Classical ThermodynamicsA branch of physics developed in the nineteenth century that deals with the
study of heat, and thus with the collision and interaction of particles in
large, nearequilibrium systems.
In the 19th century, thermodynamics, the study of heat transformation and
exchange, was concerned with closed systems (i.e., systems which do not exchange
matter or energy with their environment). In such systems although the total
amount of energy E is always conserved (the “first” law, DE=0),
the amount of available energy inevitably decreases to zero (the “second”
law); equivalently, the entropy S of the system, defined as the amount of
unusable energy, increases to a maximum: DS>=0.
During the 20th century, the field was broadened to include open systems (i.e.,
systems which exchanged matter and/or energy with their environment). These
first included nonlinear systems in which effects on the system were highly
amplified, and then nonlinear systems far from equilibrium in which spontaneous
fluctuations were even more fully amplified. Such systems demonstrated the
surprising phenomena of ‘order out of chaos’, to use Ilya Prigogine’s
famous phrase: they could spontaneously move to greater forms of organization,
driven always by the internal production and dissipation of entropy (i.e., ‘dissipative
systems’), and though, of course, the total entropy of the open system plus
its environment obeyed the second law. Two final points: 1) Whether ‘entropy’
applies to the universe as a ‘closed’ system is subject to intense debate.
2) Although most physicists reduce thermodynamics to dynamics, thus explaining
(away) time’s (thermodynamic) arrow, Prigogine and others insist it should be
the converse. In any case, nonlinear, nonequilibrium thermodynamics points to
at least one form of novelty and apparent openness in nature, although it still
comes (pace Prigogine) under the
rubric of deterministic classical dynamics, and, like chaos theory, rendering
its portrait of novelty in terms of epistemic ignorance.
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Contributed
by: Robert Russell  CTNS
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