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The other three forces' mediating particles (photons etc.) are absorbed by their appropriate charge-carrying particles, but I can't seem to find a clear answer that applies to the gravitational force in a quantified scenario.

The different answers to this most basis question seem to elude me in frameworks of String theory and LQG, though it becomes more intuitive in the latter.

Sklivvz
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Andersi2
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    please, if you want people to devote time to create a good answer, invest time to create a good question. The title is promising but you will have to de-oversimplify it. -1 until that happens – lurscher Apr 05 '11 at 18:34
  • Tried to make this a bit better - however the answer seems to be quite obvious. They interact with anything with mass or energy, I guess. – Sklivvz Apr 05 '11 at 20:17
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    yes, I think this could be a duplicate question of this: http://physics.stackexchange.com/questions/427/nature-of-gravity-gravitons-curvature-of-space-time-or-both – lurscher Apr 05 '11 at 20:20
  • Dear Sklivz thank for replying, though I wasn't aware that other people could edit ones questions. The things you edited out I liked, and thought were rather central, as of the question of the nature of the 'informing of space(time) by gravations'. The 'space' terms was important. I can't see that gravitions should have any business with matter at all, since matter just follows the spacetime trajectory of least resistance... so there is no need to communicate directly with matter. Therefore the rather provoking answer I provided: that gravitions inform everything but matter. – Andersi2 Apr 05 '11 at 20:34
  • Gravitons of course, not gravitions. Sorry. – Andersi2 Apr 05 '11 at 20:50
  • @Anders: afaik spacetime is merely a mathematical concept used to describe the universe, think "labels" or "units of measure". – Sklivvz Apr 05 '11 at 20:59
  • @Sklivvz: no, spacetime is very physical concept underlying GR. So unless you want to say that GR is pure math with no physical content I'd have to disagree. What you have in mind are probably coordinates on that spacetime. – Marek Apr 05 '11 at 22:53
  • @Marek - [citation needed], in any case gravitons interact with particles in the QM sense, and are fluctuations of spacetime so obviously they are connected, but I don't think they interact with spacetime in the sense of the other force carrying particles. – Sklivvz Apr 05 '11 at 23:02
  • @Sklivvz: citation is provided by any basic intro book into GR. Well, we don't know how precisely gravity is quantized so I am not sure what gravitons you are talking about. If just quantization of linear gravitational waves then these particles are in all regards the same as usual particles (except that they have spin 2 and are coupled to every other particle). In particular, they follow geodesics. If you mean the genuine quantum fluctuations of spacetime itself then the question obviously doesn't make sense as spacetime is gravitons on quantum level. – Marek Apr 06 '11 at 06:59
  • Marek, let's move this to chat, because it's off topic. I don't mind being wrong, but I do mind off-topic comments. – Sklivvz Apr 06 '11 at 07:04
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    @Sklivvz: 1) you started the discussion, so don't blame me. 2) How is discussion of what formalism of quantization we assume off topic in a question that has graviton in the title and is apparently confused by what a graviton is? – Marek Apr 06 '11 at 14:29
  • It probably would be good to move this to chat, this discussion could go on for a while. @Anders: everything can be edited around here, to allow people to fix typos and minor inconsistencies. Of course you can always undo the edit or apply your own edit, but do consider that Sklivvz changed your question for a reason, in an attempt to make it better. – David Z Apr 06 '11 at 18:09
  • And I do appreciate it. Initially I just couldn't see any reason why the hypothetical graviton should interact with matter at all, anagolously with the 'classical' standard model way of thinking, which was why I felt I rather missed spacetime as a seperate entity that needed to be 'informed' of the presence of matter, rather than the graviton being a matter to matter thing. Though I didn't grasp the second order Feynman loops anna referred to (Lubos has a memo as well somewhere), it seems the discussion has moved well beyond all this. – Andersi2 Apr 06 '11 at 22:15

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Well, the question as stated :

What do gravitons interact with?

is naive enough . It assumes gravitons exist in the way photons and gluons and Z exist.

In such a framework, the answer is : they interact with everything for which a Feynman diagram can be imagined.

The other three forces' mediating particles (photons etc.) are absorbed by their appropriate charge-carrying particles, is not quite correct.

The force mediating quanta interact with all matter, even if not at first order, through higher order loop Feynman diagrams , is the correct formulation.

but I can't seem to find a clear answer that applies to the gravitational force in a quantified scenario.

You mean a quantized scenario. In string theory, where the Feynman diagram formalism is appropriately modified for the extension to strings, a graviton will be a mediating particle on par with the other "forces" mediating interactions.

As was discussed in another question, the forces are an artificial carry over from the macroscopic classical world. What exist are interactions that are characterized by coupling constants which distinguish if the specific interaction is strong, gravitational, supersymmetric or...

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