The production of mechanical energy, in that case, results from the growth of
entropy, which is the driving force of that process. Such condition was pointed out
by Planck some time ago:
The real meaning of the second law has frequently been looked for in a “dissipation of
energy.” This view, proceeding, as it does, from the irreversible phenomena of conduction
and radiation of heat, presents only one side of the question. There are irreversible processes in which the final and initial states show exactly the same form of energy, e.g. the
diffusion of two perfect gases or further dilution of a dilute solution. Such processes are
accompanied by no perceptible transference of heat, nor by external work, nor by any
noticeable transformation of energy. They occur only for the reason that they lead to an
appreciable increase of the entropy. [1: 103–104]
Unfortunately, in the general thermodynamics literature, this insightful point has
been overlooked and we have the bizarre situation among students of thermodynamics that while the entropy law is accepted as the official second law, the law is
almost universally understood in terms of Kelvin’s general conclusions of universal
dissipation: “entropy and the dissipation of energy are as inseparable as Siamese
twins in the thought of every student of thermodynamics” [13]. The demonstration
in the above provides details to Planck’s observation so that it cannot be overlooked
anymore—as well as necessity, as it’ll be carried out, in a critical assessment of the
energy principle, the entropy principle and the real meaning of the second law.
It suffices to note here that the critical assessment, as it will be fully developed in
Chaps. 7 and 8, will conclude that energy is not the sole driver of change, but
instead, energy is the proxy of entropy growth (more precisely, entropy growth
potential to be introduced in Chap. 8), which is the universal driving force of all
processes in nature. That lesson, rather than entropy as a merely dissipative
mechanism, is the true lesson we should take from the second law.
5.11 Concluding Remarks: Applications to Special States
of Thermodynamic Equilibrium
Figure 5.11 suggests that the formulation of the entropy principle is a central part of
the evolution of thermodynamic thought. First of all, it notes that Kelvin and
Clausius formulated two distinctive principles of unidirectionality. The two, though
closely connected, are by no means identical (see Sect. 5.10). There is no doubt,
especially in view of the statistical mechanical interpretation being directly and
successively linked to the entropy principle (while its linkage to the dissipation
proposition is not as clear), that the entropy principle is the counterpoint to the first
law. Its privileged position accords it, like the first law, to be considered as one of
the universal principles of nature.
The position of the dissipation proposition (the energy principle), though already
repudiated in Sect. 5.10, remains to be further examined and, certainly, its
importance in thermodynamic thought warrants a more detailed assessment of it in
Chap. 8.
5.10 The Examples of Reversibly Controlled “Free Expansion” …
129
entropy, which is the driving force of that process. Such condition was pointed out
by Planck some time ago:
The real meaning of the second law has frequently been looked for in a “dissipation of
energy.” This view, proceeding, as it does, from the irreversible phenomena of conduction
and radiation of heat, presents only one side of the question. There are irreversible processes in which the final and initial states show exactly the same form of energy, e.g. the
diffusion of two perfect gases or further dilution of a dilute solution. Such processes are
accompanied by no perceptible transference of heat, nor by external work, nor by any
noticeable transformation of energy. They occur only for the reason that they lead to an
appreciable increase of the entropy. [1: 103–104]
Unfortunately, in the general thermodynamics literature, this insightful point has
been overlooked and we have the bizarre situation among students of thermodynamics that while the entropy law is accepted as the official second law, the law is
almost universally understood in terms of Kelvin’s general conclusions of universal
dissipation: “entropy and the dissipation of energy are as inseparable as Siamese
twins in the thought of every student of thermodynamics” [13]. The demonstration
in the above provides details to Planck’s observation so that it cannot be overlooked
anymore—as well as necessity, as it’ll be carried out, in a critical assessment of the
energy principle, the entropy principle and the real meaning of the second law.
It suffices to note here that the critical assessment, as it will be fully developed in
Chaps. 7 and 8, will conclude that energy is not the sole driver of change, but
instead, energy is the proxy of entropy growth (more precisely, entropy growth
potential to be introduced in Chap. 8), which is the universal driving force of all
processes in nature. That lesson, rather than entropy as a merely dissipative
mechanism, is the true lesson we should take from the second law.
5.11 Concluding Remarks: Applications to Special States
of Thermodynamic Equilibrium
Figure 5.11 suggests that the formulation of the entropy principle is a central part of
the evolution of thermodynamic thought. First of all, it notes that Kelvin and
Clausius formulated two distinctive principles of unidirectionality. The two, though
closely connected, are by no means identical (see Sect. 5.10). There is no doubt,
especially in view of the statistical mechanical interpretation being directly and
successively linked to the entropy principle (while its linkage to the dissipation
proposition is not as clear), that the entropy principle is the counterpoint to the first
law. Its privileged position accords it, like the first law, to be considered as one of
the universal principles of nature.
The position of the dissipation proposition (the energy principle), though already
repudiated in Sect. 5.10, remains to be further examined and, certainly, its
importance in thermodynamic thought warrants a more detailed assessment of it in
Chap. 8.
5.10 The Examples of Reversibly Controlled “Free Expansion” …
129