Is the speed of gravity equal to the speed of light?

Question

or Why are they taken as equal in general relativity?

Answer 1

your question has some deep implications.

"walking man" provided the best answer so far in thoroughness and open-ness.

currently there is NO experimental proof for your profound question so any answer is never too crazy ( as some have pointed out ).

quantum theory states that gravity is propagated by "gravitons" which are assumed to travel at the speed of light. these gravitons have never been observed as of yet.

general relativity states that gravity is the perceived geometric distortion of space and time ( which technically has no speed ).

there are many inconsistencies between relativity and quantum theory and i am sure they invovlve part of your question.

part of the problem lies in the fact that light itself travels "within" space and time ( which is gravity in a way ) so therefore how could the actual fabric of space and time have a speed of its own ?

i personally do NOT believe that gravity has a speed of propagation.

i think the answer lies much deeper in our perceptions of nature and is sign of our present limits of modern physics.

good luck !

Answer 2

That is a good and insightful question. Jerry P, I think that you know what she meant, your answer is very condescending, and actually incorrect. Gravity is a force, and IS acceleration. It is not a Mass * Acceleration. The acceleration that you feel when you are pressed back into your seat when your car takes off from a stoplight--that is the SAME as gravity. Gravity IS acceleration.

When someone askes what the speed of gravity is, they are very obviously asking what the speed of transmission of gravitational force is. If they wanted to know the surface gravity of the Earth, (9.8 m/s^2) they would have asked, how much acceleration do we feel at the surface of the Earth?

According to theory and from observational evidence, Gravity is transmitted at the speed of light. That means the tides lag slightly, (which I think has been measured) and that if for some reason the sun were to suddenly disappear, there would be an 8 second delay before the light stopped here on earth, and an eight second delay before the earth went careening off into space.

Just a note: For those of you that think you are so smart and can condescend to others, please stop. That is not what this forum is for. This is a place where people come to be curious, and others can share their knowledge and experience. If you want to pick on people go somewhere else. If you want to participate, you'd better realize that people asking questions is how they get smarter, and that the only dumb question is the one you didn't ask.

Answer 3

Isaac Newton thought that gravity was instantaneous. Many modern texts assume it is equal to the speed of light, and some claim that it is faster!

If you read the first link below, you will see that one reason gravity is assumed to be as fast or faster than light is that gravity has no aberation.

No one has ever proven (see second link) the speed of gravity, but if Einstein is correct in that gravity is the result of matter bending space, then the only way to determine if gravity's speed is less than instantaneous would be to determine if the gravitational field in front of a very large, very fast moving mass is stronger than the field behind it. This is difficult to do, since the Sun is apparently not a large enough and fast enough mass to have a noticably different gravitational field in front of, and behind its direction of travel.

Answer 4

Norrie is wrong. The 9.whatever metres per second squared is acceleration of objects falling in Earth's atmosphere due to Earth's gravity. The question is how quickly does gravity itself travel. I read it was exactly the same as the speed of light. I read another webpage reckoning it was instantaneous but that couldn't be true because it would break relativity.

Answer 5

for sure, the speed of gravity is equal to the speed of gravity .....

i am not 100% convinced that the speed of gravity is equal to the speed of light, you have provided no proof, , so forget it baby doll!

Answer 6

properly to start with (to my information) no one has ever chanced on a graviton yet photons have been chanced on. You shelter that the fee of gravity is a similar because of the fact the fee of sunshine - that's in user-friendly terms hypothetical. the suitable efforts by skill of experimentalists to discover gravity waves ought to date proved unsuccessful, how then are you able to communicate concerning to the fee of gravity as though it have been a widely used volume. that's a hypothetical velocity that's concept to be a similar because of the fact the fee of sunshine yet because of the fact that gravity waves (and gravitons) won't be in a position of be experimentally confirmed we will not communicate concerning to the fee of gravity until we are in a position to experimentally ensure what the fee of gravity easily is.

Answer 7

because the speed between light and gravity is very relative.

Answer 8

No!

Gravity is a *force* and is equal to mass * acceleration.
Acceleration is the first derivative of velocity in time; acceleration is *not* "speed".

The force due to gravity is strictly a function of the masses involved in the system, and of the distances separating them.

Now...
If you are asking about the phenomenon of "gravitational waves", as observed and calculated for neutron stars in theoretical astronomy, those waves *do* propagate at the speed of light.
http://en.wikipedia.org/wiki/Gravitational_wave


.

Answer 9

It's generally believed that gravitational waves travel at the same speed as light, yes.

Answer 10

OK, here comes a mouthfull taken from the website below. It concerns study on the speed of gravity. . .

Standard experimental techniques exist to determine the propagation speed of forces. When we apply these techniques to gravity, they all yield propagation speeds too great to measure, substantially faster than lightspeed. This is because gravity, in contrast to light, has no detectable aberration or propagation delay for its action, even for cases (such as binary pulsars) where sources of gravity accelerate significantly during the light time from source to target. By contrast, the finite propagation speed of light causes radiation pressure forces to have a non-radial component causing orbits to decay (the “Poynting-Robertson effect”); but gravity has no counterpart force proportional to to first order. General relativity (GR) explains these features by suggesting that gravitation (unlike electromagnetic forces) is a pure geometric effect of curved space-time, not a force of nature that propagates. Gravitational radiation, which surely does propagate at lightspeed but is a fifth order effect in , is too small to play a role in explaining this difference in behavior between gravity and ordinary forces of nature. Problems with the causality principle also exist for GR in this connection, such as explaining how the external fields between binary black holes manage to continually update without benefit of communication with the masses hidden behind event horizons. These causality problems would be solved without any change to the mathematical formalism of GR, but only to its interpretation, if gravity is once again taken to be a propagating force of nature in flat space-time with the propagation speed indicated by observational evidence and experiments: not less than 2x1010 c. Such a change of perspective requires no change in the assumed character of gravitational radiation or its lightspeed propagation. Although faster-than-light force propagation speeds do violate Einstein special relativity (SR), they are in accord with Lorentzian relativity, which has never been experimentally distinguished from SR—at least, not in favor of SR. Indeed, far from upsetting much of current physics, the main changes induced by this new perspective are beneficial to areas where physics has been struggling, such as explaining experimental evidence for non-locality in quantum physics, the dark matter issue in cosmology, and the possible unification of forces. Recognition of a faster-than-lightspeed propagation of gravity, as indicated by all existing experimental evidence, may be the key to taking conventional physics to the next plateau.

You may want to check the site for more information. . .


http://www.metaresearch.org/cosmology/speed_of_gravity.asp