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This question already has an answer here:

I have read in a book and on the internet that the graviton is the particle which causes gravity, and not even light can escape gravity.

Suppose our Sun has turned into a black hole. The black hole will still have the same gravitational effect on other matter as the Sun.

Nothing can escape from a black hole, but a black hole still has a gravitational effect. How is this possible? Won't the black hole stop the gravitons and lose its gravitational effect?

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marked as duplicate by AccidentalFourierTransform, Mike, Qmechanic Jan 20 '18 at 16:21

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To start with, gravitons are in the realm of quantum mechanics, and gravity has not yet been definitively quantized .

If one supposes that the classical gravitational field , in an effective gravitational quantization, would behave as photons in field theory, then the analogue is the electric field. The electric field of a charged particle does not emit photons, as it would lose energy/mass. It emits at a limit virtual photons . I.e. a test charge and the charge under measurement exchange virtual photons , which replace the concept of the classical field lines between the two charged particles.

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Virtual photons have the quantum numbers of a photon but are off mass shell.They are a mathematical entity useful in calculating interactions.

In a similar manner a classical gravitational field would be exchanging virtual gravitons with a test mass, as it is falling towards the singularity.

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  • $\begingroup$ Virtual particles do not work like that. Spreading that misleading picture is of no help to anyone. $\endgroup$ – AccidentalFourierTransform Jan 20 '18 at 16:22
  • $\begingroup$ @AccidentalFourierTransform you must not mean the picture, you must mean that the classical field lines at the quantum level become virtual photons is not consistent? But is it not true that a limit is taken to 0 frequency to model the static electric field? It is simpler to talk of test charges. $\endgroup$ – anna v Jan 20 '18 at 16:27
  • $\begingroup$ So if the gravitons fall towards singularity, how can gravity work in a blackhole in a model where gravity I'm caused by the interaction of a particle.So can't we assume that gravitons don't exist? $\endgroup$ – Theoretical Jan 20 '18 at 16:30
  • $\begingroup$ The everyday gravitational fields we see exchange virtual gravitons to attract ( presuming that gravity will very soon be definitively quantized). That is the classical field. Black holes have a classical gravitational field. In a presumed quantum field theoretical formulation of gravity, the attraction will be analogous. Real photons exist when charges are accelerated. When asymmetric masses are accelerated we get classical gravitational waves, as measured in LIGO. en.wikipedia.org/wiki/LIGO .Proof of gravitons is pending . See en.wikipedia.org/wiki/Graviton $\endgroup$ – anna v Jan 20 '18 at 16:40

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