Entropy

Entropy is a fundamental concept in the field of thermodynamics and statistical mechanics, with a broad range of applications in physics, chemistry, and information theory. It is often described as a measure of disorder or randomness in a system.

Definition

Entropy is defined in the context of a thermodynamic system as a measure of the number of specific ways in which a system may be arranged, often taken to be a measure of disorder. The concept of entropy was introduced by Rudolf Clausius who named it from the Greek word "transformation". He considered transfers of energy between bodies and observed there was a directional bias to the way energy moves.

Thermodynamics

In thermodynamics, entropy is a state function that is often interpreted as the degree of disorder or randomness in the system. The second law of thermodynamics states that the entropy of an isolated system always increases or remains constant. It never decreases.

Statistical Mechanics

In statistical mechanics, entropy is a measure of the number of ways that the particles in a system can be arranged to produce a specific macrostate, with each arrangement being a microstate. The entropy of a system is then defined as the natural logarithm of the number of microstates, multiplied by the Boltzmann constant.

Information Theory

In information theory, entropy is a measure of the uncertainty, or randomness, of a set of data. The concept of entropy in information theory is closely related to that in thermodynamics, but they are not identical.

See Also

• Thermodynamics
• Statistical Mechanics
• Information Theory
• Rudolf Clausius

Entropy

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  Clausius
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  System Boundary
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  Temperature-entropy Chart for Steam, Imperial Units
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  First Law Open System
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  Ultra Slow-motion Video of Glass Tea Cup Smashed on Concrete Floor