Ergosphere

Its name was proposed by Remo Ruffini and John Archibald Wheeler during the Les Houches lectures in 1971 and is derived from Ancient Greek ἔργον (ergon) 'work'.

The ergosphere touches the event horizon at the poles of a rotating black hole and extends to a greater radius at the equator.

[citation needed] A suspended plumb, held stationary outside the ergosphere, will experience an infinite/diverging radial pull as it approaches the static limit.

Since the ergosphere is outside the event horizon, it is still possible for objects that enter that region with sufficient velocity to escape from the gravitational pull of the black hole.

[8] As this energy is removed, the black hole loses angular momentum, and thus the limit of zero rotation is approached as spacetime dragging is reduced[citation needed].

[9] Results from computer models show that the Penrose process is capable of producing the high-energy particles that are observed being emitted from quasars and other active galactic nuclei.

At the ergospheres (shown here in violet for the outer and red for the inner one), the temporal metric coefficient *g _tt* becomes negative, i.e., acts like a purely spatial metric component. Consequently, timelike or lightlike worldlines within this region must co-rotate with the inner mass. Cartesian projection , equatorial perspective. ^{[

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Animation: A test particle approaching the ergosphere in the retrograde direction is forced to change its direction of motion (in Boyer–Lindquist coordinates ).