Szilard invited Singer and his niece to lunch in London, visited his country house at Parr in Cornwall, and seemed to use him as a sounding board for ideas about social and political organization. To finance research, Szilard urged that it would be necessary “gradually to bring about something like a conspiracy of those scientists who work in this field,” citing the Research Corporation as an exemplary institution for controlling dangerous information through patents. “I am looking for a Maecenas,” he said. For his part, Singer was “somewhat mystified” by Szilard, although his wife, Dorothea, a classicist, found him “charming and convincing to my ignorance.”60
Szilard was more personally revealing when he sent two letters to Singer, one about social engagements, the other about research, and admitted: “I wish it would be as easy as that to keep private and public life in watertight compartments.”61 Sometimes affecting an air of mystery about his affairs, Szilard enjoyed masking his personal reactions in social situations. When he unexpectedly met his AAC colleague Esther Simpson at a tea one afternoon, Szilard showed no surprise or reaction to her and afterward boasted that he was anxious to conceal his emotions. Miss Simpson assured Szilard that he had but failed to understand this behavior at all.62
Szilard’s desire to keep his friendships in isolated compartments surprised many people who thought they knew him. He could be intensely personal, and playful, in one-to-one encounters but controlled carefully these unguarded moments. Throughout 1934, Szilard was infatuated by Jean dePeyer, a free spirit he had met through Trude Weiss. Occasionally, dePeyer came to the Strand Palace Hotel to type for Szilard, and one day she helped him with a scientific article.
“What is one word for looking glass?” Szilard asked.
“Mirror,” she replied faintly, and then passed out in her chair. When Szilard tried to revive her, she began coughing violently, and he called a doctor he knew.
“Tonsillitis,” the doctor announced, and Szilard promptly packed dePeyer into a taxi and off to her small flat in Holland Park. He called the next day, bearing a straw-covered bottle of Chianti and a bundle of fish- and-chips wrapped in newspaper. And every day thereafter he followed her recovery carefully.
With Jean dePeyer, Szilard could be giddy and “childlike” by sharing “a wonderful sense of the ridiculous,” she recalled years later. He enjoyed telling the same silly stories over and over again. In one she remembered, he asked a young girl what she wanted to do with her life, and her mother interrupted with “Oh, she wants to go into politics.” Szilard asked the girl how she meant to begin going “into politics,” and again her mother replied: “Oh, she is taking elocution lessons!” Szilard laughed and laughed as he told and retold this story.
DePeyer felt close to Szilard and years later recalled one sunny spring day when they boarded an excursion steamer at Westminster Pier and cruised up the Thames to Richmond Lock. During a long and leisurely walk through Richmond Park, which she recalled as “full of laughter and sunshine,” Szilard spied a hollow tree and quickly climbed inside— laughing all the while—then peered out impishly. Later, they noticed that several children had discovered the tree. “You see,” said dePeyer, “all the children have to get into that tree!”63
As he did with people he liked, Szilard told dePeyer what to read: “Three Old Men,” a story by Tolstoy, and Grand Hotel, by the Austrian novelist Vicki Baum. While humor enhanced their understanding, the two found a deeper bond in candor. DePeyer’s boarding school had trained her to tell “only the strictest truth,” a discipline that reminded Szilard of the rigorous honesty that bound him to his mother. And, like Szilard, dePeyer valued her privacy and felt comfortable around this “discreet and sensitive” man. Indeed, it was “because he distanced himself” that dePeyer “felt so easy and close to him.”
“You only understand a person when you love them,” Szilard announced one day.
“I think,” dePeyer replied, “the more you love someone, the less you understand them.” Szilard flashed a quick, sad look.
Still, Szilard’s depth of understanding appealed to both Jean dePeyer and Trude Weiss. “He spoils you for other men,” Trude once told her in London, meaning that he instantly understood so many things that most men never recognize. “Not only for other men,” Jean later thought, “but for other people.”64
Separated by World War II and other romances, Jean dePeyer forgot about Szilard until she saw him interviewed on television in 1960. She wrote. He replied, merrily recalling their escapades and remembering two friends whom Jean had forgotten. He reported trying to find her on his first postwar trip to Europe, two years before, and proposed a detour to see her if a planned trip to Moscow and Paris came about. “Why did you think that I may have forgotten about you?” Szilard added at his letter’s end. “As a matter of fact, I have a very vivid memory of everything, including ‘the color of your hair,’ “a private joke.65 Several people who knew Szilard say that he remembered some of their friends longer than they did, an indication that, though often brief, his concern and involvement with people were intense.66
Szilard’s playful walks in London’s parks and his earnest discussions about literature were escapes from his nagging concern for what his chain-reaction research might mean to the coming war. Ironically, he said later, he helped keep Germany from winning World War II. If he had raised the money and painstakingly tested all seventy elements, Szilard concluded, he could have discovered as early as 1935 or 1936 that uranium released neutrons—a fact not recognized until 1939. Such a discovery could not have been kept secret, and Germany, then planning for war, would likely be quick to apply this knowledge to building an A-bomb.67 After the war, Szilard said jokingly that he, Fermi, and other physicists should receive the Nobel Peace Prize for not having conducted uranium experiments in the mid-1930s. Had they done so, Szilard said, Hitler might have conquered the world.68
Summoned to Paris in 1935 by news that his brother-in-law, Roland Detre, was ill with tuberculosis, Szilard boarded a plane at the Croydon aerodrome south of London, landed at LeBourget, and visited the Detres in their garret studio near Place de la Bastille. After giving them money for medical expenses, Szilard decided to walk into the Joliot-Curies’ Radium Institute. Unannounced, he entered a laboratory and spotted Walter Elsasser, a German-refugee physicist whom Szilard had first met in Berlin in the late 1920s.
Szilard described his efforts to organize refugee scientists in England, then announced that he wanted to start something similar in France. “Form an association of some kind and the French government will be forced to treat you better, grant you better benefits, better jobs,” urged Szilard. Elsasser listened carefully, for as a Sorbonne professor he held the senior position among the refugee scientists and was just the man Szilard should be speaking to. But as Szilard chattered, Elsasser felt “a sudden violent fright,” perhaps the most ominous of his life. “This is the perfect setup for a fifth column,” Elsasser thought.69
“This is a good idea, Szilard,” he replied, “but I think it is very dangerous to confront the French with an organization. They may just get sour and throw all the refugees out.”
“You must organize,” Szilard insisted. “You must.” This dialogue continued for more than an hour, with neither man softening his views. Then, just as suddenly as he appeared, Szilard stood up, walked out, and flew back to his English campaign.70
Unable to finance chain-reaction research, Szilard decided that his last chance to keep the concept secret lay in his 1934 patent. On September 16, 1935, he offered his patent to the War Office as a military secret and visited the army’s research department at the huge Woolwich arsenal on the Thames east of London. There Szilard met with the director of radiological research and for several hours explained how nuclear chain reactions might be made explosive. When the army’s Directory of Artillery wrote that “there appears to be no reason to keep the specification secret so far as the War Department is concerned,” Szilard took his idea to the British Admiralty.71
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br /> Still the chain reaction haunted Szilard, and with no funds available to study it, Szilard continued haphazard research on his own. Back in Oxford, he rented two rooms in a Victorian row house at 8 Keble Road, around the corner from the Clarendon, and immersed himself in research to understand how neutrons interact with atomic nuclei. The only time in his career that Szilard conducted an experiment alone, he became so selfabsorbed that almost everywhere he appeared he toted two black leather bags: a medium-sized valise for clothes and papers and a small, square case for his research equipment. In the small bag Szilard stuffed a Geiger counter, shaped-metal amplifiers, paraffin wax, and flat metal foils stacked in cigarette tins. Szilard was not a smoker, but whenever someone offered him a cigarette, he replied: “No, thank you, but I’ll take the tin,”72
For his experiment Szilard placed radon gas and beryllium together so that gamma rays from the radon released slow neutrons from the beryllium. He beamed these slow neutrons through a sixteen-inch tube lined with paraffin, which acted to slow them further before they were absorbed by thin sheets of cadmium or indium. Szilard measured the different absorption rates for the neutrons, noting that “residual neutrons,” which are slowed but not stopped by the sheets, behaved very differently, depending on whether they passed through cadmium or indium. Completing his work on November 14, Szilard mailed a manuscript about it to Nature and, obviously pleased with his findings, sent another copy to Rutherford in Cambridge. In reply, Rutherford acknowledged that Szilard had advanced the understanding of slow-neutron absorption beyond the work of two Cavendish colleagues.73
Szilard’s work with “residual” or “resonance” neutrons, which was performed independently by Fermi in Rome, soon contributed to a new understanding of the way neutrons are absorbed and how the atomic nucleus is structured—concepts expressed in 1936 by the Breit-Wigner formula for neutron absorption and by Bohr’s compound model of the nucleus.74 Szilard sent detailed notes on his work to Breit and Wigner, and Bohr replied a few weeks later, saying that when he visited Donnan in London, he hoped they could meet. “We have of course all been very interested in your beautiful recent researches on the nuclear problems,” he wrote. Szilard’s work, Bohr said, had contributed to his own recent search for “some simple views about the constitution of the nucleus,” and this, rather than a more general subject, would be his topic at a forthcoming lecture in London.75 Szilard’s work may have contributed to Bohr’s conclusion that neutrons might create “an explosion of the whole nucleus,” although he would not foresee a weapon from this process until 1939.76
Szilard’s paper on neutron absorption established him as a serious participant in the field of nuclear physics, a self-taught outsider finally respected as a serious researcher. John Cockcroft, one of the Cavendish physicists who had first split the atom, invited Szilard to address the Kapitza Club about his slow-neutron work.77 Szilard was now advising Breit, Wigner, and Bohr—three respected pioneers in the field. Fermi mailed him a manuscript of his latest paper.78
In meetings around the Clarendon with Lindemann, Szilard repeatedly urged that nuclear scientists agree to prevent their work from being applied to “lethal purposes,”79 Beginning in 1936, Szilard also pleaded with nuclear scientists outside Germany not to publish their neutron research. Such assertions, especially from an interloper in the field, were resented as being “unscientific.” But Szilard kept pleading. He saw a war coming and feared that atomic weapons would determine the outcome. When Germany reoccupied the demilitarized Rhineland on March 7, 1936, Szilard heard that the British government would do nothing and concluded that Hitler could not be stopped. Szilard vowed that day to leave England.80
The same month, Szilard wrote from Oxford to Enrico Fermi, proposing to turn over his patents on atomic-energy discoveries to some new nonprofit research corporation. “I feel that I must not consider these patents as my private property and that if they are of any importance, they should be controlled with a view of public policy.” He further spelled out for Fermi how research money should be spent: to investigate all the elements systematically, to rent radium sources for this work, and to pay travel costs for “any of us to move from one laboratory to another” to share necessary apparatus.81
But for all his pledges, Szilard’s motives remained suspect. In Cambridge that March, Maurice Goldhaber reported to Szilard that someone had sent a copy of his neutron patents to the Cavendish Laboratory, where they were discussed at tea, “and, of course, your intentions were misunderstood to be financial or otherwise unscientific.” Goldhaber defended Szilard by saying he intended to direct science “in a way which will be useful to science and not damaging to the public.”82
In three important ways, Thursday, March 26, 1936, was a turning point in Szilard’s life, a conjunction of professional and personal events that would shape his decisions for years to come. First, the director of navy contracts wrote to report that a certificate of secrecy for the chain-reaction patent had just been filed, along with the assurance that it would be reassigned to Szilard “if and when secrecy . . . is waived.”83
Second, Szilard wrote to Bohr, alerting him to the possibility that the isotope uranium235 was “somewhat analogous to the case of indium,” still Szilard’s candidate for the element that might create a nuclear chain reaction. Szilard cited a paper by Otto Hahn and Lise Meitner that reported uranium has several “isomers,” different forms all having the same atomic number. In this conclusion Hahn and Meitner were mistaken; they were actually observing the products of nuclear “fission,” when the atom’s nucleus breaks apart while releasing extra neutrons. But this process would not be understood or named until 1939. By pointing out that these “isomers” of uranium might have behaved in the way he predicted indium should, namely, through a chain reaction, Szilard edged very close to recognizing the fission process itself. And, by identifying uranium235, he intuitively picked the one isotope in nature that would fission most easily.84
A third event on March 26 would change the course of Szilard’s personal life: He wrote a long letter to Trude Weiss in Vienna, speculating about what she should do “after the war” and inviting her to join him in England. As a “push,” he offered to pay her train fare. Trude had just graduated from the University of Vienna’s medical school and had written Szilard for advice about her career. Szilard was, by turns, bossy and patient. He warned her that in two years she would not be able to work in Austria. He described life in England but recommended America instead. And he debated, then dismissed, her own idea about emigrating to Palestine. “You must first try that which you yourself prefer to do so that you know whether it works out or not,” he insisted. “So, come immediately to England.”85 Within three weeks of writing this letter Szilard traveled by train across France and Switzerland to Vienna and sat Trude down and lectured her about a career as a doctor and about her survival as a European Jew. His warnings worked, and Trude moved to London, at first sharing Esther Simpson’s flat on Brunswick Square.86
When Szilard returned to England two weeks later, he tried to enlist Fermi, Chadwick, Cockcroft, and Rutherford in an international scientists’ research corporation, repeatedly assuring them that the chain-reaction patents were not his property. But he deepened their skepticism by remaining vague about the reasons for secrecy, refusing, for example, to describe his research before the Kapitza Club.87
“I am . . . in the uncomfortable position of a man who during a fire (either real or existent perhaps only in his imagination) tries to remove some jewelery [sic] which does not belong to him to some place of safety,” Szilard admitted to Fermi’s colleague Emilio Segrè. “Some passers-by who meet him in the street with the jewelery in his hands must inevitably take him for a thief, even if they are too well-bred to say so. While I am quite prepared to face this if necessary,” Szilard concluded, “you will appreciate that I should like to get out of this situation as quickly as possible.”
88 But it was not until May 1936 that Szilard could bring himself t
o describe his formulations and fears. Then, writing to Rutherford, he enclosed a draft letter to Nature that speculated about the anomalous Fermi effect in indium. Should his research succeed, Szilard wrote,
. . . we would for the first time have to envisage the theoretical possibility of nuclear chain reactions. The prospect of bringing about nuclear transmutations on a large scale by means of such chain reactions is somewhat disconcerting.
It is very unlikely that the misuse of chain reactions could be prevented if they could be brought about and became widely known in the next few years. I am quite aware that the view which I am taking on the subject may be very exaggerated. Nevertheless, the feeling that I must not publish anything which might spread information of this kind—however limited—indiscriminately has so far prevented me from publishing anything on this subject.89
CHAPTER 12
Travels with Trude
1936–1938
One summer weekend in 1936, Leo Szilard distanced himself from his nightmarish fears about the nuclear chain reaction by inviting his friend Trude Weiss, who had just begun studying medicine in London, to visit him in Oxford, and together they explored the nearby countryside. By train they rode to the ancient town of Wendover and there visited Ye Olde Red Lion Hotel, a 400-year-old Tudor inn frequented by Cromwell. On a hill nearby, at the imposing South African Monument, Szilard posed for Trude’s camera among the rusticated columns, peering into the lens inquisitively, staring in absent thought at the trench coat folded over his left arm, grinning self-consciously, gazing across the rolling green hills. In Oxford, Szilard introduced Trude to his friend Nicholas Kurti, a Hungarian-born physicist working with Francis Simon on low-temperature physics.
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