For the movie, see Event Horizon

Part of a series of articles about
General relativity
\displaystyle{ G_{\mu \nu} + \Lambda g_{\mu \nu}= {8\pi G\over c^4} T_{\mu \nu} }
Introduction History Mathematical formulation Tests
Fundamental concepts Principle of relativity Theory of relativity Frame of reference Inertial frame of reference Rest frame Center-of-momentum frame Equivalence principle Mass–energy equivalence Special relativity Doubly special relativity de Sitter invariant special relativity World line Riemannian geometry
Phenomena Gravitoelectromagnetism Kepler problem Gravity Gravitational field Gravity well Gravitational lensing Gravitational waves Gravitational redshift Redshift Blueshift Time dilation Gravitational time dilation Shapiro time delay Gravitational potential Gravitational compression Gravitational collapse Frame-dragging Geodetic effect Gravitational singularity Event horizon Naked singularity Black hole White hole Spacetime Space Time Spacetime diagrams Minkowski spacetime Closed timelike curve (CTC) Wormhole Ellis wormhole
Equations Formalisms Equations Linearized gravity Einstein field equations Friedmann Geodesics Mathisson–Papapetrou–Dixon Hamilton–Jacobi–Einstein Curvature invariant (general relativity) Lorentzian manifold Formalisms ADM BSSN Post-Newtonian Advanced theory Kaluza–Klein theory Quantum gravity Supergravity
Solutions Schwarzschild (interior) Reissner–Nordström Gödel Kerr Kerr–Newman Kasner Lemaître–Tolman Taub-NUT Milne Robertson–Walker pp-wave van Stockum dust Weyl−Lewis−Papapetrou Vacuum solution (general relativity) Vacuum solution
Scientists Einstein Lorentz Hilbert Poincaré Schwarzschild de Sitter Reissner Nordström Weyl Eddington Friedman Milne Zwicky Lemaître Gödel Wheeler Robertson Bardeen Walker Kerr Chandrasekhar Ehlers Penrose Hawking Raychaudhuri Taylor Hulse van Stockum Taub Newman Yau Thorne others

In general relativity, an event horizon is the part of a black hole where light cannot escape. Imagine the black hole to be like a ball that you could see in a large spot of emptiness. The event horizon would then be an outer bubble that surrounds that ball, the space between the ball and the larger bubble would be the event horizon. If an object goes past the event horizon, it can never get away from it. Light that is emitted from inside of the event horizon near the black hole can never reach an observer on the other side. If an observer saw an object fall into a black hole, it would look like the object was stuck at the event horizon forever. The reason this happens is because of the gravity of the black hole slows down time around it, making it look like the object will take an infinite amount of time to reach it. view more...