Freeman had accepted Verena’s extenuation—the existence of the older man in Europe. Would he also accommodate himself to her need for privacy and her need to continue mathematical research? And for her part, could she accept him as he was, the cerebral scientist absorbed in his work? She wasn’t sure she loved him. He was not so much shy as he was socially awkward. He was too stiff and trapped in his own ways, she thought, too legalistic, too economical. Should she marry Freeman? Katarina deserved a more stable home and badly needed a father.
Freeman pressed his case. His mind was made up. They simply must get married. And on August 11, 1950, they were. On this day Freeman Dyson, aged twenty-six, son of Sir George and Lady Dyson of 40 Albert Hall Mansions, London SW7, England, and Verena Haefeli-Huber, aged twenty-seven, daughter of the late Charles and Berthy Huber of Zurich, Switzerland, were married in Ann Arbor.16 The ceremony was conducted by a justice of the peace before only a few witnesses. Freeman had bought two bottles of wine and then didn’t bring them out.17 Leaving Katarina with some friends, groom and bride went on a two-day honeymoon in northern Michigan.
Taking advantage of Robert Oppenheimer’s open invitation to stop over at the Institute whenever he wanted and Rudolf Peierls’s liberal leave policy at Birmingham, Freeman and his family spent the fall of 1950 in Princeton, with Verena continuing to teach at Goucher College near Baltimore.
Freeman, eager to get married, was no less eager to become a father. So after only five weeks of marriage and with no palpable signs of pregnancy, Verena was dispatched to an obstetrician, not one in Princeton but in New York City. Nothing was happening, the doctor said, and sent her home. Verena spent a few hours in the Museum of Modern Art before getting in her car and driving back across New Jersey to Princeton. A month after that she was pregnant.18
Shortly after Christmas they went to Britain by ship. In London Verena met Sir George and Lady Dyson, who previously had not been particularly keen on their son marrying this woman. Then the new Dyson family took up residence in Birmingham. That winter Verena came down with pneumonia. Katarina was also ill a lot, and in general England’s dreariness drained their morale. The newlyweds concluded that this could not be their final home.
Dyson liked his Birmingham mentor. Like Dyson himself, Peierls was interested in a wide spectrum of physics problems. Paraphrasing a common sentiment, Peierls said that a specialist is a “person who learns more and more about less and less until he knows everything about nothing,” while a generalist “learns less and less about more and more until he knows nothing about everything.”19 Both men tended toward being generalists, although no one would say that Dyson and Peierls knew nothing about everything.
Despite his affection for Peierls, Dyson decided to leave Britain. He wanted to return to where the physics action was, in the United States. The chance for doing this had already arisen months before. When Richard Feynman announced that he would be leaving Cornell for a new post at the California Institute of Technology, Hans Bethe obtained permission to extend a faculty offer to Dyson. Only Dyson, Bethe argued, could fill the vacuum left by Feynman. With the understanding that Dyson had to wait out the two-year period before he could occupy a permanent post outside Britain, he accepted Cornell’s offer. Starting in the fall of 1951 he would return to Cornell as a professor.
Meanwhile, what was Dyson’s status at the University of Birmingham? He wasn’t quite a professor, although he was teaching classes. He certainly was not a student, although he was eligible for a doctorate, which he still lacked. But you can’t give such a famous person a mere Ph.D. His accomplishments far outweighed any dissertation he could have written. His several papers in Physical Review already exceeded in impact the lifetime work of most physicists.
They had a degree for people like that: doctor of science. But here too he was to be thwarted by having fallen afoul of residency rules. You had to have been physically at the university for a period of two years. And what with his summer in Ann Arbor and his semester at Princeton, Dyson had been of, but not entirely at, the University of Birmingham. Consequently, no degree. Sorry, no exceptions allowed. A year later he was a made a fellow of the Royal Society, at the age of twenty-eight. He was destined to receive two dozen honorary doctorates but never one of the ordinary kind. He was to remain Mr.
ZURICH
Dyson was uncommonly creative in choosing his summer retreats, especially when closing one chapter in his life and opening another. His farewell to Birmingham and his return to Cornell would in this case be marked by a three-month side trip to Zurich in 1951.
Here he worked with the pugnacious Wolfgang Pauli. One of the original boy physicists, Pauli had helped found quantum science in the 1920s. Among other ideas, he had contributed the notion that particles such as electrons and protons possessed a quality called “spin.” A particle with spin might not be literally twirling around, but you could imagine that they were twirling and this made them act as if they were little magnets. Through his self-appointed role as inspirer of good ideas or tormentor of scientists with bad ideas, Pauli helped cultivate fresh thinking. He enjoyed sitting in the front row of many a seminar, where he could skewer a speaker who, in Pauli’s opinion, was delivering half-baked opinions. His most notable insult: “That idea is so bad it’s not even wrong.”
That summer Pauli was alone, except for Dyson. The two of them took long walks into the hills and valleys and around town, stopping at coffee shops, eating ice cream.20 Pauli was in a cheerful mood, Dyson a somewhat dreary mood. Why? Because his momentum was stalling.
Dyson and the other scientists who had developed QED to tame the infinity lurking inside atoms had done what scientists often do—broken the problem down into smaller parts and then reassembled them into a compact solution. The “parts,” in this case, correspond to the various levels of complexity (each illustrated by its own Feynman picture) in that blizzard of virtual particles near each electron. It had been Dyson’s distinction to show that each part, by itself, added a sensible (non-infinite) amount to the electron’s properties. But was the whole sum sensible or infinitely large?
It sounds strange to say that quantum scientists were no longer particularly bothered by the idea of possible infinities. Now that they knew how infinity arose they could neutralize it by redefining the mass and charge of the electron.
For Dyson this wasn’t enough. As you reassembled more and more parts of the interaction he wanted the sum to converge to a finite number, not diverge to infinity. Dyson was pretty sure that the sum converged, but he had to prove it. We might call this hunch “Dyson’s conjecture,” perhaps the most important of many mathematical conjectures in his career, and he now gave it his fullest attention.
He wanted the theory not merely to be useful but to be elegant, to be consistent, and this meant convergence. Aesthetics was an issue here. In this, he was more mathematician than physicist, maybe even an artist. He was the true student of G. H. Hardy, who had said that mathematics was a kind of art.
Pauli felt that the convergence effort would fail. But Dyson kept on. What if he fell short of proof as he had done during his brief career as a mathematician? Would he leave physics? More work and more mountain walks with Pauli failed to deliver perfection. His recent efforts, published in a series of papers, had won few allies to the cause. This wasn’t at all like the Physical Review papers of 1949, the publications that had won him acclaim and an armful of job offers. Feynman and Schwinger, Dyson ruefully noted, had not attempted a convergence proof. They had gotten out of the QED business when they were ahead.21
Even Dyson could see it now. Pauli had been right; convergence could not be proved. Indeed, he recognized that the grand sum actually diverged. This finding itself had to be declared in the form of a scientific paper.22 Dyson’s un-epiphany came to him on one of those walks into the hills outside Zurich, this time without Pauli. It was time to change course. Dyson had indeed fallen short, but he would not go so far as to leave physics. His frustration at not bringin
g closure to the subject of quantum electrodynamics did make him resolve, however, never again to commit himself with such intellectual force to a single research topic. His dogged pursuit of infinity had led him, this time anyway, into a wilderness. He had explored with great energy and courage and persistence, only to see the trail go cold or, as he put it, “see the river dwindle and disappear into the sand.”23 It was over, and in a way it was a relief. He didn’t have to go further.24
He had spent four years, from the start of his student studies with Bethe (1947) up to this summer with Pauli (1951), on this issue of QED. According to Dyson’s friend Silvan Schweber, a physicist who would later write a comprehensive history of QED, Dyson arrived at a decision: “Thereafter he never invested the same amount of energy and commitment into any fundamental physics program.”25
It’s as if Dyson were an imperial power that finding itself overextended in distant colonies, began a sad, slow withdrawal from its unsustainable position. The chief promoter, if not originator, of QED, Dyson would now intellectually draw back his unachievable ambition of making QED converge. His retreat was a like a miniature version of the rollback of the British Empire depicted in Rudyard Kipling’s poem “Recessional,” a word usually referring to the trim ceremony marking the end of a church service as the congregants exit from the space:
Far-called, our navies melt away—
On dune and headland sinks the fire—
Lo, all our pomp of yesterday
Is one with Nineveh and Tyre!
That is not to say that Dyson’s work was a failure. Far from it. Let’s break chronological order and leap forward fifty years and see how well QED is performing. During this span of time experimental and theoretical techniques both have improved dramatically. By the year 2006 the measured and predicted values of the electron’s magnetic moment agreed at the level of better than one part per trillion. What does that mean? Well, it means that theorists at their blackboards, or now at their computers, can compute the strength of the electron’s magnetism with terrific specificity. Then an experimenter, with no less finesse, actually measures the electron’s magnetism. Then the two numbers are compared. They differ only after many decimal places.
This is the current state of the art—or we should say state of the science—of human ingenuity in explaining nature, at least in terms of preponderance of numerical expressiveness. The agreement of these two numbers out to so many decimals doesn’t necessarily signify perfect wisdom, much less “truth,” but it does signify high knowledge. And it doesn’t matter whether the predictions or measurements are performed in Tokyo or Cambridge or Jakarta. In a letter from Dyson congratulating the experimenters on those QED measurements in 2006, Dyson expressed his pleased surprise:
We thought of QED in 1949 as a jerry-built structure. We didn’t expect it to last more than 10 years before a more solidly built theory replaced it. But the ramshackle structure still stands. The revealing discrepancies we hoped for have not yet appeared. I’m amazed at how precisely Nature dances to the tune we scribbled so carelessly 57 years ago, and at how the experimenters and theorists can measure and calculate her dance to a part in a trillion.26
HIEROGLYPHICS
A perfection of sorts was achieved on July 14, 1951, when Mrs. and Mr. Dyson became the parents of a baby daughter, Esther. Freeman’s parents—his mother now, finally, a grandmother—came over from London for the christening ceremony. Owing to legal complications in the jurisdiction of Zurich, the newborn Swiss miss did not immediately qualify for citizenship. Verena, born in Italy and raised in Greece, did have a Swiss passport because of her parents’ nationality. But Verena’s citizenship was now trumped by her marriage to Freeman, a British citizen just then about to relocate back to the United States. To make matters worse, Verena’s divorce from Hans Haefeli was not being recognized. Officially lovely little Esther was a bastard.
This became a problem two months later. Freeman had left for America in order to obtain accommodations for the family in Ithaca. Meanwhile, Verena, Katarina, baby Esther, and a nurse boarded a train from Zurich for Genoa, intending to catch a ship there to the United States. At the Swiss-Italian border, however, Esther’s lack of papers snagged their movement. The train, with Katarina and the nurse aboard, continued into Italy, while Verena and the infant remained at the border guard station.
Several phone calls and levied fees later, mother and daughter were allowed to proceed. With only a few hours to spare Verena arrived in Genoa for the sailing. They crossed the ocean and arrived safely in Ithaca. The Dyson family goods were not so lucky. A strike by dockworkers in New York meant that the luggage on the ship was sent back to Italy. For the first months of their life at Cornell, the Dysons ate from borrowed plates.27
Eventually the dishes caught up with them, and their home was complete. In the fall of 1951 Freeman was a professor, Verena a math instructor, Katarina (now six) enrolled in school, and Esther was getting teeth.
Continuing the habit established long before by Hans Bethe, students and professors lunched together, crossing the street from the Nuclear Institute to the Home Economics cafeteria. The Journal Club, meeting every Friday at 3:30, would examine the contents of recent physics articles or scrutinize an article written by some nervous student who would then have to account for his work. Bethe, Robert Wilson, and Philip Morrison gave parties to which professors and students were invited. The Dysons would often appear.
Freeman was not just back in Ithaca, but welcomed and needed. He inherited a franchise at Cornell University. The academic course on quantum science, formerly in the hands of Hans Bethe and Richard Feynman, would now be taught by Freeman Dyson. The lucky Cornell students now received the freshest tutelage from the most in demand expositor of quantum reality. Two precocious undergraduates showed up for this course meant for graduate students. Steven Weinberg and Sheldon Glashow would both win the Nobel Prize decades later for helping link QED with a description of the weak nuclear force. But Dyson’s course was a bit too advanced for them and so they stopped coming.28
Dyson was a good teacher. He really wanted his students to understand. Notes from his lectures were gathered into the form of a rudimentary textbook on quantum science, which quickly circulated around to other physics departments. The notes, along with the twin 1949 papers in Physical Review, constituted a QED Bible.29 One book company, Wiley, offered to publish it as a textbook, but Dyson didn’t follow through until decades later.30
Accounts of Dyson as a scholar and as a man often stress his generosity, his good manners, his desire to explain. Despite his correct clothing, nearly always including a necktie, he did not conform to the stereotype of the reserved Englishman. He did not stand on ceremony. One graduate student, emigrating from India and arriving at the Ithaca train station, was stunned to find Professor Dyson, the famous physicist, waiting for him.31 The student must have been thinking of the classic German model of the imposing Herr Professor. Dyson wasn’t this.
He was not a typical scientist either in being content to write up his results and sending them off to the technical journal for fellow experts to appreciate. His first chance to reach a wider audience came with an article about QED in the pages of Physics Today magazine. He began with an inscription drawn from a letter written in 1857 by the nonmathematical Michael Faraday to the very mathematical James Clerk Maxwell:
There is one thing I would be glad to ask you. When a mathematician engaged in investigating physical actions and results has arrived at his conclusions, may they not be expressed in common language as fully, clearly, and definitely as in mathematical formulae? If so, would it not be a great boon to such as I to express them so?—translating them out of their hieroglyphics, that we might also work upon them by experiment.32
In his own article Dyson took Faraday’s advice. He converted hieroglyphics into prose. He proudly declared QED to be “the only part of our science which has been completely reduced to a set of precise equations. It is the only field in which we
could choose a hypothetical experiment and predict the result to five places of decimals.” That didn’t mean science was done. Physics is not the whole of science. QED isn’t the whole of physics. It describes only things governed by the electromagnetic force. Other precincts of the universe came under the influence of other forces, such as the nuclear force and gravity.
We have seen how Dyson, striving to crystallize his ideas about electrons and light, compared his work as a scientist to a novelist creating stories and characters. Others have felt this way too. The mathematician and writer Jacob Bronowski argued that science and art were equally creative. Both required imagination. Playful activity was a large part of being an artist or a scientist.
As for the appreciation of art and science, things were not as equal. Reading a poem, Bronowski said, involved the reader in an active process of appraisal. Beauty, manifested in art, is in the eye of the beholder. You have partially to create, or at least re-create, the poem for yourself in the act of reading, in order to derive the greatest pleasure. This isn’t as easy to do with physics. Physics is not as readily in the eye of the unprepared beholder. Bronowski felt that if people find science dull, it’s because they find it difficult to participate in the creative side of science.33
Dyson began to do his part to mitigate the apparently nonparticipatory veneer of science. He sought to expand the circumference of appreciation for science. He wrote a succession of articles for Scientific American, a magazine with a large popular readership.34 The articles reported the latest findings from the shifting forefront of physics research in the 1950s and early 1960s. All that training in Latin rhetoric at Winchester, all those schoolboy essays demanded at a weekly clip, all the poems he encountered in chemistry class (of all places) now paid off. His writing was quotable: “A physicist builds theories with mathematical materials because the mathematics enables him to imagine more than he can clearly think.”35 His Scientific American pieces sparkled with analogies and historical comparisons. They showed how scientists, like explorers of coasts and forests, were bringing more territory onto their maps.
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