Entropy (disambiguation)

Entropy is the thermodynamic homogeneity of a system, limiting the ability to extract mechanical work.

Entropy can also have one of several other meanings:

In science and technology:

• Entropy (classical thermodynamics), macroscopic understanding of thermodynamic entropy
• Entropy (statistical thermodynamics), microscopic understanding of thermodynamic entropy
• Gibbs entropy, statistical entropy of a thermodynamic system
• von Neumann entropy, entropy of a quantum-mechanical system
• Boltzmann entropy formula, S = k ln W
• Information entropy (Shannon entropy), in statistics, the amount of information that is lacking in a random variable
• Entropy encoding, data compression strategies that set out to achieve message lengths close to the Shannon entropy
• Entropy (ecology), use of Shannon entropy as a measure of biodiversity in the study of ecology
• Renyi entropies, family of diversity measures generalising Shannon entropy; used to define fractal dimensions

In mathematics:

• 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

In computing:

• Entropy (anonymous data store), a computer network designed to be resistant to censorship
• Entropy (PHP), a version of PHP compiled for Mac OS X
• Entropy (computing), an indicator of the number of random bits available to seed cryptography systems.

In literature:

• Entropy (film), a 1999 film directed by Phil Joanou.
• Entropy (board game), the name of two board games
• a short story by Thomas Pynchon

In music:

• Entropy (album), a split vinyl album by Anathallo and Javelins
• Entropy ry., a student organization for electronic music at Helsinki University of Technology
• a song on the album Against the Grain by Bad Religion
• a song on the album Matter+Form by VNV Nation
• a song on the b album by Moxy Früvous
• a song by MC Hawking
• Entropy (Hip Hop Reconstruction from the Ground up), Hip-Hop Suite by DJ Shadow and the Groove Robbers

In television:

• "Entropy" (Buffy episode), an episode of the TV series Buffy the Vampire Slayer

In medicine:

• Entropy (monitor) a monitor of anaesthetic depth using analysis of a 2 lead EEG.