Posted by Scott Ellis (216.87.95.64) on January 08, 2003 at 22:30:18:
In Reply to: speed of gravity posted by Rob on January 08, 2003 at 12:15:36:
Hi Rob,
Thanks for your post. This is indeed an interesting development. However, I don't believe this particular experiment is quite as "definitive" as it is being portrayed in the media.
For one thing, placing a finite speed on gravity leads to fundamental problems in theory that conflict with observation (as described in the article: The Speed of Gravity - What the Experiments Say).
excerpt:...anyone with a computer and orbit computation or numerical integration software can verify the consequences of introducing a delay into gravitational interactions. The effect on computed orbits is usually disastrous because conservation of angular momentum is destroyed. Expressed less technically by Sir Arthur Eddington, this means: "If the Sun attracts Jupiter towards its present position S, and Jupiter attracts the Sun towards its present position J, the two forces are in the same line and balance. But if the Sun attracts Jupiter toward its previous position S', and Jupiter attracts the Sun towards its previous position J', when the force of attraction started out to cross the gulf, then the two forces give a couple. This couple will tend to increase the angular momentum of the system, and, acting cumulatively, will soon cause an appreciable change of period, disagreeing with observations if the speed is at all comparable with that of light."
I wonder whether the experiment really was truly open, or whether it might have been geared toward achieving a certain result. As one can see from this discussion on Slashdot, the experiment's methodology has stirred a little controversy, with some charging that there might be some circular logic involved.
In any case, it makes for some great reading and discussion. Here is another interesting article I ran across called Gravity and Antigravity, which describes some interesting gravity anomalies.
Best,
Scott
: Speed of gravity discovered?
: http://www.cnn.com/2003/TECH/space/01/08/gravity.speed.ap/index.html