Genius in the Shadows

by William Lanouette

  Dear Professor Lindemann:

  Three months have passed since, acting on impulse, I cabled you that I am postponing my sailing for an indefinite period on account of the international situation, and that I should be grateful if my further absence could be considered as a leave without pay. . . .

  It seems to me that the Munich agreement created, or at the very least demonstrated, a state of international relations which now threatens Europe and in the long run will threaten the whole civilized world. This cannot fail to claim the attention of all of us, and, if the situation is to be improved, the active cooperation of many of us. I greatly envy those of my colleagues at Oxford who in these circumstances are able to give their full attention to the work which has been carried on at the Clarendon Laboratory and who are able to do so without offending their sense of proportions. To my great sorrow I am apparently quite incapable of following their example.

  It seems to me that those who wish to continue to dedicate their work to the advancement of science would be well advised to move to America where they may hope for another ten or 15 years of undisturbed work. I myself find it very difficult, though, to elect such “individual salvation”, and I may therefore return to England if I can see my way of being of use, not only in science, but also in connection with the general situation. It is hardly necessary to state that, if I shall be in England and if you want me to do so, I shall be most happy again to cooperate with those who work in the Clarendon Laboratory. It may be best, however, that I should not receive financial support from the Laboratory, as such financial support is bound to be linked with fixed obligations which I would rather avoid.

  For the time being, I do not yet see my way of being of use in England in connection with the general situation, though I see certain potential possibilities in this respect. In view of these I am at present not looking for a “job” on this side of the Atlantic. Perhaps I shall have an opportunity to talk to you about all this if I shall visit England in a not too distant future. . . .

  Please excuse the three months’ delay of this letter. Immediately after the Munich agreement it did not seem possible for me to have a sufficiently balanced view, and I had to allow some time to elapse before I was able to write without bitterness of this event.

  With kind regards to all, I am

  Yours very sincerely,

  Leo Szilard3

  In this strained and unusually revealing letter Szilard bared his personal frustrations and tensions, above all by citing the concern that controlled his life’s emotional and moral decisions, a “sense of proportions,” This sense was the instinct he most trusted at critical moments: a balance of physical laws, psychological expressions, and moral convictions. Now Szilard’s emotions and motives were in turmoil. Unlike some colleagues, he could not avoid the war he saw coming and seek “individual salvation” in “the advancement of science.” He had to play a part in solving the “general situation.” But, being an alien, Szilard knew that he was not eligible to perform military research in England. Yet he might return there, anyway, provided he could still escape “fixed obligations.” Or he might stay in the United States, become a citizen, and work against the coming war as best he could.

  Three days after Szilard wrote that pained letter, on January 16, Enrico Fermi and his wife, Laura, were at the pier again, this time to meet the SS Drottningholm and to welcome Niels Bohr, the Danish physicist and Nobel laureate whom they had visited in Copenhagen the month before. Bohr landed in New York bearing the momentous news that the fission of uranium had been demonstrated by Hahn and Strassmann in Berlin.4

  Bohr himself showed mixed emotions over his report. He was fatigued by worries that war in Europe was imminent and that Germany might use its discoveries in atomic science for military ends. Yet he was also clearly exhilarated by the news of nuclear fission and further excited by the cable he received shortly after landing in New York. The radiochemist Lise Meitner and her nephew Otto Frisch reported that they had confirmed the fission process by their own experiments in Sweden. Fermi, on the other hand, was unimpressed. He failed to recognize the importance of this news and failed even to mention what he heard to his Columbia colleagues. Fermi was so typically cautious, in fact, that as the grave consequences of fission became apparent to others around him, he repeatedly denied their significance.

  On the day Bohr arrived in New York, an assistant went to Princeton and there—at an informal “journal club” where the latest scientific articles were discussed—announced the news about uranium fission.5 Still unaware of this startling discovery, Szilard spoke that Monday afternoon at John Dunning’s nuclear physics seminar, on the eighth floor of Columbia’s Pupin Laboratory, about “Radioactive Isotopes Produced by Nuclear Excitation” and afterward attended an informal tea.

  Szilard finally heard the news about uranium fission a few days later on a visit to physicist Eugene Wigner in Princeton. Wigner, his friend since their student days in Berlin, lay in the university infirmary with jaundice. As soon as Szilard entered Wigner’s room, he heard Bohr’s news that uranium could disintegrate into other elements. He was stunned. The element and the process he had searched for since 1933 had both been found. “When I heard this,” he recalled later, “I saw immediately that these fragments, being heavier than corresponds to their charge, must emit neutrons, and if enough neutrons are emitted in this fission process, then it should be, of course, possible to sustain a chain reaction. All the things which H. G. Wells predicted appeared suddenly real to me,”6

  The political implications were also suddenly obvious. “At the time it was already clear,” Szilard recalled, “not only to me but to many other people—certainly it was clear to Wigner—that we were at the threshold of another world war.” Szilard vowed to test how many neutrons are emitted in fission and to keep his discoveries secret. “So I was very eager to contact Joliot [-Curie in Paris] and to contact Fermi, the two men who were most likely to think of this possibility.”7

  Szilard wanted to reach Fermi quickly. But the morning after his visit to Wigner’s infirmary room, he woke to a heavy, cold rain. Throughout his life, and especially since his arrival in America a year earlier, Szilard invariably caught cold when he got wet, and the weather alone made him feel ill that morning. He worried that he had no rubbers or boots to wear and could find none in Wigner’s apartment, where he was staying. But he went out, anyway, to send a telegram to Trude Weiss, “RETURNING KING’S CROWN WITH MODERATE COLD STOP YOU MIGHT VISIT ME WITH STETH- OSCOP [sic] TONIGHT OR TOMORROW NIGHT = LEO.”8 But back in his hotel room he felt too weak to contact Fermi and lay sick in bed for days.

  During this time, Szilard later learned, Fermi had also thought that an extra neutron might be emitted during nuclear fission, which raised in his mind the possibility of a chain reaction. But Fermi considered this notion so remote that he gave it little thought. Szilard, on the other hand, could think of little else. On January 25, Szilard wrote to Lewis L. Strauss, a Wall Street financier interested in the atom’s commercial potential, about “a very sensational new development in nuclear physics,” the fission of uranium—something far exceeding the medical-isotope schemes the two had discussed a year earlier. Szilard predicted that fission “might make it possible to produce power by means of nuclear energy” but that this was not very exciting and might be impractical. There were graver “potential possibilities,” Szilard warned, that “might lead to a large-scale production of energy and radioactive elements, unfortunately also perhaps to atomic bombs.” This news, he said, revived “all the hopes and fears” he had felt since 1934.

  That night, in the Columbia physics labs, John Dunning and a young assistant to Fermi, Herbert Anderson, confirmed uranium fission by a procedure similar to that used by Meitner and Frisch. Dunning cabled the news to Fermi, who was in Washington for the Fifth Conference on Theoretical Physics.9 The next day, January 26, Szilard dragged his aching body across the Columbia campus to the Western Union office on Broadway and sent an urgent
cable of his own. Trying to intercept his December instruction to lift the chain-reaction patent’s military secrecy, Szilard notified the director of navy contracts at the British Admiralty in London: “REFERRING TO CP10 PATENTS 8142/36 KINDLY DISREGARD MY RECENT LETTER STOP WRITING LEO SZILARD,”10 He now believed that the chain-reaction process in his 1934 patent would create the “Violent explosions” he had warned the Admiralty about, and he wanted to be sure that the patent was kept a military secret.

  The same day that Szilard cabled the Admiralty, Fermi and Bohr met at George Washington University, where they opened discussion about uranium’s fission and its implications. But Fermi still made light of the discovery. A practical man, unlike the more theoretical Bohr or the more exuberant Szilard, Fermi saw progress in terms of experiments and mechanisms that could actually be performed. To him, scientific integrity meant being sure of your conclusions before considering their implications; to Bohr and Szilard it meant seeking the political and social implications of your work at each step.

  Once Bohr and Fermi had discussed the possibility of uranium fission in Washington, researchers rushed to test the process. At the Carnegie Institution’s Department of Terrestrial Magnetism (DTM) in Washington, on January 28, Richard Roberts and R. C. Meyers bombarded uranium with neutrons and saw unusually long spikes on their oscilloscope. They repeated the display that evening for Bohr, Fermi, University of Wisconsin physicist Gregory Breit, and Edward Teller, a Hungarian-born physicist Szilard had first met in Budapest and later befriended in London in 1934.11 The Washington Evening Star carried a page 1 piece on the DTM conference headlined: ‘Power of New Atomic Blast Greatest Achieved on Earth.” The article concluded, however, that “as a practical power source, the new finding has at present no significance.” On January 30 the Evening Star reported on page 1 that uranium fission had been confirmed at Columbia, the DTM, Johns Hopkins University, and by researchers in Copenhagen.12 The word was out. Unlike the “transformation” first seen when teams at the Cavendish Laboratory split light atoms, with uranium fission one of nature’s heaviest atoms was easily burst by neutrons.

  Recovering from his cold just as the DTM conference ended, Szilard caught a train to Washington and from the station called Teller. Mici Teller was weary from the parade of conference visitors who had come to their small wood-frame house on Garfield Street, so with Szilard’s call she insisted to her husband that he not spend the night. They did agree to pick him up at the station, however, and once Szilard climbed into the car, Mici blurted out, “Will you stay with us?” He accepted promptly, then turned to Edward.

  “You know what fission means,” Szilard said as the car pulled into traffic and gained speed. “It means bombs.” At the Tellers’ house, Mici led Szilard to the small guest room. He dropped his bag and sat on the bed. “Too hard,” he announced. “I’d prefer to stay in a hotel.”13

  When back in New York, Szilard called on Rabi, adding to the news about fission his own conviction that it might set off a nuclear chain reaction. Rabi told Szilard that Fermi, too, had made this connection but that he had expressed little desire to test the idea himself. “Fermi was not in,” Szilard later recalled, “so I told Rabi to please talk to Fermi and say that these things ought to be kept secret because it’s very likely that if neutrons are emitted, this may lead to a chain reaction, and this may lead to the construction of bombs.”14 A few days later, Rabi told Szilard what Fermi thought of his warning. Fermi enjoyed the punchy vernacular of American English, and his reaction to Szilard’s message was immediate: “Nuts!” Rabi couldn’t explain what Fermi meant by this remark, so Szilard urged that they both call on Fermi in his office.

  “Well . . .” Fermi told his visitors, “there is the remote possibility that neutrons may be emitted in the fission of uranium and then of course a chain reaction can be made.”

  “What do you mean by ‘remote possibility’?” asked Rabi.

  “Well, ten percent,” Fermi said.

  “Ten percent is not a remote possibility,” Rabi said, “if it means that we may die of it.”15

  From this meeting on, Szilard realized how differently he and Fermi could view the same scientific evidence. “We both wanted to be conservative,” Szilard recalled later, “but Fermi thought that the conservative thing was to play down the possibility that this may happen, and I thought the conservative thing was to assume that it would happen and take the necessary precautions.” Bernard T. Feld, who became Szilard’s research assistant at Columbia, characterized their difference in this way: “Fermi would not go from point A to point B until he knew all that he could about A and had reasonable assurances about B. Szilard would jump from point A to point D, then wonder why you were wasting your time with B and C.”16

  Szilard grew increasingly frustrated with Fermi’s caution, which he only understood gradually as the two men worked together. In unpublished notes about the Manhattan Project, which he wrote in 1950, Szilard concluded that their differences stemmed from contrary views that each held about the connections between science and life. Put simply, science was Fermi’s life, whereas for Szilard science was an endeavor ineluctably united with politics and personal sensitivities.17

  After meeting Fermi on February 2, Szilard addressed the political consequences of fission in a letter to the British Admiralty, explaining vaguely his urgent cable. Indium, he wrote, “cannot be used for the process described in the patent,” but “another element” (he did not name uranium) may create a “process” (he did not mention fission) that “might very well turn out to be similar to the process described in the patent assigned to you.” Two months later, the Admiralty assured Szilard that his secret patent would be maintained.18

  Keeping his chain-reaction patent a secret was one way for Szilard to prevent Germany from realizing fission’s military potential. Another way was to urge fellow scientists to censor their own research. The most active research, Szilard knew, was under way in Paris, so he wrote to Joliot warning him not to publish the results of his neutron work. “Obviously, if more than one neutron were liberated, a sort of chain reaction would be possible,” he wrote. “In certain circumstances this might then lead to the construction of bombs which would be extremely dangerous in general and particularly in the hands of certain governments.” Szilard closed his letter, “In the hope that there will not be sufficient neutrons emitted by uranium, I am . . .” but then crossed out this conclusion, simply signed the letter, and mailed it.19

  He may have hoped that extra neutrons would not be released, but Szilard could not rest until he knew for sure; the day he wrote to Joliot, he walked to the large apartment of his friend Benjamin Liebowitz on Riverside Drive. Liebowitz had studied physics at New York University, where Szilard met him during his first visit to America in 1931–32. As a successful inventor, he had a comfortable income from royalties. Szilard explained that the chain reaction might be possible and asked to borrow some money—he was nearly broke—for experiments to confirm this.

  “How much money do you need?” Liebowitz asked.

  “Well, I’d like to borrow $2,000,” Szilard said. Liebowitz took out his checkbook. This was the first American money spent on the chain-reaction concept, and it is no exaggeration to say that this small loan helped change the fate of the world.20

  Once he had cashed the check, Szilard rushed to Fermi’s office to try to urge him to begin some fission experiments. Fermi was not interested. To him, fission was a curiosity, not a cause for concern. He was conducting a few experiments of his own, he said, but these were to answer basic questions about the behavior of neutrons, not to make the leap to chain reactions. Unlike Szilard, Fermi was not convinced that fission would lead to chain reactions or chain reactions to bombs. Still, Szilard had to be sure and called on physics chairman George Pegram to ask for permission to conduct experiments of his own. Pegram agreed, but only for three months, beginning on March 1.

  To find out if a chain reaction was now possible, Szilard had to learn more
about what happened when uranium is bombarded with neutrons. Seeking a reliable neutron source, he cabled Lindemann in Oxford, asking him to send a cylinder of beryllium—one that Szilard had ordered from Germany the year before, to begin just such bombardment experiments.21 Then Szilard contracted to rent a gram of radium, which he planned to place within the beryllium to produce relatively weak “slow” neutrons.22 Szilard suspected that uranium emitted the more energetic “fast” neutrons. If that were true, he reasoned, the difference between fast and slow neutrons would be apparent on monitors—a cloud chamber, for example, or an oscilloscope.

  A clumsy and disinterested experimentalist himself, Szilard next needed equipment and a place to work. In mid-January he had looked in on Walter Zinn, a Canadian-born physicist skilled at rigging laboratory equipment for new uses. When Zinn agreed to collaborate, Szilard pursued uranium in his usually diligent way, hiring consulting physicist Semyon Krewer to seek industrial bids. Krewer also surveyed world uranium supplies and investigated processes for producing pure uranium metal and graphite, in this way making Szilard one of the best-informed people in America about the heavy metal.23

  With fission “hope is revived that we may yet be able to harness the energy of the atom,” the New York Times reported on the morning of February 5. With this and other newspaper stories about Bohr’s appearances around the United States, word about uranium fission was slipping out. The article cited a “remotely possible atomic powerhouse” but made no mention of atomic weapons. Szilard clipped this article and mailed it to Strauss. At the same time, Newsweek reported on fission by recalling Einstein’s guess about useful atomic energy: “It is like shooting birds in the dark in a country where there are not many birds.” The magazine also quoted comedian Fred Allen’s answer from a fictional professor about why he split atoms: “Well, someone may come in someday and want half an atom.”24