Stephen Hawking is responsible for the discovery of black hole radiation, which is often referred to as Hawking Radiation. Hawking has played a part in many scientific fields and has collaborated with a number of other scientists to work on various theories and projects all over the world.
Hawking's black hole theory, in its most simple explanation, says that vacuum fluctuations in black holes causes particle-antiparticle pairs to develop on the edge of the black hole. When this occurs, the draw of the black hole pulls half of that pair in before they can destroy each other, as they are prone to do, causing the remaining part of the pair to emit radiation. From a safe distance this makes it seem as if the black hole is producing particles.