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entropy - 9 dictionary results

en⋅tro⋅py

[en-truh-pee]

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–noun

Thermodynamics.

a.	(on a macroscopic scale) a function of thermodynamic variables, as temperature, pressure, or composition, that is a measure of the energy that is not available for work during a thermodynamic process. A closed system evolves toward a state of maximum entropy.

b.	(in statistical mechanics) a measure of the randomness of the microscopic constituents of a thermodynamic system. Symbol: S

2.	(in data transmission and information theory) a measure of the loss of information in a transmitted signal or message.

3.	(in cosmology) a hypothetical tendency for the universe to attain a state of maximum homogeneity in which all matter is at a uniform temperature (heat death).

4.	a doctrine of inevitable social decline and degeneration.

Origin:
< G Entropie (1865); see en- ² , -tropy

Related forms:

en⋅tro⋅pic [en-troh-pik, -trop-ik]

, adjective

en⋅tro⋅pi⋅cal⋅ly, adverb

Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2009.
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Link To entropy

en·tro·py (ěn'trə-pē)

n. pl. en·tro·pies

Symbol S For a closed thermodynamic system, a quantitative measure of the amount of thermal energy not available to do work.
A measure of the disorder or randomness in a closed system.
A measure of the loss of information in a transmitted message.
The tendency for all matter and energy in the universe to evolve toward a state of inert uniformity.
Inevitable and steady deterioration of a system or society.

[German Entropie : Greek en-, in; see en-² + Greek tropē, transformation; see trep- in Indo-European roots.]
en·tro'pic (ěn-trō'pĭk, -trŏp'ĭk) adj., en·tro'pi·cal·ly adv.

The American Heritage® Dictionary of the English Language, Fourth Edition
Copyright © 2009 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Entropy

En"tro*py\, n. [Gr. ? a turning in; ? in + ? a turn, fr. ? to turn.] (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. --Clausius.

Webster's Revised Unabridged Dictionary, © 1996, 1998 MICRA, Inc.
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entropy [(en-truh-pee)]

A measure of the disorder of any system, or of the unavailability of its heat energy for work. One way of stating the second law of thermodynamics — the principle that heat will not flow from a cold to a hot object spontaneously — is to say that the entropy of an isolated system can, at best, remain the same and will increase for most systems. Thus, the overall disorder of an isolated system must increase.

Note: Entropy is often used loosely to refer to the breakdown or disorganization of any system: “The committee meeting did nothing but increase the entropy.”

Note: In the nineteenth century, a popular scientific notion suggested that entropy was gradually increasing, and therefore the universe was running down and eventually all motion would cease. When people realized that this would not happen for billions of years, if it happened at all, concern about this notion generally disappeared.

entropy

1868, from Ger. Entropie "measure of the disorder of a system," coined 1865 (on analogy of Ger. Energie) by physicist Rudolph Clausius (1822-1888) from Gk. entropia "a turning toward," from en- "in" + trope "a turning" (see trope).

Main Entry: en·tro·py
Pronunciation: 'en-tr&-pE
Function: noun
Inflected Form: plural -pies
: a measure of theunavailable energy in a closed thermodynamic system that is also usually considered to be a measure of the system's disorder and that is a property of the system's state and is related to it in such amanner that a reversible change in heat in the system produces a change in the measure which varies directly with the heat change and inversely with the absolute temperature at which the change takesplace; broadly : the degree of disorder or uncertainty in a system —en·tro·pic /en-'trOp-ik, -'träp-/ adjective —en·tro·pi·cal·ly /-i-k(&-)lE/ adverb

entropy en·tro·py (ěn'trə-pē)
n.

For a closed thermodynamic system, a quantitative measure of the amount of thermal energy not available to do work.
A measure of the disorder or randomness in a closed system.

en·tro'pic (ěn-trō'pĭk, -trŏp'ĭk) adj.

entropy (ěn'trə-pē) Pronunciation Key
A measure of the amount of energy in a physical system not available to do work. As a physical system becomes more disordered, and its energy becomes more evenly distributed, that energy becomes less able to do work. For example, a car rolling along a road has kinetic energy that could do work (by carrying or colliding with something, for example); as friction slows it down and its energy is distributed to its surroundings as heat, it loses this ability. The amount of entropy is often thought of as the amount of disorder in a system. See also heat death.

entropy theory
A measure of the disorder of a system. Systems tend to go from a state of order (low entropy) to a state of maximum disorder (high entropy).
The entropy of a system is related to the amount of information it contains. A highly ordered system can be described using fewer bits of information than a disordered one. For example, a string containing one million "0"s can be described using run-length encoding as [("0", 1000000)] whereas a string of random symbols (e.g. bits, or characters) will be much harder, if not impossible, to compress in this way.
Shannon's formula gives the entropy H(M) of a message M in bits:
H(M) = -log2 p(M)
Where p(M) is the probability of message M.
(1998-11-23)

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