Hiroshima_ The World's Bomb - Andrew J. Rotter [26]
When war came in September 1939, Simon and his Birmingham colleague Rudolf Peierls, not yet naturalized citizens, were forbidden to work on the top-secret military project, radar. They were shunted instead to the exploration of an atomic bomb, considered sufficiently fanciful as to allow research on it by non-citizens. (Naturalized later that year, Simon stayed with the bomb project, and also spent a good deal of time trying to get other German-Jewish scientists released from the internment to which the British government now subjected them.) Simon worked on separating out the light isotope Uranium 235, which was much more likely to fission than its more stable, and thus more common cousin U-238. Filtering gaseous uranium through an extremely fine membrane seemed to Simon the best way to achieve separation; one day in 1940 he stole the family’s metal kitchen strainer, smashed it flat, then used it to capture carbon dioxide from water vapor—a model for his means of filtering uranium. Simon’s ‘gaseous diffusion’ method was ultimately used to produce fissionable uranium for the Hiroshima bomb. Simon was also instrumental in persuading Winston Churchill that a bomb was feasible. Simon himself went to Los Alamos to help in the bomb work, returning to Oxford, and low-temperature physics, once the war was over.10
Leo Szilard, the reader and promoter of H. G. Wells, undertook a similar odyssey, from Central Europe to England and, finally, to the United States. He was the conscience and the gadfly of the physics community during the 1930s and after. By turns warmly supportive of colleagues, irascible, impatient unto captiousness, and either absent-minded or callous in his treatment of subordinates—the maids in his hotel complained that he refused to flush the toilet after use—Szilard came early to the conclusion that ‘something would go wrong in Germany’, as he put it. During the 1920s (it may be recalled) he worked in Germany, at the Kaiser Wilhelm Institute, and on the side invented and applied for patents of devices for home refrigeration. He visited the United States in early 1932, then returned to Berlin, and was there in January 1933 when Hitler assumed the chancellorship. ‘I lived in the faculty club of the Kaiser Wilhelm Institute,’ he remembered, ‘and I had my suitcases packed’; he meant this literally. He left Germany a month after the Reichstag fire. He went first to Vienna, where he met Sir William Beveridge, head of the London School of Economics, who happened to be staying at Szilard’s hotel. Szilard prodded Beveridge to help German academics, recently dismissed or soon to be, find jobs at British universities, and Beveridge agreed, establishing, following his return to London, the Academic Assistance Council with Ernest Rutherford at its head. Szilard then came to London in part to help with the placement work. Soon, Szilard noted, ‘practically everyone who came to England had a position, except me’.
Szilard’s wide variety of interests ill suited him for a single job, and his personal eccentricities made him a difficult colleague. He spent his mornings thinking about physics and other things as he sat in his hotel corridor bathtub; during the afternoons and evenings he walked the streets of London, also thinking. He considered a switch from physics to biology, but by then developments in physics—the exploration of radioactivity and the prospect of a chain reaction, prophesied by H. G. Wells—were too compelling to abandon: ‘I decided’, he remembered, ‘to play around a little bit with physics.’ It was summer 1934. He wandered over to St Bartholomew’s Hospital, whose physics director he knew slightly, and asked if he might have lab space and the use of some radium that was not otherwise needed over the summer. Working with T. A. Chalmers, a member of St Bartholomew’s physics department, Szilard experimented with the splitting-off of neutrons and published two important papers in