IN THE LATE FALL of 1955,my second year as a Ph. D. student at Trinity College, our student supervisor, James Hamilton, announced that Wolfgang Pauli would be visiting Cambridge for a couple of days. With Pauli’s rude behaviour at the Bern conference still fresh in my mind, I reacted to this announcement with a mixture of excitement and dread.
On the morning of Pauli’s arrival, I hurriedly washed up the breakfast dishes, left my room earlier than usual and walked quickly over to the Arts School, checking in at the local Barclays Bank on my way, to see how overdrawn my account was. I was excited about Pauli’s visit because he had been working recently on the same problem that had been occupying me, and I was hoping to get some insights from him, although I doubted that he would be interested in the opinions of a second-year research student. This is where the dread entered: after having observed Pauli’s behaviour in Bern, I wondered what might go awry during his visit to Cambridge.
On reaching the main room on the second floor of the Arts School, I encountered our supervisor. James Hamilton was a senior lecturer at Cambridge who specialized in particle physics and had published a textbook on the subject. He was a tall, severe-looking Irishman with cold cornflower-blue eyes and a fine, regular-featured face with greying hair at the temples. Jim had served in the British army during the Burma campaign of the early 1940s, and suffered occasionally from bouts of malaria. He was known for his acerbic comments and authoritative manner, and was feared by most of the research students.
“Ah, Moffat,” he said, giving me his habitual icy-blue stare. “Our distinguished guest will be here shortly. I would like you to take Professor Pauli to lunch. Your colleague Ian McCarthy has agreed to go with you.”
This was a disturbing request, further complicating my feelings about his visit. Pauli was a winner of the Nobel Prize, awarded to him in 1945 for his discovery of the exclusion principle—postulating that two electrons could not occupy the same quantum state simultaneously in an atom—which played a fundamental role in the development of quantum mechanics and atomic physics. He had also been instrumental in developing quantum field theory in collaboration with Werner Heisenberg and Victor Weisskopf. How could Hamilton expect two research students to take the great Pauli to lunch? “Sir, perhaps a senior member of the department should have this honour,” I suggested.
Hamilton straightened up and smoothed back his hair with a nervous thrust of his hand. He cleared his throat. “Nobody is available to take him to lunch today, so you’ll have to make the best of it. Are you refusing to do this?”
I felt the tension rising. “No, sir, I’ll go with Ian,” I said. “If he’s agreed to do this, well, then I’m ready to help him.”
Hamilton shoved his hand in his pocket and drew out a ten-pound note. “This should cover the lunch, but be sure to get a copy of the bill and give me back any money left over.”
“Yes, sir.”
“Pauli will be here at about noon, so wait here for Ian McCarthy,” Hamilton said. “Pauli was told to come to the Arts School.”
With this command, Hamilton left. I heard him walk heavily down the stairs and slam the door as he exited the Arts School.
Ian arrived about thirty minutes later, grinned at me and said in his broad Australian accent, “Well, John, I hear we’re taking the great man to lunch.”
“The two of us taking Pauli to lunch!” I exclaimed. “What about Dirac or Hamilton himself, or one of the other senior people?” I stuck my hands in my pockets and said, “Hamilton gave me ten pounds to pay for lunch. I hope that’s enough. I’m overdrawn in my bank account.”
“So am I,” Ian said, and his grin broadened.
Ian was studying nuclear physics. He was from Adelaide, Australia, and was a year ahead of me in his Ph. D. research. I had come to know Ian well thanks to an old sports car I had bought, a red Singer Le Mans two-seater that had supposedly raced in the famous French Le Mans car race in 1932. I had swapped it for my BSA motorcycle and a few pounds. I had never driven a car before, and eventually this one would cause me a lot of heartache and expense. On the day it was delivered, I unwisely started it up and put it into first gear. The little red car promptly raced down a hill and crashed into a fence. Fortunately, my foot managed to find the brake pedal in time, and the front bumper was only scraped.
When I told Ian about this incident the next day, he laughed and offered to help me out with my new red sports car. He taught me how to drive the wretched car;we could often be seen roaring around Cambridge with me trying desperately to change gears by a double-declutch maneuvre, since the cars of the early 1930s did not have a modern clutch system. Through the driving lessons, Ian and I became close friends. He often invited me home to his flat to have dinner with him and his wife, who was also from Adelaide.
The red car had recently come to a bad end. One morning when I was driving to town, the crankshaft shot its way through the engine like a torpedo, and the car came to an abrupt halt. I shot out over the open windshield, but fortunately wasn’t seriously hurt. I could not afford to repair this damage, and that was the end of the little red sports car.
Ian and I waited for Pauli in a room on the second floor of the Arts School where the theoretical physics research students met to talk about cricket matches, arrange tennis games and, occasionally, discuss physics. At one o’clock there was a sudden loud banging on the door. I jumped up and opened it, to face the familiar short, obese figure of Pauli in a wrinkled dark suit and a tie that looked twisted out of shape. Pauli stared at me with his protruding brown eyes and said, “Guten Tag! Are you the student who takes me to lunch?” Obviously he had no memory of me from the summer conference in Bern.
“Yes,” I answered nervously. “I’m John Moffat, and this is my colleague, Ian McCarthy. Dr. Hamilton asked us to take you to lunch and perhaps show you around Cambridge.”
He shook my extended hand vigorously and then marched into the room and shook hands with Ian. “Ach,well, let us go to lunch, I’m hungry,” he said peremptorily. “I do not wish to be shown around Cambridge. I have been here before and have seen the colleges and the town. Once is enough! Hamilton told me that you students will entertain me after lunch. In this room, I believe.”
This was the first I had heard of this event, so I swallowed hard and said, “Yes, Professor, we’ll bring you back here after lunch so that we can discuss physics.”
“Discuss physics!” Pauli said harshly. “You will speak to me about your research!”
“Yes, of course, Professor.”
Pauli followed us out into Benet Street with its narrow pavements, and we made our way to the King’s restaurant on King’s Parade. I had never been able to afford a meal there myself, but had often stared through the window when passing by at the dinner guests inside, enjoying a meal with wine. The maître d’ showed us to a table next to the window and gave us menus. Pauli did not open his, but glared at the waiter and commanded, “Waiter, bring red wine!”
Some time passed while Pauli sat muttering to himself, and we waited awkwardly for the wine to arrive. Pauli had a large head with thinning dark brown hair, a reddish complexion, and his fat neck was constricted by his shirt collar and the unruly tie. As I had noticed in Bern, he had a nervous tic that took the form of a nodding head. To avoid embarrassment, I stared out of the window at students and townspeople passing by in the fall sunlight. The waiter arrived with a bottle of red wine and displayed the label to Pauli. He grunted his assent and the waiter poured wine into his glass. He came round the table to pour wine into our glasses too, but Pauli exclaimed, “Nein! Nein! Put the wine here next to me.” The waiter looked uncomprehendingly at me, so I nodded my head in agreement, and he set the bottle on the table next to Pauli.
We ordered lunch, and while we waited for the food to arrive, Pauli drank more than half the bottle of wine. After the first course of soup, he finished the rest of the bottle with rapid gulps from his glass. He eyed me with an authoritative look. “Well, order another bottle, young man!”
“Yes, Professor,” I said with dismay as I tried to catch the eye of the waiter.
Another bottle of red wine arrived and Pauli told the waiter to give us a glass each, from which I understood that he intended to finish off the rest of the wine himself. I began to feel concerned about how the rest of the afternoon would unfold. I hoped that Hamilton was not going to accuse me of getting the professor intoxicated before the afternoon’s entertainment commenced. After we had finished eating and Pauli had drunk the rest of the second bottle of wine, he became noticeably more voluble. He turned his attention to Ian. “So, young man, where are you from?”
“Australia . . . Adelaide, I’m doing research in nuclear physics.”
“Ah, Australia!” Pauli exclaimed. “You must know H. S.Green. He works with Max Born in Edinburgh.”
“No, I don’t know him personally, but of course I’ve heard of him and his published work,” Ian replied.
Pauli exploded, saying in a loud voice, “He is a dumkopf ! An idiot, you understand.”
“Oh, I see,” Ian responded nervously.
I noticed that when Pauli spoke angrily, his head stopped nodding. “I have told Max to get rid of him, but he doesn’t listen to what I say these days. This work Green has done on para-statistics in field theory is utter nonsense! What do you have to say about that?” He glared at Ian. I was hoping that Pauli was not considering ordering yet another bottle of wine.
I could sense that Pauli was not going to let Ian off the hook easily. He fixed Ian with a steely-eyed gaze and said, “Are all of you Australian physicists stupid?”
Ian looked at Pauli, speechless. I could see that he was making every effort to control himself. Pauli went back to nodding his head, and stared morosely out the window at the view of King’s College that could just be glimpsed in the distance. I thought that it was best to make our way back to the Arts School, to cut off this harangue against Green and Australian physicists. But Pauli stopped nodding his huge head and said, “Now, Abdus Salam, he is here in Cambridge at St. John’s College, yes?” I nodded in agreement. “He is brilliant, you understand. He has a great future in physics.” He smiled. His face was flushed and his eyes looked somewhat unfocused.
I waved to the waiter and asked him to bring the bill. I paid, pleased that despite the two bottles of wine, the total was less than ten pounds. We left the restaurant and escorted Pauli back to the Arts School and whatever calamitous events awaited us there. As we turned into Benet Street, I took in the variegated scene of King’s Parade. Beyond the street lamps King’s Chapel rose towards the sky, its pinnacles dark grey against the cumulus clouds. Down at the other end of King’s Parade, the sandy-grey bulk of the Senate House jutted out and merged with the narrow beginning of Trinity Street. As we approached the iron gate of the Arts School, a crowd of students poured out, wearing their flowing black academic gowns. Their excited voices echoed in the small confines of the Arts School entrance. I suddenly felt a thrill of anticipation mingled with dread at the prospect of giving an unprepared talk to Wolfgang Pauli.
We returned to the research students’ room, which was long and narrow with dark oak-panelled walls and a blackboard at one end. A single chair had been placed in the middle of the room facing the blackboard. Paul Dirac was waiting for us, together with Jim Hamilton and several other research students who were seated in chairs against the walls. The room had the eerie atmosphere of a Spanish inquisition. Dirac came forward and shook Pauli’s hand, and Pauli smiled with pleasure. I hoped that Dirac was not able to detect the smell of the wine that had been drunk at lunch. I was impressed by Pauli’s ability to hold what seemed to my youthful inexperience a large quantity of alcohol.
After some preliminary polite conversation between Pauli and Dirac, Pauli began pacing back and forth across the room, while Dirac stood watching him, his spare, wiry figure in a grey tweed suit smudged by chalk marks, as if he had just given a lecture and hadn’t bothered to brush off the chalk. “I have been reading your recent work on quantum field theory, Wolfgang,” Dirac said. Pauli stopped his pacing, his head nodding with his nervous tic.
“Yes, Paul, I am still not happy with the lack of rigour of the subject,” Pauli responded. “I feel that renormalization theory is just a passing preliminary solution. There is also Werner Heisenberg’s unified field theory. This theory of his could unite the forces and explain many mysteries, although I have serious problems with it.” *
Pauli looked expectantly at Dirac, who replied, “I agree, of course, that the renormalization program is unsatisfactory. I do not think this cancellation of infinities makes sense. I cannot accept it as a final description of nature. As for Werner’s unified theory, I do not think that we should try to solve all the problems at once. We should solve one problem at a time.”
Pauli frowned and said, “Well, Paul, the renormalization program does give answers that agree remarkably well with experiment. However, I agree that it cannot be the final answer. As for Werner’s unified theory equations, I feel that we must unify the forces of nature and then the correct theory will solve many problems simultaneously.”
“No, no! I must disagree,” Dirac responded immediately. “This is not the way to approach theoretical problems. We solve one problem at a time . . .”
Pauli looked irritated at Dirac’s response. “No, Paul, physics is solved by unifying principles and this leads us to the correct theory.”
Dirac smiled, and said, “Well, Wolfgang, it seems that we have always disagreed on this issue. I am not impressed with Albert’s attempts to construct unified field theories. He seems to have wasted years looking for this theory with poor results.”
“Ach!Albert and his unified theory!” Pauli exclaimed. “Absolute nonsense. He never listened to me. The old man wasted his time!”
I was amused by this exchange between the two great men. It was unusual for us students to witness Dirac verbalize any arguments at such length. In addition, I was disconcerted by Pauli’s attitude towards Einstein, which was as dismissive as Bohr’s and Schrödinger’s had been.
Dirac bid his farewells, as he was on his way to attend a committee meeting. Pauli settled himself into the chair in front of the blackboard and said, “Achtung, let us begin!” As his massive head began nodding, the nervous tension in the room became palpable. Hamilton signalled to Riazuddin to begin. He was a second-year research student working on problems in quantum field theory. He was very quiet and hardly ever spoke to any of us; in his muted behaviour, he was the Pakistani equivalent ofDirac. He had acquired a reputation among us for performing very long, arduous calculations in quantum field theory. He approached the blackboard with chalk in hand and began in tiny, spidery handwriting to carry out one of his lengthy calculations. He had reached the bottom of the blackboard, working in the conventional left-to-right fashion, without uttering a word. Suddenly, Pauli’s head stopped nodding and he shouted, “This man is deaf and dumb! I will not witness any more of this uninteresting calculation! ’raus! ” He gesticulated with both arms and poor Riazuddin smiled apologetically and returned to his chair.
Hamilton then signalled to David Candlin, a young research fellow at one of the colleges. He got out of his chair and smiled nervously at Pauli. David was tall and gangly and his face tended to become pink when he was nervous, which he indeed appeared to be now. He also suffered from a slight speech impediment and would stutter when excited. Pauli’s head was nodding again. As before at lunch, I realized that Pauli’s nervous tic would always stop just as he was preparing to unleash one of his violent verbal attacks. I waited in suspense as David began to speak. He was working on an obscure problem in scattering theory and quantum field theory, which none of us had yet been able to follow. He stuttered and spoke very fast and occasionally wrote some equations on the blackboard. We waited. After about ten minutes, Pauli’s head stopped nodding and I knew David was in for it.
“This young man hasn’t said a comprehensible word since he started. Utter rubbish! I won’t listen to this anymore!” Pauli shouted in his thick Viennese accent.
David lost the chalk on the floor; his face was flushed and perspiration was shining on his brow. Hamilton said, “All right, David, you can sit down now.” We waited with apprehension to see who the next victim would be. Hamilton looked at me with an expressionless face, and said, “John, you’re next. Don’t make your presentation too long.”
As I rose from my chair and walked to the blackboard, I felt like Danton approaching the guillotine as Madame Defarge sat knitting in the Place de La Concorde. I began with some introductory comments about Haag’s theorem in quantum field theory. This was the same Haag I had met a couple of years before at the Niels Bohr Institute, when I had given my first talk ever, before I was even technically a student. Pauli himself had been working on Haag’s theorem and its consequences for quantum field theory, so I knew that I was intentionally entering the lion’s den. I soon became caught up in my arguments, however, and temporarily forgot that Pauli was sitting there in his chair like a large toad, his head nodding vigorously. But after about ten minutes, out of the corner of my eye, I suddenly saw that Pauli’s head had stopped nodding. I froze.
“Moffat, this is utter nonsense you are saying!” Pauli roared, waving an arm furiously.
At this point I had built up a considerable amount of adrenaline, and I reacted without careful consideration. I shouted back at Pauli, “Professor Pauli, it is not nonsense!”
There was a long moment of hushed silence in the room, and Hamilton looked at me, startled and alarmed. Suddenly, Pauli rose from his chair and moved his bulk towards me where I still stood frozen at the blackboard. He came up close to me, threw his fat arms around my chest and shoulders in a bearish embrace and said, “Wunderbar! This young man speaks back!”
My fellow students were in awe of my audacity in disagreeing with the great man. I didn’t explain to them that it was simply an ill-motivated knee-jerk reaction due to my nervous state, and that I wasn’t sure at all why I had disagreed with him. I did learn from this episode an important lesson that has always remained with me: When you believe that you are right, defend your point of view.
Pauli was intensely devoted to physics. His attacks were not personal. He was used to being correct in his intuitive feelings about physics, and he felt impatient with any display of sloppy thinking or carelessness. I realized that this was a hallmark of many of the great physicists of his generation, who had developed the remarkable, innovative theory of quantum mechanics.
In spite of this, it was common knowledge among physicists that Pauli had caused several prominent physicists to abandon important ideas because they had not been able to withstand his withering criticisms. One was Ralph Kronig, a young Columbia University Ph. D. who had studied in Europe for two years. He had discovered the idea that the electron had a quantum spin, and he had proposed the idea to Pauli, who had ridiculed it, saying that it was a clever idea but it had nothing to do with reality. Consequently, Kronig did not pursue this idea and publish it. A few months later, two of the Dutch physicist Paul Ehrenfest’s students, Samuel Goudsmit and George Uhlenbeck, suggested the idea of a quantum spinning electron. Another famous Dutch physicist, Hendrik Lorentz, pointed out that the idea of a spinning electron was incompatible with classical electrodynamics. Nevertheless, Ehrenfest insisted that Uhlenbeck submit the paper, and it was published in 1925. It was an important discovery in the development of quantum mechanics, and Pauli, in the year following the paper’s publication, successfully included the idea in the formalism of quantum mechanics.
After the embrace at the blackboard, Pauli did not return to his chair. We understood that the entertainment session with the great man was over. Pauli shook Jim Hamilton’s hand, turned his big head to me and smiled. “This young man—Moffat—can walk with me and help me find my hotel again. I must rest.”
Pauli and I left the Arts School and proceeded back down King’s Parade. In spite of his obesity, Pauli walked rapidly beside me down narrow Trinity Street as we headed towards the Blue Boar Hotel opposite Trinity College. “You must work harder at understanding these problems in quantum field theory,” Pauli advised me, wheezing slightly from the exertion of the brisk walk.
“Yes, Professor, I will make more efforts to find a way to solve the problem,” I said. “I see that you don’t agree with Professor Dirac’s approach to solving physics problems.”
“Absolutely not!” Pauli replied emphatically. “Paul and I have always disagreed about this issue. Ultimately we must unify the laws of nature. I believe that during the next fifty years, physicists will see this as their ultimate goal. Maybe they will even succeed, who knows?”
Today, almost six decades later, unifying the four known forces in nature—gravitation, electromagnetism, and the strong and weak nuclear forces—is as illusory a goal as it was then.
At the door of the hotel, I shook Pauli’s hand and wished him a safe journey back to Zurich.