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jnorman
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I was just re-reading some of Hawking's writings, and apparently he is fairly stong supporter of a quantum theory of gravity, as opposed to GR, and writes extensively about gravitons. this brought up a question for me which perhaps one of you can help clarify.
classical gravity indicates that only mass and distance control gravitational attraction, and treats it as a spooky force but does not describe any mechanism. GR indicates that gravity is not a force, but a reflection of the curvature of spacetime created by the presence of mass. quantum gravitational theory would indicate that gravity results from the interaction of two masses via particle exchange (gravitons), and is supported by the search for GUTs (i think).
however, the question that popped into my head is with regard to gravitational effects on photons. experiment has shown clearly that light is effected by gravity, as in lensing of light around massive stars. in GR this is accepted as light follows the geodesics created by the curved spacetime - no particle interaction required.
so, in a quantum theory of gravity, where the interaction is the result of graviton exchange between the two bodies/particles - how would gravitons interact with individual photons, which as i understand, have no specific location between the time they are emitted and absorbed? and photons, being massless, would not be emitters of gravitons themselves, and would not generate gravitational effects - which is not consistent with experiments which have demonstrated that beams of light do indeed affect each other via gravitational attraction (correct?).
i know i am a dunce here, so i hope my question is not too confused...
classical gravity indicates that only mass and distance control gravitational attraction, and treats it as a spooky force but does not describe any mechanism. GR indicates that gravity is not a force, but a reflection of the curvature of spacetime created by the presence of mass. quantum gravitational theory would indicate that gravity results from the interaction of two masses via particle exchange (gravitons), and is supported by the search for GUTs (i think).
however, the question that popped into my head is with regard to gravitational effects on photons. experiment has shown clearly that light is effected by gravity, as in lensing of light around massive stars. in GR this is accepted as light follows the geodesics created by the curved spacetime - no particle interaction required.
so, in a quantum theory of gravity, where the interaction is the result of graviton exchange between the two bodies/particles - how would gravitons interact with individual photons, which as i understand, have no specific location between the time they are emitted and absorbed? and photons, being massless, would not be emitters of gravitons themselves, and would not generate gravitational effects - which is not consistent with experiments which have demonstrated that beams of light do indeed affect each other via gravitational attraction (correct?).
i know i am a dunce here, so i hope my question is not too confused...