The density matrix was introduced to develop one quantity of this type in quantum mechanics, named for Von Neumann.
One quantity of this type used for fractals is named for Renyi, and the topological type is an extension of the Kolmogorov-Sinai variety. The density matrix was introduced to develop one quantity of this type in quantum mechanics, named for Von Neumann. Bekenstein and Hawking showed that black holes mazimize this quantity for a given object size. Equal to the integral of heat over temperature, it is the only physical quantity associated with an arrow of time. Also having notable Shannon and Boltzmann varieties, for 10 points, name this quantity, which increases constantly according to the Second Law of Thermodynamics.
One quantity of this type used for fractals is named for Renyi, and the topological type is an extension of the Kolmogorov-Sinai variety.
{Entropy}