Speed of Gravitational Waves confirmed by Experiment?

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Discussion Overview

The discussion revolves around the experimental confirmation of the speed of gravitational waves, particularly in relation to the 2016 LIGO and VIRGO observations. It explores the implications of these observations on the speed of gravitational waves as predicted by general relativity, and the potential for future measurements to refine this understanding.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • Some participants assert that the 2016 LIGO and VIRGO observations confirm that the speed of gravitational waves is the speed of light.
  • Others highlight that the observations only provide an upper limit on the speed of gravitational waves, noting that different directions could yield different speeds.
  • One participant mentions that the current configuration of observatories allows for a two-dimensional location but suggests that a fourth observatory would be necessary for direct speed measurements.
  • There is a proposal that observing events in the electromagnetic spectrum could lead to more accurate speed measurements of gravitational waves.
  • Some participants express confidence that the speed of gravitational waves is indeed the speed of light, though this is not universally agreed upon.

Areas of Agreement / Disagreement

Participants express a mix of confidence and uncertainty regarding the speed of gravitational waves. While some believe it is the speed of light, others emphasize the need for further measurements and caution against definitive conclusions based on current data.

Contextual Notes

Limitations include the dependence on the current number of observatories and their configurations, as well as the unresolved nature of speed measurements in different directions.

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Hi and welcome to PF!
If you read to the bottom of your link, the last section states "The speed of gravitational waves (vg) is predicted by general relativity to be the speed of light (c)."
This is obvious in the delay between the sites separated by 3002km.
 
The observation only sets an upper limit on the speed. Different directions lead to different speeds, with the fastest one corresponding to a wave propagation aligned with the line between the two observatories. The expectation is the speed of light, of course.
 
Once more observatories are built, it will be possible to accurately determine the direction and speed.
 
Three observatories, as we have it now (2*LIGO and VIRGO), give a 2-D location in the sky, with a fourth one we will get a direct speed measurement. Seeing an event in the electromagnetic spectrum could give a much more accurate speed measurement.
I don't think there are serious doubts that it is the speed of light.
 

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