Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: jeffreyH on 23/08/2014 12:50:49
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Light and all mass types experience time dilation in a gravitational field. Would gravitons themselves experience the same effect. If not doesn't this mean that the graviton would exceed the speed of light as measured in the observer's frame?
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Would gravitons themselves experience time dilation?
If gravitons exist, and they travel slower than the speed of light, then they would experience time dilation.
However, there is thought to be only one type of spin 2 boson (the graviton), so it is not clear how this time dilation would show itself - perhaps by decay of the graviton over cosmological distances?
If the graviton is massless (as is currently thought), then it would have an infinite range and not change with distance (until it interacts with a mass). Time has no meaning for such a particle.
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Would gravitons themselves experience time dilation?
If gravitons exist, and they travel slower than the speed of light, then they would experience time dilation.
However, there is thought to be only one type of spin 2 boson (the graviton), so it is not clear how this time dilation would show itself - perhaps by decay of the graviton over cosmological distances?
If the graviton is massless (as is currently thought), then it would have an infinite range and not change with distance (until it interacts with a mass). Time has no meaning for such a particle.
If we consider two frames of reference where one is time dilated significantly more than the other and an observer in each measures the speed of light they will both agree. However if you could directly compare the two the photon in the slower frame would appear slower to the observer in the faster frame. That is: light is slowed by gravitation. If the graviton does not experience this same effect then it is effectively superluminal in its velocity for any time dilated observers.
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You're using the 'eye of a God' there Jeffery. That means assuming a defined universe, consisting of all frames of reference possible, then assuming something else (God) outside it, that 'objectively' can define each frame relative each other, in terms of clocks.
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If we consider two frames of reference where one is time dilated significantly more than the other and an observer in each measures the speed of light they will both agree. However if you could directly compare the two the photon in the slower frame would appear slower to the observer in the faster frame. That is: light is slowed by gravitation.
Good stuff Jeffrey. IMHO the "God's eye view" is the way to understand it.
If the graviton does not experience this same effect then it is effectively superluminal in its velocity for any time dilated observers.
The graviton remains hypothetical. But note that the photon "conveys inertia between the emitting and absorbing bodies". It has a zero rest mass but a non-zero inertial mass, and a non-zero active gravitational mass. And it isn't surrounded by a cloud of gravitons. Instead it's the only particle there. So in a way, a photon is a graviton. IMHO it's a pity the name graviphoton (http://en.wikipedia.org/wiki/Graviphoton/) has been taken.
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Howdy, John. Let me be the first one here to welcome you to this forum. Welcome! [:D]
It's nice to see you again. I hope we get along better than we did in the last forum where we spoke to each other. I'm not one for holding grudges of taking them from one forum to another with people who aren't genuinely evil, which you're not. :)
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Depends, theoretically I assume you're free to assume either approach, experimentally you're not :) Then again, what I wanted to do was to point out the inconsistency in assuming a outside, not Jeffreys approach as such. You could possibly imagine it as a entity consisting of all those slivers of 'frames', able to differ between them too? But you won't be able to define that 'objective platform' I think, not without destroying relativity. What I mean is that even if we define a universe from those frames of reference 'co-existing', we still will have to agree on what should be the 'objective' gold standard of 'time/clock' from where you then define the others.
the solution to me is the same solution as to what gives us our experiments, using ones 'local' golden standard, meaning my clock and my ruler defining others. We use that standard to define constants too, and those you should be able to measure equivalent anywhere. assuming a god like approach would give me a hard time defining any constant, as we now should have to define those different, for different frames.
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The notorious frames of reference where you are mired in Lorentz transforms and partial differentials. A good club to beat the uninitiated with. I now have a point of reference to which everything else can be related so I really don't care.
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If we consider two frames of reference where one is time dilated significantly more than the other and an observer in each measures the speed of light they will both agree. However if you could directly compare the two the photon in the slower frame would appear slower to the observer in the faster frame. That is: light is slowed by gravitation.
Good stuff Jeffrey. IMHO the "God's eye view" is the way to understand it.
If the graviton does not experience this same effect then it is effectively superluminal in its velocity for any time dilated observers.
The graviton remains hypothetical. But note that the photon "conveys inertia between the emitting and absorbing bodies". It has a zero rest mass but a non-zero inertial mass, and a non-zero active gravitational mass. And it isn't surrounded by a cloud of gravitons. Instead it's the only particle there. So in a way, a photon is a graviton. IMHO it's a pity the name graviphoton (http://en.wikipedia.org/wiki/Graviphoton/) has been taken.
I have to politely disagree with this viewpoint. The photon may hypothetically partner the hypothetical graviton and Schrodinger's cat may be a hypothetical zombie.
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I don't know the answer to this, and it seems as if no one on the forum can do more than speculate (myself included), but it's worth pointing out that gravitational time dilation is a consequence of the general theory of relativity, which is a classical field theory. Particles such as the graviton come from quantizing the classical field theory and so they should be able to explain how to build the classical theory from more fundamental, quantum building blocks.
For example, the properties of the electromagnetic field arise from photons.
So since time dilation as its currently understood is a consequence of general relativity and gravitons should explain how to build general relativity from particles, a graviton theory should probably explain how time dilation comes to be as a result of fundamental particles.
And although we know some properties that a graviton theory has to satisfy, there is no accepted theory of a graviton yet...
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No Jeffery, where I stand is where constants definition come from. Constants and relativity has no problems with each other, defined locally. And I do not mean to beat anyone with a club by it.
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You might say it is a matter of taste. I prefer my universe as simple as possible, and hope that it agrees with me. but I can't guarantee it, so your approach might be the way it is, although I'm unsure on what you consider your point of reference there?
there's no theory or hypothesis that can't be adjusted :) That's the beauty of science.
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I don't know the answer to this, and it seems as if no one on the forum can do more than speculate (myself included), but it's worth pointing out that gravitational time dilation is a consequence of the general theory of relativity, which is a classical field theory. Particles such as the graviton come from quantizing the classical field theory and so they should be able to explain how to build the classical theory from more fundamental, quantum building blocks.
For example, the properties of the electromagnetic field arise from photons.
So since time dilation as its currently understood is a consequence of general relativity and gravitons should explain how to build general relativity from particles, a graviton theory should probably explain how time dilation comes to be as a result of fundamental particles.
And although we know some properties that a graviton theory has to satisfy, there is no accepted theory of a graviton yet...
There have been proposals that the graviton should exceed c. I doubt that. However there may be more to that point of view than meets the eye. At the moment I am grappling with the Maxwell equations very badly. Better people than me have attempted such things. I'll keep going simply because I love a mystery and you learn an awful lot on the way. Mathematics never ceases to amaze me.
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You might say it is a matter of taste. I prefer my universe as simple as possible, and hope that it agrees with me. but I can't guarantee it, so your approach might be the way it is, although I'm unsure on what you consider your point of reference there?
there's no theory or hypothesis that can't be adjusted :) That's the beauty of science.
I am still working on the proof for my point of reference. I have to go back over everything to make sure I haven't fallen into any errors on the way. I have already encountered several problems. What I want to get to is a law similar to Lambert's cosine law but for gravitation instead of light sources. This should eventually map the density and relationship between the hypothetical graviton and the photon. That is enough speculation for this forum.
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I don't know the answer to this, and it seems as if no one on the forum can do more than speculate (myself included), but it's worth pointing out that gravitational time dilation is a consequence of the general theory of relativity, which is a classical field theory. Particles such as the graviton come from quantizing the classical field theory and so they should be able to explain how to build the classical theory from more fundamental, quantum building blocks.
For example, the properties of the electromagnetic field arise from photons.
So since time dilation as its currently understood is a consequence of general relativity and gravitons should explain how to build general relativity from particles, a graviton theory should probably explain how time dilation comes to be as a result of fundamental particles.
And although we know some properties that a graviton theory has to satisfy, there is no accepted theory of a graviton yet...
There have been proposals that the graviton should exceed c. I doubt that. However there may be more to that point of view than meets the eye. At the moment I am grappling with the Maxwell equations very badly. Better people than me have attempted such things. I'll keep going simply because I love a mystery and you learn an awful lot on the way. Mathematics never ceases to amaze me.
While I can't help you much with Einstein's field equations and gravitons, I am an expert in Maxwell's equations should you have any questions.
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I don't know the answer to this, and it seems as if no one on the forum can do more than speculate (myself included), but it's worth pointing out that gravitational time dilation is a consequence of the general theory of relativity, which is a classical field theory. Particles such as the graviton come from quantizing the classical field theory and so they should be able to explain how to build the classical theory from more fundamental, quantum building blocks.
For example, the properties of the electromagnetic field arise from photons.
So since time dilation as its currently understood is a consequence of general relativity and gravitons should explain how to build general relativity from particles, a graviton theory should probably explain how time dilation comes to be as a result of fundamental particles.
And although we know some properties that a graviton theory has to satisfy, there is no accepted theory of a graviton yet...
There have been proposals that the graviton should exceed c. I doubt that. However there may be more to that point of view than meets the eye. At the moment I am grappling with the Maxwell equations very badly. Better people than me have attempted such things. I'll keep going simply because I love a mystery and you learn an awful lot on the way. Mathematics never ceases to amaze me.
While I can't help you much with Einstein's field equations and gravitons, I am an expert in Maxwell's equations should you have any questions.
Oh I definitely have questions and I will take you up on that. I am currently reading through "A dynamical theory of the magnetic field". Maxwell gives over only a very brief section to gravitation and brings up the point of negative energy. I need to read up on a few more things before I get back to you.
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I have to politely disagree with this viewpoint...
Noted Jeffrey. Perhaps another tack you could take is whether gravitons get out of a black hole. That might tell you that the graviton is a virtual particle and a field quantum. A "chunk of field" as it were, rather than a real particle that moves from A to B.
pmb: noted! It's good to talk. Sometimes people disagree, but if we didn't, life would be so dull.
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I have to politely disagree with this viewpoint...
Noted Jeffrey. Perhaps another tack you could take is whether gravitons get out of a black hole. That might tell you that the graviton is a virtual particle and a field quantum. A "chunk of field" as it were, rather than a real particle that moves from A to B.
pmb: noted! It's good to talk. Sometimes people disagree, but if we didn't, life would be so dull.
That is a very interesting and potentially problematic area. It goes to the heart of the relationship between the hypothetical graviton and the photon. It raises the possibility of the graviton being virtually undetectable in any circumstances. This could mean that field density would make no difference in helping the detection effort. This was something I looked into a while back but abandoned. Part of the field would require phonons to generate it. All the interactions would then be virtual. The trouble is you would be talking about a particle traveling at a significantly small fraction of c. You would basically break the Schwarzschild metric. Also field density has to increase dramatically to compensate.
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I remember reading somewhere that if you reach the speed of light then time stops completely. I always wondered what that meant, for if light experiences no time then how could it move in time?
light moves at a certain speed (the speed of light) it travels faster then any thing but how can it move at all if it takes time to move? Could light exist in time but not experience time? Who knows how that works?
I guess the answer to your question is that if gravitons do exist and travel at light speed then gravitons would experience no time, if they travel a little slower then they would experience time dilation.
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I remember reading somewhere that if you reach the speed of light then time stops completely. I always wondered what that meant, for if light experiences no time then how could it move in time?
light moves at a certain speed (the speed of light) it travels faster then any thing but how can it move at all if it takes time to move? Could light exist in time but not experience time? Who knows how that works?
I guess the answer to your question is that if gravitons do exist and travel at light speed then gravitons would experience no time, if they travel a little slower then they would experience time dilation.
I abandoned the work on virtual particles because of the velocity problem. The constant c is used in the calculation of the Schwarzschild radius and a lot of other equations too. So it appears likely that gravity travels at c. The problem is if light is affected by gravity but gravity does not affect ITSELF in a similar way you end up with all observers measuring superluminal speeds for gravity. What is worse the velocity would appear faster the more time dilated you were. The problem with gravity affecting itself in the same way as light is that gravity could also be trapped inside the event horizon. In which case the dense objects at the centres of galaxies would radiate no gravitational field at all. So how do the galaxies orbit such objects? It is this dilemma I am grappling with at the moment. This became an issue shortly before I started examining the Maxwell equations and got worse afterwards. I need a detour into another area to see if I have missed something obvious because the situation is vexing me. One thing I did come to realise is that sag a* would not have the effect on gas cloud G2 that everyone expected. This may yet change. I had hoped I was wrong.