Penrose process

The Penrose process (also called Penrose mechanism) is theorised by Roger Penrose as a means whereby energy can be extracted from a rotating black hole. That extraction can occur if the rotational energy of the black hole is located not inside the event horizon but outside in a region of the Kerr spacetime called the ergosphere in which any particle is necessarily propelled in locomotive concurrence with the rotating spacetime. All objects in the ergosphere become dragged by a rotating spacetime. The Penrose process (also called Penrose mechanism) is theorised by Roger Penrose as a means whereby energy can be extracted from a rotating black hole. That extraction can occur if the rotational energy of the black hole is located not inside the event horizon but outside in a region of the Kerr spacetime called the ergosphere in which any particle is necessarily propelled in locomotive concurrence with the rotating spacetime. All objects in the ergosphere become dragged by a rotating spacetime. In the process, a lump of matter entering the ergosphere is triggered to split into two parts. For example, the matter might be made of two parts that separate by firing an explosive or rocket which pushes its halves apart. The momentum of the two pieces of matter when they separate can be arranged so that one piece escapes from the black hole (it 'escapes to infinity'), whilst the other falls past the event horizon into the black hole. With careful arrangement, the escaping piece of matter can be made to have greater mass-energy than the original piece of matter, and the infalling piece has negative mass-energy. Although momentum is conserved the effect is that more energy can be extracted than was originally provided, the difference being provided by the black hole itself.