Jos Uffink, professor at the University of Minnesota, p. 39: "A more important objection, it seems to me, is that Clausius bases his conclusion that the entropy increases in a nicht umkehrbar [irreversible] process on the assumption that such a process can be closed by an umkehrbar [reversible] process to become a cycle. This is essential for the definition of the entropy difference between the initial and final states. But the assumption is far from obvious for a system more complex than an ideal gas, or for states far from equilibrium, or for processes other than the simple exchange of heat and work. Thus, the generalisation to all transformations occurring in Nature is somewhat rash." http://philsci-archive.pitt.edu/313/
"Ireversible process closed by a reversible process to become a cycle", implying that an irreversible process can move the system from one equilibrium state to another, is oxymoron. Here Uffink misleadingly suggests that this might be realistic for an ideal gas system, but elsewhere in the paper he effectively refutes the suggestion:
Uffink, ibid. p. 4: "The Second Law, in this view, refers to processes of an isolated system that begin and end in equilibrium states and says that the entropy of the final state is never less than that of the initial state (Sklar 1974, p. 381). The problem is here that, by definition, states of equilibrium remain unchanged in the course of time, unless the system is acted upon. Thus, an increase of entropy occurs only if the system is disturbed, i.e. when it is not isolated."
So the all-powerful version of the second law of thermodynamics
Entropy always increases in an isolated system
refers to processes that occurred in Clausius' head, a century and a half ago, and has nothing to do with processes in the physical reality.
Uffink drew essentially the same conclusion is his paper, but since he was to become professor at the University of Minnesota, his words were maximally euphemistic:
Uffink, ibid.: "I therefore argue for the view that the second law has nothing to do with the arrow of time...This summary leads to the question whether it is fruitful to see irreversibility or time-asymmetry as the essence of the second law. Is it not more straightforward, in view of the unargued statements of Kelvin, the bold claims of Clausius and the strained attempts of Planck, to give up this idea? I believe that Ehrenfest-Afanassjewa was right in her verdict that the discussion about the arrow of time as expressed in the second law of the thermodynamics is actually a red herring."
"Ireversible process closed by a reversible process to become a cycle", implying that an irreversible process can move the system from one equilibrium state to another, is oxymoron. Here Uffink misleadingly suggests that this might be realistic for an ideal gas system, but elsewhere in the paper he effectively refutes the suggestion:
Uffink, ibid. p. 4: "The Second Law, in this view, refers to processes of an isolated system that begin and end in equilibrium states and says that the entropy of the final state is never less than that of the initial state (Sklar 1974, p. 381). The problem is here that, by definition, states of equilibrium remain unchanged in the course of time, unless the system is acted upon. Thus, an increase of entropy occurs only if the system is disturbed, i.e. when it is not isolated."
So the all-powerful version of the second law of thermodynamics
Entropy always increases in an isolated system
refers to processes that occurred in Clausius' head, a century and a half ago, and has nothing to do with processes in the physical reality.
Uffink drew essentially the same conclusion is his paper, but since he was to become professor at the University of Minnesota, his words were maximally euphemistic:
Uffink, ibid.: "I therefore argue for the view that the second law has nothing to do with the arrow of time...This summary leads to the question whether it is fruitful to see irreversibility or time-asymmetry as the essence of the second law. Is it not more straightforward, in view of the unargued statements of Kelvin, the bold claims of Clausius and the strained attempts of Planck, to give up this idea? I believe that Ehrenfest-Afanassjewa was right in her verdict that the discussion about the arrow of time as expressed in the second law of the thermodynamics is actually a red herring."
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