Re:Entropy as Disorder: History of a Misconception
by kgwgk on Sunday September 22, 2019 @07:47AM
(#21040895)
> Thermodynamics doesn't care about our ignorance of potential system configurations, but that these configurations are available for microscopic system evolution!
Thermodynamics equations are based on the macroscopic constraints on the system that we choose to measure and manipulate, implicitely admitting our ignorance about the potential microscopic configurations. Thermodynamic entropy, unlike energy, is not an intrinsic property of the physical system; it is a property of our macroscopic description of the system and the experimental processes that we decide to perform on it.
"Recognition that the "entropy of a physical system" is not meaningful without further qualifications is important in clarifying many questions concerning irreversibility and the second law. For example, I have been asked several times whether, in my opinion, a biological system, say a cat, which converts inanimate food into a highly organized structure and behavior, represents a violation of the second law. The answer I always give is that, until we specify the set of parameters which define the thermodynamic state of the cat, no definite question has been asked!"
Thermodynamics equations are based on the macroscopic constraints on the system that we choose to measure and manipulate, implicitely admitting our ignorance about the potential microscopic configurations. Thermodynamic entropy, unlike energy, is not an intrinsic property of the physical system; it is a property of our macroscopic description of the system and the experimental processes that we decide to perform on it.
See section VI. THE "ANTHROPOMORPHIC" NATURE OF ENTROPY in https://bayes.wustl.edu/etj/articles/gibbs.vs.boltzmann.pdf
"Recognition that the "entropy of a physical system" is not meaningful without further qualifications is important in clarifying many questions concerning irreversibility and the second law. For example, I have been asked several times whether, in my opinion, a biological system, say a cat, which converts inanimate food into a highly organized structure and behavior, represents a violation of the second law. The answer I always give is that, until we specify the set of parameters which define the thermodynamic state of the cat, no definite question has been asked!"