Entropy (disambiguation)

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Entropy, in thermodynamics, is a state function originally introduced to explain why part of a thermodynamic system's total energy is unavailable to do useful work.

Entropy may also refer to:

Thermodynamics and statistical mechanics

• Entropy (classical thermodynamics), thermodynamic entropy in purely 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

Introductory articles

• Introduction to entropy an explanation on entropy as a measure of irreversibility
• Entropy (order and disorder) an explanation of what heat and work have to do with disorder
• 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, research concerning the relationship between the thermodynamic quantity 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.
• Algorithmic entropy an (incomputable) measure of the information content of a particular message.
• Rényi entropies, 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.
• Volume entropy, a Riemannian invariant measuring the exponential rate of volume growth of a Riemannian metric
• Maximum entropy (disambiguation)

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

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

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 VNV Nation from Matter + Form
• "Entropy", a song by Moxy Früvous from The 'b' Album
• "Entropy", a song by MC Hawking
• "Entropy", a song by Grimes and Bleachers
• Entropia (album), an album by Pain of Salvation

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