# Thread: Light Vs Gravity

1. Lets say you can turn the sun's light and gravity on or off. If you turned off the light and the gravity at the same time, is there any way to prove the light would stop reaching the planet before the gravitational pull of the sun disappeared?

2.

3. No, because it wouldn't.

4. Originally Posted by Ophiolite
No, because it wouldn't.
So you are saying the effects of the removal of the suns gravity pull would reach the earth before the light?

This would mean that gravity is faster than light!

5. Originally Posted by SuperNatendo
Originally Posted by Ophiolite
No, because it wouldn't.
So you are saying the effects of the removal of the suns gravity pull would reach the earth before the light?

This would mean that gravity is faster than light!
Or that they're the same speed

6. If the sun vanished, we would see it blink out and be released from its gravity well at the same time.

7. If that is the case, then why has light been chosen as the universal constant? Light is supposed to be the fastest moving particles in the universe, if gravity effects happen at the same time the light goes out then we could replace light with gravity as the constant. Wouldn't this have the potential to change alot of things we understand about the universe?

8. Originally Posted by SuperNatendo
If that is the case, then why has light been chosen as the universal constant? Light is supposed to be the fastest moving particles in the universe, if gravity effects happen at the same time the light goes out then we could replace light with gravity as the constant. Wouldn't this have the potential to change alot of things we understand about the universe?
We mainly went with light because it's very easy to measure the speed of light - just send a pulse of light from one place to another and time how long it takes to get there. It's easy for us to create and detect light, not so much with gravity.

And no, it wouldn't have the potential to chang a lot of things we understand about the universe because our understanding of the universe is already built on the assumption that gravity travels at the speed of light...so all the math would work out the same.

9. But what if gravity is FASTER? As you said it is pretty much impossible in our current state of technology to measure the speed of gravity, so might it be possible the speed could be faster?

10. No its not faster, this is why Einstein came up with General Relativity, to explain Newtons graviational prediction of the sun disappearing using relativity. Gravity does not go faster than light. Nothing does.

11. Originally Posted by svwillmer
No its not faster, this is why Einstein came up with General Relativity, to explain Newtons graviational prediction of the sun disappearing using relativity. Gravity does not go faster than light. Nothing does.
How do you know for sure gravity is not faster than light? Has someone been able to measure gravity enough to know how 'gravitrons' work or how quickly a change in gravity effects an object as far as the earth from the sun? We know light from the sun takes about 4 minutes to reach earth, but how quickly would the instant absence of the sun cause a change in gravity?

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

"anyone with a computer and orbit computation or numerical integration software can verify the consequences of introducing a delay into gravitational interactions. The effect on computed orbits is usually disastrous because conservation of angular momentum is destroyed"

So how does gravity generated by an object, lets say a star, have to instantaneously effect a planet in its orbit while still travelling slower than light?

13. It can't. Gravity cannot go faster than light. Perhaps 'gravitons' if they exist can be manipulated using the Quantum entanglement theory to act faster than light, but that it science of perhaps 2 centuries if not more ahead. Einstein went through all of this when creating GR, and that took him years given his intellect. Sorry.

14. Originally Posted by svwillmer
It can't. Gravity cannot go faster than light.
Why not?

It seems to me gravity has the same effect on planets around stars going at different speeds than each other.

What if Gravity is also constant and it just so happens to travel faster than light?

How is this impossible? please tell me.

15. It's not impossible just that naturally it cannot go faster than light. Who knows why. Who knows if it can't?

16. Somebody has to know why.

This has been bothering me for some years now and I wish there were more experiments being carried out to this end.

I do think light was chosen as the constant because it was easier to produce and measure than gravity.

I think since it is harder to "detect" gravity that it is impossible to determine if the change in gravity happened before we saw the event that caused the change to occur in the first place.

We may never know until some new method of measuring gravity is thought up.

17. elementary forces are transmitted by elementary particles / bosons, none of which can travel faster than light

in short, any force only can make itself be felt at the speed of the particles that transmit it

18. there is a theory that all particles share their motion through the differant dimentions. That is why time slows down as we speed up. As we move faster through the physical dimentions, that speed is taken from other dimentions, such as time. If I remember right, in a vacume, light does not touch the "time" dimention. (at light speed, time stops) relativly, of course. forces such aselectromagnetic and strong, and weak nuclear occure because of extremely small particles. The strong force, for example is controled by gluons. Gravitons are the only of the four connecting particles that have not been found yet, but... They should exist. This means, that they would have to travel through the differant dimentions to reach the object that they are effecting. Nothing can travel faster than light through the dimentions.
I'm speaking of multiple dimentions. This would work if there were only four dimentions. I'm not advocating string theory, so don't complain about multiple dimentions. If anyone who knows more sees any problems with my post, please tell me. I'd like to learn more about this subject to.

19. The result of such an event is actually quite simple. Since planets in orbit around the sun are actually in continuous 'freefall' around the sun, should the sun suddenly disappear all objects in its orbit would contiue on their paths out into open space, tangeant to their previous orbits.

In other words, the stability of the solar system would certainly collaps. However, realise that gravity is not measured in terms of speed. It is measured as the inverse square of an object's mass while in motion. In other words, its not based on accelateration, it is based on attraction.

The speed of light IS based on acceleration. Thus the speed of light is dependant on ESCAPING gravity. If the sun disappears, there is neither light, nor gravity. Realise that the planets are already in motion and that there is no need for them to acceletate away from anything. They drift off into spact at the same speed they were orbiting the sun.

Now, this is what would occur if there were no gas giants. In our ssystem, what would likely happen that the planets rendez-vous with Jupiter, as Jupiter would become the systems central massive body.

In other words, planetary orbits would decay INSTANTLY, However, this is not 'faster' that the speed of light, since the planets are already moving. The gravity is already THERE. It doesnt need to 'travel' anywhere. Since multiple things happen at the SAME INSTANT (orbital decays), there is no 'speed' involved. Remember, speed is a squared value. Gravity is inverse squared. The only spacial property here is a difference in space.

Light from the sun...rather no light from no sun is depentant on acceleration, and IS compared to gravity. Acceleration is the second a gravitational derivative.

This is explaned by the general theroey of relativity.

Eventually, the absense of light would catch up and pass the drifting planets while they search for a new home; likely the surface of Jupiter, or where ever the centre of mass of the solar system would be, which of course depends on the planetary configuartion at the time.

Hope this helps

***SuperNatendo, You can try doing this in Newtons Aquarium, a free download from filedudes.com.

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