My Life as a Quant (11 page)

The exact nature of the hypothetical weak force responsible for the decay of the putative heavy lepton was not known—it had to be conjectured, and there were a variety of forms it could reasonably take. Lay Nam, John, and I calculated the relative speeds of the muons for a wide (but not exhaustive) range of forces. We showed that for all the cases we considered, the predicted disparity between the speeds of the positive and negative muon, when both were produced by the decay of a heavy lepton, was much smaller than the disparity observed by Mann and his collaborators. Therefore, we claimed, it was highly unlikely that the dimuon events signaled the production of a new heavy neutral lepton.

We circulated our work as a “preprint,” a mimeographed prepublication report sent out to other physicists in the field, and it drew a gratifying spurt of attention. Now, almost down to the wire, I had completed a piece of research that would get me my next postdoc position, just as my two-year stint at Penn trailed off into its last few months. I sent out my letters of application and, late in the spring of 1975, in the nick of time, I received postdoctoral offers from the University of Wisconsin at Madison and from Oxford University in England. Eva, who still needed one more year in New York to complete her PhD was obliged to stay at Columbia. If I was going to spend one more year on my own, I preferred European Oxford rather than ur-American Madison. I had had enough of empty-streeted Philadelphia.

The work we did on heavy leptons was topical and timely, but not quite thorough enough. Though we had shown that it was
unlikely
that a heavy lepton had produced the dimuons, we had not proved it truly impossible—we had not calculated the asymmetry for every possible form of the hypothetical weak force that caused its decay. A few months later, Bram Pais (one of the few Columbia seminar speakers I had seen stand up to T. D. Lee) and his long-time collaborator, Sam Treiman of Princeton, entered the scene. Both of them old hands at analyzing weak interactions, they derived a very general upper bound to the asymmetry between the speeds of the positive and negative muons produced in the decay of a heavy lepton, no matter what the form of its still unknown weak force. They showed that the maximum value of the asymmetry under any circumstances was smaller than the one observed by Mann and his collaborators, and so truly excluded heavy leptons as a source of the dimuons. What we had shown to be unlikely Pais and Treiman had then demonstrated to be impossible. More experienced and professional than Lay Nam, John, and me, they received the lion's share of the credit, but we got a little, too; it was more than enough to get me that second postdoc offer from Oxford.

I was through with Philadelphia, although I had survived and eventually prospered. I spent one month that summer in Cape Town visiting my mother, and another month at a theoretical physics summer institute at SLAC, where I renewed my acquaintance with Doug Hofstadter, now living at home with his family. He invited me to their house on campus, where I finally met his father Robert and his electron-scattering colleague Robert Herman, the two ex-City College physicists my cousin had told me so much about during my first years in New York.

As I prepared to leave for England, once again invigorated by physics but now slightly fearful of moving to a new country on my own until Eva could eventually join me, I looked back at my nine years in America.

Physics was filled with so many extraordinary talents, old gods from the past as well as budding stars preparing to dominate the future. In those first few years, I saw and sometimes met many of them.

At Columbia, I had taken classes in statistical mechanics from T. D. Lee. I had listened to his many seminars and discussed my thesis with him. I had taught problem sessions in electromagnetic theory for Polykarp Kusch, watching him on campus in his late fifties as he bent over stiffly to play with his small son from a second marriage. I had drunk coffee and eaten cookies at countless departmental coffee hours in the company of Leon Lederman, Jack Steinberger, and Jim Cronin, all future Nobel Prize–winners then on the Columbia faculty. I had given lectures on my thesis work to theorists and experimentalists and had been questioned by many of them. I had heard colloquia delivered by the legendary Dirac and Heisenberg. I had heard Feynman, too, an enormously charismatic performer who spoke like a Brooklyn-born taxi driver, so much more casually charming than the Columbia faculty, and yet so aware of the charm he radiated. One Friday I listened to Edward Teller, the notorious cocreator of the hydrogen bomb and destroyer of Oppenheimer's reputation, as he lectured in the Columbia theatre while a crowd of antiwar protesters picketed him with posters and then silently walked out as he spoke. Later we flocked to watch a seminar on Uri Geller, the Israeli spoon bender, presented by two scientists from the Stanford Research Institute who were investigating his psychic skills. They were invited, of course, by Gary Feinberg.

At Penn, the physics department starred Bob Schrieffer, who had just won the Nobel Prize for his role in developing the theory of super-conductivity. His white gull-wing Mercedes, reportedly bought with Nobel Prize money, lent a glamorous touch to the physics parking lot, as did the glimpses of his elegant, Scandinavian-looking wife. In 1976 our department hosted the international Neutrino Conference in the Amish countryside of Pennsylvania, and I again heard Feynman lecture. Later I summoned the courage to join a conversation of his in the bathroom. Seminar speakers came to Penn from all over the country. One fall Victor Weisskopf, a hero from the early days of quantum theory and one of the leaders of the Manhattan Project, came down for a visit from MIT. Another week brought a seminar by Steven Weinberg, whose standard theory of weak and electromagnetic interactions was just beginning to be vindicated. Among the pile of résumés that flowed into the department from postdocs in search of jobs, I remember one from Alan Guth, then a relatively run-of-the-mill applicant but soon to become the inventor of the theory of the inflationary universe.

I was beginning to become very aware of my limitations. There were people you met in physics who were simply off any scale you could imagine. When I read classic papers by Einstein or Feynman, I realized that though I could understand and utilize their framework, I could never have created it. My wife, having left physics for biology, knew something about both areas, and said that even the smartest biologists didn't leave you feeling that they were out of your league. Physics was different.

I have a friend who liked to point out the obviousness of various great discoveries in physics and finance. The obviousness is a delusion. Many things seem clear only once they have been taught to you in a historical context, with all the prejudices, confusion, and competing theories omitted. Every iota of discovery, in finance or theoretical physics, comes at the cost of long immersion, hard labor, and struggle. “Improvement makes straight roads, but the crooked roads without improvement are the roads of genius,” wrote the English Romantic poet William Blake. Most of us in physics were lucky to be improvers, and knew we could never negotiate the crooked roads at all, though we had occasional glimpses, during sudden epiphanies in our work, of what it might feel like to stumble onto one.

Although I now sensed my limitations, I was nevertheless happily astonished at the recent reversal of my fortune. Only a few months earlier I had been morose and ready to quit; now, with one successful bit of work behind me, I was again thrilled by the hunt and longed to figure out some puzzle no one had solved before. Ever since, through ups and downs, I have tried to remember that no matter how low you get, about work or life, you can take some solace from the fact that the future is unpredictable. Even in the midst of misery, unexpectedly good things can happen without warning.

1
My physicist friends and I spoke of what we did as “doing physics.” My wife's molecular biology colleagues, strangely, never spoke of “doing biology,” but rather of “doing science,” a broader name for what seemed to me an equally narrow field.

2
The European Center for Nuclear Research.

3
A sort of electron, with the same charge but about 200 times the mass.

4
An even heavier sort of electron, but neutral, that is, carrying no charge. There was no good reason why one should not exist, and so, according to Gell-Mann's totalitarian principle, it had to be there.

Oxford's civilized charms

One physics paper leads to another

English idiosyncrasies

The anthroposophists

From October 1975 to August 1977, I spent my days happily doing physics at Oxford. Once again, I arrived there alone; my wife arrived seven months later to begin her first postdoc. Once again, predictably, I found it difficult to be alone in a strange city, just as I had during my first few solitary weeks in New York nine years earlier; the same intense feelings recurred.

It didn't help that social life at Oxford revolved around the autonomous and distinct colleges that comprised the university, and I didn't belong to one. I had been hired directly by the Department of Theoretical Physics, which was housed in two old, single-family brownstones that had been joined together. The Anglo-Irish novelist Joyce Cary had lived in one of them before he died of amyotrophic lateral sclerosis, my mother's disease. While faculty colleagues went off to eat lunch or dinner with port and walnuts at their exclusive High Table at the head of the college dining hall and to then smoke their postprandial cigars, and while graduate students joked together at their much lower tables in the same dining halls, my uncollegial postdoc friends and I (Indians, Pakistanis, Cypriots, Australians, and a few Americans) sought out one of the few Indian restaurants in the nongown section of the city.

I felt naively proud to be at Oxford. Coming from Anglophile South Africa, I saw Oxford as the epitome of academic life. And doing physics when I got there was suddenly much easier; I had struggled through the valley of the shadow in my first year at Penn, but now I knew how to find suitable problems on which to work. I had learned how to complete a piece of research or, failing that, how to at least salvage something publishable and interesting. I learned to let one piece of work flow into the next. I finally knew how to treat research a little more like a business.

At Oxford I continued working on the theory of dimuon production. Heavy neutral leptons were dead, as my colleagues and I had suggested and as Pais and Treiman had proved. The dimuon events could instead signal the production and subsequent decay of a short-lived charmed quark, an equally interesting possibility. I set about calculating the distribution of dimuons that would correspond to the decay of newly produced charmed quarks. It was useful work, professionally done. I did more theoretical calculations, wrote more FORTRAN programs to compute dimuon distributions, documented the work, circulated the preprints I wrote to other physics departments, and published the papers. I still remember the excitement of working late into the night, hurrying to debug programs and then submit them to the computer center. I recall best the unspoiled joy of spontaneously waking early, tired but driven, and then rushing off to work because I
wanted
to go to work and couldn't sleep any more. I was excited to see what came next.

Meanwhile, back in Philadelphia, Lay Nam and John continued on their related but independent work. We had no email or ten-cent-per-minute telephone calls to link us. Collaboration across the Atlantic was cost-prohibitive and communication was viscous in those pre-Internet days. Not only did we think it unrealistic to telephone to discuss research, but even airmail postage and xeroxing were expensive. The Department of Theoretical Physics at Oxford, itself on a limited budget, restricted each of its postdocs to 40 free photocopies a month. After that we paid for copies of articles we wanted. Computation was more difficult, too. There were no PCs and no Matlab™ or Mathematica™ programs. I used to crosscheck my Monte Carlo computer programs, written in FORTRAN 66, by programming similar but simpler calculations for special cases on the latest Hewlett-Packard 25 programmable pocket calculator I had bought before I left New York.

I spent that whole year working on the phenomenology of charm production. It was a good life. I felt adult because I was earning a living, yet I was often fancy-free in the way that I imagined a life spent on acquiring knowledge should be. Eva finally arrived in early 1976 and we settled into the habits of Oxford. We saw exhibitions and art performances at the Oxford Museum of Modern Art, and took in old movies at the bitterly freezing Penultimate Picture Palace in working-class Cowley. Once I saw Iris Murdoch at a College garden party. Eva and I went for long walks on Port Meadow next to Jericho, where we lived, and drove to the Vale of the White Horse and the Cotswolds, where the skies could become menacingly grey in just a few minutes. We watched touring boats wait patiently for locks to slowly fill and empty in the nearby canals of the Thames. We took picnics with graduate students in punts on the Cherwell River in the late afternoon. The northern summer evenings were so long that I could first have supper and then still have time to go for a late barefoot run on the trimmed grass cricket fields and tennis courts that tiled the University Parks next to the Department of Theoretical Physics. I was invited to give seminars in Cambridge, London, and Paris. I attended another neutrino conference in Aachen, Germany, where at midsummer the western sky still continued to glow slightly as the eastern sky began to lighten. We drove down to London to visit friends on weekends; we went to Crete on vacation. It was idyllic.

I made one tactical mistake in my research. Though I had been hired by Chris Llewellyn Smith, a well-known theorist who later became the head of CERN, I worked alone most of the time that first year. When I completed my study of charmed quark production and decay, and was ready to write it up for publication, I thought I sensed a small unspoken expectation on Chris's part that we should write the paper jointly. Like the little red hen, I felt that I had done the work, and so I should publish it. In retrospect, I was wrong. He had hired me and I had benefited from his advice; there would have been nothing seriously amiss in working together on a joint paper. More to the point, it would have been good for my career. Chris was a much better known (and a better) physicist than I was, and with his name on the paper, it would have been more widely read and perhaps would have led to further collaboration. But my pride stood in the way. Later that year, when another physicist carried out a similar analysis and received broader attention, Chris pointed out to me that I would have been better off if I had written the article with him. He was right. Years later, working on financial models at Goldman Sachs, I became much less compulsive about such strict authorial cost accounting.