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## Speed of Gravity?

I was sent this linkby a colleague who is trying to assert that Gravity travels faster than the speed of light, I don't believe this is the case and I have pointed him to the Hulse Taylor binary but he's looking for specific refutation of the examples in the link, could anyone help?

2. Originally Posted by Zideq
I was sent this link by a colleague who is trying to assert that Gravity travels faster than the speed of light, I don't believe this is the case and I have pointed him to the Hulse Taylor binary but he's looking for specific refutation of the examples in the link, could anyone help?
Your link is to metaresearch.org, and you're looking for refutation? Shouldn't metaresearch do its own refuting? Testing the speed of gravity is not a trivial problem.

3. That is the late Tom Van Flandern's site. We've covered this many times over the years here. Do a forum search of "Speed of Gravity" and will bring up the various threads.

Short answer, which is detailed in all those threads: In GR, gravitational influences propagate at 'c', or along null paths would be a better way to phrase it. However, GR gravity has some little tricks up its sleeve that cancel the propagation delay to high order, which it makes Newtonian instantaneous gravity seem to hold up to high speeds.

EM cancels the propagation delay to velocity, but GR gravity does it up to acceleration as well, so it is only changes in acceleration of the source bodies, "jerk", that cause the propagation delay to show up.

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Originally Posted by publius
That is the late Tom Van Flandern's site. We've covered this many times over the years here. Do a forum search of "Speed of Gravity" and will bring up the various threads.

Short answer, which is detailed in all those threads: In GR, gravitational influences propagate at 'c', or along null paths would be a better way to phrase it. However, GR gravity has some little tricks up its sleeve that cancel the propagation delay to high order, which it makes Newtonian instantaneous gravity seem to hold up to high speeds.

EM cancels the propagation delay to velocity, but GR gravity does it up to acceleration as well, so it is only changes in acceleration of the source bodies, "jerk", that cause the propagation delay to show up.