Gravitational energy is
potential energy associated with the
gravitational field. This phrase is found frequently in scientific writings about
quasars (quasi-stellar objects) and other
active galaxies. Quasars generate and emit their energy from a very small region. The emission of large amounts of power from a small region requires a power source far more efficient than the nuclear fusion that powers stars. The release of gravitational energy by matter falling towards a massive black hole is the only process known that can produce such high power continuously. Stellar explosions –
supernovas and
gamma-ray bursts can do so, but only for a few weeks.