# How can gravitation force not have a speed?

Asked by windex (2901 ) August 13th, 2009

If the sun or the earth or a plant/star that effects other planets disappeared or moved from point A to point B (at the speed of light), you are telling me that it would effect the other planets instantaneously? It wouldn’t take X seconds/minutes or something?

Observing members: 0 Composing members: 0

No, it does have a speed, the speed of light. Who told you it didn’t?

Jayne (6729 )

<—-waiting for Jayne’s answer, since Jayne is one smart cookie.

But I am one dumbass muffin :)

Jayne (6729 )
Response moderated

bah, sry just finished watching

sry guys

windex (2901 )

Uh, @Jayne? Who told you that the speed of gravity is finite? I think you will find that a force is not an object, and is not limited to c by Einsteinian physics.

dpworkin (26890 )

@pdworkin

Why don’t you stop telling everyone how stupid their answer is and give it a shot yourself?

Ivan (13364 )

@pdworkin; Forces are theorized, and have indeed been convincingly shown for all forces but gravity, to be the result of force carrier particles. The particle responsible for gravity, the graviton, is postulated, but awaits confirmation. Regardless of the physical mechanism by which forces are transmitted, however, it is considered theoretically impossible for any form of information, including the absence or presence of a gravitational field, to be communicated faster than light. Please, this is fairly basic and common knowledge.

Jayne (6729 )

@Ivan found the Higgs Boson?

dpworkin (26890 )

As @Jayne said, the speed of gravity is the speed of light, because if it was instantaneous then it would be possible to measure an object from outside its own light cone. I don’t know who told you it was instantaneous, but space-time can only warp at a certain rate.

The search for gravitational waves, which like light waves, should travel at c = 299,792,458 meters per second in all inertial frames… LIGO

The other problem with the thought experiment of “instantly removing something” is that it’s not likely possible to do that without exceeding the speed of light.

The only way I can think of is if you were to convert a significant % of the mass to photons, which also would be hard to do fast enough to detect the difference.

bpeoples (2516 )

@Jayne, OK, so obviously I’m confused, but help me understand something then. What about particle “twinning” in quantum mechanics? Isn’t that instantaneous, and isn’t that information? Are we certain how a graviton acts on both a macro and a micro level when we don’t seem to have found one yet? I’m not trying to be contentious, I just don’t understand.

dpworkin (26890 )

@pdworkin On gravitation, there’s some specific observations that show that gravity AT LEAST has a finite speed, and that’s likely to be within 1% of c. Read the wikipedia article on Speed of Gravity for more info. We’re not certain of how the graviton works (or even exists), but observations have put bounds on how fast gravity can act.

The particle twinning (“spooky action at a distance”) can’t be used to transmit information, at least as far as we can tell. That’s how an ansible works, at least in the Enderverse.

Anyway: Quantum Entanglement is the article you should read, or at least read the section on applications =)

bpeoples (2516 )

Thanks.

dpworkin (26890 )

or