The scientists had faith that, whatever they were conjuring with, whatever danger inhered in the explosive potential of the nucleus, they would, as a group, never allow their discoveries to be used by nation states against humanity. For they had their higher allegiances, whose purposes transcended those of petty polities shaped by the whims of nationalism or politics and susceptible to abuse by despots. They were part of what the philosopher of science Michael Polanyi would call ‘the republic of science’. The republic had its own rules, cultures, practices. New initiates served as apprentices to elder masters, were taught how to do their work and evaluate the work of their colleagues. The point was, as Rhodes describes it, to create a ‘political network among men and women of differing backgrounds and differing values’, by establishing conventions of judgment and trust. The scientific republic did not replace the nation state but rested in consolidating fashion atop all such states.8
Above all, the republic must allow its constituents to work alongside each other, if not literally then with full knowledge of what all its other members are doing. Polanyi likened the process to assembling a jigsaw puzzle: while each person involved in the assembly contributes his or her skills to matching colors and shapes to make the pieces fit, in the end the puzzle must be a group enterprise, wherein skills, and puzzle components, are merged to form a whole. Each scientist (to depart from the metaphor) must see the entire problem laid out, and must contribute to its solution. There was no real hierarchy among scientists: ‘The authority of scientific opinion remains essentially mutual; it is established between scientists, not above them.’ That discoveries concerning the atom would be shared, through journal articles, at conferences, in coffee houses and taverns and labs, was a matter of faith among the world’s physicists before the Second World War. One could not patent or nationalize the atom.9
James Chadwick was caught in Germany at the onset of the First World War and interned at a prison camp outside Berlin. A number of German scientists supplied him with enough equipment to set up a small laboratory, in which he worked with other scientist prisoners. In the midst of the war’s carnage in May 1918, Chadwick wrote reassuringly to Rutherford that he was about to start work ‘on the formation of carbonyl chloride in light’—scientist language for phosgene gas. The pace of scientific exchange quickened considerably with the end of the war, during Oppenheimer’s ‘heroic time’. (‘It involved’, Oppenheimer wrote, ‘the collaboration of scores of scientists from many different lands ...It was a time of earnest correspondence and hurried conferences, of debate, criticism and brilliant mathematical improvisation.’) In Munich’s cafes, students of the physicist Arnold Sommerfeld scrawled formulas on the marble tabletops; waiters at the Cafe Lutz were told never to wipe the tables without permission. Oppenheimer was one of many young American scientists who came to Gottingen during the 1920s (he was there nicknamed ‘Oppie’, or ‘Opje’, which he had difficulty getting used to). A group of remarkable Hungarian Jews—Polanyi, Edward Teller, Eugene Wigner, John von Neumann, Theodor von Karman, Leo Szilard—left their home country during the 1920s and 1930s, driven out by political instability, state violence, and a rising tide of anti-Semitism. The Japanese physicist Nishina, who would be the first scientist contacted by the Japanese government to explain what had happened at Hiroshima, worked with Rutherford and Bohr, and in 1927 hosted Albert Einstein in Tokyo.10
Like Nishina, many came to study with Bohr in Copenhagen, and Bohr himself frequently seemed to be in several places at once. He consulted men who would stay and work in Nazi Germany, most famously Carl Friedrich von Weizsacker and Werner Heisenberg. He also welcomed those escaping the oppressions of dictators and helped hundreds get safely off the Continent as Hitler’s darkness fell. (He himself would escape, first to Sweden, then to Britain and the United States, in late 1943.) In Polanyi’s scientific republic, Bohr was primus inter pares. He embodied the ideal of a scientific community, offering by example a model of integrity and probity, encouraging others in their work, sharing, with his wife, Margrethe, his hospitality, and most of all failing, in the most admirable ways, to respect political and national boundaries that stood in the way of scientific progress.
Bohr’s supreme cosmopolitanism would bring him to understand that a terrible explosive based on the energy of the atom was no more susceptible to monopoly than the atom itself. More than anyone else, Bohr would grasp the ultimate unity of the world’s scientific community. The secret of the atomic bomb was in his judgment no secret at all, since intelligent men and women across the globe had come together to understand the forces that made it work. Borders between nations, hardened by mistrust and war, were finally ineffective against the spread of scientific knowledge. ‘The chain of scientific events that led to the threshold of the bomb’, wrote Laura Fermi, had gone ‘zigzagging without interruption from one country to another’. In 1943, Bohr felt that the republic of science, looming transcendently over the artificial collection of nation states, would be the final arbiter of the bomb. He knew the Russian scientists, including Peter Kapitsa, and he knew that they would figure out how to build a bomb. Why not admit that secrets were impossible to keep in a polity based on sharing, and acknowledge the scientific republic by letting the Soviets know that an international group of scientists was making a bomb in the United States?11
Bohr’s teacher, colleague, and friend Ernest Rutherford was gone by then; he would never see his ‘moonshine’ made horribly manifest at Hiroshima. Rutherford apparently once claimed that he could do his research at the North Pole, provided he had a lab and the right equipment. Rudolf Peierls, a German who came to work in England in 1933 and later helped to develop the bomb in Los Alamos, knew Rutherford (and Bohr) well, and doubted either could have worked successfully in isolation. ‘The Rutherford and Bohr types thrive on contacts,’ he wrote. ‘They are kept going by their own initiative, but they must share their knowledge and their discoveries with friends and colleagues.’ Both men were too much part of the scientific republic to have left it for a smaller, more parochial place.12