Gravity: How Fast Does it Travel?

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In summary: I believe is that the fields do propagate at the speed of light, but that the waves themselves are not the fields, but the disturbances in the fields. Still, I think I could be wrong. In summary, the gravitational force, as well as the electromagnetic force, both travel at the speed of light. It is not certain if the same applies to the other two forces of nature. The concept of gravitational influence exceeding or going below the speed of light is still a subject of investigation. There is a possibility that the fields of nuclear interactions propagate at a lower speed than light, but this is still a matter of debate.
  • #36
Could we expect to pick up a "ping" and possibly "ringing" in the Earths crust from gravity wave coupling all the way from the moon?
Not a chance. Gravity waves, even of some decent astrophysical events (not a feeble H-Bomb) are very very very weak. You need a very high quality resonator with the correct resonance frequency to see, well, still nothing, but no by these orders of magnitude.
 
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  • #37
Ich said:
Not a chance. Gravity waves, even of some decent astrophysical events (not a feeble H-Bomb) are very very very weak.


Good point.

However if two neutron stars in mutual orbit, merge on the far edge of the Milky Way, their gravity 'disturbance' would diminish by inverse square law over about a 100K light years.

Would the effect as received on Earth from the merger be more or less than that of an H-Bomb on the moon, which is tightly coupled to the Earth (relatively)?

Its all relative and I know its all in the numbers.

Thanks for your feedback.
 
  • #38
I know its old, but then so is time... :-)

If Gravity, the affacts of a body in space time, are infinite (exerted on all points in the universe at the same time to a greater or lesser extent dendent upon distance from the body) , then the speed at which the affcets can be experinced cannot be limited to C! So hypertheticaly, we remove the moon instanateoulsy, will the tides stop instantly or after a minute or so in reation to C?

Cheers

JB
 
  • #39
B1ffB0ff said:
I know its old, but then so is time... :-)

If gravity's effect on a body in space time are infinite (exerted on all points in the universe at the same time to a greater or lesser extent dependent upon distance from the body)
Your supposition is false. While it does have an infinite extent, changes to the gravitational field are limited to propagating at c.

B1ffB0ff said:
, then the speed at which the effects can be experienced cannot be limited to c! So hypothetically, we remove the moon instantaneously, will the tides stop instantly or after a minute or so in relation to c?

Cheers

JB
You cannot remove a mass instantaneously. It doesn't work that way. The mass would be limited to movement below the speed of light.

However, even if it were not so, the change in gravitational force felt by the disappearance of the Moon would take time to propagate. It takes about 1.2 seconds.

Same with the sun. If the sun suddenly fell through a wormhole and disappeared, we would neither see it nor feel for 8 minutes.
 
  • #40
So, that being the case we should be able to prove this then...

A variation of the other much older experiment with two large mass objects suspended next to each other and the attraction force between them. However.

Main difference we have a massive object suspended (100m) above a smaller weight placed on a very sensitive set of scales, capable of sampling in microseconds.

Allow the high mass object to fall on the much less mass object and the scales.

Film it with a high frame rate camera and time with v accurate clock.

Will need to be located in geologically stable area, maybe in a near vacuum to eliminate affects of air movement.

We should see the measurement of the weight of the small mass object reduce slightly as the high mass object gets closer, further this effect should be measurable against C in proportion to distance, relative to the observer.

Thoughts?

JB
 
  • #41
B1ffB0ff said:
So, that being the case we should be able to prove this then...
A much easier experiment would be to observe a large, distant mass such as Jupiter with both a telescope and something to measure gravity (gravitational interferometer?). If gravity is instantaneous the latter instrument should tell us it is further along its orbit than the former.
 
  • #42
B1ffB0ff said:
A variation of the other much older experiment with two large mass objects suspended next to each other and the attraction force between them. However.

Main difference we have a massive object suspended (100m) above a smaller weight placed on a very sensitive set of scales, capable of sampling in microseconds.

Allow the high mass object to fall on the much less mass object and the scales.

Film it with a high frame rate camera and time with v accurate clock.

Will need to be located in geologically stable area, maybe in a near vacuum to eliminate affects of air movement.

We should see the measurement of the weight of the small mass object reduce slightly as the high mass object gets closer, further this effect should be measurable against C in proportion to distance, relative to the observer.

Ryan_m_b said:
A much easier experiment would be to observe a large, distant mass such as Jupiter with both a telescope and something to measure gravity (gravitational interferometer?). If gravity is instantaneous the latter instrument should tell us it is further along its orbit than the former.

Possibly relevant is George Jones's post #12 of https://www.physicsforums.com/showthread.php?t=562042. He links to Carlip's paper: "By analyzing the motion of the Moon, Laplace concluded in 1805 that the speed of (Newtonian) gravity must be at least 7×106c." Carlip goes on to show why this is consistent with GR, in which gravitational waves travel at c. Evidence for GR's gravitational waves was obtained by Taylor and Hulse.
 
Last edited:
<h2>1. How is gravity related to the speed of light?</h2><p>Gravity is not directly related to the speed of light. The speed of light is a fundamental constant in the universe, while gravity is a force that is affected by the mass and distance between objects.</p><h2>2. Does gravity travel at the speed of light?</h2><p>No, gravity does not travel at the speed of light. According to Einstein's theory of general relativity, the speed of gravity is equal to the speed of light, but this has not been proven and is still a topic of debate among scientists.</p><h2>3. How fast does gravity travel on Earth?</h2><p>On Earth, gravity travels at approximately 9.8 meters per second squared. This is the acceleration due to gravity, which is the rate at which objects fall towards the Earth's surface.</p><h2>4. Can gravity travel faster than the speed of light?</h2><p>According to current scientific understanding, no, gravity cannot travel faster than the speed of light. The speed of light is considered to be the maximum speed at which any form of energy or information can travel in the universe.</p><h2>5. How does the speed of gravity affect the motion of objects?</h2><p>The speed of gravity affects the motion of objects by exerting a force on them, causing them to accelerate towards each other. This is what keeps planets in orbit around the sun and objects on Earth from flying off into space.</p>

1. How is gravity related to the speed of light?

Gravity is not directly related to the speed of light. The speed of light is a fundamental constant in the universe, while gravity is a force that is affected by the mass and distance between objects.

2. Does gravity travel at the speed of light?

No, gravity does not travel at the speed of light. According to Einstein's theory of general relativity, the speed of gravity is equal to the speed of light, but this has not been proven and is still a topic of debate among scientists.

3. How fast does gravity travel on Earth?

On Earth, gravity travels at approximately 9.8 meters per second squared. This is the acceleration due to gravity, which is the rate at which objects fall towards the Earth's surface.

4. Can gravity travel faster than the speed of light?

According to current scientific understanding, no, gravity cannot travel faster than the speed of light. The speed of light is considered to be the maximum speed at which any form of energy or information can travel in the universe.

5. How does the speed of gravity affect the motion of objects?

The speed of gravity affects the motion of objects by exerting a force on them, causing them to accelerate towards each other. This is what keeps planets in orbit around the sun and objects on Earth from flying off into space.

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