The Physicists.

C.P. Snow.

About the Author.

Charles Percy Snow was born in Leicester, on 15 October 1905. He was educated from age eleven at Alderman Newton's School for boys where he excelled in most subjects, enjoying a reputation for an astounding memory and also developed a lifelong love of cricket. In 1923 he became an external student in science of London University, as the local college he attended in Leicester had no science department. At the same time he read widely and gained practical experience by working as a laboratory a.s.sistant at Newton's to gain the necessary practical experience needed.

Having achieved a first cla.s.s degree, followed by a Master of Science he won a studentship in 1928 which he used to research at the famous Cavendish Laboratory in Cambridge. There, he went on to become a Fellow of Christ's College, Cambridge, in 1930 where he also served as a tutor, but his position became increasingly t.i.tular as he branched into other areas of activity. In 1934, he began to publish scientific articles in Nature, and then The Spectator before becoming editor of the journal Discovery in 1937. However, he was also writing fiction during this period, with his first novel Death Under Sail published in 1932, and in 1940 'Strangers and Brothers' was published. This was the first of eleven novels in the series and was later renamed 'George Pa.s.sant' when 'Strangers and Brothers' was used to denote the series itself.

Discovery became a casualty of the war, closing in 1940. However, by this time Snow was already involved with the Royal Society, who had organised a group to specifically use British scientific talent operating under the auspices of the Ministry of Labour. He served as the Ministry's technical director from 1940 to 1944. After the war, he became a civil service commissioner responsible for recruiting scientists to work for the government. He also returned to writing, continuing the Strangers and Brothers series of novels. 'The Light and the Dark' was published in 1947, followed by 'Time of Hope' in 1949, and perhaps the most famous and popular of them all, 'The Masters', in 1951. He planned to finish the cycle within five years, but the final novel 'Last Things' wasn't published until 1970.

He married the novelist Pamela Hansford Johnson in 1950 and they had one son, Philip, in 1952. Snow was knighted in 1957 and became a life peer in 1964, taking the t.i.tle Baron Snow of the City Leicester. He also joined Harold Wilson's first government as Parliamentary Secretary to the new Minister of Technology. When the department ceased to exist in 1966 he became a vociferous back-bencher in the House of Lords.

After finishing the Strangers and Brothers series, Snow continued writing both fiction and non-fiction. His last work of fiction was 'A Coat of Vanish', published in 1978. His non-fiction included a short life of Trollope published in 1974 and another, published posthumously in 1981, 'The Physicists: a Generation that Changed the World'. He was also inundated with lecturing requests and offers of honorary doctorates. In 1961, he became Rector of St. Andrews University and for ten years also wrote influential weekly reviews for the Financial Times.

In these later years, Snow suffered from poor health although he continued to travel and lecture. He also remained active as a writer and critic until hospitalized on 1 July 1980. He died later that day of a perforated ulcer.

'Mr Snow has established himself, on his own chosen ground, in an eminent and conspicuous position among contemporary English novelists' - New Statesman.

Dedication.

TO.

MY NIECE, STEFANIE.

The First Excitement that Knowledge Gives.

Most of us can remember the first time we heard or read something which seemed to throw a new light upon the world. In my own case, it comes back with extreme clarity. I was a child of eight or nine, and I had got hold of a bound volume of Arthur Mee's Children's Encyclopaedia. It was a dark afternoon, and I was sitting by the fire. Suddenly, for the first time, I ran across an account of how atoms were supposed to be built up. The article had been written before Rutherford had discovered the nucleus, although by the time I read it the nuclear atom must have been well known. However, I was innocent of all that, I had never seen the word 'atom' before; this article it was quite short and was contained, I think, in a section called the Child's Book of Wonder explained that its descriptions were only a guess, that no man knew the truth, and yet it seemed to open up a new sight of the world.

It told me that if you could go on cutting up any sort of material, you would arrive at atoms in the end. These atoms were so small that no one would ever see them and you could crowd countless millions on to a pin point. There were different sorts of atoms: and yet, if you cut up the atoms themselves, you found in some mysterious way that they were made of the same stuff. That idea probably came more easily to a child than to an adult, and I swallowed it whole.

The actual description of these atoms was rather quaint, in the light of later knowledge. Small as they were, they were packed with much smaller things called electrons (which, of course, had been known about since J J Thomson's work in the nineties). According to the article, these electrons were like tennis b.a.l.l.s in a cathedral; and, again according to the article, the tennis b.a.l.l.s were in violent and random motion across the interior of the cathedral. It is a little difficult nowadays to see how that picture was ever conceived; I found it very easy to unlearn a few years later.

Yet, though so much of that article could not endure, it gave me the first sharp mental excitement I ever had. Somehow it gave me the heightened sense of thinking and imagining at the same time. And one is lucky if those exalted moments visit one more than ten or twenty times in a whole life...

Taken from 'The First Excitement that Knowledge Gives': editorial by the author in Discovery, April 1939.

Introduction.

The Physicists is a first draft, completed just before his death on 1 July 1980, of a book which C P Snow intended to write at greater length he planned in particular to put more material in the last chapters. However, written as it was, straight off and at great speed, it has an unimpeded narrative impulse together with a completeness over the period of time, which simply ask for it to stand on its own as a literary work.

When he first told me about the book, I said: 'Good G.o.d, you'll have to do some research for that, won't you?' To which he replied: 'I'm writing it largely from memory.' I was silenced. He had one of the most remarkable memories I'd ever come across, a constant source of envy to me. Furthermore, we'd been close friends for nearly fifty years in fact ever since the time when I was a Cambridge undergraduate reading physics, sent to him, then a Research Fellow of the College, to be taught and so I was qualified to understand that he didn't always do exactly what he said he was doing, not absolutely exactly. Wrong again! When I read the draft I recognized that it actually had been written largely from his memory. It's odd memory, even a memory as comprehensive as his, has its selectiveness, its patches, its things that stand out for reasons of other than factual importance. When an artist calls upon memory, what he writes has a life and a moving quality which scarcely ever infuses the product of the filing cabinet which we nowadays refer to as researched information.

A la recherche du temps perdu the book naturally took me straight back, at the beginning, to the days in the early 1930's when I myself was going to lectures by Rutherford and Dirac and Kapitsa, days so glorious that even my memory recalls something of their heroes. Rutherford, big and fresh-complexioned, his spectacles shielding light, transparent eyes, was indeed boomingly Jehovianic, albeit in an attractive way one could see how the physicists near to him came to give him such devotion. Looking back on it, one is tempted to speculate on how far the aggressive boom, like Anthony Trollope's aggressive boom, had grown as an outer protective sh.e.l.l Snow remarks on this in the book for a more sensitive, delicately responding nature. (Actually Blackett, in later years, always struck me as more Jehovianic tall, thin, high-shouldered, with wavy hair and a flashing eye, in manner altogether loftier, n.o.bler, graver: more of a Jehovah's Jehovah, perhaps.) Dirac was very, very different taciturn in both languages, as Snow remarks. Quantum mechanics, whether one could understand it or not, was clearly the creation of a remarkable mind; but at five o'clock of a winter's evening in an overheated lecture-room, one would have given anything for the exposition of a remarkable mind's creation to be illumined by just the occasional human spark of temperament. Kapitsa, on the other hand, provided a running succession of human sparks of temperament, a lot of them of a wonderfully clowning kind, typically Russian, and typically deceptive struggling with the English language, he appeared to keep getting things wrong and having to put them right. His broad face was smiling, his hair sticking straight out from its parting, and his nose, blunt and fleshy, making one wonder if that was the sort of nose Dostoievsky described as 'plum-shaped'. Everyone loved going to Kapitsa's lectures.

But I'm writing about Snow and his Weltanschauung, not embarking on a supplement of my own to The Physicists. (I'm tempted to make a quip to the effect that his Weltanschauung a good word from the 1930s seemed to me as comprehensive as his memory, with insights penetrating the worlds of science, of literature, of human affairs.) I'd recently been reading through some of the public speeches he made throughout the latter half of his life, about science and scientists, human affairs and human beings: reading through The Physicists I was frequently reminded of them; a sentence in the book setting up a resonance one of his favourite words with the beginning of a train of thought that he had followed at length, elsewhere on some other occasion, to a revealing conclusion.

A first case in point his reference in the book to Arthur Schuster's deliberate resignation from the Chair of Physics at Manchester University, in order to make way for Rutherford, resonated with his account of an incident three hundred years ago, when the Cambridge Professor of Mathematics, named Barrow, resigned his Chair on condition that his pupil was appointed to it, his pupil being Isaac Newton an account with which Snow began his 1962 Rectorial Address to the University of St Andrews, 'On magnanimity'. The essence of the address was a plea for magnanimity in our use of scientific and technical knowledge for 'seeing to it that the poor of the world don't stay poor...'

The great majority of the world's population don't get enough to eat: and from the time they are born, their chances of life are less than half of ours. These are crude words: but we are talking about crude things, toil, hunger, death. For most of our brother men, this is the social condition. It is different from our social condition. That is one reason why there is a direct call upon our magnanimity. If we do not show it now, then both our hopes and souls have shrivelled. It may be a longish time before men at large are much concerned with hopes and souls again.

I have quoted the pa.s.sage because to my mind it ill.u.s.trates Snow's realistic view some people, myself included, would call it a dark view of human nature, counterbalanced as it was in his own nature by another strong element, that of hope; and a belief that our hope's coming to fruition depends on men's magnanimity. He was one of the most magnanimous of men, in all senses, public and private, I've ever known. I venture to suggest that the dark view, the hope, and the magnanimity all shine through The Physicists.

And, by G.o.d, when he comes in his story to The Bomb, the hope and the magnanimity are more than necessary. (The dark view comes, as it were, in the package.) Incidentally, it's fascinating to note, propos his remarking in the book that the scientific facts essential to making the bomb were commonly known among scientists before the war, the publication in Discovery (a scientific journal Snow edited) of a notice in April 1939 of Hahn's discovery in Berlin of uranium-splitting, and in May 1939 of Joliot's discovery in Paris of what were subsequently called chain-reaction neutrons. Snow himself in the May 1939 issue wrote an editorial, 'Science and air-warfare', in which he attempted to reduce the then current hysteria about the excessively destructive effects of air-attack with TNT bombs about which, as those were the attacks we subsequently survived, he turned out to be correct. But in September 1939 his editorial was ent.i.tled 'A new means of destruction'. The world had changed. (Just to put things into perspective, it's also fascinating to recall that in 1913 H G Wells, in The World Set Free, had forecast something like an atomic bomb.) The world had changed, and after 1945 it was riven by the moral issue arising in the first instance from the destruction of Hiroshima and Nagasaki. There may have been some justification for Hiroshima: for Nagasaki I, like many of the physicists, believe there was none. If ever the dark view of human nature had a profound source, the destruction of Nagasaki touched that source. The book tells the story of how the physicists understood and responded to the moral situation they were in, tells it movingly and magnanimously. The issue in a broader sense has since become, and remains today, one of such emotional, intellectual and moral significance to everybody, scientists and non-scientists alike, that I am including at the end of his book a speech in full, called 'The moral un-neutrality of science', which Snow delivered to the American a.s.sociation for the Advancement of Science in 1960. Snow's view of science as an intrinsically moral activity (in the sense that it is an undeterred search for observable truth), which has a moral influence on the men and women who engage in it, is a view which we talked about and which meant a great deal to him. It strengthened his belief that it was through science and technology that we could, and must, 'see to it that the poor of the world don't stay poor.'

Yet 'The moral un-neutrality of science' doesn't say the last word about the dilemmas in which physicists, and scientists in general, found themselves after the war. Up till 1945 dilemmas were well below the surface: the Hitler war, as Snow calls it, had to be won. And for that purpose the bomb had to be made and secrecy had to be kept, and there was no difficulty about it. In those days Snow and I were hiving off selected physicists into what was artfully called the Directorate of Tube Alloys, of whose function I had only the vaguest intimations to begin with. Then, along with the intimations taking clearer, fearful shape, there was a half-saving grace which I always remember being expressed by F Simon, another distinguished Jewish refugee physicist, holding a Chair at the Clarendon Laboratory in Oxford: a dark, starless night, and Simon walking with us to the gateway of the Clarendon we had been working late and he said: 'I hope it won't work...' Spoken with great prescience and deep emotion; yet I felt sure that au fond he knew it actually was going to work.

It did work, and after 1945 the physicists were burdened with the moral dilemma over the making and the using of the bomb; and on top of that the dilemma over secrecy which in effect meant keeping things from the Russians. That latter dilemma sharpened as the Cold War came into being, sharpened as the conflict between loyalty to the nation-state and loyalty to the individual conscience became absolutely explicit. That dilemma, too, may be one to which there is no solution in the abstract; and Snow himself seems to recognize that. In 'The moral un-neutrality' his view appears to go one way: in another speech, called 'State v. individual' it appears, if not to go the other way, at least to be unresolved.

Human affairs, it seems to me, depend upon a degree of trust. If, within one's own society and state, one can't rely on that degree of trust, the social life becomes, to put it mildly, precarious. Individual conscience is essential and mustn't be denied. But often it isn't a sure guide to action. As a general rule, it isn't a guide sure enough to let one break one's obligations and one's oaths. That, for me at least, is a general rule. Clearly there are situations when it wouldn't be overriding. The problem is, as in all ethical problems in real life as opposed to the textbooks, where the line is drawn.

Nevertheless, although during the Hitler war secrecy obtruded in the lives of professional scientists who until then, especially during the Golden Age, had never given a thought to it; although it has still not been cast out as well as national secrecy we now have commercial secrecy, G.o.d wot Snow still considered the scientific profession to be the one that offers its members the greatest freedom. (He did not die as Wells did, seeing many of the things he'd hoped for not having come to pa.s.s in despair, far from it.) In 1970 he delivered a speech at Loyola University in Chicago, 'Freedom and the scientific profession', in which realistic acquiescence to the way the world was going is uplifted by hope. As I have used the word 'freedom' myself, I must quote his menacing opening paragraph about it.

Freedom is a word that needs using carefully. Too often we have used it as a political slogan and done ourselves no good in the process. If you use words for political purposes, they soon lose whatever meaning they may have had. If you are tempted to brandish the word 'free', remember that over the gates of Auschwitz there stretched and still stretches the inscription Arbeit Macht Frei. Language is the most human thing about us: in a sense, the invention of language made us human: but language, perhaps for the same reason, is the greatest expression of human falsity, or if you like, of original sin.

So much for the word 'free'. Snow excludes both the political and metaphysical usages, and concentrates on its usage in our day-to-day living, particularly in our working-lives.

It was in order to avoid that kind of subjectivity that I chose some questions which we can all answer. They are matter-of-fact questions, just as the freedom to which they refer is a matter-of-fact freedom. I don't apologize for this. Unless we know what being free means in our working-lives, we aren't likely to be specially sensible about what being free means anywhere else. Well then. How free are you to choose your work? From day to day? From year to year? How free are you to explain it? To say what you think about it? How free are you to earn your living through your work? In your own country? In other countries? Anywhere in the world?

And then in answer: Of all the people I've known, the only group who would say 'Yes' to that whole set of questions are the professional scientists. Even then not without qualification and distinctions, which I shall come to presently. But, by and large, professional scientists have the possibility of acting more freely than any other collection of human beings on earth. Answering my simple questions, they can say at least as soon as they are out of their apprenticeship or training for research that they can choose what kind of work to do. Their subject for research that is at their own disposal, just as much as what a writer selects to write about or a painter to paint. Very few of us have that degree of freedom: certainly no politician has, though the more inflated may fool themselves that they have. And the scientists are entirely free to publish what they have done, how and where they please: they are under no constraints: they can publish the results of their work however they like. Unlike other kinds of creative person, they are normally not interested in any kind of commercial influence. There is another fact which separates them decisively from the rest of us. Their skill is international in the fullest sense. No other group of professional people (except perhaps musicians and ballet dancers) can say as much. A scientist has the potential to earn his living, and to do his proper work, anywhere. Many have demonstrated this.

The qualifications have to be taken seriously. Especially in the physical branch of the scientific profession, for those physicists who have remained or become soldiers-not-in-uniform: they are restricted in their choice of work, in their movement from country to country, and in their right to publish. The next restriction upon physicists comes with the necessity, as Snow remarks in the book, to work, if they want to choose particle physics, in teams and wherever the necessary large machines happen to be. The third comes from safety: that is a restriction that is looming ever more ominously over the work of molecular biologists, and genetic engineers.

Yet, realistically acquiescing to the increasing articulation of society and conceding the restraints that arise therefrom, Snow still sees the scientific profession as the one to which the replies to his questions come nearest to a universal 'Yes' a 'Yes' that is strengthened by the increasing importance of science in the post-industrial society, by the expansion of its scope and the funds devoted to it. And even in an era when nationalism is having a grisly recrudescence everywhere, science remains above all international. The great majority of scientists have a wider choice than the rest of us, in our professions, of what topic they'll work on: they are freer than the rest of us to move to any country where that work is going on; and when they publish the results of their work, it can be, and it is, read all over the world. From this Snow in the speech draws his conclusion: I have been speaking, deliberately, about one of the most privileged groups of human beings in my view the most privileged group bar none in the world today. I have no doubt that they will continue to be as privileged, relative to the rest of us. So that they set a kind of limit when we think of what we others can realistically expect of free behaviour in an increasingly interlinked society. That is why I have talked so practically and prosaically. Free behaviour, being free, acting freely in our existential choices, freedom they are not usually helpful concepts in our life as we live it. What we need, I think, especially when we are young, is a sense of non-utopian expectations: of measuring our expectations against what people are doing in their professional existence. The professional existence I have selected is the one which most clearly points towards the future. In some ways, as I have said, its members will by the end of the century not have the option to behave as freely as they do now. In some ways they have increased degrees of freedom. There is nothing to be pessimistic about. If our expectations are anywhere near right, the scientific profession will still provide a desirable life, within the human limits. If we hold up that model as something which other working-lives can aspire to, we still won't do badly. It is a better model than other ages have had: much better than that of the Homeric warriors or the Norman pattern of chivalry or the philosophers of the Early Church: much better, and believe it or not, much more genuinely free.

William Cooper.

LONDON, DECEMBER 1980.

1: The Direction of Time's Arrow.

IN not much over a generation, physicists have changed our world. That applies to the most elemental of situations, life and death. Nuclear weapons are an achievement of applied physics. To many people they have brought a new kind of fear. It is hard to be cool-headed about this, in the atmosphere of our times. Perhaps a look at the present situation of the world, including the state of modern physics, will help us to see things with calmer eyes. Even so, it isn't comfortable to live with the thought that it is within human power to exterminate a sizeable fraction of the world population within a matter of hours.

It won't do any harm, however, to be reminded that applied physics can have an entirely benevolent face. The most dramatic example, as will be seen when this account comes to an end in the year 1980, may be the prospect of abundant energy for ever. If this happens, it will be when nuclear fusion (a process which produces the energy of the hydrogen bomb) is controlled for peaceful purposes. If this happens, and it is not a certainty, then we shall have a new source of social hope. It is the most exciting promise that applied science has yet suggested not a firm promise so far, but more than a dream.

The gifts of applied science and this will have to be said more than once are two-faced. We have to see that the benevolent face gets the better of it. That is, of course, the public responsibility of all of us. It is going to need tough and far-sighted minds, not easily paralysed by dread. The possibility of nuclear energy is a good example in front of us here and now.

These results there are plenty more come through the physicists' power over the natural world. This has happened very quickly, and has become concrete in the s.p.a.ce of a generation. The roots of these changes go back further, to the emergence of nuclear and electronic physics, but even that is not very far away, almost within an old man's lifetime. This book will attempt to tell about some of the people who played a part to begin with, naturally enough, without any clear idea of where their thoughts and actions were leading. It is a mistake to imagine that the founding fathers of modern physics were actively concerned with practical applications. With almost all of them, that was a subsidiary interest, if as much as that.

That certainly wasn't the motive which drove them on. The essential motive, if one is going to simplify, was curiosity. The old name for their subject was natural philosophy, as it still is in Scottish universities, and that gives a better impression of what they were trying to do. They wanted to understand the natural world. Anyone who can add even a little to such understanding, as Einstein said, has been granted a great grace. Understanding the natural world was enough to engross any man's power, and enough to justify any man's life.

For a good many of the personages in this account including those who were serious world citizens and more reflective than most of us the first time that they were meshed into immediate practical problems was in the Second World War, and then out of bitter necessity. They proved to be singularly effective; Fermi is a star example. A number remained influential in applied science afterwards, but many longed for the peaceful days of the 1920s, which still glow as the golden age of natural philosophy. Mark Oliphant, more eloquent and outgoing than most, spoke for them just after the war: 'We couldn't have done anything else, but we have killed a beautiful subject.'

Oliphant was and is a strong man, but that was a cri de coeur. (Later in his life he became Governor of South Australia; almost the only scientist of high achievement to occupy such a position.) However, events have proved that he underestimated both the dynamic of natural philosophy and the shortness of human memory. True, physicists have never quite recaptured the hopeful and benevolent internationalism of the 1920s, when their community was the nearest approach our century will know to an 'island of peace'. Still, the great edifice of physical science has continued to be built, one of the few human activities where only a fool could deny the reality of progress. There is no progress in art, just change. Today's writers write differently from Homer and Aeschylus, but they don't write better.

Our understanding of the natural world shows, like nothing else in human enterprise, the direction of time's arrow. Isaac Newton was, by common consent, the greatest scientist who has ever lived: but any adequate A-level student now knows more about the physical universe than Newton could have done. Incidentally, the recent additions to the edifice of physics have not only revealed more of the details of the physical universe; they have shown the universe to be a far stranger place than we could have conceived even thirty years ago. We have learned to accept notions such as antimatter, black holes in s.p.a.ce, and the bewildering properties of quarks the ultimate const.i.tuents of matter. Scientific discovery is a process without limits, as Newton realized three hundred years ago, when he said, 'I seem to have been only like a boy playing on the seash.o.r.e, and diverting myself in now and then finding a smoother pebble or a prettier sh.e.l.l than ordinary, while the great ocean of truth lay all undiscovered before me.'

2: From Macrocosm to Microcosm.

WHEN did modern physics begin? That isn't a question with much meaning, since the process is continuous. For our present purposes, we can make a crude statement about physicists, practically and intellectually. Modern physics began with the discovery of the particles of which atoms are made: first electrons, then protons and neutrons. These discoveries began to be made in the last years of the nineteenth century.

Through most of the nineteenth century, cla.s.sical physics was advancing fast. Scientists were studying the large-scale laws of matter and energy: Newton's law of gravitation explained how the planets and stars move; the laws of thermodynamics laid bare the properties of energy and heat, with practical results in the steam engine; and electricity and magnetism were being swiftly unravelled. Some people, even eminent scientists, believed that scientific effort was getting near to its end, and that there remained only mopping-up operations they sensed the day of total victory in man's understanding of the physical universe. The same feeling, that scientists have reached final statements, has occurred in other domains of science since: it has always been an intuition gone wrong. They were not greatly concerned with the structure of matter on the smallest scale. The general run of scientists a.s.sumed that matter was made of atoms, indestructible, eternal, and that these presumably differed from one element to another, as chemical experiments indicated.

Chemists, far more than physicists, were concerned with atoms, for it was now clear that chemical reactions were simply the rearrangement of atoms into larger groupings called molecules. Chemists knew the relative weights of the atoms of the different elements. The Russian chemist Mendeleev had found that when he arranged the elements according to their atomic weight, curious patterns emerged elements with similar chemical properties recurred at regular intervals. Although physicists thought vaguely there must be something in Mendeleev's law, they usually brushed the topic aside. Atoms were a convenient concept especially for chemists but the major nineteenth-century physicists had plenty to keep them busy without speculating about atoms.

The physicists were settling the great laws, the macrocosmic laws, of electromagnetism and thermodynamics, as difficult to penetrate as the microcosmic laws of their successors, and obviously of immense applied significance. Faraday was the greatest of experimental physicists (the only compet.i.tor being Rutherford in the next century) and he applied his gifts to probing the properties of electricity and magnetism, and the relation between them. When Faraday started his researches, electricity and magnetism were nothing but playthings. Before he died, the laws of the electromagnetic field were being worked out, and big electrical industries were already set up, though not in his own country.

Faraday was one of the saints of science, gentle, una.s.suming, generous, preserving the virtues of the Sandemanian sect (a relaxed derivative of Calvinism) in which he was brought up. He was one of the very few of the great scientists to be born among the very poor. Somehow he was spotted as a bright and dexterous lad, and he became a laboratory a.s.sistant to Sir Humphry Davy, who treated him with some condescension (as from parvenu bourgeois to proletarian) but gave him a kind of scientific opening. Faraday didn't repine. Quite rapidly, he became one of the Victorian glories, and his lectures at the Royal Inst.i.tution one of London's treats. d.i.c.kens offered to help write the lectures so as to make them accessible to a wider audience. Victorians were remarkably good at recognizing and celebrating their own great men.

Meanwhile another man of supreme gifts was at work turning Faraday's results into mathematical form one of the great theoretical feats of the nineteenth century. Clerk Maxwell was, like Faraday, a man of unusual sweetness and light. Unlike Faraday, he was comfortably off, a Scottish landowner, and when his health failed (he died in his forties) he retired from the Cavendish Chair of Physics to his own estate. The Chair had just been created at Cambridge, thus initiating the only research school in England at a time when American universities such as Michigan had already had well-organized research for thirty years past. Maxwell left a pleasant legend in Cambridge. He was high-spirited and entertaining. His only vice was the writing of indifferent light verse with an obsessive facetiousness that has since been emulated by other scientists.

There was another mind, at least as powerful as Maxwell's, operating in hermit solitude on the other side of the Atlantic. Willard Gibbs was, single-handed, establishing the conceptual laws of thermodynamics, and thus the whole of cla.s.sical physical chemistry. Originally, thermodynamics was the science of how heat and energy are related, and the impetus of studying it came from the practical importance of the steam engine. Gibbs' theoretical insight discovered that the same laws of thermodynamics control the chemical reactions between atoms. It was said that you had only to read Gibbs' great works to understand everything about chemical thermodynamics but since his exposition was in a notation known only to himself, it would probably be easier to work the subject out for oneself. Gibbs was a shy eccentric, something like Kant, with habits so regular that people could set their watches by him. He lived with his sister in New Haven, and was impossible to stir. He was, along with the a.n.a.lytical philosopher C S Pierce, the most original abstract thinker born in America so far. It is uncommon to meet an American student who has heard either of those two great names.

Theirs were the heights of cla.s.sical physics before the modern age (more correctly the particle age) began. Of course, cla.s.sical physics didn't end in the 1890s, when the electron was discovered. Essential work is being done today. Most of the problems of hydrodynamics and aerodynamics are solved by applying the laws of cla.s.sical physics. G I Taylor, one of this country's most gifted theoreticians, devoted his life to them, except when he was called on like a fire-engine for one of the jobs that required his superlative technical mastery as when he computed the properties of the blast-wave from a nuclear explosion. The principles of s.p.a.ce travel are cla.s.sical, and Tsiolkovsky, the early twentieth-century Russian scientist-engineer of genius who predicted much of what has occurred, would have no difficulty in making his way round a modern s.p.a.ce centre were he still alive he would no doubt wish that he could have laid his hands on our metallurgy and propellants.

Still, cla.s.sical physics lost its dominance and there was a change of direction among physicists, somewhere near the turn of the century. The initiative didn't come from abstract thought, but from some puzzling observations (much more as romantics expect scientific revolutions to start, though history often tells us otherwise). With the development of efficient air pumps, scientists could now investigate air and other gases at very low pressures. When an electric current was pa.s.sed through such a gas, physicists were surprised to find 'rays' streaming off one of the electrodes (the cathode). A German physicist, Eugen Goldstein, christened them cathode rays but what were they?

In 1895, another German physicist, Wilhelm Roentgen, found that cathode rays produce another, even stranger, type of radiation when they hit a solid object. He called them X-rays: X for unknown, for these highly penetrating rays were unlike anything then known. The following year, a French physicist, Henri Becquerel, found that minerals containing uranium also produce radiation, quite spontaneously. Where did radiation come from? Clearly from components of the mineral itself but how? It is not known whether any of the early observers guessed that the answer was individual atoms. Scientific papers are always written as though no one ever antic.i.p.ated anything.

Much of this activity was taking place in Paris. That itself was rather odd, for France at the time wasn't as scientifically developed as England or Germany. Academic salaries were meagre, and laboratory equipment primitive beyond belief. (The latest TV film of Marie Curie and her husband Pierre at work in Paris minimizes, rather than exaggerates, the paucity of resources with which they had to do their work.) But people with the scientific obsession aren't easily put off by poverty of that kind. Rutherford used to boom: 'I could do research at the North Pole.'

There was a lot of determination and ability in Paris: in addition to Becquerel there was the Polish woman, Marie Sklodovska, who had just become Madame Curie, and the young Paul Langevin who was eventually to invent among other things sonar. In a partly accidental, but scientifically meticulous, fashion, some of the first discoveries in modern physics were made. The Curies isolated a new element, and called it radium. Radium had various curious properties; for example, it had a finite lifespan, losing weight by degrees as it emitted several distinct kinds of radiation. The idea that atoms might not always be permanent, but could sometimes disintegrate of their own accord, hung vaguely in the air.

Then J J Thomson proved in 1897 that cathode 'rays' were not waves of radiation at all Thomson deflected them with both magnetic and electric fields, evidence that they were minute particles of matter each carrying an electric charge. His experiment also showed that these particles electrons weighed far less than hydrogen atoms. That is, particles of a different order from any atoms were proved to exist. It took some years for scientists to guess or realize that these particles could be emitted from atoms themselves, or to speculate that atoms were not simple but had const.i.tuents of their own. From the first, these results cut across the grain of most preconceptions. There were cla.s.sical physicists who died unconvinced. But in fact this convulsion of scientific thought, like those which came later, was quickly domesticated. Scientific reason showed itself too strong for doubt.

he existence of the electron was soon taken for granted. As a matter of history, there was something of a personal row. Who had really discovered the electron? Who had the priority? Scientists, as a great pract.i.tioner, Peter Medawar, has recently reminded us, are very much like other people. They come in all shapes, sizes, temperaments. Some are very clever, as the outside world judges cleverness. Some aren't. Some are n.o.ble, and again, some aren't. There are often disputes about priority, and they can be very bitter. Newton, it is sad to say, was venomously ungenerous in this respect. Charles Darwin was magnanimous, and so was Alfred Wallace, who arrived at Darwin's conclusions about the evolution of the species at the same time.

That may have happened over the electron. Philipp Lenard, a German physicist, certainly thought so, and said so with vehemence. He also said, with even more vehemence, that he had got in first. But he didn't get the major credit, which went to the Cavendish Professor, J J Thomson. Most neutral opinion seems to have thought that there was no injustice done. As someone said, in a great discovery the scientist must satisfy two criteria. He must know what the discovery is, and he must know how important it is. Thomson satisfied both criteria. He had a much more lucid intellect than Lenard who, incidentally, as an old man was one of the only two eminent German scientists who became active spokesmen for the n.a.z.i faith. (The other was Werner Heisenberg, a great theoretician not yet born at the time of Lenard's dispute with Thomson.) When the electron had been identified, there was no doubt from that time on about the existence of sub-atomic particles. Electrons must be an integral part of every atom, and Thomson replaced the earlier, chemists' concept of the atom as a structureless 'billiard ball' with a more sophisticated model. Thomson's atom was a diffuse sphere of positive electric charge, with the negatively charged electrons embedded in it. In the cathode ray tube electrical forces ripped the electrons out of the residual gas atoms and sent them flying down the tube as 'cathode rays'.

At last physicists began to take the atom seriously, and began to think about its interior structure. Many of the best minds in physics became devoted to the structure of microcosmic matter. Within forty years they had consummate success.

3: Founding Fathers.

THOSE forty years, that is from the end of the nineteenth century to the outbreak of the Second World War, were a wonderful time for physicists to be alive. Both experimental physicists and theoreticians had their phases of triumph, and it is instructive to notice how the balance swung. There was a long record of experimental discoveries beginning with elucidation of the radiations emitted from radioactive elements and evidence that most of an atom's ma.s.s lay in a central nucleus. Rutherford and Chadwick's disintegration of atoms by particles from radioactive sources led on to disintegration of atoms by controlled means by c.o.c.kcroft and Walton. Meanwhile there was identification of further sub-atomic particles neutrons and positive electrons. And in 1938 the most fateful experiment of all, the splitting of some uranium atoms with an emission of particles which could lead to further splitting, with the possibility of a chain reaction and the release of huge amounts of energy.

Through most of this period, the dominant figure was Ernest Rutherford who was born in 1871. As has been said, he ranks with Faraday among British experimental physicists. As a man, he was wildly different from Faraday exuberant, outgoing, not noticeably modest or una.s.suming. He was taken at face value, a simple face value, by most of the people round him. Internally, he was not so simple. There were deep layers of diffidence concealed beneath that robust and noisy facade. He was a prey to nerves. He found it hard to manage an overweighted nature. Kapitsa, one of the most gifted of his pupils, an engineering-physicist of genius in the high Russian tradition, and in addition equipped with psychological observation and insight, seems to have been the only member of Rutherford's scientific entourage who understood him well. Kapitsa's letters to his mother in Leningrad, dating from the time he first came to England to work with Rutherford, have recently been published in the Soviet Union. Within a few days Kapitsa was writing, 'The Professor is a deceptive character. They [the English] think he is a hearty colonial. Not so. He is a man of immense temperament. He is given to uncontrollable excitement. His moods fluctuate violently. It will need great vigilance if I am going to obtain, and keep, his high opinion.'

About the only item true in the stereotype of Rutherford is that he was a colonial. His father was a Scottish immigrant to New Zealand, who managed after sc.r.a.ping a living, doing odd jobs, to become a small farmer and a kind of general utility man, employing one or two workmen and doing anything in the way of domestic repairs. He seems to have had a good deal of technical ingenuity.

Rutherford knew nothing in the way of privilege. New Zealand was a remote province. He received a good education, however, rather on the Scottish model. He was top of his school in all subjects, being very far from the dumb-ox kind of scientist who occasionally turns up. But when he came to England on a scholarship he felt an outsider who didn't know the rules. There were a good many chips on those heavy shoulders. He couldn't get along with English intellectual chit-chat, and insisted on behaving like a country boy who had never read a book (actually he was very widely read) with people of about one-hundredth of his cultivation, not to say intelligence.

He was a great man, and a good one. He didn't like being outfaced, though, by people who had learned tricks denied him. He wasn't comfortable in the company of well-trained theoreticians. Of course he could have mastered theoretical physics, or anything else in science, but some of those shoulder chips got in the way. When he was Cavendish professor, Cambridge became the world centre of experimental physics, but it didn't rank with Copenhagen and Gttingen in theory except for the accidental occurrence of a young theoretical physicist of great genius, Paul Dirac. His appearance had nothing to do with Rutherford; that the divide in Cambridge between theoretical and experimental physics was sharp, did have something to do with Rutherford.

As a physicist, he had extraordinary intuition. He seems scarcely ever to have tried a problem which wouldn't go. If any scientist had a nose for, to use Medawar's phrase, 'the solution of the possible', Rutherford had. His attack was simple and direct, or rather he saw his way, through the hedges of complication, to a method which was the simplest and most direct.

An example is the most dramatic event of his career, the experiments by which he proved the existence of the atomic nucleus. The Curies had shown that radium emits various kinds of 'radiation', and one of these was now known to consist of a stream of electrically charged particles. These 'alpha particles' were identical to helium atoms with their electrons removed; but they originated not from helium gas but sprang spontaneously from the radium atoms as they disintegrated.

Even though atomic disintegration was still little understood, Rutherford saw these high-speed alpha particles as useful projectiles. He intercepted them with a thin sheet of gold foil, to see what happened as they pa.s.sed through. If atoms were diffuse spheres of electrical charge, as Thomson had imagined, then most of the alpha particles should have gone straight through; a few should be deflected slightly. But some of the alpha particles bounced straight back again. It was like firing artillery sh.e.l.ls at a piece of tissue paper, and getting some of them returning in the direction of the gun.

Rutherford could only explain this by postulating that these alpha particles were hitting small, ma.s.sive concentrations within the atoms. He thus concluded that most of an atom's ma.s.s resided in a minute, positively charged nucleus at the centre, while the electrons went around the outside very much like the planets...o...b..ting the ma.s.sive sun. Most of the atom was just empty s.p.a.ce. If an atom were expanded to the size of the dome of St Paul's Cathedral, virtually all its ma.s.s would lie within a central nucleus no larger than an orange. The large majority of alpha particles pa.s.sed the atoms' emptiness and carried on through the foil; but just occasionally one would hit a nucleus head-on, and rebound along the way it had come.

Positive, like all Rutherford's physics. He said that he knew it was convincing, and maintained that he was completely surprised. One wonders if he hadn't had a secret inkling. He was superlatively good at making predictions about nature.

It is hard to think of a prediction of his which didn't come off. He predicted the existence of an electrically neutral particle within the atomic nucleus, which was duly proved when Chadwick discovered the neutron in 1932. He predicted the splitting of atoms by accelerated protons, duly achieved by c.o.c.kcroft that same year. He made just one negative prediction: as late as 1933, he announced that the energies in the atom were unlikely ever to be used. That apart, he was almost always right. His Cavendish 'boys' as he called them men as gifted as Chadwick, Kapitsa, c.o.c.kcroft, Blackett (all n.o.bel prize winners), Oliphant, Dee, half a dozen others tended to think that, though he might be overpowering or deafeningly noisy, he was next door to infallible.

That was his kind of paternal leadership. His own greatest individual work wasn't done at Cambridge at all. With singular folly, Cambridge didn't try to keep the young Rutherford possibly because the place wasn't big enough to hold both him and his seniors. He went off to a professorship at Montreal. American universities bid for him, better talent-spotters than Cambridge, but at the time America wasn't a major force in the scientific world, and Rutherford returned to England, after a touching and deliberate resignation by the head of the physics department at Manchester, Arthur Schuster, who thought that Rutherford must at any cost be preserved for this country. It was at Manchester that Rutherford proved the nuclear structure of the atom.

It is instructive to remember how little money was spent on these great scientific researches. Faraday's apparatus (some still preserved in the Royal Inst.i.tution) was humble, knocked up in the laboratory. Things hadn't changed much by Rutherford's time. His experiments were built with the help of one laboratory technician, or if he were feeling well-financed, perhaps two. There was no engineering. All was home made. The old phrase was 'string and sealing wax', and it is not far from the truth. The Cavendish was a great experimental laboratory, but it would look like a badly equipped high school compared with the big physics inst.i.tutions of today. It was not until trained engineers such as Kapitsa and c.o.c.kcroft became active that the Cavendish knew any approach to big physics. Rutherford marvelled and cheered them on, but sometimes thought that it might be overdone.

Until the Second World War, there was little industrial support for physicists. Chemists had been looked after by the chemical industry for many years: other industries had been peculiarly obtuse in not seeing any conceivable use for physicists. Young men in the l930s, with doctorates and good research to their credit, considered themselves lucky to get decent jobs in schools. A few years later, in the war, they were being s.n.a.t.c.hed up as the rarest and most valuable of all human commodities.

It seems strange now that the Cavendish at its peak should have stayed so remote from industry. With the harsh wind of approaching war, however, c.o.c.kcroft, the Cavendish all-purpose functionary, was set to indoctrinate selected young men in the latest military prospect what was later called by the American name of radar, and was the most successful British scientific weapon in the Hitler war. Few un.o.btrusive steps have paid off better. By the by, that happened in the same university which contemporary opinion seems to believe was devoted entirely to espionage.

Rutherford and his colleagues had little to do with money. It seems to have bored Rutherford himself about as much as academic philosophy. He was a remarkably unmercenary man. He could have earned large fees as a consultant. He would have thought that a ludicrous waste of time. As a professor at Montreal he was paid 500 a year. At Manchester and Cambridge he got about 1600, a good academic salary for the period, but he never earned more than that. When he died, he left almost exactly the amount of his n.o.bel prize, which at that time was something like 7,000.