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After reading Sagnac effect one thing immediately come to my mind is LIGO, I only read that the team building LIGO have already considered the curvation of Earth surface but what about Earth's rotation which might affects the 2 laser beams?

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    $\begingroup$ The Sagnac effect is proportional to the area enclosed by the interferometer. To a first approximation that is zero in LIGO. $\endgroup$ – Emilio Pisanty Dec 15 '18 at 4:28
  • $\begingroup$ @EmilioPisanty: is it due to Earth rotation speed? $\endgroup$ – user6760 Dec 15 '18 at 4:40
  • $\begingroup$ Let’s say, a one meter beam of light and its source is moving in one direction and another one meter beam of light and its source is moving in another direction; their journey times vary depending on their direction of motion. Sounds like a violation of SR, but mainstream physics says, not so. $\endgroup$ – Lambda Dec 15 '18 at 17:24
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At its current level of sensitivity, LIGO is not sensitive to the Sagnac effect. However, future devices may be precise enough to see it. There are plans to detect and account for the effect as part of future generations of Michelson-Morely gravitational wave detectors.

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  • $\begingroup$ sensitivity on light or gravitational wave? $\endgroup$ – user6760 Dec 15 '18 at 3:35
  • $\begingroup$ @user6760 I don't know what you mean by that. $\endgroup$ – Buzz Dec 15 '18 at 3:38
  • $\begingroup$ sorry I was thinking if gravitational wave can also experience sagnac effect but I was afraid to sound a bit crazy. $\endgroup$ – user6760 Dec 15 '18 at 3:46
  • $\begingroup$ @user6760 Oh, that makes sense. I assume that there would be an analogous Sagnac effect on the gravitational waves, but the future detectors would be measuring the Sagnac affect on the interferometer photons. $\endgroup$ – Buzz Dec 15 '18 at 3:47

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