Freeman Dyson had not worked at Los Alamos on the A-bomb, but he came to know many who had, especially those at the top of the organizational pyramid—Oppie, Bethe, and Teller. Moreover, Dyson himself would in coming years be associated with the design and potential use of nuclear devices. He was a frequent commentator in The Day After Trinity, a 1981 television documentary about the early nuclear age. He had by then become an opponent of nuclear weaponry, but even he marveled over the lure of bomb research:
I have felt it myself. The glitter of nuclear weapons. It is irresistible if you come to them as a scientist. To feel it’s there in your hands, to release this energy that fuels the stars, to let it do your bidding. To perform these miracles, to lift a million tons of rock into the sky. It is something that gives people an illusion of illimitable power, and it is, in some ways, responsible for all our troubles.5
Oppenheimer was the prime example of how this Faustian bargain worked. His picture had been on the cover of Time magazine. His was the face of big science. He had engineered the explosions that, many believed, led to the Japanese surrender. Following the war, his responsibilities were still great. He continued to help shape America’s nuclear policy.
But fortunes can change suddenly. The spirit of the time can swerve. Old resentments can produce fault lines. New personalities come to power. Oppenheimer, long an influencer of events, was himself about to be buffeted.
In the fall of 1953 a portfolio of accusations against him, or at least queries pertaining to his past views and activities, was being prepared by men with grudges. Two Oppenheimer antagonists merit attention. One was Edward Teller, who, even while the A-bomb was being built in Los Alamos, directed his energies toward designing the more powerful H-bomb. He resented Oppenheimer’s apparent attempts, during and after the war, to rein in H-bomb development. Teller’s tireless advocacy of the thermonuclear weapon won him powerful friends in Congress and elsewhere. By 1953 he had built up a new weapons lab, at Livermore, California, which thereafter competed with the lab in Los Alamos for the design of nuclear devices.
The other opponent was Lewis Strauss. A businessman by profession, Strauss had risen during World War II to a prominent advisory position in government, and had acquired the honorary rank of rear admiral in the Naval Reserve. After the war he became an AEC official, and at an otherwise innocuous hearing in 1949, Oppenheimer had made sarcastic remarks at Strauss’s expense. Strauss, a man easily offended, would thereafter look for a chance to revenge himself. As an AEC commissioner and as a close advisor to presidents Harry Truman and Dwight Eisenhower, he had wide latitude to oversee nuclear matters. To Strauss the continued presence and influence of Oppenheimer in shaping policy was offensive.
Strauss’s chance came in December 1953. The renewal of Oppenheimer’s security clearance should have been a routine matter, but Strauss transformed the process into a tribunal resembling a criminal prosecution. In the spring of 1954 the shrill hunt for Communist influences in American government was reaching its peak intensity. Televised hearings conducted by Senator McCarthy sought red infiltration of the army. In these same weeks, the matter of J. Robert Oppenheimer also came to a crescendo.
Strauss had not discovered any major new revelations against Oppenheimer. Oppie’s 1930s leftist affiliations, his admission years before of lying during an interview in order to protect his friend Haakon Chevalier, and his brother Frank’s membership in the Communist Party were brought up again. Oppenheimer’s wartime boss, General Leslie Groves, had known all these things and had, for the sake of the war effort, condoned these aspects of Oppenheimer’s résumé.
Political climate change had occurred. The Soviet Union was seen as the paramount threat and any leftist sympathies, even if they had long since been modified or rejected, were taken as possibly incriminating. Should America’s ultimate defense depend so prominently on the views of a man of leftist sympathies?
Weeks of draining testimony brought into public view Oppenheimer’s deeds, his adulteries, his political opinions, and his private thoughts. He admitted to mistakes. Why had he lied during that interview a dozen years before? Because, he admitted, he was an idiot.
Dyson and other scientists were of course watching the proceedings, and like many others they were worried about the implications. Not only could the holding of certain political views lead to being fired from your job—and not just government jobs, but also as teachers, artists, and other occupations—but even holding certain views pertaining to the application of physics to military technology, in this case to doubt the efficacy of H-bombs, could bring accusations of disloyalty.
Robert Oppenheimer, facing the principal crisis of his professional life, was practically incommunicado. One day, Freeman Dyson, down from Princeton to Washington, D.C., delivered Oppenheimer’s laundry to a hotel. In the lobby Dyson ran into his friend Hans Bethe, who was fresh from what Bethe would later refer to as the most unpleasant conversation of his life. Bethe had failed to talk Teller out of testifying against Oppenheimer.6
In determining this vital question of Oppenheimer’s security clearance, nothing would be as decisive as the words of Edward Teller. While not exactly calling Oppenheimer disloyal, Teller made it clear at the hearing that America’s nuclear arsenal could be better served:
I thoroughly disagreed with him in numerous issues, and his actions, frankly, appeared to me confused and complicated. To this extent, I feel that I would like to see the vital interests of this country in hands which I understood better and therefore trust more.7
Leaving the room, Teller reached out his hand to Oppenheimer and said, “I’m sorry.” Oppenheimer took the hand but responded, “After what you’ve just said I don’t know what you mean.”
The investigation ruled against Oppenheimer. His security clearance was not renewed. His classified papers, held at the Institute for Advanced Study in a safe protected by guards, were withdrawn. His days as a high-level government advisor were over. This whole episode has entered the political history of science and society, almost on a par with Galileo’s seventeenth-century interrogation by the Catholic Church over the holding of heretical views.
Freeman Dyson was not yet a government advisor himself. He had played a peripheral role in the Oppenheimer drama. But he wasn’t entirely free from the fallout of the security frenzy. By a cruel stroke of irony, Oppenheimer’s arch-nemesis, Lewis Strauss, was also chairman of the Institute’s board of directors. In this capacity he now tried to have Oppenheimer fired.
Dyson, who had lived through the melancholy atmosphere of the late 1930s as Europe veered toward war, felt now in 1950s America that something bad might be happening too. He resolved that if Oppenheimer could be fired from his Princeton job for holding certain views, then he, Dyson, would consider returning to Europe. He wasn’t sure how far the McCarthyite inquisition would proceed. In his mind at least he kept a suitcase packed and was ready to depart. He made discreet inquiries about a job, and talked to people at Birmingham and at Imperial College in London.8
Some physicists lost jobs. David Bohm, Dyson’s Princeton friend during his 1947–48 year at the Institute, was suspended by Princeton University when he would not cooperate with the House Committee on Un-American Activities. He left the country. Robert Oppenheimer’s brother, Frank, also a physicist, had belonged to the Communist Party in the 1930s, and as a consequence was unable to find a job. Years later he founded the Exploratorium science museum in San Francisco.
Writing about these events later, Freeman Dyson saw tragedy all around. The Bethe-Teller friendship expired. Oppenheimer was in disgrace—McCarthyism’s “most prominent victim,” said two historians.9 And Teller was regarded thereafter as a great betrayer. Like the villain in Wagner’s opera who treacherously stabs the noble hero Siegfried in the back, Teller was perceived by many scientists as envious and even evil. At a scientific meeting a few months after the hearing, several physicists, including the usually statesmanlike Rabi, refused to shake Teller’s hand. This ha
rd attitude persisted for many years.
Fear of nuclear conflict also persisted for as long as the Cold War held sway, but it was particularly intense in the 1950s. What would a nuclear explosion look like? Survivors of the Nagasaki and Hiroshima blasts provide many gripping eyewitness accounts. Works of art, like Doctor Atomic, also vividly portrayed the general sense of nuclear dread. In the opera’s production on the grand stage of the Metropolitan Opera House, the climax of the story, the nighttime detonation of the “gadget” in the New Mexico desert, comes in the very last moment of the opera. In slow motion, with all the characters leaning in toward the distant explosion, as if to listen in on the revelation of an awful secret, the blast seems to shiver space itself apart and turn darkness into a ball of fire.
A CRACK IN THE MIRROR
The war was over. Not the Cold War; that would go on for decades. But the war over Oppenheimer. His security clearance was revoked and his involvement with government matters ceased. But at least he had not been fired from his post at the Institute. Dyson felt that Oppie, back in Princeton with fewer distractions, was a better director than ever.10 He met each Tuesday afternoon with senior Institute scientists, and continued with his sharp questioning of seminar speakers.
Freeman Dyson had one of the most prestigious jobs a scientist could have. He was a professor at the Institute for Advanced Study. The most famous residents at the Institute were physicist Albert Einstein and mathematician Kurt Gödel. Dyson never got to know either man. When Dyson came for the 1948–49 academic year, he didn’t know enough physics and had been too shy to talk to Einstein.11 Now, coming to the Institute as a professor, Dyson still generally avoided seeing the man because of Einstein’s outmoded views about quantum mechanics.12
Dyson also spoke little with Gödel. It was said that Gödel and Einstein only talked with each other. The ideas Gödel introduced were no less important for mathematics than Heisenberg’s uncertainty principle had been for physics. Gödel demonstrated that within a formal mathematical system with a finite number of rules some logical propositions existed that could not be proved or disproved by the logical rules of that system. In other words, no finite system of mathematics, no matter how extensive, would ever be satisfactorily complete. This demonstration is now generally called Gödel’s incompleteness theorem. And then, like his friend Einstein, Gödel effectively retired from active participation in forefront research. In later years, however, Gödel became interested in cosmology and would occasionally ask Dyson to update him on the latest astronomical observations.13
A few years after the H-bomb tests, von Neumann moved over to the AEC, and his computer project became endangered. It was seen by many as an engineering endeavor intruding amid a grove of intellectuals. Dyson was one of those who fought (unsuccessfully) for its survival. Years later he observed that the Institute had thrown away its chance to have been a leader in the birth of two new sciences, weather forecasting and computer science.14
Coming to the Institute gave Dyson the intellectual freedom he wanted. Sometimes that meant something in “pure mathematics.”15 Mostly, though, Dyson’s mathematical thinking was used in the service of physics.
In the summer of 1955 Freeman flew west while Verena, the children, and Freeman’s sister, Alice, drove out, dropping Katarina at a summer camp in Ohio on the way. In Berkeley, Dyson again worked in condensed matter physics. This time he studied how the atoms in a magnet interact with each other. These atoms can themselves be considered as little magnets oriented at various angles. Sometimes the atoms can interact with each other in a collective way, not just with their immediate neighbors, in the form of a traveling magnetic disturbance. Dyson showed how these disturbances, called spin waves, could be described using the mathematical tricks of field theory.
Indeed, Dyson was one of the first to introduce quantum fields, and some of the other techniques he’d used in formulating the equations of quantum electrodynamics, into condensed matter physics.16 This work was just as much fun to do as QED. Dyson felt that it might just be the most important physics work he ever did.17
He’d never entirely given up on QED. In fact in 1954 he spent the whole summer teaching QED at a school, launched by his friend Cécile Morette, perched on a mountain in Les Houches, France. It rained for six weeks. During this time Enrico Fermi and some of the teachers took a hazardous trip to a nearby mountaintop to visit a cosmic ray experiment.18
Besides adding to his catalog of physics interests, Dyson continued to cultivate his desire to explain science to the public. For example, his interest in atoms and magnetism grew into a general article about heat, energy, and disorder in Scientific American.19
In the mid-1950s the next thing that captured Dyson’s attention was the idea of symmetry. Artists love symmetry as an element of design, and so does nature. The balance of bilateral symmetry in architecture—the same number of windows to the left of the door as to the right—tends to be satisfying. In choosing mates, psychologists tell us, we take reassurance from facial symmetry, the left side looking just like the right, as if this outward beauty were a sign of healthfulness within. Plenty of things in nature, such as pinecones, have symmetry. Snowflakes are hexagonally symmetric. Turn them one-sixth of the way around and they look the same. Another sixth, and they are still the same.
Scientists think of symmetry in a more general way to refer to the properties of an object that remain the same even when a certain transformation takes place. For example, when two billiard balls collide, we expect the process to be mirror symmetric: we shouldn’t be able to tell whether we’re seeing the movie straight on or in a mirror. The collision should also be symmetric with respect to time: watching the movie of the balls knocking about momentarily we shouldn’t be able to tell whether we’re seeing the movie in forward or reverse. Of course for complicated objects symmetry might be hard to sustain; watching a movie of an egg falling to the ground and breaking we would know whether it’s forward or reverse.
Scientists’ belief in symmetries like these, and for simple things like billiard balls or interactions between two atoms, wasn’t exactly a law. There is no way to prove that mirror or time symmetry should be true, but the evidence of experiments up until then seemed to suggest that they were. That’s equivalent to saying that swans must be white, an assertion based on the experience of seeing only white swans. The jarring discovery of a black swan, however unexpected, would of course end the swans-must-be-white rule.
Then two of Dyson’s colleagues at the Institute, Chen Ning Yang and Tsung-Dao Lee, predicted that nature might not be mirror symmetric after all at the level of subatomic particles. Some rare decays of nuclear particles, they said, might exhibit a left-right imbalance. Extended to all three spatial dimensions (left-right, up-down, back and forth), the idea of mirror symmetry is referred to as parity. Like all swans seeming to be white, subatomic transactions seemed to be parity symmetric.
Maybe not, said Lee and Yang. Parity might not be conserved in some circumstances. How could such a blemish in nature—if indeed it was a fault to be nonsymmetric—reveal itself? Physicists had previously discovered that the nuclear force is not one but two forces. The stronger of the two is responsible mainly for holding the nucleus together most of the time and, in the case of some unstable nuclei, for fission. The weaker of the two nuclear forces presides over radioactive nuclear decays, such as the transformation of neutrons into protons. The weak nuclear force, Yang and Lee figured, could make a distinction between left and right.
Dyson read the Yang-Lee paper. He read it twice, was intrigued, and talked with the authors. But even then, he claims, he did not have the imagination to see the implications of what Lee and Yang were saying.
And then it happened. A black swan turned up. An experiment displayed a small hint as to the secret signature of things. Experiments at the National Bureau of Standards involving the radioactivity of cobalt nuclei showed that parity was not sacred. Suddenly the study of the symmetries that scientists thought
were sacred was a hot topic. Dyson excitedly incorporated his thoughts into another Scientific American article, one devoted to the way theoretical physicists like himself absorb new observed facts into an updated framework.20
The discovery that the universe isn’t so supremely symmetric—nature seems to differentiate between left and right or back and forth or up and down—shows once again that science is provisional. “Rules” have to be removed from the roll of knowledge when they are shown to be incorrect. Like a compost heap, science needs to be turned over. The more turning it gets the more nourishing it becomes.
HIS OWN COLD WAR
Freeman Dyson was a professor at a premier institution of higher learning, an author of several important technical articles and numerous science popularizations in magazines. He was a much invited lecturer, and a candidate for the Nobel Prize.
He was also a husband, a brother, a son, and a father. A biography must be part bio and part graph. We’ve looked at the intellectual interests, the letters of recommendations, the research papers, and the nuclear politics that have shaped Dyson’s career so far. Now we must look at the home front.
We saw Dyson, in the spring of 1949, at the end of a long period of almost continuous intellectual exertion, his QED frenzy, suddenly letting his guard down and being smitten by Verena Huber. Like King Henry at the end of Shakespeare’s Henry V climbing out of the saddle after the Battle of Agincourt and, out of his element for the first time, awkwardly wooing the beautiful French princess, so Dyson, fresh from his single-minded battle with electrons and photons, now turned from chalkboards and departmental colloquia to court, in his fashion, the beautiful Dr. Huber. Freeman sent Verena letters filled with poetic quotation and with details from his daily life. He missed her terribly, he said, while they were apart. But he seldom seemed to respond to the things she said in her letters back to him. He didn’t tender the personalized endearments a lady wants to hear. It’s as if he were responding to a generic sweetheart.21
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