# Entropy: Disorder or energy dispersal?

The first definition of entropy given by Clausius is I believe this $$S=Q/T$$ It is as I understand a common fact to understand entropy and maybe often teach it as a measure of disorder through the statistical definition of Boltzmann or Gibbs( depending on the ensemble) $$S=k\lnΩ$$ My question depending entropy, after some searching (look at A MODERN VIEW OF ENTROPY by Frank L. LAMBERT ) is this:

Is the physical meaning of entropy to be understood only in statistical terms as disorder because of the change in the statistical weights $Ω,$ or by looking to the thermodynamics as well, move to a definition of entropy as energy dispersal? In other words, conceive the physical meaning of entropy as a dispersal of the energy inside (or maybe at some points outwards) the system under consideration, where dispersal stands for a more wide allocation through the interior parts of the system( classical or quantum mechanical).

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Thermodynamic entropy is not a definition. Contrary to the sickeningly numerous sources stating that it is, entropy is NOT disorder. Entropy is also NOT a measure of how much we know about the physical system. In a sentence, entropy is a measure of the number of distinct energy microstates consistent with the total energy and the physical constraints of the system. This is a property unique to each system which could care less who measures it (in fact it cannot be measured, only entropy changes can be measured).

• " entropy is a measure of the number of distinct energy microstates consistent with the total energy and the physical constraints of the system." That's only true if energy is the only constrained quantity. More generally, entropy is the set of states consistent with all constraints imposed on the system, including energy, volume, etc. (and temperature and pressure are the Lagrange multipliers associated with those constraints). – DanielSank Jul 12 '17 at 21:35