| Abstract from DBPedia | In Einstein's theory of general relativity, the Schwarzschild metric (also known as the Schwarzschild solution) is an exact solution to the Einstein field equations that describes the gravitational field outside a spherical mass, on the assumption that the electric charge of the mass, angular momentum of the mass, and universal cosmological constant are all zero. The solution is a useful approximation for describing slowly rotating astronomical objects such as many stars and planets, including Earth and the Sun. It was found by Karl Schwarzschild in 1916, and around the same time independently by , who published his more complete and modern-looking discussion four months after Schwarzschild. According to Birkhoff's theorem, the Schwarzschild metric is the most general spherically symmetric vacuum solution of the Einstein field equations. A Schwarzschild black hole or static black hole is a black hole that has neither electric charge nor angular momentum. A Schwarzschild black hole is described by the Schwarzschild metric, and cannot be distinguished from any other Schwarzschild black hole except by its mass. The Schwarzschild black hole is characterized by a surrounding spherical boundary, called the event horizon, which is situated at the Schwarzschild radius, often called the radius of a black hole. The boundary is not a physical surface, and a person who fell through the event horizon (before being torn apart by tidal forces), would not notice any physical surface at that position; it is a mathematical surface which is significant in determining the black hole's properties. Any non-rotating and non-charged mass that is smaller than its Schwarzschild radius forms a black hole. The solution of the Einstein field equations is valid for any mass M, so in principle (according to general relativity theory) a Schwarzschild black hole of any mass could exist if conditions became sufficiently favorable to allow for its formation. In the vicinity of a Schwarschild black hole, space curves so much that even light rays are deflected, and very nearby light can be deflected so much that it travels several times around the black hole.アインシュタインによる一般相対性理論において、シュワルツシルト解（シュワルツシルトかい、英: Schwarzschild solution、シュワルツシルト計量 Schwarzschild metric、シュワルツシルト真空 Schwarzschild vacuum とも。なお、シュワルツシルトでなくシュヴァルツシルトとも呼ばれる）とは、アインシュタイン方程式の厳密解の一つで、球対称で静的な質量分布の外部にできる重力場を記述する。ただし、電荷や角運動量、宇宙定数はすべてゼロとする。この解は太陽や地球など、十分に自転の遅い恒星や惑星が外部の真空空間に及ぼす重力を近似的に表わすことができ、応用されている。名称については、この解を1916年に初めて発表したカール・シュヴァルツシルトに由来する。 (Source: http://dbpedia.org/resource/Schwarzschild_metric) |
