How can virtual particle become real particles? It involves an energy transfer from the potential energy of the black to the virtual particles?
What does it mean for a particle to have a negative energy wrt an observer outside the black hole?
Can this prediction be tested experimentally? Is there any progress in this direction so far?
Best Answer
There are several physical systems that can be analogous to a black hole. One of which is the sonic/acoustic black hole (or dumb hole) in which phonons can't escape a Bose-Einstein condensate that flows faster than local speed of sound, in a similiar manner to photons that can't escape the gravity well of a black hole.
In such an apparatus, Beckenstein-Hawking radiation analogue was measured expiramentally, for example:
Steinhauer, J. (2014). Observation of self-amplifying Hawking radiation in an analogue black-hole laser. Nature Physics, 10(11), 864-869. doi:10.1038/nphys3104