The mainstream majority is divided on this question. Some say the speed of gravity is the speed of light; others say it has no speed, being instantaneous. As I see it the question boils down to the direction in which the force vector of gravity points. But the word "force" ain't in the lexicon of GR. GR does recognize the existence of momentum, though. I suppose someone with a good grasp of GR could calculate the change of the momentum vector for a planet near a black hole for a very short time interval; the direction of the change is the direction of the force of gravity. If the force vector points exactly toward the center of the black hole, then the speed of gravity force is infinite.

Any claims of a finite speed other than light speed are

*new theories*, so maybe this thread should be moved there.

Van Flandern made some important discoveries that were rejected for many years - but his denial of GR and other off the wall theories (faces on mars etc) are so beyond mainstream to be slightly crackpot.

I have to agree that VanFlandern had some crackpot theories, like spontaneously exploding planets, for example. Nevertheless, I am persuaded that he was right about the speed of gravity. The force of gravity definitely does not point in the direction where we see the sun; if it did, it would pull us into higher and higher orbits, and solar systems could not exist. So it can't be the speed of light.

If VanFlandern had had a better understanding of the difference between Euclidean space and Minkowski space-time, he might have argued his points more convincingly. As I see it, both VanFlandern and GR may be correct; they only seem to contradict one another because they are using the same words to mean different things. When Minkowski redifined "straight line", he tacitly changed the meanings of all the old familiar parameters. The mainstream point of view seems to be that Minkowski eliminated the existence of Euclidean space; I believe both types of space are valid, but they are merely mathematical analogies of physical space.

I believe both e/m waves and gravity waves propagate at light speed, but the forces associated with them are as fast as VanFlander said they are, at least in Euclidean space. I don't have sufficient understanding of GR to say whether they are faster than light in Minkowski space-time. Measuring the speed of gravity (and all the other forces) is extremely difficult.

If I am right about all the forces having the same FTL speed, then it should be about 10^44 times easier to measure the speed of electrostatic force, and then translate that to gravity force. The trouble is that you can't relocate an electrostatic charge instantaneously; you can only accelerate it from A to B at sub-light speed, and when you do so, you get an electromagnet wave which overwhelms your attempts at measureing the electrostatic force. There have been attempts to do so, and even claims of success, but no widely accepted proof. I'm pretty sure I have seen a more credible source, which placed it at 3 x 10^10 c, but for now I can only find this [urlhttp://www.holoscience.com/synopsis.php?page=11]Electric Universe [/url] source, which places it at about 8 x 10^13 c. VanFlandern's estimate was > 2 x 10^10 c.