Making of the Atomic Bomb

by Richard Rhodes

  Here Teller indicts Aston’s measurement of the mass of helium (the same that had misled Szilard to beryllium), which “introduced a systematic error into calculating the mass and energy of nuclei.”

  Segrè finds Teller’s version of the story possible but not persuasive. The helium mass number problem would not necessarily have ruled out breaking up the uranium nucleus. “You know, occasionally Fermi would tell you things, then you asked him, ‘But really, how? Show me.’ And then he would say, ‘Oh, well, I know this on c.i.f’ He spoke Italian.871 ‘C.i.f.’ meant ‘con intuito formidable,’ ‘with formidable intuition.’ So how he did it, I don’t know. On the other hand, Fermi made a lot of calculations which he kept to himself.”

  Leona Woods’ version sheds light on Teller’s:

  Why was Dr. Noddack’s suggestion ignored? The reason is that she was ahead of her time. Bohr’s liquid-drop model of the nucleus had not yet been formulated, and so there was at hand no accepted way to calculate whether breaking up into several large fragments was energetically allowed.872

  If Noddack’s physics was avant garde, her chemistry was sound. By 1938 her article was gathering dust on back shelves, but Bohr had promulgated the liquid-drop model of the nucleus and the confused chemistry of uranium increasingly preoccupied Lise Meitner and Otto Hahn.

  9

  An Extensive Burst

  “I believe all young people think about how they would like their lives to develop,” Lise Meitner wrote in old age, looking back; “when I did so I always arrived at the conclusion that life need not be easy provided only that it was not empty. And this wish I have been granted.”873 Sixty years old in 1938, the Austrian physicist had earned wide respect by hard and careful work. When Wolfgang Pauli had wished to propose an elusive, almost massless neutral particle to explain the energy that seemed to disappear in beta decay—it came to be called the neutrino—he had made his proposal in a letter to Lise Meitner and Hans Geiger. James Chadwick was “quite convinced that she would have discovered the neutron if it had been firmly in her mind, if she had had the advantage of, say, living in the Cavendish for years, as I had done.”874 “Slight in figure and shy by nature,” as her nephew Otto Frisch describes her, she was nevertheless formidable.875

  During the Great War she had volunteered as an X-ray technician with the Austrian Army; “there,” says Frisch, “she had to cope with streams of injured Polish soldiers, not understanding their language, and with her medical bosses who interfered with her work, not understanding X-rays.”876 She arranged her leaves from duty to coincide with Otto Hahn’s and hurried to the Kaiser Wilhelm Institute for Chemistry in Dahlem to work with him; that was when they identified the element next down from uranium that they named protactinium. After the war she did physics separately until 1934, when, challenged by Fermi’s work, she “persuaded Otto Hahn to renew our direct collaboration” to explore the consequences of bombarding uranium with neutrons.877 Meitner headed the physics department at the institute then, of which Hahn had become the director. She had attained by middle age, Hahn remarks fondly, “not only the dignity of a German professor, but also one of his proverbial attributes, absentmindedness.” At a scientific gathering “a male colleague greeted her by saying, ‘We met on an earlier occasion.’ Not remembering that earlier occasion, she replied in all seriousness, ‘You probably mistake me for Professor Hahn.’ ”878 Hahn supposed she was thinking of the many papers they had published together.

  If she hid her shyness behind formidable reserve, among friends, Frisch says, “she could be lively and cheerful, and an excellent storyteller.”879 Her nephew thought her “totally lacking in vanity.”880 She wore her thick dark hair, now graying, pulled back and coiled in a bun and her youthful beauty had muted to bright but darkly circled eyes, a thin mouth, a prominent nose. She ate lightly but drank quantities of strong coffee. Music moved her; she followed it as other people follow trends and fashions in art (a family cultivation—her sister, Frisch’s mother, was a concert pianist). She made a duet at the piano on visits with her musical nephew, “though hardly anybody else knew that she could play.”881 She lived in an apartment at the KWI and when there was time she took long walks, ten miles or more a day: “It keeps me young and alert.”882 Her most holy commitment, Frisch thought, “the vision she never lost” that filled her life, was “of physics as a battle for final truth.”883

  The truth she battled for through the later 1930s was hidden somewhere in the complexities of uranium. She and Hahn, and beginning in 1935 a young German chemist named Fritz Strassmann, worked to sort out all the substances into which the heaviest of natural elements transmuted under neutron bombardment. By early 1938 they had identified no fewer than ten different half-life activities, many more than Fermi had demonstrated in his first pioneering survey. They assumed the substances must be either isotopes of uranium or transuranics. “For Hahn,” says Frisch, “it was like the old days when new elements fell like apples when you shook the tree; [but] Lise Meitner found [the energetic reactions necessary to produce such new elements] unexpected and increasingly hard to explain.”884

  Meanwhile Irene Curie had begun looking into uranium with a visiting Yugoslav, Pavel Savitch. They described a 3.5-hour activity the Germans had not reported and suggested it might be thorium, element 90, with which Curie had years of experience. If true, the Curie-Savitch suggestion would mean that a slow neutron somehow acquired the energy to knock an energetic alpha particle out of the uranium nucleus. The KWI trio scoffed, looked for the 3.5-hour activity, failed to find it and wrote the Radium Institute suggesting a public retraction. The French team identified the activity again and discovered they could separate it from their uranium by carrier chemistry using lanthanum (element 57, a rare earth). They proposed therefore that it must be either actinium, element 89, chemically similar to lanthanum but even harder than thorium to explain, or else a new and mysterious element.

  Either way, their findings called the KWI work into doubt. Hahn met Joliot in May at a chemistry congress in Rome and told the Frenchman cordially but frankly that he was skeptical of Curie’s discovery and intended to repeat her experiment and expose her error.885 By then, as Joliot undoubtedly knew, his wife had already raised the stakes, had tried to separate the “actinium” from its lanthanum carrier and had found it would not separate. No one imagined the substance could actually be lanthanum: how could a slow neutron transmute uranium into a much lighter rare earth thirty-four places down the periodic table? “It seems,” Curie and Savitch reported that May in the Comptes Rendus, “that this substance cannot be anything except a transuranic element, possessing very different properties from those of other known transuranics, a hypothesis which raises great difficulties for its interpretation.”886

  In the course of this exotic debate Meitner’s status changed. Adolf Hitler bullied the young chancellor of Austria to a meeting at the German dictator’s Berchtesgaden retreat in Bavaria in mid-February. “Who knows,” Hitler threatened him, “perhaps I shall be suddenly overnight in Vienna: like a spring storm.”887 On March 14 he was, triumphantly parading; the day before, with the raw new German Wehrmacht occupying its capital, Austria had proclaimed itself a province of the Third Reich and its most notorious native son had wept for joy. The Anschluss—the annexation—made Meitner a German citizen to whom all the ugly anti-Semitic laws applied that the Nazi state had been accumulating since 1933. “The years of the Hitler regime . . . were naturally very depressing,” she wrote near the end of her life. “But work was a good friend, and I have often thought and said how wonderful it is that by work one may be granted a long respite of forgetfulness from oppressive political conditions.”888 After the spring storm of the Anschluss her grant was abruptly withdrawn.

  Max von Laue sought her out then. He had heard that Heinrich Himmler, head of the Nazi SS and chief of German police, had issued an order forbidding the emigration of any more academics. Meitner feared she might be expelled from the KWI and left unemployed and
exposed.889 She made contact with Dutch colleagues including Dirk Coster, the physicist who had worked in Copenhagen with George de Hevesy in 1922 to discover hafnium. The Dutchmen persuaded their government to admit Meitner to Holland without a visa on a passport that was nothing more now than a sad souvenir.

  Coster traveled to Berlin on Friday, July 16, arriving in the evening, and went straight to Dahlem to the KWI. The editor of Naturwissenschaften, Paul Rosbaud, an old friend, showed up as well, and together with Hahn the men spent the night helping Meitner pack. “I gave her a beautiful diamond ring,” Hahn remembers, “that I had inherited from my mother and which I had never worn myself but always treasured; I wanted her to be provided for in an emergency.”890

  Meitner left with Coster by train on Saturday morning. Nine years later she remembered the grim passage as if she had traveled alone:

  I took a train for Holland on the pretext that I wanted to spend a week’s vacation. At the Dutch border, I got the scare of my life when a Nazi military patrol of five men going through the coaches picked up my Austrian passport, which had expired long ago. I got so frightened, my heart almost stopped beating. I knew that the Nazis had just declared open season on Jews, that the hunt was on. For ten minutes I sat there and waited, ten minutes that seemed like so many hours. Then one of the Nazi officials returned and handed me back the passport without a word. Two minutes later I descended on Dutch territory, where I was met by some of my Holland colleagues.891

  She was safe then. She moved on to Copenhagen for the emotional renewal of rest at the Carlsberg House of Honor with the Bohrs. Bohr had found a place for her in Sweden at the Physical Institute of the Academy of Sciences on the outskirts of Stockholm, a thriving laboratory directed by Karl Manne Georg Siegbahn, the 1924 Physics Nobel laureate for work in X-ray spectroscopy.892 The Nobel Foundation provided a grant. She traveled to that far northern exile, to a country where she had neither the language nor many friends, as if to prison.

  * * *

  Leo Szilard was looking for a patron. Frederick Lindemann had arranged an ICI fellowship for him at Oxford beginning in 1935, and for a while Szilard worked there, but the possibility of war in Europe made him restless. From Oxford in late March 1936 he had written Gertrud Weiss in Vienna that she should consider emigrating to America; he appears to have applied his reasoning to his own case as well. Szilard had met Weiss in his Berlin years and subsequently advised and quietly courted her. Now she had graduated from medical school. At his invitation she came to Oxford to see him. They walked in the country; she photographed him standing at roadside before a weathered log barrier, rounding at thirty-eight but not yet rotund, with a budding young tree filigreed behind him.893 “He told me he would be surprised if one could work in Vienna in two years. He said Hitler would be there. And he was”—the Anschluss—“almost to the day.”894

  Szilard had written in his letter that England was “a very895 likeable country, but it would certainly be a lot smarter if you went to America. . . . In America you would be a free human being and very soon would not even be a ‘stranger.’ ” (Weiss went, and stayed to become a distinguished expert in public health and, late in their wandering years, Szilard’s wife.) During the same period Szilard wrote Michael Polanyi he would “stay in England until one year before the war, at which time I would shift my residence to New York City.”896 The letter provoked comment, Szilard enjoyed recalling; it was “very funny, because how can anyone say what he will do one year before the war?” As it turned out, his prognostication was off by only four months: he arrived in the United States on January 2, 1938.

  Before then Szilard had located a possible patron there, a Jewish financier of Virginia background named Lewis Lichtenstein Strauss, his first and middle names honoring his East Prussian maternal grandfather, his last name softened in Southern fashion to straws.897 Forty-two years old in 1938, Lewis Strauss was a full partner at the New York investment-banking house of Kuhn, Loeb, a self-made millionaire, an adaptable, clever but thin-skinned and pompous man.

  Strauss had dreamed as a boy of becoming a physicist. The recession of 1913–14 had staggered his family’s Richmond business—wholesale shoes—and his father had called on him at seventeen to drum a four-state territory. He did well; by 1917 he had saved twenty thousand dollars and was once again preparing to pursue a physics career. This time the Great War intervened. A childhood accident had left Strauss with marginal vision in one eye. His mother doted on him. She allowed his younger brother to volunteer for military service but looked for some less dangerous contribution for her favorite son. It turned up when Woodrow Wilson appointed the celebrated mining engineer and Belgian relief administrator Herbert Hoover as Food Administrator to manage U.S. supplies during the war. The wealthy Hoover was serving in Washington without pay and assembling a prosperous, unpaid young staff, Rhodes scholars preferred. Rosa Lichtenstein Strauss sent her boy.

  He was twenty-one, knew how to ingratiate himself, knew also how to work. Improbable as it appears against a field of Rhodes scholars, within a month Hoover appointed the high-school-graduate wholesale shoe drummer as his private secretary. After the Armistice young Strauss shifted with Hoover to Paris, hastily picked up French at tutoring sessions over lunch and helped organize the allocation of 27 million tons of food and supplies to twenty-three countries. On the side he assisted the Jewish Joint Distribution Committee in its work of relieving the suffering of the hundreds of thousands of Jewish refugees streaming from Eastern Europe in the wake of war.

  Strauss believed God had planned his life, which contributed greatly to his self-confidence. God let him take up employment when he was twenty-three, in 1919, at Kuhn, Loeb, a distinguished house with a number of major railroads among its clients. Four years later he married Alice Hanauer, daughter of one of the partners. His salary and participation reached $75,000 a year in 1926; the following year it escalated to $120,000. In 1929 he became a partner himself and settled into prosperous gentility.

  The 1930s brought him pain and grief. After resisting Chaim Weizmann’s attempts to convert him to Zionism at a Jewish conference in London in 1933—“My boy, you are difficult,” Weizmann told him; “we will have to grind you down”—he returned to the United States to discover his mother terminally ill with cancer.898 She died early in 1935; the disease took his father as well in the hot summer of 1937. Strauss looked for a suitable memorial. “I became aware,” he reports in his memoirs, “of the inadequate supply of radium for the treatment of cancer in American hospitals.”899 He established the Lewis and Rosa Strauss Memorial Fund and turned up a young refugee physicist from Berlin, Arno Brasch. Brasch had designed a capacitor-driven discharge tube for producing bursts of high-energy X rays, a “surge generator.” When Leo Szilard was working at St. Bart’s with Chalmers in the summer of 1934 he had arranged for Brasch and his colleagues in Berlin to break up beryllium with hard X rays; the experiment had been a success and Brasch and four other contributors had signed the report to Nature along with Chalmers and Szilard.900 If X rays could break up beryllium they might at least induce radioactivity in other elements. “An isotope of cobalt thus produced,” writes Strauss, “would be radioactive and would emit gamma rays similar to the radiation produced by radium. . . . Radioactive cobalt could be made . . . at a cost of a few dollars a gram. Radium was then priced at about fifty thousand dollars a gram. . . . I foresaw the possibility of producing the isotope in quantity and of giving it to hospitals as a memorial to my parents.”901

  Enter Leo Szilard, still in England:

  August 30, 1937902

  Dear Mr. Strauss:

  I understand that you are interested in the development of a surge generator with the view of using it for producing artificially radioactive elements. . . .

  At present . . . I am not in the position of [offering manufacturing rights under this patent]. It is possible, however, that at a later date . . . I shall obtain full liberty of action concerning this patent. If this happens I shall let
you have a non-exclusive license, royalty free, but limited to the production of radioactive elements by means of high voltage generated by a surge generator.

  Yours very truly,

  Leo Szilard

  Brasch and Szilard owned the patent in question jointly.903 Szilard’s letter offers to give his interest away free of charge nonexclusively to Strauss, a politic salutation to a rich man. But not even Leo Szilard could live on air, and as Strauss makes clear in his memoirs, the two young physicists eventually “asked me to finance them in the construction of a ‘surge generator.’ ”904 On the other hand, Szilard as usual seems to have sought no personal financial gain from the project beyond, perhaps, basic support. In the time he could spare from observing the developing disaster in Europe he was apparently trying to promote the building of equipment with which he might explore further the possibility of a chain reaction.

  He crossed the Atlantic in late September to reconnoiter. A friend remembers discussing the feasibility of an atomic bomb with Szilard during this period. “In the same conversation he spoke of his ideas for preserving peaches in tins in such a way that they would retain the texture and taste of the fresh fruit.”905 When the surge-generator negotiations bogged down in debates among the lawyers, the resourceful Szilard distracted Strauss with the idea of using radiation to preserve and protect the natural products of farm and field.906 The tobacco worm might be exterminated, for example. But would irradiation harm the tobacco? Among Szilard’s surviving papers is lodged a fading letter from Dr. M. Lenz of the Montefiore Hospital for Chronic Diseases that reports the decisive experiment: