W. Muschik
Comment to J. Kestin: Internal variables in the local-equilibrium
approximation
J. Non-Equilib. Thermodyn. 18, 1993, 380-388
As Kestin [Kestin, J.: Variables in the Local-Equilibrium
Approximation, J. Non-Equilib. Thermodyn ] remarked it seems to be a
'fact that there exists no consensus amoung the practitioners of
thermodynamics concerning the very basis of their subject'. This first
impression is supported by two other facts: There are a lot of 'schools'
of thermodynamics [Muschik, W.: Thermodynamical Theories - Survey and
comparison, J. Appl. Sci. 4 (1986), 189; Hutter, K.: The foundations
of thermodynamics, its basic postulates and implications, Acta
Mech. 27 (1977), 1], and there are even different formulations and
interpretations of Laws of Thermodynamics [Muschik, W.: Formulations
of the Second Law - Recent Developments, J. Phys. Chem. Solids 49
(1988), 709] and of basic concepts such as temperature [Muschik,
W. Empirical Foundation and Axiomatic Treatment of Nonequilibrium
Temperature, Arch. Mech. Anal. 66 (1977), 379] and entropy [Muschik,
W. Fundamentals of Dissipation Inequalities,
J. Non-Equilib. Thermodyn. 4 (1979), 277, 377]. Kestin is quite right
argueing that parts of all these varieties can be traced to semantics
and terminology: A 'clarifying glossary' is not developed up to
now. And also in his contribution[Kestin, J.: Variables in the Local-Equilibrium
Approximation, J. Non-Equilib. Thermodyn ] concerning internal
variables and local-equilibrium approximation well-known concepts are
used whose interdependence needs some clarifying comments which is the
aim of this contribution.