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Question on the new gravity wave discovery

  1. Feb 11, 2016 #1
    Up until today I understood, in my own feeble way, that masses distorted space/time and explained how gravity worked. So I have one pre-discovery question to see if I understood that before we move on to the new discovery...

    Pre-discovery question: If a mass like our earth distorts space/time wouldn't the distortion require an expenditure of energy on the part of the mass? And if so where does that energy supplied from?

    Post discovery question: This is sort of related. Gravity waves must get their energy from a mass. Even the example of two massive bodies used by CalTech suggested that the body gets smaller over time through the loss of this gravity wave generating energy. So is the mass of the body converted into the energy used to create the gravity waves? How does this work? This is like question one.

    tex
     
  2. jcsd
  3. Feb 11, 2016 #2

    phyzguy

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    Yes, energy is radiated away as gravitational waves. The energy comes from decay of the orbit. As the Earth radiates gravitational waves, it moves slightly closer to the sun. Gravitational potential energy is released, which is converted into energy of gravitational waves. In the case of the Earth, the gravitational waves are so weak that the change of the orbit is immeasurably small, but in the case of massive bodies which are close together, like black holes, the energy release can be large.

    Yes. In the case of the BH merger reported on today, approximately 3 solar masses were converted to energy and radiated away as gravitational waves which were detected by LIGO. The statement was made that at the peak (for a few milliseconds), the power emitted in gravitational waves exceeded to power emitted in light by all of the stars in the observable universe.
     
  4. Feb 11, 2016 #3
    So the more intense the gravity effect on space/time the more gravity waves produced? For example, two massive bodies orbiting each other has a great distortion as opposed to a free floating body where the gravitational pull from some other body thousands of light years away is very small...therefore little distortion and waves?

    Is that about it?
     
  5. Feb 11, 2016 #4

    phyzguy

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    That's about it. Two bodies of mass m orbiting at a distance r will emit gravitational wave energy at a rate proportional to m^3/r^5. So it goes up very fast as they get closer together.
     
  6. Feb 11, 2016 #5
    Were there any respectable theories proven wrong by this discovery? Did some astronomers claim gravity waves were not real?
     
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