Theoretical Physics (Dover Books on Physics) 3rd Revised ed

Book Preface

FROM its inception, the aim of this book has been to bring the reader to an intermediate level of attainment in the main branches of theoretical physics from which he may be able to proceed, with the help of special literature, to the field of research. Experience shows that it is often the first contact with a complex problem that presents the major difficulty, and it is here that help is most urgently needed. Nevertheless, it is necessary to make a certain selection from the many topics that seem to offer promise of development. For example, there is the question of whether an extensive treatment of the HamiltonJacobi mechanics, which at the time of the first edition (1932) formed the basis of the old atom theory, is still advisable. The decision to retain it is founded on the conviction that only in this way is the compelling and logical evolution of atomic physics in the form of wave mechanics clearly seen. Ensuing revisions of the book have made possible the recasting of the presentation of many topics. The subject of nuclear physics required, of course, the most extensive changes. In this connexion it is felt that a concise survey of the main lines of cosmic ray research is now in order, since knowledge in this field has progressed far beyond the stage of mere speculation. In this brief presentation much of the great mass of experimental material has been omitted, and it is hoped that specialists in this field will not be too critical of what is apparently a somewhat oversimplified picture. Geometric optics has been given more space and the theory of the top has been modernized on the basis of a treatment suggested by Professor Bauersfeld.

The range of subject matter has been extended by the inclusion of selected topics in what might be called “ applied theoretical physics ”. To have included these items in the respective chapters dealing with these subjects would have interrupted the continuity of development, and so they have been grouped in a separate Part of the book. In response to numerous suggestions, a Mathematical Addendum on the properties of Bessel Functions and Spherical Harmonics has been prepared. This material has been placed intentionally at the end of the work rather than in the Mathematical Introduction, in as much as it demands a somewhat higher order of computational skill on the part of the reader. Other changes include: (a) introduction of the M.K.S. system, chiefly in the formulas of macroscopic electromagnetism (there is no reason to change the familiar numerical relations in atomic physics); (b) addition of a considerable number of new exercises; (c) revision of the numerical values of physical constants; and (d) extension of the list of references for further study. It is hoped that these alterations will increase the usefulness of the work in its dual role of text and reference book.

G. J.
I. M. F.