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B Have we directly observed the speed of gravitational waves?

  1. Apr 20, 2016 #1
    To me, it seems that with our current technology it would be difficult to observe the speed of gravitational waves. Can anyone correct me if I am wrong?
  2. jcsd
  3. Apr 20, 2016 #2
    no doubt about difficulties.....but it was announced recently by an international team of 'measurement' people and about three /five months of data analysis and sifting through the huge reading...check and recheck it was confirmed and published in journal. the path difference was of the order of 1.0*E-18 m so the difficulty is very much there.
  4. Apr 20, 2016 #3


    Staff: Mentor

    We don't have a way to directly measure the speed of gravitational waves because we don't have a source of them that we can control experimentally, in order to turn it on or off at will and make measurements. The best we can do is to extract bounds on the speed from other measurements, such as the ones recently made by LIGO. So far all the data is consistent with GWs moving at the speed of light, which is what GR predicts. But there isn't very much data.
  5. Apr 21, 2016 #4


    User Avatar
    Science Advisor

    We've currently only got two gravitational wave detectors. This only lets us put an upper bound on their speed (1.7c at the moment, I think) since we don't know where they are coming from. There is some indirect evidence that they travel at the speed of light, in that there was no dispersion.

    When we have more detectors, direct estimates of the speed will be possible.
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