Herbert Butterfield was still only twenty-six when, as a young don at Peterhouse, Cambridge, he published The Whig Interpretation of History and made his reputation.51 Controversial as it was, and although he was not really concerned with evolution as such, his argument concerned ‘the friends and enemies of progress’ and was nonetheless therefore a useful corrective to the emerging consensus. Butterfield exploded the teleological view of history – that it is essentially a straight line leading to the present. To Butterfield, the idea of ‘progress’ was suspect, as was the notion that in any conflict there were always the good guys who won and the bad guys who lost. The particular example he used was the way the Renaissance led to the Reformation and then on to the contemporary world. The prevailing view, what he called the Whig view, was to see a straight line from the essentially Catholic Renaissance to the Protestant Reformation to the modern world with all its freedoms, as a result of which many attributed to Luther the intention of promoting greater liberty.52 Butterfield argued that this view assumed ‘a false continuity in events’: the Whig historian ‘likes to imagine religious liberty issuing beautifully out of Protestantism when in reality it emerges painfully and grudgingly out of something quite different, out of the tragedy of the post-Reformation world.’53
The motive for this habit on the part of historians was, said Butterfield, contemporary politics – in its broadest sense. The present-day historian’s enthusiasm for democracy or freedom of thought or the liberal tradition led him to conclude that people in the past were working toward these goals.54 One consequence of this tendency, Butterfield thought, was that the Whig historian was overfond of making moral judgements on the past: ‘For him the voice of posterity is the voice of God and the historian is the voice of posterity. And it is typical of him that he tends to regard himself as the judge when by his methods and his equipment he is fitted only to be the detective.’55 This fashion for moral judgements leads the Whig historian into another mistake, that more evil is due to conscious sin than to unconscious error.56 Butterfield was uneasy with such a stance. He offered the alternative view – that all history could do was approach its subjects in more and more detail, and with less and less abridgement. No moral judgements are necessary for him because it is impossible to get within the minds of people of bygone ages and because the great quarrels of history have not been between two parties of which one was ‘good’ and the other ‘evil’ but between opposing groups (not necessarily two in number) who had rival ideas about where they wanted events, and society, to go. To judge backward from the present imposes a modern mindset on events which cannot be understood in that way.57
Butterfield’s ideas acted as a check on the growth of evolutionary thought, but only a check. As time went by, and more results came in, the evidence amassed for one story was overwhelming. Progress was a word less and less used, but evolution went from strength to strength, invading even history itself. The discoveries of the 1920s pushed forward the idea that a complete history of mankind might one day be possible. This expanding vision was further fuelled by parallel developments in physics.
15
THE GOLDEN AGE OF PHYSICS
The period from 1919, when Ernest Rutherford first split the atom, to 1932, when his student James Chadwick discovered the neutron, was a golden decade for physics. Barely a year went by without some momentous breakthrough. At that stage, America was far from being the world leader in physics it has since become. All the seminal work of the golden decade was carried out in one of three places in Europe: the Cavendish Laboratory in Cambridge, England; Niels Bohr’s Institute of Theoretical Physics in Copenhagen; and the old university town of Göttingen, near Marburg in Germany.
For Mark Oliphant, one of Rutherford’s protégés in the 1920s, the main hallway of the Cavendish, where the director’s office was, consisted of ‘uncarpeted floor boards, dingy varnished pine doors and stained, plastered walls, indifferently lit by a skylight with dirty glass.1 For C. P. Snow, however, who also trained there and described the lab in his first novel, The Search, the paint and the varnish and the dirty glass went unremarked. ‘I shall not easily forget those Wednesday meetings in the Cavendish. For me they were the essence of all the personal excitement in science; they were romantic, if you like, and not on the plane of the highest experience I was soon to know [of scientific discovery]; but week after week I went away through the raw nights, with east winds howling from the fens down the old streets, full of a glow that I had seen and heard and been close to the leaders of the greatest movement in the world.’ Rutherford, who followed Maxwell as director of the Cavendish in 1919, evidently agreed. At a meeting of the British Association in 1923 he startled colleagues by suddenly shouting out, ‘We are living in the heroic age of physics!’2
In some ways, Rutherford himself – now a rather florid man, with a moustache and a pipe that was always going out – embodied in his own person that heroic age. During World War I, particle physics had been on hold, more or less. Officially, Rutherford was working for the Admiralty, researching submarine detection. But he carried on research when his duties allowed. And in the last year of war, in April 1919, just as Arthur Eddington was preparing his trip to West Africa to test Einstein’s predictions, Rutherford sent off a paper that, had he done nothing else, would earn him a place in history. Not that you would have known it from the paper’s title: ‘An Anomalous Effect in Nitrogen.’ As was usual in Rutherford’s experiments, the apparatus was simple to the point of being crude: a small glass tube inside a sealed brass box fitted at one end with a zinc-sulphide scintillation screen. The brass box was filled with nitrogen and then through the glass tube was passed a source of alpha particles – helium nuclei – given off by radon, the radioactive gas of radium. The excitement came when Rutherford inspected the activity on the zinc-sulphide screen: the scintillations were indistinguishable from those obtained from hydrogen. How could that be, since there was no hydrogen in the system? This led to the famously downbeat sentence in the fourth part of Rutherford’s paper: ‘From the results so far obtained it is difficult to avoid the conclusion that the longrange atoms arising from collision of [alpha] particles with nitrogen are not nitrogen atoms but probably atoms of hydrogen…. If this be the case, we must conclude that the nitrogen atom is disintegrated.’ The newspapers were not so cautious. Sir Ernest Rutherford, they shouted, had split the atom.3 He himself realised the importance of his work. His experiments had drawn him away, temporarily, from antisubmarine research. He defended himself to the overseers’ committee: ‘If, as I have reason to believe, I have disintegrated the nucleus of the atom, this is of greater significance than the war.’4
In a sense, Rutherford had finally achieved what the old alchemists had been aiming for, transmuting one element into another, nitrogen into oxygen and hydrogen. The mechanism whereby this artificial transmutation (the first ever) was achieved was clear: an alpha particle, a helium nucleus, has an atomic weight of 4. When it was bombarded on to a nitrogen atom, with an atomic weight of 14, it displaced a hydrogen nucleus (to which Rutherford soon gave the name proton). The arithmetic therefore became: 4+14–1=17, the oxygen isotope, O17.5