Maverick Genius

by Phillip F. Schewe

  NUCLEAR INFINITY

  The territory he himself explored now was the atomic nucleus. Nucleus: the name proclaims centeredness. Even though the nucleus is 100,000 times smaller than the atom in which it sits, it accounts for a vast majority of the atom’s mass. More importantly, the forces operating at the nucleus are a million times stronger than those governing the rest of the atom.

  At this time, in the early 1950s, physicists thought that just as photons carried the electromagnetic force among electrons flying around the atom, so the strong nuclear force would be carried among the inhabitants of the nucleus, protons and neutrons, by particles called mesons. Experiments were then beginning to measure how protons and mesons interacted. These nuclear tests weren’t as precise as the earlier atomic tests (like the Lamb shift) that probed the interaction between electrons and photons, but they were giving theorists like Dyson some “truth” to aim at.

  Was it possible to contrive an explanation for the nuclear force analogous to QED, one that portrayed the nuclear force as the sum of a series of terms, representing ever more complicated scenarios of particle interactions? This time the process of dividing up a complicated process into smaller parts wasn’t going to be easy. At least with QED the successive terms were smaller and smaller since the electromagnetic force was relatively weak. By comparison, the main nuclear force is more potent, and the successive terms did not shrink down to nothing; instead they remained sizable.

  Here was another potential infinity. If Dyson wasn’t careful, his equations would yield nonsense predictions for nuclear activities just as, twenty years before, quantum science had yielded nonsense predictions for atomic activities.

  Dyson’s new conjecture was that he could accurately calculate nuclear properties by segregating the parts of the problem corresponding to the high-energy interactions and low-energy interactions among the nucleons and mesons, and deal with them separately. Then he would tame these collections of terms, or at least sweep them under a carpet somehow. Moreover, Dyson suspected that gravity might play a role in making this theory work.

  As a new graduate student in the fall of 1947 Dyson had cleverly worked out a form of the electromagnetic force that could predict a value for the Lamb shift that matched the value actually measured in experiments. Now he wanted to do the same sort of thing with the strong force. Dyson and his students compared their calculated numbers with the early nucleon-meson scattering experiments being conducted by Enrico Fermi at the University of Chicago, and found an intriguing similarity. Had Dyson succeeded in creating a model for the nucleus?

  In trying to settle the QED business two years before, he had consulted with Wolfgang Pauli. Now he would take his nuclear conjecture to another master. He decided to go to Chicago and confer with Fermi in person. Fermi, one of the few scientists renowned for both experimental and theoretical work, would be in a good position to judge Dyson’s progress.

  In April 1953 Dyson made another of his lengthy travels on a Greyhound bus, this time from Ithaca to Chicago. A month before, Dyson’s son, George, had been born. So the first thing Fermi did when Dyson arrived was to ask him to sit. How was the baby?

  Then they got to the point. Dyson made his case and Fermi rendered his verdict. A good theory, Fermi said, had to be built either on a clear physical picture of what was going on at the microscopic level or on a structure of rigorous mathematics. Dyson’s theory, Fermi declared, had neither clarity nor rigor. The tentative agreement between Fermi’s data and Dyson’s theory was only accidental, he argued.36

  Dyson, who prided himself on his rigorous mathematics, was crestfallen. He had defended his explanation of the electron-photon interaction against a skeptical Oppenheimer and had prevailed. This time things were different. Dyson knew not to dispute Fermi’s dismissal of the proton-meson explanation. Fermi was right. Dyson’s model was feeble.

  His personal recessional continued. Dyson retreated to Ithaca. This defeat, coming on top of his earlier problems with proving the consistency of QED, was a heavy blow. When he failed to finish QED, his folly (if it can be called that) affected only himself, since he had been doing the work by himself. But now he was a professor, with graduate students to guide. He had persisted with theoretical nuclear research that was leading nowhere, and he had led others with him into this blind alley. Trying to find consolation in his dreary sojourn in Chicago, Dyson could say that at least Fermi had saved him and his students even more years of wasted effort. What this new round of fruitless work had shown him, however, was that he was not really a particle physicist at all.37

  BERKELEY

  For some time Dyson had been frustrated by academic life. He enjoyed teaching, but the graduate study framework, in which a senior scientist oversees the years-long research of a student working toward a doctorate, was for Dyson too constraining. It committed him to a particular research direction, whereas by nature he wanted to try new ideas as the fancy struck him, and he had been around long enough to see that his fancy changed often. Richard Feynman, who disliked ceremony and pedigrees, agreed. He envied Dyson his lack of a Ph.D.38

  Even before the sobering trip to Chicago, Dyson had resolved to alter his circumstances. In December 1952 he discreetly contacted Robert Oppenheimer and asked if the liberal visiting arrangement with the Institute for Advanced Study could be turned into something more lasting. Since his days in Bomber Command, Dyson hadn’t worked in one place for more than a year or so. He wanted to establish himself and not have to move around so much. Oppie readily responded with the offer of a permanent faculty position. In his position as Institute director he had sent many such offers, he said, but none had given him such so much pleasure as this one.39 The starting salary would be $12,500, a pretty good salary by university standards.

  Before moving to Princeton, Dyson and his family crossed the continent to Berkeley. For three months they lived on the edge of the West Coast in a rented house in the Berkeley Hills on Buena Vista Way, a street name that encapsulated the gorgeous view of San Francisco Bay. Dyson appreciated lovely views. From this perch he could think about what he wanted to do with the rest of his life.

  Previously he had studied the inner workings of atoms and then the inner workings of nuclei. He had turned his hand to writing popular articles. Now he would try to encompass another part of the world, namely the interactions among atoms, trillions and trillions of atoms at a time locked within a solid material. The branch of science devoted to this inquiry is called condensed matter physics. Collaborating with University of California professor Charles Kittel, Dyson reveled in the work of drawing up explanations of how the atoms tangle with each other. This work wasn’t as fundamental as QED had been, but it was just as satisfying. Why? Because it was another occasion for bringing elegant mathematics to bear on a practical problem.40

  There was no guilt here, no frustration, since no one was expecting him to change the world. He was studying something as commonplace as the jiggling of atoms in a glasslike solid. But even this motion was difficult to understand. Dyson had not moved into the study of condensed matter because the problems were easier. Once again he resorted to the trick of transforming a complicated problem into something simpler. He pretended that the solid consisted of a one-dimensional string of interacting atoms, like birds sitting on a telephone line. Working in one dimension instead of three made the mathematics much simpler. True, a one-dimensional solution can’t fully explain a three-dimensional problem. But a retreat in dimensionality just might provide some clues about how to address the fuller reality.

  As so often happens, one scientist will have a brilliant idea that is later carried to fruition by someone else. In this case Dyson’s mathematical work from that summer of 1953 was streamlined and generalized by a physicist named Helmut Schmidt.41 There is to this day an equation, the Dyson-Schmidt equation, which describes one-dimensional “solids.”

  Dyson’s summer in Berkeley was therapeutic. Years later, at the height of the hallucinogenic 1960s, when Dys
on was reviewing a book about one-dimensional physics, he extolled the virtues of making strategic simplifications:

  A man grows stale if he works all the time on insoluble problems, and a trip to the beautiful world of one dimension will refresh his imagination better than a dose of LSD.42

  6. Nuclear Opera

  Dyson and the Cold War

  (1954–1956)

  The detonation proceeds. Seeing the manicured lawn and the ivy-covered halls, you wouldn’t have guessed that an unprecedented device, bristling with wires and vacuum tubes, is shuttling through a phased escalation of violence. Right there at the Institute for Advanced Study, in a building off by itself through the woods, a bomb explodes. Not just any bomb, but a hydrogen bomb. Over microsecond increments internal conditions ratchet toward catastrophe.

  Outside the room few know. Above, the sky is not being riven by X-rays. Inside the wood-paneled central hall, looking like a posh gentleman’s club, the members are taking their afternoon tea. At the Institute, which even the director, J. Robert Oppenheimer, refers to as an intellectual hotel, the only obligation you incur is to undertake advanced study. Actually you aren’t even required to do that. You can stare out the window for nine months if you like. Of course, most that come do more than stare, but they don’t have to account for themselves in any way. This is exactly what Freeman Dyson wants.

  All are brilliant and arrive highly recommended. Nearly all are thinkers rather than doers. Few did experiments. In fact, the permanent faculty frowns upon the construction of apparatus. This would go against the spirit of the place, which is intellectual efflorescence. And yet here is John von Neumann doing an experiment. Worse, he is exploding a bomb by unleashing a runaway chain reaction. But von Neumann is a senior man, and he has permission to proceed from Oppenheimer himself.

  Bombs at Princeton? There was a time when Oppenheimer opposed the development of a hydrogen bomb, but now he was coming around. He had originally felt that the atom bomb, the one he invented in that desert lab during the war, was enough, more than enough, to deter future wars. Now he was seeing things differently. From a physics viewpoint and from a political viewpoint it had started to make sense. He allowed the explosion to proceed.

  The bomb at Princeton would implode no building and ultraviolate no bystanders. No mushroom cloud would appear over southwestern New Jersey. Instead, the bomb would explode entirely within von Neumann’s computer. Von Neumann, like his friend and compatriot Hungarian Edward Teller, was now an American and ardent anti-Communist. Having promoted the importance of the more destructive hydrogen bomb even as the “smaller” atom bomb was being developed during World War II, Teller had helped finally to contrive a workable design, and von Neumann was carrying out a trial run in the form of a computer simulation.

  Von Neumann was brilliant. He made important contributions to quantum physics, mathematics, economics, and game theory. But his two most important achievements were in the development of thermonuclear weaponry that has dominated strategic defense planning for the past sixty years and in the development of one of the first stored-program digital computers.

  The Institute’s Electronic Computer Project would later go on to perform some of the first ever simulations of weather fronts and of biological evolution. But now on its maiden voyage, for a period of sixty days and nights, executing the largest arithmetical calculation ever performed at the time, von Neumann’s room-sized machine was serving as a proxy for an H-bomb blast.1 The actual test detonation of the bomb would occur a few years later on a remote Pacific island. The sponsors who helped put up money for the computer included RCA (maker of all those vacuum tubes), the army, the navy, and the still young Atomic Energy Commission (AEC).

  A potential misnomer is at work here. In both the atomic bomb and the hydrogen bomb the energy of the explosion comes out of the nucleus at the core of atoms, zillions of atoms. In an A-bomb or H-bomb what explodes is not atoms but the nuclei at the hearts of atoms. But Berkeley physicist Richard Muller has pointed out that it is not entirely inappropriate to refer to the bombs developed at Los Alamos and dropped on Hiroshima and Nagasaki as atom bombs. All previous bombs in history, Muller argues, were molecular bombs. They depended on the unleashing of chemical energy locked up in the bonds of molecules, which are groupings of atoms. Only in the 1945 bombs did this kind of chemical energy not play a role. Molecules weren’t involved, only atoms—uranium and plutonium atoms. True, only the energy at the center of those atoms, in the nuclei, mattered. But it was energy flying out of atoms and not molecules.2 In general, for the same weight of fuel, an atomic bomb is a million times more powerful than any molecular bomb.

  So what’s the difference between an A-bomb and an H-bomb? Both involve the release of pent nuclear energy but are otherwise very different in their methods. The A-bomb explosion occurs when the nuclei of special heavy atoms like uranium break in half. By contrast, the H-bomb explosion occurs when the nuclei of light atoms, specifically the variant forms of hydrogen known as deuterium and tritium, weld together. These two processes are called, respectively, fission and fusion.

  The fusion bomb was much more powerful than the fission bomb, but was harder to design. Also, the politics surrounding the two bombs was different. The A-bomb was a child of World War II and was built originally to be dropped on Germany, although the targeting later shifted to Japan. The H-bomb was a child of the Cold War and was thought of as a response to the Communist menace.

  Freeman Dyson hadn’t been present at the creation of either the H- or A-bombs. In the 1940s he’d been a junior partner in the dropping of conventional molecular bombs on Germany. Now in the early 1950s he was a theoretical physicist. But he too would be drawn into nuclear matters in a big way, first as an observer, later as a participant, and finally as a critic.

  NUCLEAR FRISSON

  To account for Dyson in the 1940s, the biographer needs to supply a quantum context. Quantum science is what Dyson loved; it’s what he did well; it’s how he came to distinction. To explain Dyson in the 1950s, the surrounding context is one of nuclearism. This means not only performing theoretical nuclear physics at a chalkboard, but also designing and implementing nuclear things—bombs, reactors, spaceships, and treaties.

  In Michael Frayn’s play Copenhagen, Niels Bohr and Werner Heisenberg meet for a posthumous argument over their wartime behavior and the development of atomic bombs. The most chilling line in the play comes when Bohr, who at this moment in the drama believes, mistakenly, that a nuclear explosion is impossible, says, “I don’t think anyone has yet discovered a way you can use theoretical physics to kill people.” Interestingly, the same nuclear reactions that kill people when wielded as a weapon can, when deployed in diluted form in a reactor, usefully light up a city with electricity.

  Manifestly, the nuclear age, in which we still live, is operatic in scope. It’s practically Wagnerian. In the first of Richard Wagner’s cycle of operas devoted to the Nordic myths, the evil troll Alberich forges a powerful ring from a critical mass of gold pulled out of the River Rhine. Thereafter this ring is the focus of contention—a sort of strategic weapon—between warring superpowers. Alberich, leader of the underground Niebelung nation, went to war with Wotan, leader of the sky-dwelling gods.

  Like the development of the ring by Alberich, the development of nuclear weaponry seemed at first to have conferred absolute power. But this illusion was short lived. Two powerful dynasties, the Soviet and the American, struggled to amass the deeper stockpile of megaton explosiveness. In this feverish competition, perceived internal enemies were just as loathsome as external enemies. In Russia show trials were common; even more common would be quiet arrests and liquidations without any public hearings. In America, the number of executions (such as those of Julius and Ethel Rosenberg) was much smaller but the public investigations were conspicuous. Senator Joseph McCarthy led a crusade of press conference denunciation and floodlit hearings to root out apparent Communist influence wherever it existed, whether in go
vernment, at universities, or in the film industry.

  Robert Oppenheimer was a tempting target of suspicion, partly because of his prewar leftist leanings and partly because his stewardship of the nation’s nuclear program seemed to be less than enthusiastic. The AEC General Advisory Committee, which Oppenheimer chaired, had initially been against the development of an H-bomb, chiefly on the grounds of its over-powerfulness. Oppenheimer was joined in this opinion by a majority of the influential physicists involved, including Enrico Fermi, Isidor Rabi, and Hans Bethe. They felt the much more destructive H-bomb could only be an instrument of genocide and not an effective defensive weapon. One could easily imagine that the use of such an ultimate weapon would ignite the sort of global conflagration portrayed in the concluding opera of Wagner’s Ring cycle, the aptly named Götterdämmerung.

  Actually an opera has since been constructed around this nuclear theme. John Adams’s 2005 work Doctor Atomic is about the 1945 test shot in the New Mexico desert, but it captures the nuclear paranoia that typified the following decades, a tempestuous time when Oppenheimer jousted with powerful rivals over the political use being made of nuclear force.

  When in 1949 the Soviet Union tested an A-bomb of its own, H-bomb skeptics on the American side, including Oppenheimer, began to view the H-bomb more favorably, partly because they could see that the Cold War was heading toward a more dangerous phase.3 Partly Oppenheimer’s view of the H-bomb changed because as a scientist, as a bomb designer himself, he could be seduced: “When you see something that is technically sweet you go ahead and do it … and you argue about what to do about it only after you had your technical success.”4