Black hole

A black hole is an object in spacetime that is the result of collapsing matter following the explosion of large stars into supernovae. For a star to be capable of compaction into a singularity, it must have a mass greater than 3.4 times that of the Sun. There are both rotating and stationary black holes, a singularity and event horizon(s) being the major features of both. The event horizon is the boundary of a black hole where gravitational forces become so strong that not even light can escape. Relativity states that the singularity is a point of infinite space time curvature, and the singularity of a black hole is covered by the event horizon.

Specifically, if the remnants of a star which has exhausted the energy available from nuclear fusion reactions are greater than about 3.4 times the mass of the sun, electron degeneracy and neutron degeneracy are insufficient to prevent the star from collapsing into a black hole. A black hole's density is so great that the escape velocity at the surface is greater than the speed of light, therefore no light can escape. To an observer, objects falling into a black hole will take an infinite amount of time to reach the event horizon. However, the amount of time as measured by the object falling into the black hole can be very short.

According to quantum mechanics, the location of the matter within a black hole is uncertain. Additionally, a phenomenon called Hawking radiation predicts that black holes can "leak" a very small amount of mass. So theoretically, black holes are not truly "black" due to emitted radiation. Black holes have a surface temperature defined by their mass. The larger the mass of a black hole, the larger the diameter, and the lower the amount of energy which escapes, thus the lower the temperature, and the longer the time it takes for the black hole to "evaporate".