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[edit]

  • Classical thermodynamic entropy, the original meaning, a state function introduced by Rudolph Clausius to explain why part of a thermodynamic system's total energy is unavailable to do useful work
  • Gibbs entropy Entropy in classical statistical physics, a measure of disorder, proportional to the logarithm of the number of microstates comprising a macrostate
  • von Neumann entropy Entropy in quantum statistical physics, the quantum analog of Gibbs entropy

Introductory articles[edit]

Other aspects[edit]

Information theory and mathematics[edit]

  • Entropy (information theory), also called Shannon entropy, a measure of the unpredictability or information content of a message source.
  • Algorithmic entropy an (uncomputable) 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

Other uses in science and technology[edit]

  • 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[edit]

Film and television[edit]

Games[edit]

Literature[edit]

Music[edit]

Software[edit]

See also[edit]