In general relativity, an **event horizon** is a boundary in spacetime beyond which events cannot affect an outside observer. In layman's terms it is defined as "the point of no return" i.e. the point at which the gravitational pull becomes so great as to make escape impossible. The most common case of an event horizon is that surrounding a black hole. Light emitted from beyond the horizon can never reach the observer. Likewise, any object approaching the horizon from the observer's side appears to slow down and never quite pass through the horizon, with its image becoming more and more redshifted as time elapses. The traveling object, however, experiences no strange effects and does, in fact, pass through the horizon in a finite amount of proper time.

More specific types of horizon include the related but distinct absolute and apparent horizons found around a black hole. Still other distinct notions include the Cauchy and Killing horizon; the photon spheres and ergospheres of the Kerr solution; particle and cosmological horizons relevant to cosmology; and isolated and dynamical horizons important in current black hole research.

Read more about Event Horizon: Event Horizon of A Black Hole, Particle Horizon of The Observable Universe, Apparent Horizon of An Accelerated Particle, Interacting With An Event Horizon, Beyond General Relativity

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**Event Horizon**- Beyond General Relativity

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... The particle

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**horizon**, the light

**horizon**, or the cosmic light

**horizon**) is the maximum distance from which particles could have traveled to the observer in the age of the ... The existence, properties, and significance of a cosmological

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**Event Horizon**(disambiguation)

... An

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**events**can not affect an outside observer ...

**Event horizon**or

**Event Horizon**may also refer to

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**Event Horizon**", a 2006 track by Detroit techno moniker Arpanet

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**Event Horizon**

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### Famous quotes containing the words horizon and/or event:

“Four spectres haunt the Poor—Old Age, Accident, Sickness and Unemployment. We are going to exorcise them. We are going to drive hunger from the hearth. We mean to banish the workhouse from the *horizon* of every workman in the land.”

—David Lloyd George (1863–1945)

“A society which allows an abominable *event* to burgeon from its dungheap and grow on its surface is like a man who lets a fly crawl unheeded across his face or saliva dribble unstemmed from his mouth—either epileptic or dead.”

—Jean Baudrillard (b. 1929)