# Speed of gravity vs speed of light?

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I'm a little confused (again). Aren't quantumn theory and GR incompatible?

I get the impression on one hand you're siding with GR and on the other' date=' against it...[/quote']

1) Yes they are but if you believe string theory, it could be the answer to this problem.

mrblond5311: Gravity can be considered a boson, a force transmitter. It has no mass but it does have evergy. You could say the number of these gravitons per area dectates the strength of the gravitational pull between two objects.

The relation between photons and gravitons are thay they are both bosons, have no mass and travel at the speed of light.

So, in your example youwould have the sun as an object in space time emmitting these gravitons to the planets thus causing the gravitation attraction we see.

Gravitons move at the speed of light because they have no "rest mass" and it does not matter as to something weakness or strongness, all it matters is the rest mass is zero so the gravitons travels at light speed.

As for the last question I do not have the answer sorry

Cheers,

Ryan Jones

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If gravitons exist and they radiate out from a gravitating object, and although they have no mass, they do have energy. Where does this energy come from?

If it comes from a gravitation potential, does the gravitating object loose some of this gravitational potential over time, or does it come from some other source of energy, or could it come from the mass of the gravitational object (which means it would also reduce the gravitational pull of the object)?

So if gravitons radiate from an object, it should mean that the object (over a period of time) would loose either energy, or mass. Or am I missing something?

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I'm not an expert on this matter but how can gravity have a set "force" or "energy" when it's power is determined by the mass of the object creating it? If it had a set force how would satelittes orbit it & wouldn't outer planets sizes be proportionate to the set force of the suns gravity i.e. the planets would have to lose mass as you move farther from the sun? Like how earth orbits the sun & the planets & sun don't orbit each other. And to go back to the beginning of the thread - gravity is a weak force so how can it have the same speed of light? Wouldn't it have the same strength to move at the same speed? And wouldn't gravity be considered a negative force:confused: ? I'm failing to see any similarites between photons & gravitrons. I might be way off on this so fill me in, please. Thanks! One more thing....does anyone have any similarites between magnetism & gravity? Fill me in!

Uh, try looking gravity up somewhere. You have some major misconceptions about how gravity works and it would take a lot of time and effort to set you straight.

Why would gravity be considered negative?

Why would the strength of the force have anything to do with its speed?

The sun and planets DO orbit eachother, its just because the sun is so massive it doesn't really look like it.

Gravity has a fixed force at a given distance.

So you need to look at gravity, and newtons laws at the very least. Find a highschool physics website or something, it should help.

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Interesting indeed.

My question about gravitons is this; if gravity is caused by these gravitons, then how do these gravitons escape from a black hole to cause the gravitational effect?

My understanding of a black hole is that it has so much gravity that NOTHING can escape it.

Eirher this is incorrect, and some things can escape, or there are no gravitons?

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I'm a little confused (again). Aren't quantumn theory and GR incompatible?

I get the impression on one hand you're siding with GR and on the other' date=' against it...[/quote']

There is no working quantum theory of gravity. Which is why gravitons don't appear in GR. But they will be part of quantum gravity, and since GR shows gravity to propagate at c, the quantum theory had better do this, too.

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If gravitons exist and they radiate out from a gravitating object' date=' and although they have no mass, they do have energy. Where does this energy come from?

If it comes from a gravitation potential, does the gravitating object loose some of this gravitational potential over time, or does it come from some other source of energy, or could it come from the mass of the gravitational object (which means it would also reduce the gravitational pull of the object)?

So if gravitons radiate from an object, it should mean that the object (over a period of time) would loose either energy, or mass. Or am I missing something?[/quote']

The gravitons would be virtual particles, so no energy is lost, as they only interact when something is there with which they can interact. And whatever that "something" is, interacts back an equal amount. AFAIK objects only radiate gravitational energy if they undergo an acceleration.

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Interesting indeed.

My question about gravitons is this; if gravity is caused by these gravitons' date=' then how do these gravitons escape from a black hole to cause the gravitational effect?

My understanding of a black hole is that it has so much gravity that [b']NOTHING[/b] can escape it.

Eirher this is incorrect, and some things can escape, or there are no gravitons?

That's an intriguing point - how can gravitons escape the event horizon?

So there is no theory of quantumn gravity yet, although it's believe there will be one that incorporates gravitons into it.

It will be intersting to see how that theory works out, as I still believe the concept of a gravity force carrier particle to be inherently flawed.

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That's an intriguing point - how can gravitons escape the event horizon?

So there is no theory of quantumn gravity yet' date=' although it's believe there will be one that incorporates gravitons into it.

It will be intersting to see how that theory works out, as I still believe the concept of a gravity force carrier particle to be inherently flawed.[/quote']

If it wasn't for a whole lot of Really Smart People I'd think relativity was inherently flawed, since it makes my brain hurt so much.

I know what you mean though. Sometimes I long for the days of Newtonian thought where stuff made sense, instead of just the math.

One thought on gravitons escaping a black hole - if you have a light source, the photons will never interact with each other right? They are a steady stream in all directions, but they would never cross each other's paths.

Likewise, a radiant source of gravitons would be emmiting gravitons, which would be sorrounded by but never collide with each other - even if the type of particle is affected by gravity.

Now the next question: if other sources of gravity can bend light, would it also bend the path taken by gravitons? Or was it, gravity bends space, but not light? I forget the right answer to that one, since I've heard both.

Edit:

I also had the thought just now, that while on earth, we refer to any work done by an object falling, as the release of potential energy that was moving the object up to a place where it could fall in the first place.

If the big bang is the source of all matter in the known universe, then all mass was "lifted" from that point during the event, and all work done by gravity subsequently will be that potential energy being used up to come to relative rest, which if the universe doesn't experience a big crunch, will not happen. Still, it means there is a maximum potential amount of work that can be done by the gravity of all matter in the universe is equal to the energy that went into flinging everything out in the first place.

Maybe I'm overapplying newtonian physics or misreading it entirely.

Also, could the particle raditation of gravitons be associated with atomic decay in any way? Somehow the idea that a mass can emmit something - anything, without loosing something itelf just doesn't sit well with me.

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That's an intriguing point - how can gravitons escape the event horizon?

Because gravitons cannot affect gravitons in that way.

Thisnk of it this way, how cna you pull on something with the thing that is transmitting the force in the first place? If you believe string theory you could say they can "drift" between membranes because they are closed strings whereas non-closed strings can't.

Cheers,

Ryan Jones

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']Uh' date=' try looking gravity up somewhere. You have some major misconceptions about how gravity works and it would take a lot of time and effort to set you straight.

Why would gravity be considered negative?

Why would the strength of the force have anything to do with its speed?

The sun and planets DO orbit each other, its just because the sun is so massive it doesn't really look like it.

Gravity has a fixed force at a given distance.

So you need to look at gravity, and newtons laws at the very least. Find a highschool physics website or something, it should help.[/quote']

Gee thanks for the pep talk. I guess I came to the wrong place. I'll take my questions & comments somewhere else so not to take up your valuable computer time & effort. Wouldn't want you to break a nail typing. Take a vacation dude, I think you need a break. Thanks for the help!!!!

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Gee thanks for the pep talk. I guess I came to the wrong place. I'll take my questions & comments somewhere else so not to take up your valuable computer time & effort. Wouldn't want you to break a nail typing. Take a vacation dude, I think you need a break. Thanks for the help!!!!

If you are looking for decent informaiton on gravity, have a look at Wikipedia.org or even get a good book like The Elegant Universe or The Fabric Of The Cosmos.

Cheers,

Ryan Jones

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Thanks Ryan! Would you suggest those books as a good starting point? Just say I'm starting from scratch. Websites can't help me much since I have so little free time at home. Anyone have any suggestions & a little free time feel free to reply or e-mail me. Thanks!

"You have to start somewhere to get somewhere"

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Thanks Ryan! Would you suggest those books as a good starting point? Just say I'm starting from scratch. Websites can't help me much since I have so little free time at home. Anyone have any suggestions & a little free time feel free to reply or e-mail me. Thanks!

"You have to start somewhere to get somewhere"

Yes! Those books are great' date=' I bet a lot of people here have read them and a lot of people here willprobably say they are good

http://www.amazon.com/exec/obidos/tg/detail/-/0375708111/qid=1133249567/sr=2-3/ref=pd_bbs_b_2_3/002-9875685-8820859?v=glance&s=books

http://www.amazon.com/exec/obidos/tg/detail/-/0375727205/qid=1133249567/sr=2-1/ref=pd_bbs_b_2_1/002-9875685-8820859?v=glance&s=books

Be warned, String Theory is addictive and its a wide range subject so there is a lot to study

Incase you do get some time online here are some links for you:

[list']

[*]http://www.pbs.org/wgbh/nova/elegant/ (Online videos - great!)

Cheers,

Ryan Jones

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I think I get what Parden is trying to say although the point may have gotten lost in the confusion (and perhaps some unneeded terms). And I concur unless someone can explain in QM terms not GR terms what is happening.

Here goes my hopefully clearer example of what Parden brought up...

Say we have a sun and two planets orbiting - planet A is closer than planet B and every now and then planet B is eclipsed by planet A. IFF there is such a 'virtual' particle as a graviton (which BTW has not been found or observed) and by QM, gravity is the exchange of this graviton particle between non-massless particles THEN during the eclipse planet B would not be exchanging the same amount of gravitons because the sun (the source of most of the gravitons) would be blocked by planet A. If this graviton is truly the cause behind gravity would a drop in gravity not be already observed on earth during a lunar eclipse?

And yes, it can easily be explained using GR etc. but that is not the point here, I am questioning the reasoning behind a graviton when we have already come to the conclusion that gravity is caused by space-time curvature.

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I think I get what Parden is trying to say although the point may have gotten lost in the confusion (and perhaps some unneeded terms). And I concur unless someone can explain in QM terms not GR terms what is happening.

Here goes my hopefully clearer example of what Parden brought up...

Say we have a sun and two planets orbiting - planet A is closer than planet B and every now and then planet B is eclipsed by planet A. IFF there is such a 'virtual' particle as a graviton (which BTW has not been found or observed) and by QM' date=' gravity is the exchange of this graviton particle between non-massless particles THEN during the eclipse planet B would not be exchanging the same amount of gravitons because the sun (the source of most of the gravitons) would be blocked by planet A. If this graviton is truly the cause behind gravity would a drop in gravity not be already observed on earth during a lunar eclipse?[/quote']

One must conclude that the graviton does not interact the way you are proposing.

And yes, it can easily be explained using GR etc. but that is not the point here, I am questioning the reasoning behind a graviton when we have already come to the conclusion that gravity is caused by space-time curvature.

To explain what's going on in cases where the classical theory fails.

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Maybe gravitons are almost like the neutrino, except whereas the neutrino dosn't interact with matter at all, the graviton barely interacts... resulting in a really weak force of gravity, but the graviton itself being really powerful just... unnoticed.

*IF* the graviton is real.

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One must conclude that the graviton does not interact the way you are proposing.
And I agree, so how does it interact? I guess this is still a grey area? But the strange thing is that we have all these models how other gauge bosons interact only to make an exception to the graviton. Seems like Occam would be turning in his grave. There is something fundamental missing in the picture.

Maybe gravitons are almost like the neutrino, except whereas the neutrino dosn't interact with matter at all, the graviton barely interacts... resulting in a really weak force of gravity, but the graviton itself being really powerful just... unnoticed.
If this was so, then we'd have clues to the graviton in existing particle colliders however, AFAIK, they're building a collider that should be able to detect them in higher E levels. I'm just going by memory here and it's not the best nowadays.
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But then what result would that produce?

Gravity is weaker than magnetism, so you couldn't say "Ah, that lepton is off it's projected spiral course by 0.003 degrees, accounting for magnetic attraction, so it must be gravity attracting it to the other particle!"

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Yes, perhaps there would be no absolute correlation but my point is that we have detected other particles including the evasive neutrino and that which pervades all (graviton) is still just a speculation.

But all-in-all if the graviton was something like the neutrino, Planet A obstructing Planet B would still take the hit of gravitons and leave planet b with less and therefore less gravity during the eclipse.

I think Swansont is correct in saying that my proposal (or more correctly - my understanding) of how gravitons are exchanged during gravity is not correct. But how is the correct way (with a graviton in mind) that this is achieved will lead us into even more speculation.

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I think Swansont is correct in saying that my proposal (or more correctly - my understanding) of how gravitons are exchanged during gravity is not correct. But how is the correct way (with a graviton in mind) that this is achieved will lead us into even more speculation.

This is pretty much what has been breaking my brain. You can tell someone a photon emmits from a light source and its all very straight forward collision stuff, with a little bending of space here and there and lightspeed/relatively thrown in, but the behaviors just 'fit' with our understanding of nature*. (*Ok, wave interference patterns occuring with single photons freak me out but thats another story.)

Since someone mentioned EM field stuff earlier, I'd like to ask just to know: what particle emmits from a magnet to draw metal close to it? I've seen magnetic field lines drawn in diagrams where they are lines from north to south etc, but according to Quantium Mechanics, what particle emmisions are responsible for that behavior, and is the force delay in magnetic fields also c? If a magnet pops into existance, does it take c before metals begin to feel attraction?

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And I agree' date=' so how does it interact? I guess this is still a grey area? But the strange thing is that we have all these models how other gauge bosons interact only to make an exception to the graviton. Seems like Occam would be turning in his grave. There is something fundamental missing in the picture.

[/quote']

This is pure speculation - I have little to no competence in anything related to quantum gravity - but what if the interaction were second order? i.e. the gravitons don't interact directly with the mass. They interact to warp space, and the warped space interacts with the other mass.

I have no idea if this fits in with current hypotheses, or if it creates more problems than it solves.

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This is pure speculation - I have little to no competence in anything related to quantum gravity - but what if the interaction were second order? i.e. the gravitons don't interact directly with the mass. They interact to warp space' date=' and the warped space interacts with the other mass.

I have no idea if this fits in with current hypotheses, or if it creates more problems than it solves.[/quote']

Wouldn't it be easier to just say gravity *is* the curving of spacetime itself, withouth needing any particle to act as a "middle-man"?

You know, multiplying things beyond need be etc.

Since someone mentioned EM field stuff earlier' date=' I'd like to ask just to know: what particle emmits from a magnet to draw metal close to it? I've seen magnetic field lines drawn in diagrams where they are lines from north to south etc, but according to Quantium Mechanics, what particle emmisions are responsible for that behavior, and is the force delay in magnetic fields also c? If a magnet pops into existance, does it take c before metals begin to feel attraction?[/quote']

I don't know - I'd like to know, though... can anyone elaborate?

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Since someone mentioned EM field stuff earlier, I'd like to ask just to know: what particle emmits from a magnet to draw metal close to it?

AFAIK: Ii is the exchange of virtual photons that cause magnetic and electrical attrations.

Ie partical A emmits a virtual photon and it is picked up by particle B. Scine there has bee an exchange of energy between A and B then B must change its postion closer to A (If I'm wrong please correct me).

This is pure speculation - I have little to no competence in anything related to quantum gravity - but what if the interaction were second order? i.e. the gravitons don't interact directly with the mass. They interact to warp space, and the warped space interacts with the other mass.

I have no idea if this fits in with current hypotheses, or if it creates more problems than it solves.

Photons are a warping/ripple of the electromagnetic field. Could Gravitons be a similar thing, a warpin or ripple in the space/time fabric?

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AFAIK: Ii is the exchange of virtual photons that cause magnetic and electrical attrations.

Ie partical A emmits a virtual photon and it is picked up by particle B. Scine there has bee an exchange of energy between A and B then B must change its postion closer to A (If I'm wrong please correct me).

How does changing B's position give virtual energy back to A?

Photons are a warping/ripple of the electromagnetic field. Could Gravitons be a similar thing' date=' a warpin or ripple in the space/time fabric?[/quote']

I thought photons were entities in their own right, like a drop of water being compared to a ripple on a pond...?

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This is pure speculation - I have little to no competence in anything related to quantum gravity - but what if the interaction were second order? i.e. the gravitons don't interact directly with the mass. They interact to warp space, and the warped space interacts with the other mass.
I too have limited knowledge of quantum gravity but with the proposal above when it comes to warped spacetime interacting with the other mass, warped spacetime would 'somehow' have to create gravitons to interact again with the particles of the mass that is being affected.

Although again pure speculation (until we don't observe gravitons no matter how powerfull a collider we create), I would lean towards Transdecimal's proposal that there really are no gravitons and relativity with its warped spacetime explanation (with no particles as mediators) of gravity is all there is to it. Well, at least on the surface anyway. As I keep on hinting, and some may get annoyed with it, there is something fundamental we are missing. And it is not anything new, just a more 'realistic' interpretation of space (dimensionality) than what we have become accustomed to over the millenia. On a macroscopic level, sure we perceive space as 3 dimensional but there certainly are some odd phenomena on a quantum level that although overlooked, to me, would suggest that our view of dimensionality is flawed.

And just to answer the original topic question, gravity propagates at the speed of light c as I think Swansont has already mentioned.

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