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How Fast Is Gravity?

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You haven't heard me do so either. Gravitons are not photons, and bear no resemblance to them, except that being massless particles both travel at the same speed.

 

It would, then, be equally accurate to say that light travels at the speed of gravity. (Again, assuming that current hypotheses are correct.)

 

Not if gravity obeys a universe-wide form of interaction. If we're talking particles then I have no problem with that, but what we've seen of gravity, its effects appear to be universal which sets it apart from photons.

 

Then again, the universe does appear to be relatively constant...

 

I'm so mellow, I'm even arguing against myself now :P

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This is absolutely correct.

 

However, I'll still say it's possible that it is some kind of particle / waveform and it could absolutely travel at the speed of light, or observe some other as yet unknown phenomena.

 

I think we'll discover the truth in another 100 years or so :)

 

Bugger that! Lets discover it here! Tonight! :D

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Hang on... "Graviton"? Is that a unit of gravity...?

 

It is the name given to the postulated "unit of gravity," but we can't prove it exists yet.

 

Personally I've always thought that auto98uk's argument (also being put forward by Karis) made more sense, but modern science has very little truck with it. It is assumed that in order to have a gravitational effect on each other, two objects must interact; in order to interact they must exchange some sort of sub-atomic particle or wave form; that particle/waveform is called a graviton.

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Right, Im off for a while, this is turning into an interesting thread with some fascinating stuff on it! I look forward to returning later to see what else I can learn!

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It is the name given to the postulated "unit of gravity," but we can't prove it exists yet.

 

Personally I've always thought that auto98uk's argument (also being put forward by Karis) made more sense, but modern science has very little truck with it. It is assumed that in order to have a gravitational effect on each other, two objects must interact; in order to interact they must exchange some sort of sub-atomic particle or wave form; that particle/waveform is called a graviton.

 

Ok got that! Very interesting stuff!

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Personally I've always thought that auto98uk's argument (also being put forward by Karis) made more sense, but modern science has very little truck with it. It is assumed that in order to have a gravitational effect on each other, two objects must interact; in order to interact they must exchange some sort of sub-atomic particle or wave form; that particle/waveform is called a graviton.

 

Yeah. I'll go with that.

 

Even though I don't want to... :)

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I also agree with that. There's still so much we don't know and so many really fundamental questions left unanswered...

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I think part of the problem is that people think that space/time is in some way related to just space, so think the limitation of light speed applies.

 

If you're going to argue it doesn't, what alternative explanation do you have for the results of the Michelson/Morley experiment?

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The extension produded in a spring is directional proportional to the load applied. Provided the elastic limit is not exceeded.

 

Oh, hang on a minute, long time since I got my O'Level physics :hihi:

 

It's 9.81 m/s2 = 32.2 ft/s2 on earth.

Hope no one else has posted this. I didn't read the whole thread :(

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It's 9.81 m/s2 = 32.2 ft/s2 on earth.

Hope no one else has posted this. I didn't read the whole thread :(

 

I don't think they have. However, when Jabberwocky refers to the "speed of gravity" he doesn't mean the acceleration that it will cause in an object; he wants to know how long it takes for the existence of planet A to affect the motion of planet B, assuming that planet A just suddenly appeared out of nowhere.

 

 

If you remember that the formula for spring extension is called "Hooke's Law," named after Robert Hooke, you might interested to know that Robert Hooke tried to steal credit for the laws of gravity discovered by Isaac Newton. He was a notorious credit-grabber in his day.

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Or if the gravity from an object say a million light years away is the gravity from today or a million years ago?

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Imagine a trillion mile long pole. If I pull on one end, the other end moves instantantly.

 

Now, imagine that stick was a sheet, and that sheet was space/time (we will keep it simple, the newest theories are a lot more complicated that just space/time lol.

 

So if gtravity was suddenly applied somewhere, it would be felt immediately elsewhere.

 

I have a problem with this analogy in that the elasticity of the pole determines when the removal of force at one end is felt at the other. A pole of iron would still need a period of time for its effect to be felt, albeit a smaller period of time than for one made of, for instance, wood.

 

Similarly, if we look at the effects on earth of the removal of a large gravitational object, i.e. one which has a discernible effect on earth, the elapsed time between its removal and our measuring the effect of its removal would have several determinates such as the force of the gravity exerted (a constituent of the relative masses of the object and earth), the distance between the object and earth, the make up of the constituent matter between the object and earth, etc.

 

In a nutshell, I don't know.

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