# What is the “speed” of gravity?

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flyskyposted 9 years ago

What is the “speed” of gravity?

Hypothetically, if one remove the Sun from its place, when the Earth would be affected? Momentary, by the speed of light or by some speed specific to the gravity...?

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one2get2noposted 9 years ago

I'm no physicist but O would imagine that the earth would be affected within 8 seconds. We would all be dead.

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point2makeposted 9 years ago

Actually the speed of light would be involved here. At 186,000 miles per second it would take approx. 8 1/2 minutes, not seconds, for you to notice the Sun was gone. Gravity does not have a specific speed per se. It is one of the fundamental forces of the Universe and while the "force" of gravity can be measured...the source of that "force" is an ongoing challenge for science.

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one2get2noposted 9 years agoin reply to this

Yes sorry I did mean 8 Minutes and not seconds. A senior moment I'm afraid.

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billgaedeposted 9 years ago
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billgaedeposted 9 years agoin reply to this

Gravity is not a force. Gravity is a tension, and tension is NOT a force. Stretch a rubber band and hold. Feel the tension. There is no motion. If someone cuts the rubber band, the tension HAD BETTER disappear INSTANTANEOUSLY! It won't take 8 mins!

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Gravity doesn't exist it's just logic, logically things have to fall down otherwise what would happen?lol.

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tsmogposted 9 years ago

I am no physicists or mathematician, however is not the sun already being removed from 'its place' and it is a constant. The sun does rotate and travels within its galaxy . . . the earth's galaxy too. If the sun simply ceased to exist for the thought exercise then we must first define existence.

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billgaedeposted 9 years agoin reply to this
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tsmogposted 9 years agoin reply to this

So, then there is not matter unless existence. In the case the sun becomes non-existent then the  laws of physics would not apply as there would not be anything to act upon, unless something remained?

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samanthajohnesposted 9 years ago

Speed of gravity equals the speed of light.  Earth would flight in straigh path as soon as you see the sun disappear, but not sooner.

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point2makeposted 9 years agoin reply to this

Actually the speed of gravity is unknown. We are working hard to assign a value to "gravity" but it has proven elusive to all attempts. We just don't know enough, with our current physics, to solve the "mystery" of gravity.....yet!

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arksysposted 9 years ago

from what i understand, if you move the sun the earth will also move at the same time, because there is a gravitational force between the planets.

the word you are looking for is "Universal Gravitation" or "Gravitational Constant".

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flyskyposted 9 years agoin reply to this

I am not sure that the Earth will also move at the same time, as you say. It is reasonable to expect that it would be almost at the same time, but I am not sure if we can say so precisely. I think that this is an open problem in physics...

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arksysposted 9 years agoin reply to this

flysky : it is an assumption of course... but the reason i said it would move right away is because the size of the sun in proportion to the earth... I was thinking of the concept of magnetism while stating my assumption. A little delay : yes.

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billgaedeposted 9 years agoin reply to this

We make an assumption: all atoms are interconnected. There is permanent tension b/w the Sun and the Earth and b/w the Earth and you. We call this tension ‘gravity’. We make the Sun disappear. The Earth HAD BETTER fly away INSTANTANEOUSLY!

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arksysposted 9 years agoin reply to this

Agreed.

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John Parksposted 9 years ago

There is no proper theory of the speed of gravity, relativity tells us that gravity curves space and time in the presence of mass.  It does not tell us the speed.  If you look at a star, you see it as it was however long ago in time it took the light to travel to your eye.  I believe gravity propagates at infinite speed.  If the suns' gravity took time to travel, then it would influence our orbit at a point, distant from its actual position in space, and would tend to accelerate the earth's orbital speed.  Since we do not see acceleration happening, then it stands to reason that gravities' speed is much faster than light, even though Einstein said light was the upper speed limit.

Look at the interaction of the Sun-Earth-Moon.  The moon's orbit around the earth is an ellipse which is distorted by the Sun's gravitation. Observations by astronomers have shown that the Sun's force comes from its' true position rather than it's visual position, to a precision of one arc second.  This observation alone, indicates that the speed of the Sun's gravitational force must be many times the speed of light.

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