افق ِ رویداد ofoq-e ruydâd (#)
*Fr.: horizon d'événement*
1) The surface surrounding a → *black hole* with the property
that any light ray emitted inside it cannot escape to the outer space because of the
strength of the → *gravitational field*. The radius of the
event horizon is called the → *Schwarzschild radius*.
See also → *photon sphere*.
2) For an observer *A* at the instant *t*_{0}, the surface in the
→ *space-time* that divides the collection of
all events into two non-empty classes: those events that
have been, are being, or will be observed by *A*, and those that *A*
has never observed and will never be able to observe
(J. Plebanski, A. Krasinski, 2006, An Introduction to General Relativity
and Cosmology, Cambridge Univ. Press). → *event*; → *horizon*. |