BIBLIOGRAPHY

Acad. A. F. Ioffe, Course of Physics, Volume I. Mechanics. Heat. Electricity, third edition, newly revised, State Publishing House of Technical-Theoretical Literature, Leningrad—Moscow, 1940, 520 pp., price 11 rubles 75 kopecks.

The third edition of A. F. Ioffe’s course differs so substantially from the preceding ones that it deserves special consideration. The most important changes have been introduced by the author into the introductory chapter and into the chapters devoted to the study of electricity. The introductory chapter is an outline of modern atomic physics. In 80 pages the author presents, in a vivid and engaging form, contemporary ideas about the structure of matter. The exposition begins with physical proofs of the atomic nature of matter, but from the very outset the wave–particle dualism is considered. The wave aspect of the nature of the electron is established not as a theoretical proposition but as an experimental fact (the experiments of Davisson and Germer), and the formula

\[ \lambda = \frac{h}{mv} \]

is indicated as a conclusion from measurements. In the following paragraph an outline is given of the theory of atomic structure, with Bohr’s condition for the selection of stationary orbits being graphically justified, following de Broglie, as the requirement that an integral number of waves fit along the orbit. By contrast, the existence of stationary states and Bohr’s frequency condition are introduced in the form of a postulate, although, in the spirit of the author’s exposition, it would have been advisable to give them an experimental justification, referring to the experiments of Franck and Hertz. The further exposition considers: the theory of the periodic system of elements, radioactivity and the structure of the atomic nucleus, and, finally, in conclusion, an outline of physical statistics is given. The entire chapter is written so accessibly, vividly, and interestingly that it could have been published as a separate popular brochure.

Undoubtedly, reading this chapter will introduce the student into the circle of ideas of modern physics. As for the possibility of using the facts and theories set forth in it as teaching material at the very beginning of the course, this question is, of course, debatable. The unusualness and “non-visualizable” character of the fundamental ideas of quantum theory are so great that students can hardly assimilate them at once, without having passed along the long path of studying classical physics. If, however, at the very beginning of the course a student learns and understands at least something of the ideas of modern physics, this will make the further study of the subject more interesting for him and will help him better understand these new ideas when they are presented in the appropriate place in the course. From this point of view the introductory chapter of A. F. Ioffe’s course should be regarded as material for independent reading by the student, but an attempt to include it among the obligatory requirements would hardly lead to a satisfactory result.

Chapter I is entitled “Fundamental Concepts in the Field of Mechanics.” This title itself already shows that the author does not lay claim to any complete exposition of the physical foundations of mechanics. Evidently, he assumes that such an exposition should be given in a course of theoretical mechanics, where a more advanced mathematical apparatus can be used. What is presented in this chapter is set forth to the highest degree clearly, freshly, and interestingly. Everywhere not only are modern points of view on the fundamental questions of mechanics emphasized, but a brief exposition of the theory of relativity—special and general—is also given. It should be noted that in university teaching at the present time considerably more attention is devoted to mechanics in a course of general physics—

Bibliography

...place, and moreover on quite reasonable grounds. In view of this, when studying this part of the course the student will not be able to confine himself to A. F. Ioffe’s textbook and will have to turn to other manuals. Nevertheless, in this case too one may insistently recommend that students read in parallel Chapter I of A. F. Ioffe’s course, since it will help them understand much more clearly.

The next chapter is entitled “Properties of Thermal Energy.” According to the author’s plan this chapter is intended “to set forth only the physical foundations of energetics” (Preface, p. 4). It seems to us very expedient to place a chapter of this kind precisely here. Indeed, a full exposition of the mechanism of thermal phenomena is possible only in connection with molecular physics, which at present it is reasonable to place not at the beginning, but at the very end of the course. On the other hand, it is absolutely impossible to go through the whole course of physics without once touching at the start upon thermodynamics, which lies at the basis of all physical phenomena. Willy-nilly, one must therefore violate the logical strictness of the arrangement of the material—incidentally, impeccable logical strictness in the arrangement of material when presenting physics is generally unattainable—in particular, by dividing the doctrine of heat into two parts. In all other respects, concerning this part one may repeat what was said about the positive aspects of the chapter devoted to mechanics. The exposition is clear, lively, and in a few words contains a great deal of substance.

All the remaining part of the book (Chs. III–IX, pp. 196–520) is devoted to the theory of electricity, except for electromagnetic oscillations, which are set forth in the second volume. Thus it is precisely the theory of electricity that constitutes the principal content of the volume under review; everything preceding it, in essence, serves only as preparation for it. In the exposition itself, the description of the microscopic mechanism of phenomena is interwoven with great tact with phenomenological theory. Thus, in electrostatics the electron appears from the very beginning, but at the same time sufficient space is given to the exposition of field theory. The fact that the author operates with vivid molecular representations allows him to avoid the formalism that so unpleasantly strikes anyone who begins the study of electrostatics from ordinary textbooks. Thus, for example, before considering typical cases of macroscopic fields (plane, cylinder, etc.) the author dwells in detail on elementary systems of charges—dipoles, quadrupoles, octupoles. Their field, interaction, and energy are considered. But the dipoles which are then introduced into the theory of dielectrics turn out, in A. F. Ioffe’s treatment, not to be schematic little circles divided into white and black halves, but, so to speak, “real,” genuine molecular dipoles.

The entire exposition of electrostatics is characterized by a transparent clarity that gives the reader great pleasure and satisfaction. There is no doubt that in this exposition not only students but also teachers will find much that is useful for themselves.

A distinctive feature of A. F. Ioffe’s exposition is the considerable space that he devotes already in this first volume to the description and theory of the electrical and magnetic properties of matter. Here not only dielectrics and conductors are considered, but also semiconductors, which recently have attracted such a large role and application. The mechanism of electronic and ionic conductivity in metals, gases, and electrolytes is studied. However, clearly too little attention is given to electrolytes (only one small paragraph, and even that not fully). Yet, apart from the fact that there are a number of elementary facts here which must be firmly mastered by students after working in this field as laboratory physicists (Debye–Hückel and others), there is much that is interesting and worthy of attention. On the other hand, the modern quantum theory of the conductivity of conductors, dielectrics, and semiconductors is expounded in detail. The exposition is distinguished by the author’s customary clarity, but the reviewer, having no experience in presenting these problems in a course of general physics, does not venture to judge how far this exposition can be consciously assimilated by first-year students. Inevitably the question arises whether it would not be more expedient to postpone the exposition of these problems until Volume IV? Of course, for the exposition of the completely new questions mentioned, there has not yet accumulated...

sufficient pedagogical experience and willy-nilly has to use the “trial and error” method.

The exposition of macroscopic electrodynamics is given in a more or less customary way. The book ends with a chapter on the laws of electromagnetic phenomena, where an elementary derivation of Maxwell’s equation is given. The foundations of Lorentz’s electron theory are briefly set forth, and in the concluding paragraph the properties of elementary particles (electron, positron, proton, neutron, etc.) are discussed in detail.

We have by no means exhausted the entire content of the book. In summing up, it should above all be noted that Acad. A. F. Ioffe’s book is a striking phenomenon in our scientific-pedagogical literature. It would be difficult here to note all those places in the book whose reading evokes in the specialist reader a feeling of satisfaction and sincere pleasure. The true master’s hand is felt in it everywhere, a master who sees with remarkable penetration every phenomenon he describes. There is much in it that is new and fresh. Even if the author, as it seems to us, has paid a certain tribute to enthusiasm, having proved thereby to be younger in spirit than the physicists of the generation of his pupils, there is no need to regret this; it too has its great advantage. This book will awaken the student’s thought, help the teacher, and be read from beginning to end with deep interest.

One can only sincerely wish that, after the war, Acad. A. F. Ioffe will bring to completion the new revision of the remaining parts of this course as well.

E. V. Shpolsky.