BIBLIOGRAPHY

Prof. D. N. Nasledov. Physics of Ionic and Electronic Processes. ONTI. Main Editorial Office for Technical-Theoretical Literature. Leningrad—Moscow, 1937. Pp. 312, price in binding 6 rubles 25 kopecks.

The book by Prof. Nasledov, which arose from lectures given at the Leningrad Industrial Institute, was intended by the author to serve as an introduction to modern atomic physics. The book is divided into two parts. The first is devoted to ions and electrons. It considers the mechanism of conductivity in gases, the determination of the charge and mass of electrons, the determination of the mass of ions by mass spectroscopy, the mechanism of electrical conductivity of solid dielectrics and metals, and thermionic emission. In the second part, entitled “Waves and Quanta,” there is a brief account of the theory of black-body radiation, the experimental foundations of the hypothesis of light quanta (the photoelectric effect and the Compton effect), and the theory of atomic structure (scattering of α-particles and the nuclear theory of the atom, spectral series and Bohr’s elementary theory), atomic excitation by electronic impact and optical excitation (fluorescence), X-rays, and, finally, the experimental evidence for the wave nature of the electron.

Thus, in terms of its material, the book could indeed serve as an introduction to modern atomic physics. In its level of presentation it is suitable for students in the second or third year of physics specialties. However, the author’s style—fragmentary and not always faultless from the point of view of Russian syntax—somewhat hinders the reading of the book.

Mathematical derivations are not carried through completely everywhere, and the degree of their completeness is apparently determined by chance. Thus, for example, the author derives in every detail the integral law of the weakening of the intensity of X-rays, and even does this twice: once on p. 175—for scattering, and a second time on p. 255—for absorption; on the other hand, he often leaves much more difficult calculations to the reader. These include, for example, the calculation of the total energy of the magnetic field of a moving charge (p. 91); it is also a great pity that, in presenting the theory of radiation, the author confines himself to deriving the Rayleigh–Jeans formula, while he gives Planck’s formula without derivation, although it could have been derived very simply by the same method, replacing only integration by summation.

As for the more detailed choice of material, one must note the author’s excessive attachment to “classical” things. This applies not only to the theory of atomic structure, where the author does not go beyond Bohr (which is still excusable!), and not only to the theory of the conductivity of metals, where the author does not go beyond Drude, but also to much simpler questions. For example, in addition to (or perhaps instead of) the classical methods for determining the charge of the electron found in all elementary textbooks, it would not have hurt to present one of the modern methods, distinguished by great elegance and a high degree of accuracy.

A substantial shortcoming of the book is its episodic character. The book has no single logical thread; it is a rather loose collection of separate essays, rather than a completed whole. Why, for example, is X-ray scattering considered in Chapter XII, while the other properties of X-rays are considered in Chapter XVII? Why is the charge of the nucleus discussed on

pp. 197–200, and the Moseley law—on p. 288? Why are the Franck and Hertz experiment and others considered after the theory of atomic structure, and not before it, as one of the fundamental experiments providing experimental justification for Bohr’s postulates?

But what spoils the book most of all is the carelessness of the presentation. This carelessness is especially noticeable in the second half of the book. It shows up also in trifles—for example, in the absence of uniform notation for the same quantities (the azimuthal quantum number on pp. 216–220 is denoted by \(n_\varphi\), and on p. 227 by \(n_c\)); in the lack of attention to units—in the formula for the Bohr magneton on p. 223 it is tacitly assumed that the charge is expressed in electromagnetic units, while on p. 230 it is also tacitly assumed that it is measured in electrostatic units; in view of this the two formulas differ by a factor \(c\) in the denominator, and the reader has to guess the reasons for this, and so on. The same carelessness, however, is evident also in the style and character of the exposition. As an example one could cite the whole small chapter on the phosphorescence of gases and vapors, written from beginning to end completely unsatisfactorily.

In the paragraph devoted to the Stern and Gerlach experiment, it is not explained at all why the magnetic field must be “sharply inhomogeneous,” and nothing is said about the influence of spin on the result of this experiment. The entire paragraph on the Zeeman effect is extremely unsatisfactory. In essence, in this paragraph very little is said about the Zeeman effect itself—in it the correspondence principle is set forth very approximately and obscurely—and what is said there about the Zeeman effect gives a distorted picture of reality: it is incorrect that the simple effect is produced only by “hydrogen and atoms similar to it (??)”—in fact all monovalent atoms produce the complex effect—and one cannot write about the theory of the Zeeman effect without saying a word about spin. The author’s remarks on spin are all the more unfortunate, since the specially devoted § 13 of Chapter XIV is badly presented. Here we read the following assertion: “each electron possesses a constant mechanical angular momentum, numerically equal to \(\frac{h}{4\pi}\), and consequently also a constant magnetic moment \(\mu_0\), equal to the Bohr magneton” (p. 230, emphasis mine, E. Sh.). Since nothing is said either before or afterward about the anomalous value of the ratio of the magnetic moment to the mechanical one, this “consequently” sounds rather unpleasant to a competent reader.

A few lines below, the author gives an expression for the intrinsic magnetic moment of the electron, and if the reader compares this expression with formula (70) on p. 223—and he will have to do this willy-nilly—then he will have to conclude that the mechanical moment of spin is equal to \(\frac{h}{2\pi}\)! Sloppiness of this sort in a book intended for students is utterly unforgivable.

From all this only one conclusion can be drawn: the author undertook to publish some separate notes from his lectures and did not even take the trouble to edit them properly. The publishing house treated its task formally and, evidently without any internal editing, sent the book to press, while the Committee for Higher School Affairs (on the cover incorrectly called the “Committee on Higher School”) put its stamp on all this amateurism. Incidentally, by way of self-criticism, the reviewer must acknowledge that the very possibility of the publication of a book in such a form also lies with the responsibility of our scientific criticism, which has not yet been brought up to the proper level.

E. Shpolsky, Moscow