My Life as a Quant (9 page)

Feynman's diagrams and rules were a sort of bookkeeping-by-picture process that miraculously captured all the details of the standard model in a series of diagrams; they allowed people less talented than Feynman to perform the most complex calculations carefully and correctly. Many of the great advances in physics are like this; they codify and make routine what was formerly almost impossible to think about. Whenever I have a new problem to work on—in physics or options theory—the first major struggle is to gain some intuition about how to proceed; the second struggle is to transform this intuition into something more formulaic, a set of rules anyone can follow, rules that no longer require the original insight itself. In this way, one person's breakthrough becomes everybody's possession.

After several months I completed the calculations for electrons scattering off quarks. But in the real world electrons scatter off protons—that is, bags of quarks. My next task was therefore to calculate what happened when an electron hit a bag. I embarked on extensive numerical computations using old-fashioned, punched card programs that I submitted to the university computer center to run overnight on their IBM mainframe. It was tedious: In those days we had no interactive terminals or PCs; one typographical mistake in punching the cards could lose you a full day's work.

It was then that I learned never to trust any new formula I had derived without thoroughly cross-checking it for consistency from all angles. Usually, anything new and complex is an extension of some older, simpler, and more familiar calculation. The first check is therefore to switch off the complexity and verify that you obtain the familiar results. I found it so easy to make mistakes in my calculations that I began to wonder about the safety of flying—how could engineers possibly trust their calculations when they designed airplanes, where life and death rather than theories and reputations were at stake?

It took me seven years in graduate school to get my PhD, an astonishing ten percent of a lifetime. There were three preparatory years of coursework, one subsequent warm-up year in the area of my research, and two more years of my actual thesis research. Finally, I spent a half-year writing the thesis, composing a paper for publication, and preparing for my thesis defense. A small number of my friends got out of Columbia in five years, but many took eight or nine.

Sometimes we tried to save others from our fate. In the early 1970s Doug Hofstadter came by our office in Pupin. He was still unknown, a PhD student in physics at Eugene, Oregon, and not yet the famous author of
Gödel, Escher, Bach
. It took some time before I realized that he was the son of my cousin's friend Robert Hofstadter of electron-proton scattering fame. Doug was contemplating a switch to Columbia from the University of Oregon where he was in graduate school. Though it felt deliciously like biting the hand that fed us, we tried to warn him away from Pupin.

Most of us grew to hate our stay in the physics department. We spent the better part of our twenties shuttered there. For the most part we were ignored, receiving little attention from the people to whom we were apprenticed. My friend Chang-Li Yiu spent more than six months working on a thesis problem without conversing with his advisor, only to discover that his advisor had solved the same problem a few months earlier. Then he had to begin again. Though I was better off—Norman Christ was responsible and I met with him weekly—I often thought I might never complete my degree. You could coast from year to year, receiving your Department of Energy research grant, while no one seemed to care when or whether you finished, or what you would do afterwards.

In defiance, I struggled to look unbeaten during the final few years. I remember walking hand-in-hand with my wife down Broadway and passing a crowd of Columbia professors strolling up Broadway on the way back from lunch at the Moon Palace. As our paths crossed, I tried hard to look nonchalantly happy and carefree, talking animatedly, pretending to myself and to the professors passing by that they had no effect on the other parts of my life.

But of course they did. One summer in the early seventies, during the student protests against the American invasion of Cambodia, Eva and I went camping in the Catskills mountains with Chang-Li and his wife. After several days in a tent, cut off from any news, we went to meet my in-laws who were vacationing in a nearby hotel. As we arrived, my father-in-law somberly announced to us that a small bomb had exploded in one of the physics department's bathrooms. Without a moment's hesitation Chang-Li and I leapt in the air for joy, whooping and cheering. My in-laws looked at us in bewilderment, and I suddenly realized how far beyond the elastic limit we had been stretched.

I had waited four years to begin my thesis work, but once I knew enough to get going, I progressed steadily. Halfway through the research I gave a seminar on some of my early results to T. D. and the rest of the departmental faculty. In early 1972 I finally published my first paper, in which I used Feynman's parton model to try to explain the results of a recent Columbia experiment carried out by Leon Lederman and collaborators. My calculation was simply a warm-up exercise for the thesis work to come, but its publication and the sight of my name in print after so many years of waiting exhilarated me briefly. I completed my thesis research by late 1972 and, at long last, in the spring of 1973, formally defended my work in front of a committee consisting of T. D. himself, Christ, and Lederman. I answered their questions and then I was done.

My thesis,
Tests for a Weak Neutral Current in l
 
±
+
N
→
l
 
±
+
Anything
, was published in 1973 in the
Physical Review
. It was a competent piece of work that analyzed how the then-unverified standard model of weak and electromagnetic forces would uniquely manifest itself through parity violation in electron-proton scattering. In 1978, a collaboration led by Charles Prescott and Richard Taylor at SLAC published the results of an elegant and careful experiment that confirmed a level of parity violation consistent with the standard model. A recent book on the history of twentieth-century particle physics
1
refers to the audience's prolonged applause after Prescott's first presentation of their experimental results as “the long elegiac salute given to the end of an age.” Their experiment put the final stamp of approval on the standard model of Glashow, Weinberg, and Salam. I was pleased to note that my 1973 paper was one of the first papers they referenced.

Despite the amount of time it took to finish my thesis, I have no real regrets; in a way, I am proud of the struggle. What I learned in those years—perseverance as much as mathematics—has stood me in good stead on Wall Street as well as in academia. When trying to discover something new in any field, one has to spend many years thinking, making false starts, wandering down blind alleys and stumbling into ditches, only to emerge again and keep going. For this, a PhD is a good, if painful, training.

Years later on Wall Street I was horrified to notice quant résumés listing the nonexistent degree A.B.D. That, I soon discovered, was a common business-world acronym for “All But Dissertation,” a way of describing those who had tried to obtain a PhD but left academia before they had completed their dissertation. Since a PhD is by definition a research degree, the main achievement of which is the completion of a piece of original research described in a dissertation, I looked at A.B.D. as a kind of “Wayne's World” PhD (not!). I resented the way it devalued the innovation and effort involved in doing research.

I then began the search for a postdoctoral position, a two-year, low-paying research appointment that was the standard first step towards an academic career in science. I mailed out scores of letters with my
curriculum vitae
to physicists whose names I knew. I gave research seminars at any of the schools that invited me. But academic jobs were scarce—the universities were filled to the brim with young, tenured faculty hired during the past decade; I might well have to wait for a generation of physicists to die.

As in most endeavors, it helps to have someone pulling for you. At Goldman Sachs, people like to say that you need a “rabbi” to become a partner, and the Columbia physics department was definitely short on rabbis. In the end, because my work was topical and I was lucky, I received a two-year postdoctoral position at the University of Pennsylvania in Philadelphia, set to commence in September 1973.

I did not attend Columbia's May graduation, held outdoors on the giant plaza in front of Low Library where only a few years earlier I had watched New York City policemen chase students with truncheons during the nights of the 1968 student occupation. None of my graduate school friends seemed to bother with the ceremony either.

I spent one month that summer in Erice, a beautiful town high above Trapani in western Sicily, where I attended the annual Ettore Majorana particle physics summer school. Up on the mountain I had a tantalizing glimpse of the life of successful physicists on the conference circuit, who visited exotic places each summer. I sat with some of them in the town plaza, smoking cigarettes and sipping Italian aperitifs. One morning I had a hot shave at the local barber shop, where I lay tilted back in a heavy leather chair while the barber sharpened his razor on a strop. Years later I met corporate lawyers and Wall Street salesmen who touted the fringe benefits of their jobs—first-class flights, expensive meals, and fancy hotels. I silently scorned their focus on the material benefits of work. In physics, I thought, the life itself was the benefit; talking about physics to interesting people in interesting places was the main dish, not the cutlery.

In Erice I observed with slight envy another attendee, Frank Wilczek. He had just graduated from Princeton and was already the coauthor of a famous paper in field theory. Yet a large part of me was exhausted with physics and the seven-year struggle to shine. I consoled myself with a few sentences Einstein wrote in his autobiographical notes, composed at the age of 67, about the aftereffects of his final examinations: “This coercion had such a deterring effect [upon me] that, after I had passed the final examination, I found the consideration of any scientific problems distasteful to me for an entire year.”

1
Crease, R. P., and C. C. Mann,
The Second Creation
, Rutgers University Press, Revised Edition (1996).

The priesthood of itinerant postdocs

Research isn't easy

Almost perishing, then publishing

The delirious thrill of collaboration and discovery

On Labor Day of 1973 I hired a friend of a friend who ran a small part-time moving business to transport me and my belongings to Philadelphia. In order to gain respect and imply responsibility, I had told my landlord that I was “Dr. Derman,” feeling only a slight twinge of guilt at exploiting my title and trying to pass for a “real” doctor. Our mover, who drove my wife and me down the turnpike from New York, told us that he routinely rolled back the odometer on the van he rented before returning it to Hertz, a common 1960s-style view of the legitimacy of stealing from large impersonal companies.

At the end of that weekend I began trying to settle into solitary Philadelphia while Eva returned to our familiar Columbia graduate-student apartment overlooking Tom's Restaurant at Broadway and 112th Street, a location later made famous beyond the Columbia community by Suzanne Vega and the television show “Seinfeld.” Eva still had several years to go on her PhD in molecular biology. I had hoped she could move to Philadelphia with me, but it was impossible for her to change schools and PhD advisors. She had only recently switched from physics to biology, and as a condition of entry into the biology PhD program, she had needed to promise that she would complete her doctorate in the department. In making the move to biology she had asked for a recommendation from Madame Wu, who herself lived in Morningside Heights near Columbia, 50 miles apart from
her
physicist husband at Brookhaven National Laboratories. Madame Wu had met with Eva and lectured her on the need for sacrifice, making it plain that, since they knew she was married to me and that I would graduate before her, she would not be admitted to the biology doctoral program unless she gave her word that she would stay on there when I graduated. In an era when no one had yet invented the notion of political correctness, it was quite permissible for faculty to gauge a woman's seriousness before admitting her to graduate school. A few years later, when I went to work in industry, we heard stories of interviewers in business who asked women whether they would have an abortion if they unintentionally became pregnant and thought that childbearing would interfere with their work.

For the next two years Eva and I saw each other only on weekends and during parts of the summer. The tension of living like this was to be a perennial feature of my future years in academia.

I had imagined postdoctoral life as a sort of priesthood, the blissful apotheosis of a life dedicated to knowledge. In top-notch universities, a postdoc in theoretical physics had no mundane obligations—no teaching, no administration, no fixed hours. What remained was transcendental. You were hired for your research talent. All you had to do was find something conceptually worthwhile that interested you and then work on it. All that mattered was what you achieved. It was simple, but the stakes were high. No one I knew thought much about getting rich or about what they would earn. Everyone hoped to achieve something numinously great and was willing to work an entire lifetime at it. We looked down on professors who ceased “doing physics” once they achieved tenure. As we got older, we took solace in the stories of people who made great discoveries after the age of thirty. It was very different from Wall Street, where I heard twenty-something traders talk about “their number,” the amount of money they figured they needed to be able to quit, certain that they would never have to work again.