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 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.’