Turing's Cathedral

by George Dyson

  “He was a maverick, a very complicated man, a Pole, and, above all, a study in contrasts and contradictions,” Françoise explains. “He lived mainly in the confines of his mind.” He was also gregarious. “Many of us at the Laboratory who were associated with him knew how much he disliked being alone, how he would summon us at odd times to be rescued from the loneliness of some hotel room, or from the four walls of his office, after he had exhausted his daily round of long-distance calls,” says his mathematical colleague Gian-Carlo Rota. “One day I mustered the courage to ask him why he constantly wanted company and his answer gave him away. ‘When I am alone,’ he admitted, ‘I am forced to think things out.’ ”5

  Ulam became von Neumann’s frequent collaborator and closest friend. “I don’t think von Neumann knew anybody more intimately than me,” says Ulam, “and vice-versa.” They shared a common background as upper-class Eastern European Jews, and first met in Warsaw in 1935, after corresponding over their common interest in measure theory in 1934. Von Neumann extended an invitation to Princeton, and with the promise of a stipend of $300 from the Institute for Advanced Study, Ulam sailed in December of 1935 aboard the Aquitania for the United States. He then secured a three-year fellowship under George David Birkhoff at Harvard, while spending the summers back in Poland at the cafés. He brought his younger brother, Adam, then seventeen, with him when he left Poland for the last time in August of 1939. They were on board the Polish liner Batory, sailing for America, when word came over the ship’s radio of the Molotov-Ribbentrop Pact. “This is the end of Poland,” announced Stan.6

  In the fall of 1939, Françoise Aron was a twenty-one-year-old graduate student at Mount Holyoke College, attending a party at a friend’s apartment in Cambridge, when she met Stan. “He spent the first evening we met leaping from his seat towards mine to light my cigarette,” she recalls. “Besides calling himself a ‘mathematician’—an unusual profession—he was elegant, witty and entertaining in spite of being very depressed, despondent about the war, the absence of news from his family and many financial worries. There was nothing professorial or academic about him. From the very first I fell under the spell of his charm, found him enchanting, intriguing, remarkable. I was hooked.”7

  Neither Françoise nor Stan would ever again see the parents they had left behind. “These were the darkest days of the war: the German invasion, followed by the collapse of France, with its hordes of refugees fleeing the Panzer divisions that had circled the Maginot Line; the Dunkirk debacle, the heroic battle of Britain,” says Françoise. “For a five-cent cup of coffee Stan sat for hours in the Georgian cafeteria with Polish and other foreign mathematicians who had found their way to Cambridge, discussing the anxious war news or talking mathematics. They became my friends too and I would join them after work.”8 Before long, Françoise was cooking for the two brothers, and joining them for meals. The Ulams were too impoverished in Cambridge to afford restaurants, and had been too wealthy in Poland to have learned to cook for themselves.

  In 1941, unable to secure a position at Harvard, now flooded with refugees, Stan Ulam accepted an instructorship at the University of Wisconsin, for $2,300 a year. After obtaining her degree from Holyoke, Françoise joined him in Madison, where they were married before a justice of the peace.

  “Do you want the long or the short ceremony?” asked the judge.

  “How much are they?” asked Stan.

  “The long costs five dollars, the short one two.”

  “We’ll take the short,” answered Stan.9

  Even in Wisconsin, the tragedy in Europe was impossible to escape. Françoise’s father had died when she was ten and was thereby spared; and her younger brother, still in his teens, escaped via Spain to England, where he trained as a paratrooper for the Free French Forces of de Gaulle. Her mother, however, rounded up on the street in Marseilles, was forced aboard a train for the Nazi concentration camps and never seen again. On Stan’s side the picture was equally grim. “The news came slowly and piecemeal that during the Nazi occupation of Poland Stan’s sister, her husband, their children and those of the uncles and aunts who did not leave Lwów, the family’s home town, had all perished in the Holocaust,” Françoise notes. “Stan’s father Joseph Ulam, who had not been rounded up, died of ill-health and despair in the one-room apartment he had been relegated to when the Nazis requisitioned his house. A young boy he took in during these terrible times, who succeeded in escaping to this country, brought us the sad, sad news and described how they had to burn his law books to keep warm.”10

  Ulam and von Neumann shared their frustration at the lack of response to the European crisis by the United States. “When … this country announced … that 20 torpedo boats will go to England, I could not help thinking that 50 bicycles would also be valuable,” Ulam wrote to von Neumann in the spring of 1941.11 He signed up for private flying lessons and, upon acquiring U.S. citizenship in 1941, passed his army physical and tried to enlist in the air force, hoping to become a navigator if not a pilot. However, due to his age and severely uneven eyesight, he was turned down.

  Von Neumann, already a consultant to the Office of Naval Research, the Army Ballistics Research Laboratory, and the Office of Scientific Research and Development, reported to Ulam, in April 1942, that “I’m getting more and more snowed under by war work.” Ulam kept asking how he could become involved, and “one day Johnny answered with an intimation that there was interesting work going on—he could not tell me where.”12

  “The project in question is exceedingly important, probably beyond all adjectives I could affix to it,” von Neumann wrote on November 9, 1943, adding that “the secrecy requirements of this project are rather extreme.” This letter was followed by an invitation, signed by Hans Bethe, “to join an unidentified project that was doing important work, the physics having something to do with the interior of stars.” Ulam accepted the appointment, without knowing what he had agreed to, or where. “Soon after, other people I knew well began to vanish one after the other. Finally I learned that we were going to New Mexico, to a place not far from Santa Fe.”13

  The Ulams, with their first child on the way, received their security clearances and headed west. “We made the long journey by train and got off at a whistle stop called Lamy, about eighteen miles from Santa Fe, in what seemed the middle of nowhere on February 4, 1944,” remembers Françoise. “Snow was on the ground yet the sun was warm, the sky was an intense blue, and as Stan said, ‘the air felt like champagne.’ ”14

  The Los Alamos mesa rested against the eastern slope of the Jemez Mountains, on the rim of the Valles Caldera, formed as a result of two explosive super-eruptions 1.6 and 1.1 million years ago. On the other side of the rim, with a lava dome at its center, lay a flat grassland—a miniature Serengeti—left behind when the volcano collapsed. A favorite destination for Los Alamos residents, and a refuge to New Mexico’s largest herd of elk, the Valle Grande was a remnant of one of the most violent explosions on earth. The scientists who arrived on the mesa in the summer of 1943 intended a nuclear explosion to be the next.

  “The place was a mysterious encampment, a sort of Magic Mountain in a Land of Enchantment,” says Françoise, astonished by “inhabitants who seemed to be scientists from everywhere—America, Canada, Germany, Switzerland, Hungary, Austria, Italy, you name it. Many had come to this country to escape from Hitler and Mussolini and their Fascist regimes. Some were already famous. Most were incredibly young, many in their early twenties with reputations yet to be made.”15

  Stan found himself back in the world of the Lwów cafés. “In the entire history of science there had never been anything even remotely approaching such a concentration,” he marveled. “At thirty-four I was already one of the older people.” Ulam found the improvised structure of wartime Los Alamos a refreshing contrast to the formalities of academia, and the close-knit community suited his Polish roots. “People here were willing to assume minor roles for the sake of contributing to a common enterprise,” he
explained. “Jules Verne had anticipated this when he wrote about the collective effort needed for his Voyage to the Moon.”16

  Officially under the command of General Leslie Groves of the U.S. Army, the Laboratory was directed by Robert Oppenheimer, who managed to take command of General Groves. “Groves never realized that he had been co-opted to the scientific task,” says Harris Mayer. “To the end of his life he really believed that he had made the atomic bomb.”17

  Stan Ulam was assigned first to T-Division (or Theoretical Division), under Hans Bethe, and then, when the divisions were reorganized, to F-Division, under Enrico Fermi. Nominally, he reported to Edward Teller, whom he regarded more as his colleague than his boss. “As a theoretician, Stan could work anywhere,” says Françoise. “He went to his office when he wanted. He came home for lunch and usually reappeared early in the afternoon.”18

  Claire was born in July, with her birthplace certified as Post Office Box 1663, Santa Fe. With free medical services, subsidized housing, and community child care, Los Alamos beat the postwar baby boom out of the gate. The hospital began charging for diapers at one dollar per day. “Los Alamos became a great baby farm,” says Françoise, “which annoyed General Groves.”19

  The physics at Los Alamos captivated Stan. “I found out that the main ability to have was a visual, and also an almost tactile, way to imagine the physical situation, rather than a merely logical picture of the problems,” he explains. “One can imagine the subatomic world almost tangibly, and manipulate the picture dimensionally and qualitatively, before calculating more precise relationships.”20 Ulam’s intuition complemented von Neumann’s precisely logical view of the world. “Johnny gave the impression of operating sequentially by purely formal deductions,” Ulam noted, describing the difference between the two approaches as “something like the distinction between a mental picture of the physical chess board and mental picture of a sequence of moves on it written down in algebraic notation!”21 Monte Carlo, the best of both worlds, used von Neumann’s formal, computational system to capture Ulam’s intuitive, probabilistic approach.

  Ulam, who was not directly involved with the design or construction of the bomb, did not witness the Trinity test. “In the early morning the day the bomb went off we were at home and still in bed,” says Françoise. “Finally, a tired, pale, and badly shaken Johnny, who had been there with the VIPs, came to see us on his return.”22 Three weeks later, the second bomb was exploded, above Hiroshima, followed by Nagasaki on August 9.

  With the war over, the entire Theoretical Division had been reduced to eight people by 1946. Oppenheimer had returned to Berkeley; Fermi and Teller had returned to Chicago; Bethe had returned to Cornell. The U.S. Department of State had established a Committee on Atomic Energy, including Vannevar Bush, James Conant, and General Groves, with a board of consultants including Oppenheimer, who formulated the “Baruch Plan,” calling for international control of atomic energy in all forms. Albert Einstein, Léo Szilárd, Harold Urey, Linus Pauling, Victor Weisskopf, and Hans Bethe formed the Emergency Committee of Atomic Scientists, holding their inaugural meeting at the Institute for Advanced Study in November 1946. Control over Los Alamos was transferred from the army to the newly formed Atomic Energy Commission, effective January 1, 1947. But who would control the AEC?

  Upon Oppenheimer’s departure, Norris Bradbury stepped in as temporary replacement—and stayed for twenty-five years. He launched an ad hoc Los Alamos University to keep some momentum going in the interregnum between the army and the AEC, and made the case for continued design and testing of new bombs. “The occasional demonstration of an atomic bomb—not weapon—may have a salutary psychological effect on the world—quite apart from our scientific and technical interest in it,” he argued. “Properly witnessed, properly publicized, further TR’s [tests] may convince people that nuclear energy is safe only in the hands of a wholly cooperating world.” He then made a prophetic suggestion: “Another TR might even be FUN.”23

  When Ulam was hired back, after his convalescence from encephalitis, he was appointed group leader: of a group consisting of him alone. One of his areas of interest was the back-burner effort, now led by Carson Mark, with Edward Teller supervising in absentia, to establish the feasibility of a thermonuclear bomb. “Stan had no moral qualms about returning to Los Alamos,” says Françoise. “What he wanted to concentrate on were the theoretical aspects of the work, and he did not see anything wrong in that.”24

  Teller couldn’t decide whether Ulam was a young scientist to be encouraged, or a rival to be upstaged. “Mr. Ulam is a brilliant mathematician but does not have the proper background for the work we are doing and does not seem to be able to adjust himself to our work,” Teller had noted in Ulam’s personnel file in February 1945. He then hedged his bets: “He is an independent thinker and might conceivably turn up most important results.” As Françoise puts it, “I suspect he sensed he had met his match.”25

  For Teller, the hydrogen bomb was a crusade to be pursued at any cost, whether the country was at war or not. To Ulam, the probability or improbability of a self-sustaining thermonuclear reaction was for the laws of nature alone to decide. As to military consequences, Ulam argued that if one started to question the possible misuse of scientific research, then the infinitesimal calculus should have been abandoned, to preclude destructive effects. “In my mind I knew he made sense. In my heart I could not quite follow,” adds Françoise. Nonetheless, “myself and my friends were startled,” Ulam testified during the ENIAC trial, concerning the calculations that led to the H-bomb, “how some scribbles on a piece of paper or on the blackboard leads finally to a physically existing, and in this case a very violent thing.”26

  Hydrogen bombs had first appeared, during Ulam’s childhood, in H. G. Wells’s The World Set Free, a prophetic novel published at the dawn of World War I. “These atomic bombs which science burst upon the world that night were strange even to the men who used them,” wrote Wells, envisioning a future transformed by atomic energy, until the lack of a requisite transformation of human nature leads to the “Last War”—the one we now imagine as World War III. Nuclear fission was unknown in 1914, so Wells’s atomic bombs were powered by fusion, like the sun. They consumed cities in a slow, inextinguishable fire, and were dropped from aeroplanes by hand. “It was a black sphere two feet in diameter,” wrote Wells. “The Central European bombs were the same, except that they were larger.”27

  “When Bethe’s fundamental paper on the carbon cycle nuclear reactions appeared in 1939,” explains Ulam, “few, if any, could have guessed or imagined that, within a very few years such reactions would be produced on Earth.”28 When the Soviet Union exploded a three-stage bomb yielding over 50 megatons at Novaya Zemlya on October 30, 1961, it was estimated that, for a moment, the energy flux exceeded 1 percent of the entire output of the sun.

  In June of 1942, almost a year before the Los Alamos National Laboratory was established, a group of eight physicists, convened by Oppenheimer and including both Hans Bethe and Edward Teller, met in Berkeley to begin thinking about nuclear weapons. They concluded that not only was the atomic bomb a possibility, but the resulting temperatures and pressures, more extreme than those within the sun, could be used to trigger a thermonuclear reaction. A very small sun might be brought into existence, which in the next instant, without the gravity that holds the sun together, would blow itself cataclysmically apart. “We were not bound by the known conditions in a given star but we were free within considerable limits to choose our own conditions. We were embarking on astrophysical engineering,” remembers Edward Teller. “By the middle of the summer of 1942, we were all convinced that the job could be done and that … the atomic bomb could be easily used for a stepping-stone toward a thermonuclear explosion, which we called a ‘Super’ bomb.”29

  In their report to the secretary of war, James Conant and Vannevar Bush went one superlative further, suggesting “we may therefore designate it as a super-super-bomb.”30 Such a �
��hydrogen” bomb could burn deuterium, a stable isotope of hydrogen, easily separated from seawater and constituting the cheapest fuel available on earth.

  “Atomic bombs would be powerful but expensive,” explains Teller. “If deuterium could be ignited, it would give a much less expensive fuel.”31 In 1950 the cost of adding a kiloton’s worth of deuterium to a hydrogen bomb was about sixty cents.

  Teller admitted, once the Los Alamos project was under way, that “we had to win the war and there was no time for the Super.”32 With the war over, he believed it was time to return to work on the hydrogen bomb. Others believed, just as strongly, that weapons a thousand times as powerful as those that had destroyed Hiroshima and Nagasaki should never be built. To help determine whether the Super was something the United States should pursue, or be afraid of its enemies pursuing, it was decided to run the big December 1945 ENIAC calculations, and to hold a conference, in April 1946, on the results.

  Under von Neumann’s supervision, Stanley Frankel and Nicholas Metropolis went to the Moore School (where the ENIAC was still undergoing acceptance testing) and ran their one million punched cards through the machine. “I advised them as far as the physics is concerned,” Edward Teller later testified. “John von Neumann advised them as far as the computation work.”33 The results were interpreted by Teller as indicating thermonuclear ignition, although it later became evident that the physics was flawed. The calculation, limited by the ENIAC’s small amount of memory, had neglected important secondary effects.

  “Nobody will blame Teller for the erroneous calculations of 1946, especially because adequate computers were not then available,” Hans Bethe wrote in 1954. “But he was blamed at Los Alamos for leading the Laboratory, and indeed the whole country, into an adventurous program on the basis of calculations that he must have known to have been very incomplete.”34 Teller remained unapologetic, arguing that the end justified the means. “My perseverance was in considerable part, due to faith in the results which were wrong,” Teller explained, “but which were hopeful, and this carried us, at any rate, to a point where the necessity of a new development showed itself.”35