The Physicists Read online

  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, God 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 pass – 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 wor
ld. This has happened very quickly, and has become concrete in the space 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 space, and the bewildering properties of quarks – the ultimate constituents 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 seashore, and diverting myself in now and then finding a smoother pebble or a prettier shell 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, classical 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 assumed 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 competitor 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, unassuming, 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 assistant 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 Institution one of London’s treats. Dickens 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 classical physical chemistry. Originally, thermodynamics was the science of how heat and energy are related, and the impetus of studying it c
ame 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 analytical 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 classical physics before the modern age (more correctly the particle age) began. Of course, classical 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 classical 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 space travel are classical, 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 space centre were he still alive – he would no doubt wish that he could have laid his hands on our metallurgy and propellants.