ISBN: | 978-5-5110-5577-0 |
High Quality Content by WIKIPEDIA articles! In general relativity, an absolute horizon is a boundary in spacetime, defined with respect to the external universe, inside of which events cannot affect an external observer. Light emitted inside the horizon can never reach the observer, and anything that passes through the horizon from the observer`s side is never seen again. An absolute horizon is the boundary of a black hole by definition.