cosmological horizon
1Cosmological horizon — In physical cosmology, a cosmological horizon marks a limit to observability, and marks the boundary of a region that an observer cannot see into directly due to cosmological effects.The existence, properties, and significance of a cosmological… …
2cosmological horizon — noun A boundary to the universe that any particular observer can observe …
3Horizon (disambiguation) — Horizon is the line at which the sky and the earth s surface appear to meet.Horizon or horizons may also refer to:Business* Horizon Global, a corporation specializing in media compression technology, peer to peer video telephony, and video on… …
4Horizon (general relativity) — There are several types of spacetime horizons that play a role in Einstein s theory of general relativity:* Absolute horizon, a boundary in spacetime in general relativity inside of which events cannot affect an external observer * Apparent… …
5Horizon problem — The horizon problem is a problem with the standard cosmological model of the Big Bang which was identified in the 1970s. It points out that different regions of the universe have not contacted each other due to the great distances between them,… …
6Event horizon — In general relativity, an event horizon is a boundary in spacetime, an area surrounding a black hole or a wormhole, inside which events cannot affect an outside observer. Light emitted from inside the horizon can never reach the observer, and… …
7Apparent horizon — An apparent horizon is a surface defined in general relativity as the boundary between light rays which are directed outwards and moving outwards, and those which are directed outwards but moving inwards.Apparent horizons are not invariant… …
8Absolute horizon — 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… …
9Particle horizon — NOTOC In physical cosmology, particle horizon is the maximum distance from which particles could have traveled to the observer in the age of the universe. It represents the portion of the universe which we could have conceivably observed at the… …
10Killing horizon — A Killing horizon is a null hypersurface on which there is a null Killing vector field.Associated to a Killing horizon is a geometrical quantity known as surface gravity, kappa. If the surface gravity vanishes, then the Killing horizon is said to …
