At the time of his death in July of last year, C.P. Snow was working on this book. Its theme is the two-faced gift of physics and its applications, and of those who in not much over a generation have changed our world. Although he had completed only a first draft, his publishers have done well to let us have the book, for it is Snow at his best. In his fiction, particularly in the Strangers and Brothers sequence of novels, he charted the social changes of half a century. Here he looks at the same period and tells with clarity, economy and insight the story of changes no less profound. Most of what he writes about has been described many times elsewhere. But Snow uses to advantage his gift to say plainly and without pomposity things of importance which are so evidently true that others might have left them unsaid. And they needed to be said. Within the framework provided by an account of the great discoveries of 20th-century physics, particularly in the fundamental areas of nuclear and sub-nuclear physics, through biographical sketches and anecdotes, he illuminates a theme he had used in a speech delivered in 1960 which is reprinted as an appendix to this book:
So scientists are not much different from other men. They are certainly no worse than other men. But they do differ from other men in one thing ... Whether they like it or not, what they do is of critical importance for the human race. Intellectually, it has transformed the climate of our time. Socially, it will decide whether we live or die, and how we live or die. It holds decisive powers for good and evil. That is the situation in which the scientists find themselves.
Snow was a bluff sort of realist: he was also an optimist, and his other theme is that the building of the great edifice of physical science is ‘one of the few human activities where only a fool could deny the reality of progress’.
It is extraordinary how brief a span of time has encompassed the birth and coming to maturity of modern physics. The electron was discovered in 1896, and Max Planck first used the quantum hypothesis in 1900. Even ten years later many physicists were still unconvinced of the reality of atoms (unlike the chemists!). Yet by 1925 in quantum mechanics there was established a consistent and coherent theoretical foundation, as Paul Dirac put it, ‘for all of chemistry and most of physics’. And in the same short time-span first the special and then the general theory of relativity had transformed the foundations of physics from a totally different perspective. The marriage between quantum mechanics and special relativity (notwithstanding Wolfgang Pauli’s prohibition, ‘Let no man join what God has put asunder’) took place in Dirac’s 1928 paper on the relativistic electron. And from that union has come relativistic quantum field theory, the doppelgänger to particle physics. Particles and fields are different descriptions of the same reality: space is a plenum all aquiver with interactions. The electromagnetic field, which it was the heroic achievement of Michael Faraday and Clerk Maxwell to discover in the middle of the 19th century, brought together in a unified complex the disparate phenomena of electricity and magnetism. Recognition came immediately of the electromagnetic character of light, and the prediction and then production of radio waves followed. Today quantum electrodynamics is the paradigm quantum field theory, and the wider synthesis already initiated in the bringing together of electromagnetism and the weak nuclear force has fired the imagination of scores of theorists and promoted the ingenuity of hundreds of experimentalists. A grand unification of all the fundamental interactions seems tantalisingly within our grasp. Such a synthesis would presumably also incorporate Einstein’s general theory of relativity, the theory which transformed space and time from the neutral arena in which physical phenomena take place to an active participant: the action of space-time on matter is gravity. This union, or reconciliation, between general relativity and quantum mechanics is an unsolved challenge, an exquisite problem, surprisingly intractable.
Of these more recent developments Snow has little to say, though he might have gone further had he lived to complete his work. In the excellent introductory essay by William Cooper, we are told that Snow wrote the book largely from memory, and his memory rarely failed him. One error does deserve correction: Werner Heisenberg is unjustly maligned. An inevitable theme in the book is the impact on physics of the rise of Nazism and the emigration of so many Jewish scientists from Germany: for at the time of Hitler’s accession to power theoretical physics ‘was very much a Jewish science’. It is therefore important to state that it was Johannes Stark and Philipp Lenard who were ‘active spokesmen for the Nazi faith’.
The main thread of his narrative shows how the triumphs of atomic physics in the 1920s led with awful inevitability to the discovery of nuclear fission, the terrible experiment at Alamogordo and the bitter progeny of Hiroshima and Nagasaki, to the megatonnage of fusion weapons and the ever-present threat of thermonuclear war. There is in the last few chapters a sort of coda in which Snow expresses hope and some confidence that controlled thermonuclear fusion will provide mankind with cheap and plentiful energy; that the biotechnology based on the post-war science of molecular biology, and integrated circuitry and the microprocessors which have so transformed electronics – that these fruits of the 20th-century revolution wrought by the physicists will not turn to ashes in our mouths. That’s a fine upbeat note on which to end, but in reading the book I was left with a sense that something of importance was missing. As a scientist writing for a literary review about C.P. Snow on science, it is inevitable that I have in mind his commentary on the cultural divide. What he said in the 1959 Rede Lecture seemed to me to be so reasonable and self-evident that I found the dissent of Leavis and others surprising in its passion and sincerity, and, even more, its imprecision and lack of focus. But with this book Snow himself missed an opportunity to straddle the two cultures. In the early part of this century, and especially in the Twenties, novel and fertile ideas were generated, not only in science, but also in literature, music and the visual arts. Was there any connection between these two spheres of activity? Or was the emergence in the same years of these different revolutions quite fortuitous – a coincidence? This question deserves exploration, and has not so far as I know ever been adequately considered. When Hamlet bids Ophelia, ‘Doubt thou the stars are fire, doubt that the sun doth move,’ this is a direct expression of contemporary advances in astronomy. In the literature of that time there is more than just an awareness of the discoveries being made in the first great flowering of modern science. The import of these discoveries was deeply felt, and digested in the imagery, poetry, metaphysics and art of the day. Well, we are all able to make a quantum jump and may share with Heisenberg his uncertainty. But this is a mere borrowing of words. A concern with abstraction, release from convention, a re-examination of orthodoxy – these can be encountered on both sides. But in the absence of a researched attempt to explore cross-influence, one can only speculate that there was a common origin to, or a causal relationship between, developments in the two cultures. What a pity we don’t have here even the speculation, let alone the research: the issue just isn’t raised.