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From: gjphw@ihuxm.UUCP
Newsgroups: net.physics
Subject: Re: Thermodynamics and probability
Message-ID: <936@ihuxm.UUCP>
Date: Fri, 23-Mar-84 18:35:20 EST
Article-I.D.: ihuxm.936
Posted: Fri Mar 23 18:35:20 1984
Date-Received: Sun, 25-Mar-84 09:29:07 EST
Organization: AT&T Bell Labs, Naperville, IL
Lines: 44



                                 Hold on here!!

   In response to a question seeking clarification of the concepts around
 thermodynamics and probability, two well written articles were submitted
 (D. Mitchell and J. Stekas).  I would like to make a request for consideration
 of an alternate view.

   I would like to suggest that there are two major schools of thought about
 the connection between probability (statistical mechanics) and thermodynamics.
 The view with the overwhelming number of adherents holds that dynamics
 (classical and quantum) is exact and thermodynamics is an approximation (in
 addition to being an idealization).  Dynamics is the basis for statistical
 mechanics, and the usual source for the more fundamental understanding of the
 laws of thermodynamics comes from this study.  A popular graduate level text
 on statistical mechanics (Huang) states that the second law of thermodynamics
 (entropy) is an approximation.  The support of a bias toward dynamics is the
 outstanding success that can be realized using dynamical explanations for
 single particle interactions.

   A distinctly minority view, with support among some physical chemists, is
 that thermodynamics is exact and dynamics (or at least statistical mechanics)
 is an approximation.  The major spokesman for this view is I. Prigogine in
 such texts as *From Being to Becoming*.  In the experience of people who deal
 with large many body systems (N > 10^23), thermodynamics has never been
 observed to be violated and typical single particle dynamics is inadequate for
 the task of description.  Prigogine (who is not a particularly lucid writer)
 argues that dynamics and statistical mechanics need modifications to bring
 them in agreement with thermodynamics (especially the second law).  Non-
 equilibrium statistical mechanics might demonstrate the shortcomings of a
 dynamics only description, except for the fact that most expressions for these
 situations are too difficult to solve for the general case.

   You might be tempted to take your pick of these two schools with the
proviso that the current consensus holds with the preeminence of dynamics.
In the realm of large many body systems (e.g., a room full of air), the
adequacy of single particle dynamics is not so clear.
-- 

                                    Patrick Wyant
                                    AT&T Bell Laboratories (Naperville, IL)
                                    *!ihuxm!gjphw