Entropy (disambiguation)

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Entropy originates from machine engineering, where in a process involving heat it is a measure of the portion of heat becoming unavailable for doing work, e.g. reversal of the process just mentioned. Entropy is also frequently used with emphasis of order or disorder properties of disparate areas and surveyed in the following:

Thermodynamics

• Entropy (classical thermodynamics), the macroscopic approach to thermodynamic entropy
  • Entropy (energy dispersal), a variant perspective on thermodynamic entropy
• Entropy (statistical thermodynamics), the microscopic approach to thermodynamic entropy
• Gibbs entropy, statistical entropy of a thermodynamic system
  • Boltzmann entropy, an approximation to Gibbs entropy
  • Tsallis entropy, a generalization of Boltzmann-Gibbs entropy
• von Neumann entropy, entropy of a quantum-mechanical system
• Entropy (order and disorder), entropy's association with the amount of order, disorder, and/or chaos in a thermodynamic system
• History of entropy, concept of entropy that functional energy released from combustion reactions is always lost to dissipation or friction
• Introduction to entropy
• Entropy and life, research concerning the relationship between the thermodynamic quantity entropy and the evolution of life
• Entropy (astrophysics), the adiabatic constant
• Entropy (arrow of time), thermodynamic arrow of time

Interdisciplinary applications of entropy

Although the concept of entropy was originally a thermodynamic construct, it has been adapted in other fields of study, including information theory, psychodynamics, economics, and evolution.

Information theory and mathematics

• Entropy (information theory), a measure of the amount of information contained in a message
• Entropy encoding, data compression strategies to produce a code length equal to the entropy of a message
• Kolmogorov–Sinai entropy, the rate of information generation by a measure-preserving dynamical system
• Rényi entropy, a family of diversity measures used to define fractal dimensions
• Topological entropy, a measure of exponential growth in the number of distinguishable orbits of a dynamical system
• Volume entropy, a Riemannian invariant measuring the exponential rate of volume growth of a Riemannian metric

Computer science

• Entropy (computing), a discussion of entropy generation and API's in computer systems
• 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

Ecology

• Entropy (ecology), a measure of biodiversity in the study of biological ecology

Mathematics

• Kolmogorov-Sinai entropy, a mathematical type of entropy in dynamical systems related to measures of partitions
• Relative entropy, is a natural distance measure from a "true" probability distribution P to an arbitrary probability distribution Q
• Rényi entropy, a generalized entropy measure for fractal systems
• Topological entropy, a way of defining entropy in an iterated function map in ergodic theory
• Volume entropy, a Riemannian invariant measuring the exponential rate of volume growth

Sociology

The concept of entropy has also entered the domain of sociology, generally as a metaphor for chaos, disorder or dissipation of energy, rather than as a direct measure of thermodynamic or information entropy:

• Economic entropy, a semi-quantitative measure of the irrevocable dissipation and degradation of natural materials and available energy with respect to economic activity
• Psychological entropy, the distribution of energy in the psyche, which tends to seek equilibrium or balance among all the structures of the psyche
• Social entropy, a measure of social system structure, having both theoretical and statistical interpretations, i.e. society (macrosocietal variables) measured in terms of how the individual functions in society (microsocietal variables); also related to social equilibrium

Economics

• Thermoeconomics and ecological economics, applications of the laws of thermodynamics to economic theory
• Generalized entropy index, a general formula for measuring redundancy in data
  • Theil index, a special case of the generalized entropy index used to measure economic inequality
• Entropy: A New World View, a book by Jeremy Rifkin and Ted Howard

Medicine

• Entropy (anesthesiology), a measure of a patient's cortical function

Media and popular culture

Films

• "Entropy" (Buffy episode)
• Entropy (film), a 1999 film by Phil Joanou

Games

• Entropy (1977 board game)
• Entropy (1994 board game)
• Entropy is the name the character "Alchemiss" went by in Freedom Force vs the 3rd Reich, after she went insane over the sudden expansion of her powers.

Music

• Entropy (album), an album by Anathallo and Javelins
• Entropy / Send Them, a hip-hop suite 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
• Entropia (album), debut album by Swedish band Pain of Salvation

Stories

• "Entropy", a 1960 short story by Thomas Pynchon
• "Entropy", a 1995 short story by Leanne Frahm

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