C.P. Snow had an unusually wide range of interests and many different talents, but he probably was at his best in crisply summing up people and situations. I recall from my own experience the occasions when he used to visit the universities during the war, with his friend and assistant William Cooper, to decide the fate of students about to graduate in science. Each student had to be assigned to some branch of the armed services, or to a research project of military importance, or perhaps to further research training. On the strength of the paper record and a two-minute interview, he would give a thumbnail sketch of the personality and ability of the student, which usually could not be improved upon the teachers who had known the student for years.

The same power of characterizing real people, a talent which is quite distinct from the ability to make fictional characters come alive, showed up in his biographical essays, for example about Einstein, or about the mathematician G.H. Hardy. But he did not, as far as I am aware, produce a book of such portraits.

When he died in 1980 he had been working on a book that would describe a half-century of physics and some of the leading characters in it. He was able to complete only a first draft, which has now been published. We are not given the name of an editor, but from remarks in the introduction by William Cooper it appears that he was responsible for arranging the text for publication.

The drama of twentieth-century physics, which Snow presents, comes in several acts. Up to the end of the nineteenth century physicists had not regarded the structure of matter as their problem. One knew there were atoms, but their nature was the chemist’s problem, if anybody’s. The beginning of the new attitude came with the discovery of the electron, and the realization that the laws of mechanics could be applied to its behavior within the atom. From then on atoms and what went on in them became the physicists’ main preoccupation. With improved tools experimental discoveries led to a rapidly growing body of information about the atom, one of the crucial steps, which Snow describes at the start of the book, being Rutherford’s discovery of the atomic nucleus as the center of the atom, with the electrons orbiting around it.

But the new-found knowledge did not fit in with the laws of physics as they had developed since the time of Isaac Newton, and the resolution of these contradictions required the acceptance of revolutionary new concepts. These came through Einstein’s theory of relativity, and through the quantum theory of Max Planck (whom Snow barely mentions), Einstein, and Niels Bohr. At first the quantum theory was a makeshift affair, grafting ad hoc rules on to the old mechanics, and it was only in the late Twenties that a drastic revision of the most fundamental concepts about space and motion led to a deeper understanding, the foundations of which were laid by de Broglie, Heisenberg, and Schrödinger. On these foundations, as Snow emphasizes, a complete edifice was built with breathtaking speed.

Rutherford took no part in this study of the mechanics of the atom, but continued to work on the nucleus, and succeeded in demonstrating nuclear transmutations with the aid of particles from radioactive substances. Later it became possible to do so with artificially accelerated particles. Thus started the use of large and ever-growing accelerators, initiating the era of “big physics.” New chapters in the story were opened by the discovery of the neutron and of artificial radioactivity, and by Enrico Fermi’s use of neutrons for producing nuclear reactions.

All this seemed a pursuit devoted entirely to the search for knowledge. Nearly all nuclear physicists were convinced that there could never be any practical consequences from their work. But this changed dramatically with the discovery of the fission of uranium, and the possibility of a chain reaction. Soon physicists in several countries were at work on the problem whether and how a nuclear bomb could be made. The decision to drop such a bomb on Japan will be debated by historians and other for many generations.

This work was done in secret, but when the news was released physicists found themselves in the limelight. Some blamed them for the power of destruction they had released, some admired them for having helped to win the war, but either way they had become important. Atomic bombs were the most spectacular, but by no means the only, important contribution by physicists to the war effort. Other work, including particularly radar, was also of vital importance, probably more decisive than atom bombs.

After the war physicists returned to their search for the basic laws of nature. Their work on nuclear physics and their new study of subatomic particles required the use of bigger and bigger accelerators. The new respect for physicists resulting from their wartime work helped to obtain the necessary financial support. Snow repeatedly quotes a comment by Mark Oliphant about the new position of physics: “We have killed a beautiful subject”; he disagrees because physics did after all return to the old spirit of inquiry. But Oliphant might well counter that the nature of “big physics” with its large machines and gigantic measuring equipment, requiring long-term planning and large teams, makes it a very different kind of activity.


But the rapid advance of knowledge resumed, and a whole world of new particles and their transformations was discovered. The physicists are making progress with discovering the underlying laws, but much remains to be done. There was also impressive progress in other branches of physics. New discoveries in solid-state physics have led to the transistor and other electronic devices, and these have led to the modern computer and other tools for automation. Astronomy has made spectacular advances, assisted by the use of radio telescopes, which benefit from the lessons learned from wartime radar work. The new science of molecular biology has arisen from the use by physicists of X-ray methods for puzzling out the structure of biological substances, and thus the genetic code was deciphered.

Snow’s presentation of this story is brief, and he cannot be expected to do justice to details in an account of some eighty pages of text. But with his particular skill he makes the story lively and brings out the main features, perhaps like a charcoal sketch which may present the character of the subject even though details may be missing and some of the lines are not very accurate.

There are indeed many inaccuracies in the book, some amounting to very surprising errors of fact. One would assume that it was Snow’s intention to check on some of these facts in later drafts, and William Cooper (or whoever had editorial responsibility) has not done Snow’s memory a good turn by allowing these errors to stand. Cooper mentions in the introduction that Snow wrote the book from memory, and comments on how remarkable his memory was, if selective and with an occasional odd emphasis. But there are limits to the reliability of even the best human memory.

It is surprising that Snow would make some of the errors even in a rough first draft, as when he refers to the “British Nobel Prize winner A.H. Compton” (Compton was one of the most American of great physicists), or when he reports that the “ALSOS” mission to Germany at the end of the war to look into German atomic-energy work was led by Samuel Goudsmit and George Uhlenbeck (it was only Goudsmit; the other name came from an association of these two in their earlier discovery in physics). It is surprising to see the reference to Heisenberg as “an active spokesman for the Nazi faith.” Heisenberg was, as Snow remarks later, a German nationalist, and could be accused of making his peace too readily with the Nazi regime. But to call him an active spokesman is a gross distortion. General Groves is called “a singularly bad choice for his job,” apparently on the strength of his error of judgment in claiming that the United States had a twenty-year lead over the Soviet Union in making atom bombs. This deplorable, but not uncommon, arrogance should not overshadow the merits of an administrator of unusual energy and courage.

Other errors, too numerous to list, are more understandable, but might well have been eliminated in a revised draft. Atomic physics was not becoming known as “particle physics” in the 1920s—this name for subnuclear physics came into use only after the Second World War. While the Soviet physicist Peter Kapitsa was out of favor with Stalin he did not stay in his house on the grounds of his institute in Moscow, but in his country cottage or “dacha.” Murray Gell-Mann did not introduce group theory into physics (this was done by Wigner a generation earlier), though he made very effective use of it.

Some of the portraits of people known personally to Snow display much insight. The study of Rutherford penetrates beyond the superficial appearance of robust self-confidence, and Snow succinctly characterizes the personalities of Einstein and Bohr. Of Kapitsa only some aspects emerge (his contribution to physics is not mentioned, unless I have been misled by my inadequate memory, and the somewhat slipshod index), but what there is bears a true likeness. Others, such as Chadwick or Fermi, are recognizable; many appear only as rather shadowy figures. The single sentence about Wigner contains a curious juxtaposition: “Wigner was calm, judicious, ironic, temperate, mildly conservative: his sister was Dirac’s wife.”


In telling the story of the physicists one must of course refer to the problems with which they were struggling and to their solutions. This is by no means easy to do in layman’s language in so brief a space. As a physicist I am badly qualified to judge how far Snow succeeds in making these explanations intelligible, but it seems to me that, apart from some rough spots, and some inaccuracies, his brief account does remarkably well.

No such difficulty in communication arises in discussing the physicists’ role in the development of nuclear weapons. Snow does not go deeply into the technical aspect of this. I cannot refrain from noticing that he overrates the direct influence of the “Frisch-Peierls memorandum” on the atomic-energy work in the United States. This paper served to persuade the British authorities to take the possibility of a nuclear weapon seriously, and this may in turn have accelerated the American decision to back the physicists who were anxious to go ahead.

He is more interested in the moral issues. He does not blame the physicists for their part in creating these terrible new weapons. He regards this as an inevitable development. As for the German physicists, he criticizes the myth that they deliberately refrained from making bombs for ethical reasons. Instead he claims that they failed to have a clear idea of what was needed for the bomb. This view is not supported by recent historical studies: they did know, but considered—probably rightly—that there was no chance of Germany completing such a project before the end of the war. In fact they did not believe that the United States could muster the tremendous effort required. Snow does not think they would have refused to make the weapons if doing so had appeared feasible. “In comparable circumstances, American, English, Russian scientists would have felt that the evils of the regime counted for nothing against the evils of absolute defeat.” Perhaps so, but there were German scientists who felt otherwise, and who, at tremendous personal risk, worked for Allied intelligence in Germany during the war.

About the consequences of the scientists’ work, he points to the many beneficial results besides the destructive ones. Even the weapons have their positive side, since the fear of them has been a restraining influence in areas of potential conflict. While there cannot be a complete assurance that the world is safe from global nuclear war, he thinks the risk is small. However, with an increasing number of smaller nations acquiring nuclear weapons, he believes it is very likely that sooner or later there will be some local war with nuclear bombs. This and their possible use by terrorists are the risks he thinks we should worry about.

He ends without attributing to the physicists any special role in safeguarding the future: “Their own intellectual structure waits there to be added to, but is unshakeable. The application which has come out of that structure has left us with some threats and more promises. It is for the general intelligence of us all to make the best of both.”

Yet one of three appendices included in the book, presumably not by Snow’s choice, is an address he gave in 1960 with the title “The Moral Un-neutrality of Science.” In this he assigns to the scientists a much greater share in the responsibility than they bear just as citizens, because of their close association with developments that can vitally affect the future, and because of their deeper insight. They “have a moral imperative to say what they know.” He implies that the scientists can, by explaining the consequences of alternative policies (e.g., continuing the arms race or accepting some restrictions) help argue for the right course of action. Did he change his mind in the twenty years since the address was given or is this just a change in emphasis?

According to William Cooper’s introduction, the book was written at great speed. This may account for some of its weaknesses, but it gives it what Cooper calls an unimpeded narrative impulse, which makes it a pleasure to read.

This Issue

December 17, 1981