I was wondering if space-time "snaps back" into place after a body with mass moves over it. Or is it permanently "warped"?

Thanks

I your wondering why I ask, it because I have been reading up on the Great Attractor...

:)

if it did not snap back, then anyplace in the universe that had mass would still have gravity. that is not what we see.

this is a stupid question; but what the hell! :D

How long does it take for space time to return to "normal"? ie: would a body with mass leave a trail?

No, that's a good question, UnderWhelmed. Since you are speaking of spacetime and gravitational effects, your question falls under the domain of General Relativity. In relativity theory, gravity is postulated to travel at the speed of light. So, spacetime would return to pre-event conditions at the speed of light. Under Newtonian Mechanics, gravity is an instantaneous force so the vacuum would return to normal instantly after the passage of the gravitating object. Do remember that gravity follows the inverse square law, so its effects are far-reaching, so we are speaking of the rate of change of its EFFECTS on spacetime or the interstellar medium.

Your question caused me to think of something else for which I am not sure of the answer. This question is directed to physicists with a much better understanding of GENERAL RELATIVITY than I. In Special Theory, light travels at 'c' in all reference frames regardless of the motion of the observer or frame observed. Does gravity, or its effects on spacetime, do the same under General Relativity? As an example, think of the ejecta spewed outward at significant percentages of 'c' when a black hole 'eats' a neutron star, an event which astronomers believe they reciently observed with the SWIFT experiment. Does the gravitational effects of this ejected matter propogate forward and backwards at 'c' relative to an observer at rest in their reference frame, or is that reserved only for electromagnetic radiation?

how can gravity and light always be propagating at the same speed if gravity can escape black holes and light can't? How can their speeds be the same if gravity "leaves light behind" ?

Hi Underwhelmed,
I notice you're assuming that space-time is fixed, ie it has a definite state of rest and that objects move in relation to it.

I'm not sure that's a good assumption to make...

A distant observer at rest in his own frame of reference would have to make the observation of a passing object's effects on spacetime, wouldn't he?

According to General Relativity, the changes in the distortion of spacetime due to a gravitating body which is moving, happen as the information of the movement travels at c from the moving gravitating body to any particular point in spacetime.

In other words, according to GR, gravity, not only gravitational quadrupole radiation, travels at c.

And, to directly answer the thread question, according to GR, spacetime recuperates ( snaps back ) once the distorting influence moves on.

I admit I didn't explain what I was asking very well. Let me try a slightly different approach.

A photon is a wave-like particle with no rest mass and no charge. Certain photons are the 'exchange particles', information carrying particles in electromagnetic theory.

A graviton is a wave-like particle with no rest mass and no charge. Gravitons are the 'exchange particles' in gravitational theory.

Both the photon and the graviton are theorized to move at 'c'. We can use an example of a binary pulsar if you like. As well known, the photon is said to move at 'c' regardless of the speed of the observer or the source of the photon, exibiting a Doppler shift of its wavelength wrt the direction of motion. A photon will also gain energy from a blue shift from an approaching object. One does not add the velocity of the approaching object to the speed of the photon, 'c'. What happens with the graviton? The photon emitted from the binary pulsar arrives at the same time at the observer's frame regardless if one member of the pulsar is advancing or retreating wrt the observer. Is the graviton, or a gravity wave, also Doppler shifted? If not, how can it exactly equal the photon's speed relative to the distant observer? If the graviton is Doppler shifted, does that mean graviton gains energy from a blue shift like the photon? I haven't been able to find a definative answer.

What happens with the graviton? The photon emitted from the binary pulsar arrives at the same time at the observer's frame regardless if one member of the pulsar is advancing or retreating wrt the observer. Is the graviton, or a gravity wave, also Doppler shifted? If not, how can it exactly equal the photon's speed relative to the distant observer? If the graviton is Doppler shifted, does that mean graviton gains energy from a blue shift like the photon? I haven't been able to find a definative answer.That is a very interesting question. Especially since, for photons, the redshift happens both from Doppler effects and gravitational effects. My guess is that even if they are Doppler shifted they will not be gravitationally shifted. But then do they really travel through GR's bent space? Would a graviton be deflected through gravitational lensing effects etc.? That could have strange implications either way.

-Dale

Is gravitational field generated by the mass or relative mass of a moving object?
How about a "massive" photon of high frequency? Does it create a "Sonic boom" like effect in the gravitational sense?

Hi Underwhelmed,
I notice you're assuming that space-time is fixed, ie it has a definite state of rest and that objects move in relation to it.

I'm not sure that's a good assumption to make...

Is there another way to look at it?

I see another puzzling aspect to these matters. When Maxwell organized his famous " Maxwell's Equations ", he also devised and solved a wave equation which defined c. c is, according to Maxwell, caused, or, regulated, exactly by the electric and magnetic properties of vacuum.

The puzzle is this: why would the ( maximum ) velocity of mass, and the ordinary velocity of a graviton be regulated by these same electric and magnetic qualities of vacuum as are electromagnetic radiations?

I just know the question. I don't know the answer.

Hopefully I am not diverting attention away from the excellent question provided by 2inq'..

Is there another way to look at it?
Absolutely (pardon the pun!)