Black hole entropy is entropy carried by a black hole. The thermodynamic entropy S (simply entropy in the context of thermodynamics) of a system is a measure of the uniqueness of its state in terms of its energy. ... Jump to: navigation, search 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. ...

If black hole carried no entropy, it would be possible to violate the second law of thermodynamics by throwing mass into the black hole. The only way to satisfy the second law is to admit that the black holes have entropy whose increase more-than-compensates the decrease of the entropy carried by the object that was swallowed. The second law of thermodynamics is a law of thermodynamics that states that all work tends towards the production of greater entropy over time. ...

Starting from some theorems proved by Stephen Hawking, Jacob Bekenstein conjectured that the black hole entropy was proportional to the area of its event horizon. Later, Stephen Hawking showed that black holes emit thermal Hawking radiation corresponding to a certain temperature (Hawking temperature). Using some arguments rooted in thermodynamics, Hawking was also able to calculate the entropy that the black hole must carry. The result confirmed Bekenstein's conjecture: Hawking as himself on Star Trek: The Next Generation Stephen William Hawking, CH, CBE, FRS (born January 8, 1942, in Oxford, England) is one of the worlds leading theoretical physicists. ... Jacob David Bekenstein (born May 1, 1947), in Mexico City, has contributed to the foundation of black hole thermodynamics and to other aspects of the connections between information and gravitation. ... Event Horizon is a 1997 science fiction and horror film. ... a black hole formul , in natural units with G, c, and k equal to 1, and where is the surface gravity of the horizon. ... This article needs to be cleaned up to conform to a higher standard of quality. ...

where k is Boltzmann's constant, and is the Planck length. The black hole entropy is proportional to its area A. The fact that the black hole entropy is also the maximal entropy that can be squeezed within a fixed volume was the main observation that led to the holographic principle. The subscript BH either stands for "black hole" or "Bekenstein-Hawking". The Boltzmann constant (k or kB) is the physical constant relating temperature to energy. ... The Planck length is the natural unit of length, denoted by . ... The holographic principle is a speculative conjecture about quantum gravity theories, proposed by Gerard t Hooft and improved and promoted by Leonard Susskind, claiming that all of the information contained in a volume of space can be represented by a theory that lives in the boundary of that region. ...

Until 1995, no one was able to make a controlled calculation of black hole entropy based on statistical mechanics, i.e. on counting the number of actual microstates. The situation changed in 1995 when Andrew Strominger and Cumrun Vafa calculated the right Bekenstein-Hawking entropy of a supersymmetric black hole in string theory, using methods based on D-branes. Their calculation was followed by many similar computations of entropy of large classes of other extremal and near-extremal black holes, and the result always agreed with the Bekenstein-Hawking formula. Statistical mechanics is the application of statistics, which includes mathematical tools for dealing with large populations, to the field of mechanics, which is concerned with the motion of particles or objects when subjected to a force. ... American theoretical physicist who works on string theory. ... Cumrun Vafa is a leading string theorist from Harvard University where he started as a Harvard Junior Fellow. ... In particle physics, supersymmetry is a hypothetical symmetry that relates bosons and fermions. ... String theory is a model of fundamental physics whose building blocks are one-dimensional extended objects (strings) rather than the zero-dimensional points (particles) that are the basis of the Standard Model of particle physics. ... In theoretical physics, D-branes are a special class of p-branes, named for the physicist Johann Dirichlet. ... In theoretical physics, an extremal black hole is a black hole with the minimal possible mass that can be compatible with the given charges and angular momentum. ... In theoretical physics, a near-extremal black hole is a black hole which is not far from the minimal possible mass that can be compatible with the given charges and angular momentum. ...

Loop quantum gravity, viewed as the main competitor of string theory, also offered a slightly more heuristic calculation of the black hole entropy. Unfortunately, the numerical coefficient 1 / 4 was not reproduced correctly. The multiplicative discrepancy is called the Immirzi parameter. Loop quantum gravity (LQG), also known as loop gravity, quantum geometry and canonical quantum general relativity, is a proposed quantum theory of spacetime which attempts to blend together the seemingly incompatible theories of quantum mechanics and general relativity. ... The Immirzi parameter (also known as the Barbero-Immirzi parameter) is a numerical coefficient appearing in loop quantum gravity, a nonperturbative theory of quantum gravity. ...