Entropy, in thermodynamics, is a property originally introduced to explain the part of the internal energy of a thermodynamic system that is unavailable as a source for useful work.
Entropy may also refer to:
Thermodynamics and statistical mechanics
- Entropy (classical thermodynamics), thermodynamic entropy in macroscopic terms, with less emphasis on the statistical explanation
- Entropic force. The product of temperature and the gradient of the entropy density is viewed an effective force, yielding a gradient in the energy density of a system.
- Entropy (statistical thermodynamics), the statistical explanation of thermodynamic entropy based on probability theory
- Configuration entropy, the entropy change due to a change in the knowledge of the position of particles, rather than their momentum
- Conformational entropy, the entropy change due to a change in the "configuration" of a particle (e.g. a right-handed vs. a left-handed polyatomic molecule)
- Tsallis entropy, a generalization of Boltzmann-Gibbs entropy
- von Neumann entropy, entropy in quantum statistical physics and quantum information science
Introductory articles
- Introduction to entropy an explanation on entropy as a measure of irreversibility
- Entropy (order and disorder), the relationship of disorder with heat and work
- Entropy in thermodynamics and information theory, the relationship between thermodynamic entropy and information (Shannon) entropy
- Entropy (energy dispersal), dispersal of energy as a descriptor of entropy
Other aspects
- History of entropy
- Entropy and life, the relationship between the thermodynamic entropy and the evolution of life
- Entropy (astrophysics), the adiabatic constant
Information theory and mathematics
- Entropy (information theory), also called Shannon entropy, a measure of the unpredictability or information content of a message source
- Entropy of entanglement, related to the Shannon and von Neumann entropies for entangled systems; reflecting the degree of entanglement of subsystems
- Algorithmic entropy an (incomputable) measure of the information content of a particular message
- Rényi entropy, a family of diversity measures generalising Shannon entropy; used to define fractal dimensions
- Measure theoretic entropy, a measure of exponential growth in dynamical systems; equivalent to the rate of increase of Shannon entropy of a trajectory in trajectory-space
- Topological entropy, a measure of exponential growth in dynamical systems; equivalent to the rate of increase of α->0 Renyi entropy of a trajectory in trajectory-space.
- Topological entropy in physics
- Volume entropy, a Riemannian invariant measuring the exponential rate of volume growth of a Riemannian metric
- Maximum entropy (disambiguation)
- Graph entropy, a measure of the information rate achievable by communicating symbols over a channel in which certain pairs of values may be confused.
Other uses in science and technology
- Entropy encoding, data compression strategies to produce a code length equal to the entropy of a message
- Entropy (computing), an indicator of the number of random bits available to seed cryptography systems
- Entropy (anesthesiology), a measure of a patient's cortical function, based on the mathematical entropy of EEG signals
- Entropy (ecology), measures of biodiversity in the study of biological ecology, based on Shannon and Rényi entropies
- Social entropy, a measure of the natural decay within a social system
Media
Film and television
- Entropy (film), a 1999 film by Phil Joanou
- "Entropy" (Buffy episode)
- "Entropy", an episode of Criminal Minds (season 11)
Games
- Entropy (1977 board game)
- Entropy (1994 board game)
- Entropy (video game)
- Entropy or Alchemiss, a character in Freedom Force vs the 3rd Reich
- N. Tropy, a character from Crash Bandicoot: Warped
Literature
- Entropy: A New World View, a book by Jeremy Rifkin and Ted Howard
- "Entropy", a 1960 short story by Thomas Pynchon
- "Entropy", a 1995 short story by Leanne Frahm
- Entropy (journal), a scientific journal published by MDPI
- Entropy (magazine), an online literary magazine
Music
- Entropy (album), an album by Anathallo and Javelins
- Entropy / Send Them, an EP by DJ Shadow and the Groove Robbers
- "Entropy", a song by Bad Religion from Against the Grain
- "Entropy", a song by Kelly Osbourne from Sleeping in the Nothing
- "Entropy", a song by VNV Nation from Matter + Form
- "Entropy", a song by Moxy Früvous from The 'b' Album
- "Entropy", a song by Brymo from Oṣó
- "Entropy", a song by Daniel Caesar from Case Study 01
- "Entropy", a song by MC Hawking
- "Entropy", a song by Grimes and Bleachers
- Entropia (album), an album by Pain of Salvation
- Entropy, a track by Nigel Stanford
- The Book Of Us: Entropy, an album by DAY6.
- Entropy, a punk band from Grand Rapids, MI, active in the late 1990s
Software
- Entropy (package manager), a Sabayon Linux package manager
- Entropy (anonymous data store), a discontinued project to build a computer network designed to be resistant to censorship