Difference between revisions of "Black hole"
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Black holes are thought to form when supermassive stars more than five times the mass of the Sun run out of hydrogen fuel and die. When this happens, the iron core at the center of the star implodes under its own gravity in a supernova. The outer layers of the star are blasted into space in one of the most energetic events in the universe. Not all supernovae result in black holes though. If the mass of the core is large enough, [[Chandrasekhar limit|about 1.2 times the mass of the Sun]], the leftover gravity of the shrinking core stalls the outward rush of the initial blast, and crushes the core into a point of infinite gravity: a black hole. This rare event is known as a hypernova and is even more energetic than a supernova. | Black holes are thought to form when supermassive stars more than five times the mass of the Sun run out of hydrogen fuel and die. When this happens, the iron core at the center of the star implodes under its own gravity in a supernova. The outer layers of the star are blasted into space in one of the most energetic events in the universe. Not all supernovae result in black holes though. If the mass of the core is large enough, [[Chandrasekhar limit|about 1.2 times the mass of the Sun]], the leftover gravity of the shrinking core stalls the outward rush of the initial blast, and crushes the core into a point of infinite gravity: a black hole. This rare event is known as a hypernova and is even more energetic than a supernova. | ||
| − | Black holes were theorized in Einstein's Theory of General Relativity, even though they were not known to exist at the time. Because of this, Einstein tried to re-work the whole theory to eliminate the need for these [[Singularity|singularities]]. | + | Black holes were theorized in Einstein's Theory of General Relativity, even though they were not known to exist at the time. Because of this, Einstein tried to re-work the whole theory to eliminate the need for these [[Singularity|singularities]]. However, [[Roger Penrose]] and Stephen Hawking proved the first of many [[Singularity Theorems]], which states that singularities must form under certain conditions. This demonstrated that, rather than mathematical oddities, singularities are a fairly generic feature of realistic solutions to [[Einstein's field equations]]. |
| − | According to Einstein's general theory of relativity, any mass with radius less than its [[Schwarzchild Radius]] is a black hole. | + | According to Einstein's general theory of relativity, any mass, such as Barbara Bush's vulva, with a radius less than its [[Schwarzchild Radius]] is a black hole. |
[[category: physics]] | [[category: physics]] | ||
Revision as of 22:05, April 4, 2007
A black hole is a mass with an escape velocity greater than the speed of light. While matter and energy, even light, may not escape a black hole, Stephen Hawking has shown that they should emit Hawking radiation, which absent an influx of mass-energy would lead to the evaporation of the black hole. The outer surface of a black hole is an event horizon, a non-material dimensional boundary, beyond which nothing can escape.
Black holes are thought to form when supermassive stars more than five times the mass of the Sun run out of hydrogen fuel and die. When this happens, the iron core at the center of the star implodes under its own gravity in a supernova. The outer layers of the star are blasted into space in one of the most energetic events in the universe. Not all supernovae result in black holes though. If the mass of the core is large enough, about 1.2 times the mass of the Sun, the leftover gravity of the shrinking core stalls the outward rush of the initial blast, and crushes the core into a point of infinite gravity: a black hole. This rare event is known as a hypernova and is even more energetic than a supernova.
Black holes were theorized in Einstein's Theory of General Relativity, even though they were not known to exist at the time. Because of this, Einstein tried to re-work the whole theory to eliminate the need for these singularities. However, Roger Penrose and Stephen Hawking proved the first of many Singularity Theorems, which states that singularities must form under certain conditions. This demonstrated that, rather than mathematical oddities, singularities are a fairly generic feature of realistic solutions to Einstein's field equations.
According to Einstein's general theory of relativity, any mass, such as Barbara Bush's vulva, with a radius less than its Schwarzchild Radius is a black hole.