Entropy Value

An entropy value is a measure value of a system's entropy measure.

• Context:
  • It can range from being a Minimum Entropy Value to being a Maximum Entropy Value.
  • …
• Example(s):
  • 0.5
• See: Information Entropy.

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References

2013

• (Wikipedia, 2013) ⇒ http://en.wikipedia.org/wiki/Entropy
  • Entropy is a measure of the number of specific ways in which a system may be arranged, often taken to be a measure of disorder. The entropy of an isolated system never decreases, because isolated systems spontaneously evolve towards thermodynamic equilibrium, which is the state of maximum entropy.

    Entropy is a thermodynamic quantity that helps to account for the flow of energy through a thermodynamic process. Entropy was originally defined for a thermodynamically reversible process as :[math]\displaystyle{ \Delta S = \int \frac {dQ_{rev}}T }[/math] where the entropy (S) is found from the uniform thermodynamic temperature (T) of a closed system divided into an incremental reversible transfer of heat into that system (dQ). The above definition is sometimes called the macroscopic definition of entropy because it can be used without regard to any microscopic picture of the contents of a system. In thermodynamics, entropy has been found to be more generally useful and it has several other formulations. Entropy was discovered when it was noticed to be a quantity that behaves as a function of state. Entropy is an extensive property, but it is often given as an intensive property of specific entropy as entropy per unit mass or entropy per mole.

    In the modern microscopic interpretation of entropy in statistical mechanics, entropy is the amount of additional information needed to specify the exact physical state of a system, given its thermodynamic specification. The role of thermodynamic entropy in various thermodynamic processes can thus be understood by understanding how and why that information changes as the system evolves from its initial condition. It is often said that entropy is an expression of the disorder, or randomness of a system, or of our lack of information about it (which on some views of probability, amounts to the same thing as randomness). The second law is now often seen as an expression of the fundamental postulate of statistical mechanics via the modern definition of entropy.

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