ARTHUR HAAS. Atomtheorie. Zweite völlig umgearbeitete und wesentlich vermehrte Auflage. Berlin und Leipzig. W. de Gruyter. Pp. VIII + 258

A. HAAS. Atomic Theory.

Atomic theory over the last four years has taken a new major step forward. The shift brought about by the emergence of the new quantum mechanics on the one hand, and by the completion of the formal theory of spectra on the basis of the hypothesis of the rotating electron on the other, has led to the result that the numerous books on atomic theory published before 1927 (and also, in part, after that) suddenly proved to be greatly out of date. To write a new book that would present, in a sufficiently elementary form, the new aspect of contemporary physics is a very difficult matter.

The book by Haas under review, in its new edition, represents, if I am not mistaken, the first attempt to give a brief, systematic, and at the same time quite elementary exposition of atomic theory in its modern form. The book is intended for the reader who is somewhat familiar with physics and with the elements of mathematical analysis. Thus it constitutes the first step toward a serious study of the subject. The difficult task of presenting modern quantum theory in elementary form has been accomplished by the author with his customary skill. In a small number of pages and by the simplest means, the author draws a coherent and complete picture of the most important and fascinating field of modern physics. At the same time, the new theories are presented not as “additions,” but are laid into the very foundation of the book. Already in the first pages of the book (Chapter II. Foundations of Atomic Mechanics) a concise and very clear outline is given of modern quantum mechanics in its two most important forms (the wave mechanics of de Broglie–Schrödinger and the new quantum mechanics of Heisenberg). The following chapter is devoted to a very detailed exposition of the theory of spectra, including the Zeeman and Stark effects, the theory of multiplets, and the theory of the periodic system. Chapters IV, V, and VI examine the most varied questions connected with the structure of atomic nuclei and the structure of molecules (up to the dipole moments of molecules and Debye’s theory of strong electrolytes). Finally, the last chapter is devoted to problems of the interaction of light and matter: the theory of dispersion, the photoelectric effect, the Compton effect; in the concluding paragraph, an account is given of the theory of the electron developed by Dirac.

From the brief list given above it is evident that the book is in fact a whole encyclopedia of atomic physics. Of course, such completeness of content in a small volume is achieved at the cost of

the sketchiness of the exposition of many questions. On the other hand, certain inconsistencies are striking; thus, for example, 15 pages are allotted to the elementary theory of radioactive phenomena, which in essence could have been assumed known, while the experimental evidence for the wave nature of the electron is mentioned only in passing, on a single little page. These, however, are minor matters. On the whole it must be acknowledged that the book will be of great benefit to anyone who wishes to obtain a sufficiently clear and not overly superficial idea of the most pressing problems of contemporary physics.

E. Shpolsky