Preface

After many years I decided to return to an unfinished book that I wrote together with Dau, as his friends called the remarkable scientist and great-hearted man Lev Davidovich Landau. The book was Physics for Everyone. Many readers in letters had reproached me for not continuing the book. But I found it difficult because the book was a truly joint venture.

So here now is a new edition of Physics for Everyone, which I have divided into four small books, each one taking the reader deeper into the structure of matter. Hence the titles Physical Bodies, Molecules, Electrons, and Photons and Nuclei. The books encompass all the main laws of physics. Perhaps there is a need to continue Physics for Everyone and to devote subsequent issues to the basics of various fields of science and technology.

The first two books have undergone only slight changes, but in places the material has been considerably augmented. The other two were written by me.

The careful reader, I realize, will feel the difference. But I have tried to preserve the presentation principles that Dau and I followed. These are the deductive principle and the logical principle rather than the historical. We also felt it would be well to use the language of everyday life and inject some humour. At the same time we did not oversimplify. If the reader wants to fully understand the subject, he must be prepared to read some places many times and pause for thought.

The new edition differs from the old in the following way. When Dau and I wrote the previous book, we viewed it as a kind of primer in physics; we even thought it might compete with school textbooks. Reader’s comment and the experience of teachers, however, showed that the users of the book were teachers, engineers, and school students who wanted to make physics their profession. Nobody considered it a textbook. It was thought of as a popular science book intended to broaden knowledge gained at school and to focus attention on questions that for some reason are not included in the physics syllabus.

Therefore, in preparing the new edition I thought of my reader as a person more or less acquainted with physics and thus felt freer in selecting the topics and believed it possible to choose an informal style.

The subject matter of Physical Bodies has undergone the least change. It is largely the first half of the previous edition of Physics tor Everyone.

Since the first book of the new edition contains phenomena that do not require a knowledge of the structure of matter, it was natural to call it Physical Bodies. Of course, another possibility was to use, as is usually done, the title Mechanics (i.e. the science of motion). But the theory of heat, which is covered in the second book, Molecules, also studies motion except that what is moving is the invisible molecules and atoms. So I think the title Physical Bodies is a better choice.

Physical Bodies deals largely with the laws of motion and gravitational attraction. These laws will always remain the foundation of physics and for this reason of science as a whole.