Atomic Germans

Physics went through a major revolution in the first quarter of this century. It was started by Max Planck and Niels Bohr, whose use of the idea of the quantum of action brought order into a wide range of phenomena concerning the structure of matter and the nature of atoms, but was as yet incomplete, in some parts arbitrary, and even self-contradictory. The final stage of this development, which completed our understanding of atomic physics, owes as much to Werner Heisenberg as to any other single person, although another development, started independently by Schrödinger, turned out to be a different expression of the same basic laws. Many others, of course, made important progress along the path opened up by the pioneers.

Heisenberg’s greatest contribution was to recognize that the contradictions of the old quantum theory were the result of asking questions to which there was no physically meaningful answer. Physics deals with observable phenomena, and in the atomic domain the indivisibility of particles and the existence of quanta put a limit to the accuracy of possible observations, if they are not to disturb unduly the very phenomenon under observation. The lesson was, therefore, to avoid asking questions about atoms to which no experiment could give an answer, and to express the laws of physics by reference to observable quantities. Heisenberg succeeded in carrying out his program, and the set of laws he arrived at form one of the starting points of modern theory.

Physics and Beyond is an account of his thoughts, including the ideas that led him to quantum mechanics; this part will be of absorbing interest to anyone interested in the history of physics. The book is not an autobiography: details of the author’s life are mentioned only where they are needed to provide the background to the thoughts and discussions, which are the real subject of the narrative.

The thoughts described are not, however, limited to physics and to the epistemological problems that were bound up with the beginnings of quantum mechanics, but range widely over philosophy and religion, reactions to life under the Nazis before and during the war, work on atomic energy, and the reorganization of German physics after the war. It seems to be a thesis of the book that attitudes toward the more abstract and the more concrete of these problems are interconnected. This is stressed in the title of the German original “The Part and the Whole” (Der Teil und das Ganze), which in translation has mysteriously, and to me rather disappointingly, become “Physics and Beyond.”

However, the nature of this connection is not spelled out, and the reader is left to find it for himself. Is there a recognizable connection between Heisenberg’s thoughts in very different fields? I find the answer to this question very elusive. Was he better able to see what accepted ideas of physics had to be discarded because he grew up in a postwar world in which young people were questioning accepted social values? There is some plausibility in the thought, yet others, such as Einstein, Planck, or Bohr, came to equally revolutionary thoughts from very different personal backgrounds.

Were his views on politics or public affairs conditioned by his reasoning powers as a scientist? Scientists probably have something in common in their attitudes toward such problems in that there are some fallacies and some kinds of confusion to which they are not prone. But beyond that there is room for vast differences in approach. One should probably not look for such simplified connections. It remains that the thoughts on physics, on music, on world and national affairs are the thoughts of one person, and all go to make up the “Whole” of the mind behind the book.

To escape the tedium of continuous abstract argument, Heisenberg presents conversations with friends and colleagues, describing, for greater liveliness, the setting in which each conversation took place, whether in the study of one of the participants, on a bicycle ride through the mountains, or when they were watching the boats in the port of Copenhagen at night.

Even so the conversations are necessarily simplified and telescoped. The author makes it clear in the Preface that they are not meant to be accurate recordings. In fact, it is clear from the Preface, and from reading the conversations, that the other people appear only as a backdrop to the author’s thoughts. It could not be otherwise because it would be a hard task indeed to present adequately the thoughts expressed years ago by another person whose views were different from one’s own. The influence of other people’s arguments on Heisenberg comes out clearly enough, but one should not look for a faithful picture of Bohr, Pauli, or other actors in the narrative—in spite of their participation in sailing trips and mountain walks, they do not really come alive.

What does come out very clearly is the extent to which in our time scientific ideas do not materialize suddenly in the mind of one person, but grow from his interactions with others. This applies not only to the early stages, when his teachers help him to understand what is already known, but also later when many colleagues, younger and older, struggle in discussions for an understanding of the facts and of the meaning of new concepts. The influence of his environment on a scientist does not, of course, diminish our respect for one who, like Heisenberg, has taken a major step forward.

The presentation in the chapters dealing with physics is non-technical. For the reader who is a physicist this is not a disadvantage, since he will recognize the precise meaning of what is being discussed. I find it hard to judge whether the explanations given are adequate to make the arguments meaningful to a lay reader, but I believe that it is possible, without a knowledge of the technical details, to sense the essence of the story: the difficulty, and the excitement, of finding and formulating the new laws of nature, which retain the successes of the older forms, but incorporate the new and apparently contradictory findings; the struggle to find new concepts appropriate to the newly gained knowledge, but contrary to our intuition, which has grown from experience on the scale of everyday things and needs correcting when we are concerned with atoms or still smaller objects.

Another topic of great interest is the author’s attitude toward the Nazis and toward the war. Heisenberg reports the horror, and the sense of frustration, with which he watched the growth of the Nazi movement. Some of the reported conversations showed how he who as a boy had been active in the German youth movement, which stood for a rethinking of conventional values, against materialism and against hypocrisy, was pained by appearing now as a representative of the older generation, in opposition to the “adventurous” spirit of the young National Socialists.

But he saw clearly the disastrous nature of the new movement. He saw its anti-intellectual nature, he was horrified by its anti-Semitism, and he realized that its aggressiveness would sooner or later lead to war and disaster. Yet in arguing with a Nazi youth leader among his students, he presents the young man’s views with a certain amount of sympathy. His answers stress the faults of the new regime, but the student’s criticism of the old state of affairs which in his mind justified any drastic change is left uncontradicted. One guesses that Heisenberg, who evidently abhorred the methods and the inhumanity of the Nazi “revolution,” may have felt a measure of sympathy for its aims.

As the pressure of the Nazi regime mounted, with its interference in university affairs and with irksome rules, and as the ranks of university staff became more and more depleted by dismissals, Heisenberg’s thoughts turned inevitably to the possibility of resigning and emigrating. He asked Max Planck, the respected old physicist, for advice. The chapter started by the dialogue with the Nazi student is then completed by a dialogue with Planck, and Heisenberg’s own struggle with the problem on the train back. In both only the arguments for staying are marshaled; evidently the case for leaving is so obvious it does not have to be explained. In the end Heisenberg decides to stay, his strongest argument the need for keeping a group of people of good will together, who will not be able to influence what happens under the Nazis, but who will be available to help rebuild “after the holocaust.” Here, in a conversation during a trip to the United States in 1939, it appears that he was quite clear that there would be war, and equally that Germany was bound to be defeated.

War did come and soon Heisenberg was drafted into work on atomic energy. This chapter is of special interest because ever since the end of the Second World War there has been controversy about the German atomic energy project. Some writers claimed that the German scientists deliberately avoided making atomic weapons, for moral reasons, while others say that they did not take the possibility as real since they had not realized how small, and how powerful, atomic bombs were going to be. Heisenberg describes his attitude toward the moral problem in a conversation—this time specifically labeled as imaginary—with C.F. von Weizsäcker, in which they agree that it would be morally wrong to use atom bombs in any circumstances, and therefore feel relieved that there does not seem to be any realistic possibility of making them. He comments later (p. 180), “…we overestimated the technical effort involved.”

In view of this statement, it is very puzzling to read further on (p. 218) that in 1954 negotiations about permission for West Germany to start working on nuclear power were influenced favorably by the fact that “Germany had made no attempts to build atom bombs during the war, although she had not lacked the necessary skills and knowledge.” This contradicts the earlier quotation. As a result we do not know where Heisenberg stands on the question whether the German scientists could not, or could and would not, work on the making of atom bombs.

Heisenberg describes how, to the group of German atomic scientists then interned in England, the news of Hiroshima seemed at first unbelievable: their disbelief again confirms the impression that they thought the project impractical. When finally convinced of the reality of the development, whose difficulty they had overestimated, they were—like everybody else—shaken by the thought of the death and destruction caused by this manifestation of the progress of science. There follows another conversation about the moral issue and the position of the scientist.

One of the last chapters deals with the beginnings of the work on the “unified field theory” which Heisenberg initiated in 1957 and which he and his collaborators still pursue with enthusiasm. This is still a controversial subject in that a great many physicists doubt the value of the results already obtained in this work and the prospects of its developing into a valuable discipline.

There was also controversy over this between Heisenberg and Wolfgang Pauli, with whom he had often collaborated in the past, and whose judgment and critical powers Heisenberg, like all other physicists, respected highly. This is recorded in another set of conversations, Pauli being at first highly skeptical and critical, but then convinced of the promise of the new theory and enthusiastically contributing ideas to its development. Pauli left for a visit to the United States full of this new enthusiasm but, to Heisenberg’s intense disappointment, returned in his old critical spirit and fiercely attacked Heisenberg’s position at an international conference. Pauli died a few months later. The whole episode was so short that many physicists were not aware of Pauli’s period of optimism, and did not know what to make of a paper bearing both his and Heisenberg’s names which had been circulated by Heisenberg and which was later repudiated by Pauli.

An explanation of the nature of the argument would be too technical for the book, so the reader is not told what this whole episode is about, but the chapter will give him a feeling of the controversies that can arise even in an exact science, and the emotions that can be engendered even by the “dry” subject of quantum field theory.

The translation from the German by Arnold J. Pomerans is, on the whole, adequate, but there are a number of careless slips (e.g., on page 160 a German Assistent is not a “lab assistant,” but more like a research associate) and too often the translator chooses a phrase which may be good English and may even be better prose than the author’s, but which does not express the meaning or the flavor of the author’s phrase. Sample: On page 79 there is a discussion in which an effort to convince Bohr to accept the consistency of the uncertainty principle is “helpfully assisted” (hilfreich unterstützt) by Oskar Klein, but in the translation this becomes “manfully assisted.” On page 142 the young Nazi student admits that in any revolution “after the initial successes also inferior people participate.” In the translation this has become “time-servers…climbing onto a successful bandwagon.”

On page 49 a quotation from Schiller receives similar treatment. The simple verse “Und setzt ihr nicht das Leben ein, nie wird euch das Leben gewonnen sein” (unless you stake your life, life will not be won) becomes: “Who would share life must risk it, and none who refuse the hazard shall gain it—who risks it may lose!”

The English version is published in the series “World Perspectives.” The biographical note on its editor, Ruth Nanda Anshen, on the back page is as long as that on the author, and her Preface is eight pages to the author’s one. I could find no indication that the book was originally published in German in 1969.

One can sympathize with the translator’s desire to improve the language. It is not great prose, but it does get the author’s personality and ideas across in a lively manner. I think I would have preferred the arguments straight, instead of dramatized in conversations. Yet the book is essential reading for anyone interested in the history of physics, or in the personality of the man who had so great a share in making that history.