antihorizon

English

Etymology

From anti- +‎ horizon.

Noun

antihorizon (plural antihorizons)

1. (astrophysics) The opposite of an event horizon, allowing escape but not entry.
   • 2002, Jim Al-Khalili, Black Holes, Wormholes and Time Machines‎^[1], page 199:

     White holes must therefore be surrounded by the opposite of an event horizon, something known as an antihorizon, which would allow one-way traffic out and never in. Unfortunately, antihorizons are very unstable and get converted to normal horizons in a matter of seconds after forming.

   • 2009, Jon Schiller, 21st Century Cosmology‎^[2], page 54:

     The Kruskal diagram of the Schwarzschild geometry showed it to possess not only a normal horizon but also an antihorizon, beyond which there was, supposedly, another Universe.

   • 2010, Enrico Rodrigo, The Physics of Stargates‎^[3]:

     To distant observers the light appears, due to gravitational time dilation, to slow down as it approaches the antihorizon.