    Is there no one here who wants to tackle this?! (The previous caveat stands though).
     
  4. Sep 24, 2009 #3

    Ich

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    So you know what the wave tries to do with the sphere. Bonding forces will try to counteract the respective change in distance. Basically, you have a resonator: if the waves are of low frequency, bonding forces will keep the body in shape without noticeable effects. If the wave frequency coincides with a resonant frequency of the body, it will http://en.wikipedia.org/wiki/Gravitational_wave_detector#Weber_bars", as the counteracting force is out of phase then.
     
    Last edited by a moderator: Apr 24, 2017
  5. Sep 24, 2009 #4
    Thanks Ich for taking this on.
    Is there any motion of the object along the direction of impact of the waves? In other words do they act like a repulsive force? Or is all energy of the waves dissipated in the perpendecular direction of the impact, and there is no net displacement of the body in any direction?
     
    Last edited by a moderator: Apr 24, 2017
  6. Sep 24, 2009 #5
    Are you sure? I thought gravitational waves worked by length contraction and time dilation.
     
  7. Sep 24, 2009 #6

    Ich

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    I don't think so, if you don't count that "ringing", which deforms the body also along the direction of impact. There should be no net motion, however.
    But I read in a paper that a stochastic background of waves (in all directions) can act like a cosmological constant, very weakly repulsive.
     
  8. Sep 25, 2009 #7
    Intriguing! Could you please post the link to that paper.
    Do you know how that weak repulsion could be made consistent with the fact that the amplitude of gravity waves decays as the inverse of distance and therefore the energy of the waves decline. Will the repulsion decay with distance as well? If so, at what proportion to distance?

    Thanks.
     
  9. Sep 25, 2009 #8

    Ich

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    http://arxiv.org/abs/0909.1922" [Broken]
    They're talking about waves that fill the whole universe, so it makes not much sense to introduce 1/r² here either. They decay over time.
     
    Last edited by a moderator: May 4, 2017
  10. Sep 25, 2009 #9
    Thanks for the link Ich.

    Now slightly shifting the focus:

    Do gravitational waves, i.e., real gravitons, have a gravitational field, like any normal particle has a gravitational field? Or are real gravitons gravitationally 'neutral'?
     
    Last edited by a moderator: May 4, 2017
  11. Sep 25, 2009 #10

    Ich

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    Hmpf. :confused:

    Classically, gravity is nonlinear, i.e. creates gravity. I really have no idea how this translates to the quantum level.
    <speculation>
    Gravitons go at light speed, so they should gravitate like photons do.
    Gravitons carry energy, so they are "charged" like gluons. That's responsible for accelerated expansion, the pioneer anomaly,and the financial crisis.
    </speculation>
     
  12. Sep 25, 2009 #11
    Hmmm!:wink: Thanks for trying anyway.
     
  13. Sep 26, 2009 #12
    Gravitational waves do cause light and space to bend, in other words the GWs from a celestial object will cause this.
     
  14. Sep 28, 2009 #13
    Do black holes generate gravity waves?
     
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