- #141
A. Neumaier
Science Advisor
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stevendaryl said:But to me, the entropy is an artifact of how we're modeling that collection of particles; it's not objective. If there is no objective notion of entropy for 5 particles in a box, I can't see how there can be an objective notion of entropy for 50 trillion particles.
The entropy of a gallon of fluid can be calculated from the Helmholtz free energy A as S=-dA/dT, and A can be determined objectively by measurements. This is routinely and reliably done in engineering applications.
So what should not be objective about it?
The entropy of a tiny system of 45 molecules is not so well-defined as the tiny system cannot be kept in equilibrium, and entropy is (in the textbook framework) an equilibiruim property.