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Remembering Oppenheimer: The Teacher, The Man
By Edward Gerjuoy
Photo Credit: Los Alamos National LaboratoryJ. Robert Oppenheimer
Oppenheimer gave no final exams or any other tests. He did assign numerous homework problems, many of which were highly instructive and non-routine. He did not designate a textbook for any of his courses. If we students desired alternative or otherwise clarifying presentations, we had to locate them on our own.
His reluctance to designate textbooks was rational. In his electromagnetic theory course, for example, much of the material he presented was intended to serve as an introduction to the newly formulated, and still developing, quantum theory of radiation; such hyper-modern material simply could not be found in any of the then available electromagnetic theory textbooks.
Similarly at the time, barely a decade after Schrodinger's formulation of his wave equation, there weren't any English language texts for him to assign in his quantum mechanics course.
Each class hour was a lecture, delivered at high speed, accompanied by numerous equations written on the board at correspondingly high speed, along with rapidly performed, rarely erroneous calculations. The only way I possibly could grasp the material was to take hastily scribbled notes as he spoke. From these scribblings I would prepare more complete notes as soon as possible after the lecture, while it still was fresh in my mind. I am quite certain that every other serious student did the same. There were numerous occasions when several of us would argue at a blackboard about precisely what he had imparted. Each of Oppenheimer's courses required far more of my time, but taught me far more physics, than any of the other non-Oppenheimer courses I took in graduate school.
I have no memory of him ever initiating any sort of Socratic dialogue with the class, nor do I recall him pausing in any calculation to ask the class for suggestions on what to do next. If there was something a student didn't understand, said student could feel free to interrupt with a question. Oppenheimer would answer patiently unless the question was manifestly stupid; then his response was likely to be quite cutting. Unfortunately his patient answers often were not illuminating; Oppenheimer did not have the gift ofputting himself in a student's place and recognizing that what was evident to him might not be evident to the student. A student who persisted with questioning could expect to find himself on the receiving end of sarcasm. But Oppenheimer never bore any grudges against students who momentarily had taxed his patience.
Perhaps the most distinctive feature of his lectures was his chain smoking. When one cigarette burned down to a fragment, he extinguished it and lit another almost in a single motion. I still can see him in his characteristic blackboard pose, one hand grasping a piece of chalk, the other hand dangling a cigarette, and his head wreathed in a cloud of smoke.
Although his primary interest was research, he nevertheless took his classroom teaching duties very seriously. He deserves credit for his painstaking efforts to construct unhackneyed courses that would lead students into productive physics research as rapidly as their native talents would allow.
Even more vivid are my recollections stemming from my time in his group of PhD students. I joined in the spring of 1939. He didn't immediately give me a research problem; I had been at Berkeley less than two semesters. I just showed up at the weekly theoretical physics seminar he ran. Although Oppenheimer could be fearsome, he did not put on airs. He didn't mind being called Oppie, and I have done so ever since.
Quantum mechanics was developed in Europe and remained essentially arcane until 1926, when Schr”dinger's formulation of his famous equation made quantum theoretical research accessible to non- geniuses like myself.
Oppie was one of the very few American theoretical physicists who was both lucky enough to have learned quantum mechanics in Europe right around 1926, and talented enough to usably bring this learning back to the United States.
He received his PhD in 1927 from the University of Göttingen, having studied with Max Born; he joined the Berkeley physics department only two years later.
In the years between 1929 and 1935, before so many great European physicists fled Hitler and began to establish their own modern theoretical physics research groups in this country, students who wanted to do research at the forefront of theoretical physics without going abroad enrolled in the Berkeley physics department to work with Oppie, because there really were very few other professors in the US actively engaged in such research.
Oppie was tall and absurdly thin. He rarely was motionless; if nothing else he would be puffing on his cigarette or waving it around as he talked. He was well educated and well read; we all have heard of his ability to quote from the original Sanskrit. His face was mobile; how he was reacting was no secret. When I knew him he was between 35 and 40, and doubtless still at the peak of his physical and mental powers.
His relations with his students were surprisingly informal. He allowed his students to drop into his office at any time to consult physics books in his personal library. His office was deep, moderately wide, and quite bare, except for the bookshelves and a blackboard running the length of the room. He did not have regular office hours. He could be moody; if I found him alone, his demeanor instantly made it apparent whether or not I should dare speak to him. But if he was willing to talk, there was no need for an appointment. Assuming one did catch him willing to be disturbed, this didn't mean that a graduate student would toss physics questions at him without forethought. His reaction to a question he deemed stupid tended to be very caustic; one was likely to depart his company quite depressed.
The seminar was Oppie's domain, his fiefdom. He selected the speakers; except on rare occasions he totally dominated its proceedings. In complete contrast to his classroom practices, Oppie almost never allowed himself to be the seminar speaker. He preferred instead to sit in the front row and interrupt the speaker with questions. Unless he formally had scheduled a speaker from outside his group, Oppie's first choice for speaker always was whomever prominent theoretical physicist momentarily happened to be visiting the Berkeley physics department; a scheduled talk by any member of Oppie's group obviously could be and would be postponed.
In those years the Berkeley cyclotron was one of the seven physics wonders of the world. Famous physicists flocked to Berkeley from all corners of the globe. Enrico Fermi gave an extended series of lectures in 1940, and Wolfgang Pauli visited in 1941. Oppie managed to convince such visiting theorists to speak in his seminar. We were able to hear about research at the forefront of theoretical physics right from the horse's mouth.
Mostly, students would speak on research they had completed and were about to write up; occasionally Oppie would assign someone to talk on a published paper he thought worth discussing. When student speakers in such categories could not be mustered, the duty of speaking would fall back on Oppie's research associate. It was Oppie's practice each year to assign his research associate a broad subject, almost the equivalent of a course, which said associate would speak on in a continuing fashion whenever no other speakers were available.
Tossing questions at the speaker was Oppie's preferred seminar role with visiting and homegrown speakers alike. If a question was not answered to Oppie's satisfaction he would furnish his own answer, and he was not averse to brushing the speaker aside and going up to the blackboard if he felt the occasion warranted the intrusion.
Unfortunately, his answers often did not always clarify the issues at hand. I well remember the many occasions when, after one of Oppie's answers, the cry "But Oppenheimer!" uttered in a German accent, welled up from Stanford Professor Felix Bloch who approximately once a month drove to the seminar from Palo Alto. We students reveled in Bloch's discom-fiture and were fond of saying that Bloch was Oppie's most advanced student. It was not until after the war that I realized Bloch was a distinguished physicist; he won a Nobel Prize in 1952.
Oppie's seminar performances avoided disconcerting any of his visiting speakers; he was a polite man. But with his students, his questioning was fierce, often cruelly so.
I do not believe Oppie was in any way sadistic; he legitimately could be termed kindhearted. And I feel confident that the questions Oppie put to his student speakers were designed not to embarrass but to elucidate, more often for the benefit of the audience than for himself. I wouldn't be surprised if Oppie's persistent questioning was nothing more than an automatic attempt to remedy the discomfort he clearly felt when hearing any theoretical physics statements he thought wrong or even imprecise; it could have been like scratching an itch.
Sadly, Oppie lacked the empathy that would cause him to draw back, once his previous questions had reshaped the student speaker into a quivering hulk incapable of profiting from, much less answering, any further questions.
Nor, when Oppie's research associate Leonard Schiff gave a seminar, did Oppie treat Leonard any more kindly than he treated his student speakers. On more than a few occasions Oppie had Schiff visibly on the verge of tears. As with Bloch, Oppie's treatment of Schiff left his students with no real appreciation of Schiff's talents. Certainly we would not have predicted that Schiff would have a distinguished career.
I cannot refrain from contrasting Oppie's treatment of Schiff with his treatment of Julian Schwinger, who in 1940 replaced Schiff as Oppie's research associate. We were eagerly anticipating Julian's first seminar. But whereas the other students were wondering how long it would take Julian to shrivel under Oppie's questioning, I was wondering how Oppie would react to Julian's refusal to shrivel. I had been exposed to Julian's talents during my undergraduate years at City College in New York.
Julian's first seminar went exactly as I expected. Julian started talking and very soon Oppie asked Julian a question, which Julian answered. Another question followed, and Julian answered. More questions came; more questions were answered. After about a dozen questions, answered by Julian with no visible sign of distress whatsoever, Oppie stopped firing questions and let him finish his seminar without further interruption. Nor did he ever again unduly interrupt during any succeeding seminar of Julian's. Oppie stopped asking questions because it became apparent that Julian always knew what he was talking about and would sufficiently discuss any subtleties inherent in his seminar subject without having to be prodded.
With the bulk of his students, Oppie was closely involved with their PhD researches. He was interested in many of the problems they were working on, and in not a few instances himself worked on the problems alongside his students. Even if he wasn't terribly interested in the outcomes of some of those researches, the problems all were nontrivial and fully involved modern physics; any student who completed one of those assigned research problems was transformed thereby, into a significantly more competent theoretical physicist than when he had begun the work.
Of course, I would expect that in discussing their mentors my words would be echoed by the students of any of our great modern theoretical physicists, e.g., by Oppie himself as a Max Born student.
Oppie did his physics, talked about his physics, lived his physics, with a rarely duplicated passion, which had to inspire his students; he certainly inspired me.
Despite his sometimes overly ferocious questioning, despite the sarcasms that Oppie really should have suppressed, we his students respected him and felt indebted to him; knowing that Oppie so obviously passionately loved doing physics, that he so obviously always had physics in the forefront of his mind, helped us believe that becoming a competent theoretical physicist was worth the fairly enormous effort required, especially in those prewar economically depressed days when the word physics had no popular resonance and jobs for theorists were very hard to come by. And, for imbuing me with this belief, I respect and feel indebted to him still.
Edward Gerjuoy is professor of physics emeritus at the University of Pittsburgh. This article is adapted from a talk presented at a Los Alamos symposium on "Oppenheimer and the Manhattan Project", June 26, 2004.
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