31.

A FASCINATION WITH EXPLOSIONS

It was hardly surprising that a man of von Neumann’s background and experience would be afflicted with a profound sense of insecurity, which sometimes manifested itself in comic ways. One was his obsession with proper attire. A unique photograph exists of him walking down a sidewalk in Santa Fe in 1949 with his daughter, Marina, then fourteen, in business suit but with his shirt collar open and no tie. It seems to have been a singular occasion, for no friend’s camera appears to have caught him ever again in such disarray. More typical of the lengths to which he would go to maintain sartorial decorum is a photograph taken in the late 1940s of a group on a break from work at Los Alamos for an excursion into the Grand Canyon. They are about to start the descent, astride the mules that will carry them down. All, including von Neumann’s second wife, Klara Dan, who was called Klari, are wearing casual clothes and some have broad-brimmed hats to protect them from the sun. Von Neumann brings up the rear. His balding head is exposed to the sun and he sits astride his mule in business suit and tie with white handkerchief tucked into his lapel pocket. For some reason, his mule is also headed in the wrong direction.

The insecurity manifested itself as well in his concern for money. There was no need for it. His salary at the institute was ample. He also held a couple of civilian consultantships, one with IBM, which paid him thousands more. He lived in the manner of the wealthy European he had been born, sailing the Atlantic in first-class cabins each summer for international mathematical conferences in Europe, and seeking out the best hotels. He drove the best of American cars, a snappy Cadillac coupé. Yet this willingness to treat himself to luxury never stopped him from chasing down the last penny to which he felt he might be entitled. In 1955, while a member of the Atomic Energy Commission, he dictated a letter to his secretary for the management of the Nassau Tavern in Princeton. It was typed on official stationery and dispatched by government postage. Enclosed were unused vouchers for the restaurant’s parking lot. Von Neumann requested reimbursement, by check or credit. The total amounted to seventy-five cents.

He also had an identity problem. He couldn’t seem to decide whether he was a Christian or a Jew. His first wife, the daughter of a Budapest physician, was a Gentile and a Roman Catholic. The child of that marriage, Marina, was by prior agreement raised in the Roman Catholic faith. Three days before she was baptized in 1935 at Saint Mary’s Cathedral in Trenton, New Jersey, von Neumann had himself baptized at the same place. He never practiced Roman Catholicism in subsequent years, however, and his Jewish friends assumed he considered himself a secular Jew because he acted like one when he was with them. One of his closest Jewish friends, the highly talented Polish-born mathematician Stanislaw Ulam, recalled in his memoirs how von Neumann liked to tell a joke mocking the “goyim,” a derogatory Yiddish term for Gentiles. (Ulam, who also immigrated to the United States during the 1930s, was in 1951 to make the hydrogen bomb feasible by coming up with a new idea for detonating the thermonuclear core. Teller would never subsequently acknowledge the contribution because it detracted from his claim to sole parentage.) Not until death confronted him would von Neumann make up his mind.

Von Neumann displayed the same sort of intensely emotional patriotism Schriever did, the patriotism of the immigrant who is deeply grateful to a land that has been good to him. He had a fierce desire to defend this society that had given him shelter and that embodied values he cherished in the rule of law and the freedom of scholarly inquiry. The traits also made him eager to cooperate with the U.S. military. He found the relationship fulfilling, a measure of his acceptance by American society. Systematic mobilization of scientific talent then got under way at the outset of 1941. Roosevelt recruited Vannevar Bush, an electrical engineer and mathematician who was president of the Carnegie Institution and one of the country’s most eminent scientific figures, to oversee the effort as his science czar. Bush established the National Defense Research Committee (NDRC), with himself as chairman. That February 26, he wrote von Neumann notifying him that he was being made a consultant to a section of the committee under Bush’s friend James Conant, a chemist who was president of Harvard.

By now von Neumann was eager to give the slip to his scholar’s tower at the institute. His was not the contemplative genius of Einstein. His mind was quick and restless and this was an opportunity to dedicate his extraordinary talent for mathematics and mathematical physics to a cause that had such intense and personal meaning for him. He quickly developed a fascination with explosions. The subject is called hydrodynamics because of the similarity between the expanding waves of an explosion and fluids in motion. The section of the National Defense Research Committee to which he had been assigned was focused on the subject, using a laboratory at Princeton. Soon his correspondence was filled with such terms as “gas dynamics,” “shock collisions,” “shock waves in several dimensions,” and “oblique shock reflection.” He studied explosions through every technique available, including flash photography with high-speed film, and composed mathematical models for the various types, phases, and effects. By the spring of 1942 he had begun to make himself an authority on the subject, evolving a theory on explosions that he laid out in a secret report entitled “Detonation Waves.” Unaware as he sometimes was that lesser mortals had difficulty keeping pace with his mind, his initial report was composed almost entirely of mathematical models and equations. At the request of some of his colleagues, he wrote a second report, “a more ‘popular’ version,” as he called it, which contained enough of the English language so a technically qualified person could comprehend his mathematics.

His reputation for expertise on explosives became sufficiently widespread within the military and scientific communities that the Navy sent him to England for six months to advise on the effects of detonations underwater, apparently for use in antisubmarine warfare. After his return from England in the summer of 1943, Robert Oppenheimer summoned him out to Los Alamos. He wanted von Neumann’s advice on the implosion method the laboratory was attempting to develop to set off the Fat Man plutonium bomb that was to be dropped on Nagasaki. The two men had been acquainted since the late 1920s, when they had met while Oppenheimer was studying in Germany. Von Neumann endorsed the implosion concept and provided some ideas for it, but Oppenheimer then made the mistake of assigning to an American physicist from Caltech the task of perfecting it. The job was light-years beyond the man. Even Hans Bethe, the gifted German Jewish physicist who was to win a Nobel for his research on the energy production of stars, at the time chief of the Theoretical Division at Los Alamos, tried and failed to design a workable method.

Early in 1944, “Oppie” summoned von Neumann back to Los Alamos. Other developments on the plutonium bomb had rendered imperative the creation of an implosion method that would succeed. Wrapping the plutonium core of the bomb with conventional explosives and detonating them to crush the plutonium with enough force and simultaneity to drive it to the supercritical stage of a nuclear explosion was a simple idea. The details, however, were extraordinarily complex. Enlisting his friend Stanislaw Ulam to help him with the mathematics, von Neumann set out to solve the riddle. To prevail, von Neumann needed all the knowledge of explosions he had acquired from past experiments.

His first task was to determine precisely how and at what speed the detonation waves from the wrapper of conventional explosives should converge in order to force the plutonium to supercriticality. To find the answers to this part of the problem, von Neumann and Ulam had to perform an exhaustive number of mathematical calculations. Once they had the results and had put together a mathematical model of the correct convergence, von Neumann moved on to his second task—diagramming the detonation wrapper by delineating the arrangement of fast-burning and slow-burning explosives required. He had to diagram to nearly perfect exactness. The calculations showed that an error of more than 5 percent would make the difference between a conventional explosion followed by a nuclear detonation and a conventional bang followed by a nuclear fizzle. The diagram was then turned over to George Kistiakowsky, the ingenious Ukrainian-born chemist, to transform it into reality, which he so brilliantly did.

And as the bombs were dropped on Hiroshima and Nagasaki, the fruit of John von Neumann’s mind was at work again to enhance their destructiveness. It was he who had discovered in the course of his experiments that large bombs had a greater blast effect if detonated at an optimal height above their targets rather than at ground level. At both Hiroshima and Nagasaki, therefore, the bombs had been set for air bursts to maximize the obliterative effect on the cities and their inhabitants.

When Bennie Schriever went to Princeton to seek his help, von Neumann was near the height of his influence and prestige. His role in the making of the atomic bomb and then the Super were widely known within the upper reaches of government and the scientific community. His initiative in advancing the electronic computer had also brought him public recognition and the luster of his reputation for mathematical genius was undimmed. Von Neumann was liked as well as admired by his colleagues. With his wide erudition and a trove of ribald jokes, he was always an interesting and amusing companion. The militancy of his attitude toward the Soviet Union was not regarded as wild and totally irrational at the time, even by those who did not share its intensity. Fear of a Soviet invasion of Western Europe had been brought to a peak by the Korean War, and no matter how mistaken in retrospect that fear may have been, it was all too real at the time. (In 1952, von Neumann had proposed persuading the best mathematicians in West Germany to immigrate to the United States in order to deprive the Soviets of their talents when the place was overrun.)

The death of Stalin in March 1953 and the negotiations that were to bring a truce in Korea that July did not lessen the fear because the Soviet Union, rather than the person of Stalin, was now perceived as the menace. At bottom, von Neumann’s contemporaries liked and trusted him as much as they did because they sensed the fundamental decency of the man. He was to display it conspicuously in 1954 by testifying in defense of Robert Oppenheimer, who was wrongly accused of disloyalty and deprived of his security clearance because of his opposition to creating the hydrogen bomb when the issue was still open to debate before Truman had made his decision. Von Neumann’s defense of Oppenheimer was all the more striking for its moral courage because his political patron happened to be the financier Lewis Strauss, the man who, as chairman of the Atomic Energy Commission, was stage-managing the conspiracy against Oppenheimer. Despite this conflict of opinion, Strauss apparently appreciated von Neumann’s sincerity because he subsequently arranged his appointment to the commission.

Schriever recalled years later that, as he had anticipated, the technical details of the conversation between von Neumann and Teddy Walkowicz were beyond his ken. Von Neumann was generous with his time—the meeting lasted several hours. Von Neumann explained, with occasional resort to chalk and blackboard, the process by which one progressed from the eighty-two-ton, liquid-fueled Mike device exploded the previous November to the warhead Schriever needed by the end of the decade for a practical ICBM—a dry hydrogen bomb of less than a ton in weight and one megaton in yield. Von Neumann based his findings on radiation flow and other data from the Mike test, which gave him confidence that much lighter dry bombs of lesser yield could be built in the future. He said he expected more data from the Castle test series scheduled for the spring of 1954 at Bikini Atoll in the Marshall Islands of the central Pacific, when the United States was to set off its first dry thermonuclear devices fueled by lithium deuteride.

Bennie left the meeting well satisfied. He now had more than the simple confirmation for which he had originally gone to Princeton. He had scientific validation and, coming from von Neumann, perhaps the nation’s foremost authority on nuclear weaponry, that validation was unchallengeable. He also recalled returning to Washington with something else that gave him additional satisfaction. Earlier that year, von Neumann had agreed to head the recently created Nuclear Weapons Panel of the Air Force’s Scientific Advisory Board. Ironically, it was Schriever who had lobbied Jimmy Doolittle to set up the panel during the March gathering at Maxwell, so that they could obtain better information on what to expect in the size and yield of nuclear weapons to come. (Among his other roles, Doolittle served as a vice chairman of the SAB.) In the course of this meeting at Princeton, von Neumann now told Bennie he would see that the panel included in its reports a hydrogen warhead light enough for a missile to carry. When attempting to drive a project as big as the ICBM through the Air Force bureaucracy, having as much scientific judgment as possible in your favor was a key component in succeeding. Von Neumann’s ultra-hawkish views, the widespread esteem in which he was held, and his ability to marshal the talents and support of his fellow scientists were to provide assistance of the utmost importance in bringing Schriever’s vision to fruition.

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