# How do gravitons impact on general relativity?

As I'm reading about GR a lot lately, I was wondering: how do gravitons (if they exist ofc) impact the general relativity?

Since in GR, when we look at particles moving in space-time, we are only looking from geometric point of view so to say. Since gravity is represented with curvature of space-time via Einstein equations, we don't say gravity is a force that influences on bodies, gravity is just curvature affecting the bodies.

So if there is a graviton (gravitons) which would be mediators of gravity as a force within or not within the Standard Model, how would this be reconciled with the view of gravity as a curvature of space and time?

I would guess that this kinda question was asked by some scientists and answered, but I never really read anything on it. I don't even remember seeing gravitons mentioned in standard books about GR.

Are there any explanations about it?

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How do gravitons impact on general relativity? [...] I would guess that this kinda question was asked by some scientists and answered...

It's been asked but never answered satisfactorily. The full impact on general relativity would be that it would become a theory of quantum gravity. Nobody has ever been able to construct a satisfactory theory of quantum gravity. We have various guesses, and we can reason by analogy with other fields such as the electromagnetic field, but basically not much is known.

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But would that completely changed the Einstein view of gravity? Would the Einsteins equation still hold in their current form? – dingo_d Aug 27 '13 at 19:21
@dingo_d: it would obviously depend on the theory. – Jerry Schirmer Aug 27 '13 at 19:52
@dingo_d: Since general relativity has already been confirmed by lots of experiments, any new theory would have to be equivalent to GR in the appropriate limit. Any theory of quantum gravity has to be equivalent to GR for energies that are small compared to the Planck energy. – Ben Crowell Aug 27 '13 at 20:36
Well that was one of the things that kinda bothered me: GR is confirmed, and it's really elegant theory, so I couldn't see how one would fit gravitons into the picture. But I neglected the fact that dealing with gravitons I'd go into the quantum limit, and then it would be like with classical mechanics and quantum mechanics, right? Thanks for clarification :) – dingo_d Aug 27 '13 at 21:27

You would interpret this as gravitational waves being the medium through which changes in matter distributions are communicated to far away places--much in the same way that you see it with retarded potentials in E&M. If you quantize the field, (at this level) all that happens is that this transmission happens in discrete steps.

And I will say that the "medium of force" idea from QFT is an imperfect analogy. The media of force in QFT are off-shell bosons, but off-shell fields have little in common with real, physical particles.

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So gravitons would be something like Higgs boson? And with them associated graviton field like Higgs field? – dingo_d Aug 27 '13 at 19:22
@dingo_d: all bosons are like that--they're quantized fields. The thing that sets the Higgs apart is that its energy is minimized for a nonzero value of the field, and we measure fluctuations about this value, rather than zero. – Jerry Schirmer Aug 27 '13 at 19:43