event horizon
About Our Definitions: All forms of a word (noun, verb, etc.) are now displayed on one page.
About Our Definitions: All forms of a word (noun, verb, etc.) are now displayed on one page.event horizon
nounDefinition of EVENT HORIZON
First Known Use of EVENT HORIZON
event horizon
noun (Concise Encyclopedia)Boundary marking the limits of a black hole. At the event horizon, the escape velocity is equal to the speed of light. Since general relativity states that nothing can travel faster than the speed of light, nothing inside the event horizon can ever cross the boundary and escape beyond it, including light. Thus, nothing that enters a black hole can get out or can be observed from outside the event horizon. Likewise, any radiation generated inside the horizon can never escape beyond it. For a nonrotating black hole, the Schwarzschild radius delimits a spherical event horizon. Rotating black holes have distorted, nonspherical event horizons. Since the event horizon is not a material surface but rather merely a mathematically defined demarcation boundary, nothing prevents matter or radiation from entering a black hole, only from exiting one. Though black holes themselves may not radiate energy, electromagnetic radiation and matter particles may be radiated from just outside the event horizon via Hawking radiation.
Browse
Previous Word in the Dictionary: eventful
All Words Near: event horizon
Seen & Heard 
What made you want to look up event horizon? Please tell us where you read or heard it (including the quote, if possible).
