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 t0, 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.