speed of light vs. "speed of gravity"

[HarryKeogh]

say the sun popped out of existence. we wouldnt know for around 7 minutes because of it's distance and how long the sun's light takes to reach us. ok, simple enough.

but if the sun popped out of existence would it's gravity exerted on us (and every other object in our solar system) cease immediately or does it travel at a certain speed?

[CurtC]

Most scientists think it travels at c. It's really really hard to measure though (suns don't normally just pop out of existence), so work is still being done. They're trying to detect gravity waves from things with changing gravity, such as two massive stars orbiting each other in a tight orbit.

[garys_2k]

Gravitationally caused distortions in space-time move at the speed of light. We'd stay on orbit until the sun's non-existence entered our reality, about seven minutes after it went away from the point of view of an observer located right near it. The sun is not just 93 million MILES from the earth, but it is actually displaced seven minutes from us, as well. Nothing about the sun, no "communication" from it, can get here faster than light.

[scotth]

Originally posted by HarryKeogh
say the sun popped out of existence. we wouldnt know for around 7 minutes because of it's distance and how long the sun's light takes to reach us. ok, simple enough.

but if the sun popped out of existence would it's gravity exerted on us (and every other object in our solar system) cease immediately or does it travel at a certain speed?

This may be a bit out of date, but....

The speed of light and the speed of gravity should be identical. That is what current theory calls for.

My understanding of the current experimental evidence to support this:
1) Watching short period massive binary star systems over time indicate that they loose orbital energy at a rate that is consistent with the theory that they are producing gravity waves.
2) Numerically, the rate of energy loss is consistent with what is predicted if our current theory concerning gravity is correct.
3) Gravity waves have yet to be directly detected. (This may be out of date), but theory indicates detecting them would be a daunting task unless some fairly rare astronomical event occurs in our galactic neighborhood.
4) We are currently building better gravity wave detectors.

We will know alot more if/when we can directly detect gravity waves.

Some points to ponder about waves in general
1) In order to have a wave of any type, a field must be propagated at a finite speed.
2) Therefore, if gravity is propagated at infinite speed it would exclude the possibility of gravity waves.
3) Conversely, if/when gravity waves are detected, it conclusively rules out the possibility of infinite propagation speed.

[Andonyx]

You know they just did some major reserach on this a month ago:

http://www.arstechnica.com/archive/news/1042065116.html

There's one article.

And here's another:

http://physics.about.com/library/weekly/aa011503a.htm

[Agammamon]

Anyone who has seen Star Trek: Generations will have noticed that the mad scientists plan wouldn't have worked. Making the star nova would have had no effect on the path of the space thingy until the EM wavefront reached the location of the planet, frying it within a couple of seconds.