Definitions for event horizon
event hori·zon

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1. event horizonnoun

   the boundary surface surrounding a black hole, from outside of which nothing inside can be observed, because nothing inside that surface, even light, can escape beyond it. See also black hole and escape velocity.

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1. event horizonnoun

   The gravitational sphere of a black hole within which the escape velocity is greater than the speed of light, causing time to practically stop.

2. event horizonnoun

   A point of no return, by analogy to the astronomical usage

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1. Event horizon

   In astrophysics, an event horizon is a boundary beyond which events cannot affect an observer. Wolfgang Rindler coined the term in the 1950s.In 1784, John Michell proposed that gravity can be strong enough in the vicinity of massive compact objects that even light cannot escape. At that time, the Newtonian theory of gravitation and the so-called corpuscular theory of light were dominant. In these theories, if the escape velocity of the gravitational influence of a massive object exceeds the speed of light, then light originating inside or from it can escape temporarily but will return. In 1958, David Finkelstein used general relativity to introduce a stricter definition of a local black hole event horizon as a boundary beyond which events of any kind cannot affect an outside observer, leading to information and firewall paradoxes, encouraging the re-examination of the concept of local event horizons and the notion of black holes. Several theories were subsequently developed, some with and some without event horizons. One of the leading developers of theories to describe black holes, Stephen Hawking, suggested that an apparent horizon should be used instead of an event horizon, saying, "gravitational collapse produces apparent horizons but no event horizons." He eventually concluded that "the absence of event horizons means that there are no black holes – in the sense of regimes from which light can't escape to infinity."Any object approaching the horizon from the observer's side appears to slow down, never quite crossing the horizon. Due to gravitational redshift, its image reddens over time as the object moves away from the observer.In an expanding universe, the speed of expansion reaches — and even exceeds — the speed of light, preventing signals from traveling to some regions. A cosmic event horizon is a real event horizon because it affects all kinds of signals, including gravitational waves, which travel at the speed of light.

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1. Event horizon

   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 outside 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.

How to pronounce event horizon?

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How to say event horizon in sign language?

Numerology

1. Chaldean Numerology

   The numerical value of event horizon in Chaldean Numerology is: 5

2. Pythagorean Numerology

   The numerical value of event horizon in Pythagorean Numerology is: 9

Examples of event horizon in a Sentence

1. Freek Roelofs:

   There are lots of advantages to using satellites instead of permanent radio telescopes on Earth, as with the Event Horizon Telescope( EHT), in space, you can make observations at higher radio frequencies, because the frequencies from Earth are filtered out by the atmosphere.

References

1. ^ GCIDE
   https://gcide.gnu.org.ua/?q=event horizon
2. ^ Wiktionary
   https://en.wiktionary.org/wiki/Event_Horizon
3. ^ Wikipedia
   https://en.wikipedia.org/wiki/Event_Horizon
4. ^ Wikidata
   https://www.wikidata.org/w/index.php?search=event horizon