Changes

[[Image:Iu8969hu.jpg|right|thumb|300px|Artist's conception of a binary system consisting of a black hole and a main sequence star.  The black hole is drawing matter from the main sequence star via an [[accretion disk]] around it, and some of this matter forms a gas jet.]]

[[Image:Iu8969hu.jpg|right|thumb|300px|Artist's conception of a binary system consisting of a black hole and a main sequence star.  The black hole is drawing matter from the main sequence star via an [[accretion disk]] around it, and some of this matter forms a gas jet.]]

==Nature of a Black Hole==

==Nature of a Black Hole==

A '''black hole''' is a mass with an infinitesimal volume, and therefore an infinite density. This gives them an escape velocity greater than the speed of light, meaning that light cannot escape from them due to their steep “gravity wells.”  As this renders black holes invisible by traditional means of observation, scientists discover their locations through indirect means, such as the effect of their gravitational pull on nearby stars. Stars that are near black holes, e.g. by being part of a binary star system that contains one, show wobbles in their orbits similar to the tidal effects of the moon on Earth’s oceans. <ref>http://library.thinkquest.org/C007571/english/advance/english.htm</ref><ref>''Black Holes'' by Heather Cooper and Nigel Henbest (book)</ref> While matter and energy, even light, may not escape a black hole, Stephen Hawking has shown that they should emit Hawking radiation, which absent of an influx of mass-energy would lead to the evaporation of the black hole in a burst of gamma rays. Scientists are currently working to pick up one of these bursts, or the radiation itself, with any of several land- and space-based telescopes. However, the matter falling into black holes as well as the cosmic microwave background from the Big Bang obscures the radiation and inhibits its detection. The outer surface of a black hole is an event horizon, a non-material dimensional boundary, beyond which nothing can escape. The center of a black hole, where the mass exists, is called the singularity. The distance from the singularity to the event horizon is known as the Schwarzschild radius. All matter that falls into a black hole becomes part of the singularity, and as such is effectively destroyed.

A '''black hole''' is a theoretical mass with an infinitesimal volume, and therefore an infinite density. This gives them an escape velocity greater than the speed of light, meaning that light cannot escape from them due to their steep “gravity wells.”  As this renders black holes invisible by traditional means of observation, scientists discover their locations through indirect means, such as the effect of their gravitational pull on nearby stars. Stars that are near black holes, e.g. by being part of a binary star system that contains one, show wobbles in their orbits similar to the tidal effects of the moon on Earth’s oceans. <ref>http://library.thinkquest.org/C007571/english/advance/english.htm</ref><ref>''Black Holes'' by Heather Cooper and Nigel Henbest (book)</ref> While matter and energy, even light, may not escape a black hole, Stephen Hawking has shown that they should emit Hawking radiation, which absent of an influx of mass-energy would lead to the evaporation of the black hole in a burst of gamma rays. Scientists are currently working to pick up one of these bursts, or the radiation itself, with any of several land- and space-based telescopes. However, the matter falling into black holes as well as the cosmic microwave background from the Big Bang obscures the radiation and inhibits its detection. The outer surface of a black hole is an event horizon, a non-material dimensional boundary, beyond which nothing can escape. The center of a black hole, where the mass exists, is called the singularity. The distance from the singularity to the event horizon is known as the Schwarzschild radius. All matter that falls into a black hole becomes part of the singularity, and as such is effectively destroyed.

 

==Origins of Black Holes==

==Origins of Black Holes==