We now think of the vacuum as constantly producing matter and antimatter, which almost as promptly annihilate—except when near a black hole. This feature grew to prominence in Stephen Hawking’s theory of black-hole radiation; a heuristic explanation of the radiation has the intense gravitational field close to the Schwarzschild surface separating the background matter and antimatter pairs before they annihilate, sucking one into the black hole and emitting the other to infinity.
