THERMAL PHYSICS
R. Baierlein, Cambridge University Press, 1999; pp: 437, ISBN 0-521-65838-1 (pbk), Price: $42.95

It is a rare pleasure to come across a textbook on a familiar subject that adopts a fresh approach in an engaging style. This was the case when I first examined and began to read Ralph Baierlein’s Thermal Physics. While the book is suitable for both undergraduates and graduates in physics and astronomy, as the publisher claims, I believe its primary appropriate readership to be upper level undergraduates.

As thermal physics includes thermodynamics, statistical mechanics, and kinetic theory, it requires skill to have these (in the author’s own words) “woven together” and presented as a coherent whole, as Baierlein does, rather than as individual areas of study. Nevertheless, the author unapologetically emphasizes the statistical mechanical rather than the thermodynamic aspects of thermal physics, and some readers might indeed view the book as an introductory text in statistical mechanics.

The central organizing principle of Thermal Physics is the second law of thermodynamics, with the other core conceptual ideas, as viewed by the author, being the canonical probability distribution, the partition function and the chemical potential. Accordingly, the second law and entropy are introduced early on, right after an initial background chapter, through the concept of the multiplicity of a macrostate.

The writing throughout the book is clear, informal and conversational. Baierlein makes extensive use of analogies, which help to instill conceptual understanding. To give an example of an early one, a mindless person starting at an oasis and wandering aimlessly around a desert is used to represent the evolution of a molecular system toward the macrostate of largest multiplicity. The controversial relationship between entropy and the imprecise, colloquial term “disorder” is discussed by Baierlein with the help of an analogy contrasting an orderly (highly correlated, low entropy) bedroom and one that is disorderly (uncorrelated with high entropy). The transition from a blue sky with scattered clouds to one with spread out overlapping clouds is an image provided by Baierlein to represent the need to move from a semi-classical approach to a quantum one when the thermal de Broglie wavelength is no longer much smaller than the typical inter-particle separation. All too often, textbooks at this level are, in my opinion, overly formal and avoid such techniques, and while students may become adept at solving end-of-chapter problems, their grasp of the underlying concepts may remain weak.

Baierlein summarizes, makes comments and asides, and preempts student difficulties just as does a good teacher. Each chapter has a closing section called “Essentials” in which the principal ideas (not only the equations) are reviewed. In addition, each chapter includes “Further Reading,” in which the author recommends (with comments) relevant books as well as journal articles. Many of the end-of-chapter problems are of inherent interest, rather than simply of the make-work variety. Although a solutions manual is available to instructors, I believe it is unfortunate that there are no answers to problems provided to students in the book itself.

A number of relatively modern topics are discussed, including the renormalization group approach to critical phenomena and the experimental realization of Bose-Einstein condensation. An exceptionally interesting section on “Entropy and evolution” shows how a thermodynamic analysis leads to the conclusion “that life is permitted to arise and to evolve.” Although it is a matter of taste, I was surprised that Baierlein adopts the sign convention that work done by a system is positive, rather than the convention that work done on a system is positive, the latter one being physically consistent with the universally-adopted convention of heat entering a system being positive.

I believe Thermal Physics by Ralph Baierlein is a book that should not only be considered for adoption as a textbook for undergraduate courses, but in any case should be on the bookshelves of instructors of such courses as a valuable source of ideas and approaches.

Stanley Greenspoon
Capilano College