Does gravity travel the speed of light?

Question

Einstein's a great prominment man. He speculated that taking out the sun, would take roughly 8min to the light to get to us, and also 8min when the gravity is extracted from the sun.
Then Earth would be the 3rd planet to drift away, 4mins later Mars, 7min astro belt, 12 Jupitor, ect..

So does gravity travel the speed of light? 300,000 km/sec???

Answer 1

Gravity is force at a distance to technically it does.

Answer 2

Gravity travels at the speed of light. It the Sun were magically annihilated, and went from 1 solar mass to 0 solar masses instantaneously, the Earth would continue to orbit as it normally would for roughly 8 minutes, before "flying off on a tangent" into interstellar space. For an observer on the Earth, the Sun would disappear at the same time that they started "flying off." But this is only because of light speed and gravity being equal in velocity.

Answer 3

If the Sun disappeared we wouldn't know it for 8 minutes and 19 seconds, the time it takes light - and gravity - to travel that distance. There is no reason to think that gravity travels at anything but the speed of light, and certainly not instantaneously.

Astronomers are hoping to be able to detect gravity waves some day, a difficult project since it is by far the weakest of the four forces of nature.

Answer 4

As far as I know, we are currently unaware of the medium that transmits gravitational forces (gravitons?), and are thus unable to completely answer this question.

As I understand gravity, moving the sun would immediately effect the orbits of the planets, but we might not notice the change for a while due to information passing at the speed of light. To us, it might seem like the planets were moving one-by-one, but it would simply be our perception.

From what I know of physics (not terribly much), the best physical model for gravitation would be to look at space as a large, spongy surface. If you put a bowling ball on this surface, smaller objects on that surface will roll in towards it. Lifting the bowling ball levels out the surface, thus removing the forces that cause the other objects to move.

Answer 5

Gravity is a force that is created due to the mass of a planet. I.e. more massive objects have a larger gravitational force than smaller planets. Comparing a force (or acceleration) to a speed (or velocity) is nonsensical.

Answer 6

That's a good question, the answer to which might be tricky, requiring us to understand what gravity is fundamentally.

Gravity is the natural tendency of all objects to seek a symmetrical space-time environment. Most people think of gravity as an attractive "force," but I would characterize it as a "state" of instability or unrest in the strange world of curved space-time.

Space and time are two manifestations of the physical environment necessary for the existence of real things. Space-time is the "container" of real things (matter and energy). In order for anything to exist it must occupy both space and time. That is, it must necessarily exist "somewhere" in the universe and for "some period of time." Without space-time, without a "container," there can be no mass. Hence, mass must create or generates its own environment necessary for its very existence. Take away all the mass (matter and energy) in the universe and empty space (and time) would disappear (collapse) as well, leaving nothing - non-reality. We cannot separate mass from space-time. They are fundamentally inseparable, having a non-exclusive relationship. There can't be one without the other. Space-time is to mass as a shadow is to light.

Suppose there were just one object in the universe, a single, super-giant star for example. The space-time created by that mass would extend outward in a non-linear fashion. That is, its effect, its "strength," its "dimension" would diminish with distance-time. Space shrinks and time passes more quickly as one travels farther away from the mass. Hence we use the terms, "curved" and "non-linear" when describing space-time. (note that if a traveler could venture far enough away from this hypothetical single mass, eventually time would progress at such an ever increasing rate that the traveler could never reach the outer bounds of this space-time environment within the realm of eternity. Hence, to the traveler, the universe would seem infinite.)

Now place another, much smaller mass, a tiny planet, nearby. The smaller mass will create its own local, weaker, curved space-time environment, but still be within and under the influence of the larger space-time created by the larger mass. And because the smaller mass is not at the center of the larger mass, its overall space-time environment is not perfectly symmetrical.

An observer standing on the tiny planet, looking back toward the star would observe time progressing at a slow pace. When the observer turns around and looks in the opposite direction, out into empty space, the observer would notice time passing at a faster pace. Only at the center of the large mass would an observer see time passing at the same rate in every direction Only at the center of the large mass would an observer find spherical symmetry (and since we've added a smaller mass, even that's not entirely true).

Blow a soap bubble into the air and it will take on a spherical shape because its surface tension seeks uniform equilibrium and, in the process, creates the smallest possible surface for its volume. Its volume (size) quickly expands or shrinks until air pressure, inside and out, equalizes. In a similar (but not the same) sense, a mass seeks equilibrium with regard to curved space-time. If space-time is dilated more so in one direction than another, the mass will move toward an area of space-time symmetry in order to achieve relativistic equilibrium. We call this phenomenon "gravity" and experience it as an attractive "force." We say that the larger mass is "pulling" the smaller mass, but it is space-time symmetry that masses seek.

Now let's instantly remove the large mass from our hypothetical single-star/planet universe. You would like to know if its gravitational "pull" also vanishes instantly everywhere, throughout the universe, or does it propagate outward at the speed of light.

In reality, it is not, in a sense, the tail-end of a "force" that is propagating outward. Stated more correctly, it is space-time that is collapsing inward, it's symmetry "signature" repositioning to reflect the collapse. Does this happen at the speed of light, or is it instantaneous? It is difficult to say whether anything is instantaneous, but since that which is collapsing is space-time (including the speed at which time itself passes), it's difficult to define exactly what type of phenomenon would actually take place.

Answer 7

I don't see how it could.... Gravity is a force....so it doesn't have a velocity..... as soon as the sun disappeared so would the gravitational force it creates....so gravity would end instantly....it might just take time for the lack of gravity to become apparent.... but then agian... i'm not that smart...or knowlageable....so I'm prolly wrong....... this is just my thoughts

Answer 8

It probably does. It hasn't been proved but we have a little evidence. Several experiments are underway to try to detect a gravitational wave. If it is confirmed, that will help answer the question.