Black hole

:This article is about an object in astrophysics. For other uses, see Black hole (disambiguation).

Related Topics:
Astrophysics - Black hole (disambiguation)

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A black hole is a concentration of mass great enough that the force of gravity prevents anything from escaping from it except through quantum tunneling behavior. The gravitational field is so strong that the escape velocity near it exceeds the speed of light. This implies that nothing, not even light, can escape its gravity, hence the word "black". The term "black hole" is widespread, even though it does not refer to a hole in the usual sense, but rather a region of space from which nothing can return.

Related Topics:
Mass - Quantum tunneling - Gravitational field - Escape velocity - Speed of light - Light - Gravity

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Black holes are predicted by general relativity. According to classical general relativity, neither matter nor information can flow from the interior of a black hole to an outside observer. For example, one cannot bring out any of its mass, or receive a reflection back by shining a light source such as a flashlight, or retrieve any information about the material that has entered the black hole. Quantum-mechanical effects may allow matter and energy to radiate from black holes; however, it is thought that the nature of the radiation does not depend on what has fallen into the black hole in the past.

Related Topics:
General relativity - Information - Quantum-mechanical - Matter - Energy - Radiate

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The existence of black holes in the universe is well supported by astronomical observation, particularly from studying supernovae and X-ray emissions from active galactic nuclei.

Related Topics:
Supernovae - X-ray - Active galactic nuclei

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