# entropy

## Definitions

• WordNet 3.6
• n entropy (thermodynamics) a thermodynamic quantity representing the amount of energy in a system that is no longer available for doing mechanical work "entropy increases as matter and energy in the universe degrade to an ultimate state of inert uniformity"
• n entropy (communication theory) a numerical measure of the uncertainty of an outcome "the signal contained thousands of bits of information"
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Webster's Revised Unabridged Dictionary
• n Entropy (Thermodynamics) A certain property of a body, expressed as a measurable quantity, such that when there is no communication of heat the quantity remains constant, but when heat enters or leaves the body the quantity increases or diminishes. If a small amount, h, of heat enters the body when its temperature is t in the thermodynamic scale the entropy of the body is increased by h ÷ t. The entropy is regarded as measured from some standard temperature and pressure. Sometimes called the thermodynamic function. "The entropy of the universe tends towards a maximum."
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Century Dictionary and Cyclopedia
• n entropy In physics: As used by Clausius, the inventor of the word, and others, that part of the energy of a system which cannot be converted into mechanical work without communication of heat to some other body, or change of volume.
• n entropy As used by Tait and others, the available energy; that part of the energy which is not included under the entropy in sense .
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Chambers's Twentieth Century Dictionary
• n Entropy en′trop-i a term in physics signifying 'the available energy.'
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## Quotations

• Lewis Mumford
“Only entropy comes easy.”

## Etymology

Webster's Revised Unabridged Dictionary
Gr. a turning in; in + a turn, fr. to turn

## Usage

### In literature:

It is an entropy of history itself, slowly decaying into chaotic repetition.
"After the Rain" by Sam Vaknin
Your anti-entropy didn't stand a chance under those conditions.
"Empire" by Clifford Donald Simak
The increase of entropy is independent of the temperature of the auxiliary medium.
"Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 4" by Various
Entropy is known as constantly increasing, remaining constant only in an ideal limiting case.
"Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3" by Various
Encoding, entropy, noisy channel, related areas, etc.
"Life Histories of North American Wood Warblers Part One and Part Two" by Arthur Bent
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### In news:

Arena-Sized Entropy On 'The 2nd Law'.
Entropy 's new PureTemp PCM formulations help boost efficiency, safety.
Energy, Entropy And The Triumph Of Disorder.
Energy, entropy and the triumph of disorder.
Fighting Entropy to Salvage Istanbul's Historic Bazaar.
"Because the Universe Tends Toward Entropy ".
Systems, Order, Entropy, and Chaos: Why it's So Hard to Keep Things Running Smoothly.
Liz Plus Marcos vs Entropy .
'Formations of Erasure: Earthworks and Entropy '.
'Formations of Erasure : Earthworks and Entropy'.
We propose a supervised maximum entropy ranking approach to pronoun resolution as an alternative to commonly used classification-based approaches.
Overall, approximate entropy grades a continuum that ranges from totally ordered to maximally irregular (or completely random ).
It must be that anything connected with flying – with airports, with flight schedules – just gets sucked into the entropy vortex.
Rife with entropy, it typically hosts 15 or so employees and Rumpus, Griffith 's unkempt black schnauzer.
Quantum physics, parallel worlds, probability, entropy.
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### In science:

Now, after we have related kinetic entropy S kin, to ˙A, it becomes possible to express anthe statistics of other contribution to GE, S (0) (A), in terms of regular thermodynamic entropy S (A).
Generalized Entropy approach to far-from-equilibrium statistical mechanics
The entropy S can then be the von Neumann entropy SvN ≡ −trρ ln ρ of the quantum state of the nongravitational quantum ﬁeld in the classical curved metric.
Defining Entropy Bounds
Mohammad-Djafari A. and Idier J.: ’Maximum Likelihood Estimation of the Lagrange Parameters of the Maximum Entropy Distributions’, in Maximum Entropy and Bayesian Methods, C.R.
Minimax Entropy and Maximum Likelihood. Complementarity of tasks, identity of solutions
Variations in SNII heating have little effect on the entropy proﬁle or accretion shock radius in the GAc solutions because of their much greater mass. A positive entropy gradient dS/dr > 0 extends to very small radii in both GAg and GAc solutions in Figure 3d.
Entropy Evolution in Galaxy Groups and Clusters; A Comparison of External and Internal Heating
Also, in the standard Metropolis Monte Carlo technique, it is rather diﬃcult to calculate entropy (or free energy), since the entropy is a function of the probability with which a microstate occurs in a canonical ensemble.
An Introduction to Monte Carlo Simulation of Statistical physics Problem
To obtain convergence in relative entropy we use de Bruijn’s identity, which relates the relative entropy to Fisher information of perturbed random variables, which have densities we can control.
An information-theoretic Central Limit Theorem for finitely susceptible FKG systems
Steven Carlip: “Boundary conditions, constraints, BH entropy” Recent work by a number of authors has suggested that black hole entropy may have a microscopic description in terms of a boundary conformal ﬁeld theory, living either near the horizon or at spatial inﬁnity.
GR16: Quantum General Relativity
We compute averages (entropy, traces) over the ensembles of unistochastic matrices and present inequalities concerning the entropies of products of bistochastic matrices.
Random unistochastic matrices
We deﬁne the notion of entropy of bistochastic matrices and prove certain inequalities comparing the initial and the ﬁnal entropy of any probability vector sub jected to a Markov chain described by an arbitrary bistochastic matrix. A related inequality concerns the entropy of the product of two bistochastic matrices.
Random unistochastic matrices
The entropy is deﬁned as the Shannon entropy in the histogram of diagonal line lengths.
Nonlinear analysis of bivariate data with cross recurrence plots
While the entropy increases (dS > 0) as the universe expands, the entropy will not be expressed solely in terms of E and EC as above.
A Note on the Cardy-Verlinde Formula
To avoid numerical instability due to amplitude errors at high-wavenumber modes of density and entropy, diffusion terms in the continuity and entropy equations have been introduced.
The nonlinear development of the thermal instability in the atomic ISM and its interaction with random fluctuations
It has been recently argued that the classical Boltzmann entropy may not be correct for systems with long-range interactions and that Tsallis entropies, also called q -entropies, should be used instead .
Generalized thermodynamics and Fokker-Planck equations. Applications to stellar dynamics, two-dimensional turbulence and Jupiter's great red spot
In the astrophysical context, Plastino & Plastino have noted that the maximization of Tsallis entropies leads to stellar polytropes, thereby avoiding the inﬁnite mass problem associated with isothermal systems obtained by maximizing the Boltzmann entropy.
Generalized thermodynamics and Fokker-Planck equations. Applications to stellar dynamics, two-dimensional turbulence and Jupiter's great red spot
In particular, we have argued that Tsallis entropies are particular H -functions (not true entropies) whose maximization at ﬁxed mass and energy determines (nonlinearly) dynamically stable stationary solutions of the 2D Euler or Vlasov-Poisson systems [11,12].
Generalized thermodynamics and Fokker-Planck equations. Applications to stellar dynamics, two-dimensional turbulence and Jupiter's great red spot
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