Hawking radiation is caused by the production of particle-antiparticle pairs on the Schwarzschild sphere enclosing a black hole. Inside the volume enclosed by this sphere, it seems to me that gravity is strong enough for providing the energy necessary to promote a virtual particle-antiparticle pair to a real pair. But are these pairs actually formed? If not, why not? What would prevent them from being created? If so, do they annihilate again, or do they fall into the hole (which thereby increases in mass, but doesn't affect the Schwarzschild sphere, because, to speak in a very colloquial way, some curvature of spacetime is taken away after the pair is created, while the same "amount" of curvature is given back by the mass of the pair), or both, or.....what?
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2$\begingroup$ "Hawking radiation is caused by the production of particle-antiparticle pairs on the Schwarzschild sphere enclosing a black hole" - no it isn't $\endgroup$– John RennieCommented Jun 14, 2017 at 9:20
1 Answer
The cartoon picture is that Hawkring radiation will occur "near" but outside the Schwarzschild sphere, when one of the virtual particles gets trapped in the black hole, but the other escapes (becoming a real particle in the process).
What happens inside the Schwarzschild radius will depend on which model for a black hole you prefer, and how you believe quantum gravity works.
In any case, these processes should not be visible outside the black hole, since even if a virtual pair of particles where "promoted" to a real pair, they would still be inside of the even horizon, and therefore inevitably fall towards the centre of the black hole (preserving the mass/radius of the black hole).
Whether the particles annihilate again or not will also depend on the details of how quantum gravity works.
