event horizon of a black hole .
Stephen W. Hawking proposed in 1974 that {{link=subatomic particle">subatomic particle pairs ( photon s, neutrino s, and some massive particles) arising naturally near the event horizon may result in one particle's escaping the vicinity of the black hole while the other particle, of negative energy, disappears into it. The flow of particles of negative energy into the black hole reduces its mass until it disappears completely in a final burst of radiation.