Penrose process

The Penrose process is a mechanism for extracting rotational energy from a rotating black hole. It uses particle decay inside the ergosphere, where one fragment can fall in with negative energy while another escapes with increased energy.

Ergosphere: The region outside a rotating black hole’s event horizon where spacetime is dragged so strongly that no observer can remain stationary. The process depends on this region’s allowed negative-energy states.
Roger Penrose: A British mathematical physicist whose work in general relativity includes the proposal of energy extraction from rotating black holes. He introduced the particle-splitting mechanism in 1969.
Blandford–Znajek process: A mechanism that extracts rotational energy from a black hole through electromagnetic fields threading its horizon. It offers a more plausible route than individual particle splitting for powering relativistic jets.
Christodoulou–Ruffini mass formula: A relation decomposing a Kerr black hole’s mass into irreducible mass and extractable rotational energy. It quantifies the maximum energy available to Penrose-style spin extraction.
Negative energy orbit: A trajectory around a rotating black hole whose conserved energy, measured from far away, is negative. A fragment entering such a trajectory lowers the black hole’s energy.
Penrose process paper: Roger Penrose’s 1969 proposal describing energy extraction from a rotating black hole by particle decay in its ergosphere. It established the mechanism as a concrete consequence of Kerr geometry.
Relativistic jet: A narrow outflow of matter moving at near-light speed, launched from some accreting compact objects and galaxies. Black-hole spin extraction is one proposed source of energy for jets.
Irreducible mass: The part of a black hole’s mass that cannot be removed by classical reversible energy-extraction processes. The process can reduce rotational mass, but cannot lower the black hole below this bound.
Frame-dragging: The dragging of spacetime around a rotating mass, predicted by general relativity. It creates the ergosphere and constrains motion there to follow the black hole’s rotation.
Kerr black hole: A rotating black hole described by the Kerr solution, characterized by its mass and angular momentum. Penrose’s proposal relies on the distinctive exterior geometry of this black-hole model.

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Rotating black holeRelated: It converts the black hole’s rotational energy into escaping energy.