CHAPTER SEVEN

THE ROME SCHOOL

UNDER THE SPONSORSHIP OF CORBINO, BETWEEN 1927 AND 1934 Fermi brought together a young, dynamic team of professors and students who eventually established Rome as a major center for research into nuclear physics. This “Rome School” of physics has been the subject of intensive interest and study. Its hallmarks were a balance of theory and experiment; systematic development of expertise; cautious conservatism in terms of results claimed, married to a keen eye for publicity; disinterest in metaphysical or philosophical inquiry; focus on an empirical approach to all issues under study; and division of labor that enabled the team, consisting of widely differing personalities and temperaments, to work sufficiently well together to achieve major results.

Beginning in 1935, however, the group began to fall apart. The increasingly poisonous political environment was partly to blame, as were financial restrictions that made it attractive to find work abroad. Nevertheless, during the crucial years prior to 1935 the Rome group made an indelible mark on the world of physics.

Throughout the period, Fermi was the clear leader of the group, a fact acknowledged by his “disciples” when they began referring to him—much to his delight—as il Papa, “the Pope.” It wasn’t simply that he was almost invariably right when solving a thorny physics problem. At least one of his Rome students, Ettore Majorana, was nearly as brilliant as Fermi, if not more so. Yet no one would have considered referring to Majorana as il Papa simply because, outstanding though he was, he was not a leader. Fermi had a charisma and a magnetism that were apparent to all who met him. He was as close as anyone in the physics world has ever come to being a natural leader. The same magnetism that the “logarithms” felt when Fermi organized outings, hikes, afternoons at the beach drew to him the students and researchers who made up the Rome School.

FIGURE 7.1. Orso Mario Corbino. Photograph by Studio D’Arte Luxardo. Courtesy of Amaldi Archives, Department of Physics, University of Rome, La Sapienza; AIP Emilio Segrè Visual Archives.

FIGURE 7.2. Enrico Fermi as the young professor of theoretical physics in Rome. Courtesy of Amaldi Archives, Department of Physics, University of Rome, La Sapienza.

When Fermi first returned to Rome, however, there was no one for him to lead. Corbino and Fermi understood that in order to have a school they needed students, but students were not lining up for entry into physics. Engineering was a popular and prestigious subject within the Italian university system. It was technical, modern, and led to good, stable career prospects. Physics was a bit different. It was more technical, more challenging, perhaps a bit less practical, and the career prospects were generally confined to teaching. Few students of high caliber chose it, and those who did ended up working for somewhat stodgier old school physicists. With Fermi’s arrival, Corbino hoped it would be possible to draw a few students from the engineering program to physics.

The first to make the jump was a young engineering student named Emilio Segrè. In Segrè’s connection with Fermi we see the influence of the tightly knit community of intellectual Italian Jews into whose salon Fermi had been welcomed. Segrè was just a few years younger than Fermi, born in 1905 into a prosperous Sephardic Jewish family in a suburb of Rome. His father owned a successful paper mill and the family lived a comfortable, bourgeois life. Segrè had always been interested in physics, but a practical bent and a lack of inspirational physics guided him to the engineering program at Rome in 1924. He had, however, taken one of Fermi’s lecture classes on mathematical physics prior to Fermi’s stint in Florence and knew Fermi to be a brilliant teacher and an original thinker. In Fermi’s absence he simply continued his engineering studies.

In the spring of 1927 Rasetti, who had met Segrè through a mutual friend, mentioned that Fermi was returning to Rome. Segrè asked for a personal introduction. Soon Fermi and Segrè were spending time during the summer hiking in the country, informally getting to know one another. Fermi gently probed Segrè to assess his abilities and Segrè tried his best to answer Fermi’s questions. Though not deeply prepared, Segrè passed Fermi’s informal entrance exam. It probably didn’t hurt his chances that he too was an avid outdoorsman.

Fermi invited Segrè to attend the 1927 Como conference, and Segrè was inspired by the giants in the field—Bohr, Heisenberg, Pauli, Planck, and Sommerfeld—discussing new developments in physics. By the time he returned to Rome, Segrè had decided to take the plunge and transferred from engineering to physics. Fermi had his first student.

One student does not a school make. Corbino and Fermi both understood this, and Corbino used the opening of the fall 1927 term at Rome to recruit a few other students into the physics department. Word went out to the engineering classes that there was room for one or two more physics students and that Corbino would facilitate the transfer process for any capable applicant. Only one student applied. He happened to be the young, cherubic Edoardo Amaldi, that same Edoardo Amaldi whom Fermi met at the Castelnuovo salons, a charter member of the “logarithms.”

The third student in the program was introduced not by Corbino or Rasetti but by Segrè himself. His name was Ettore Majorana. A darkly quiet young man, he had a famous uncle, Quirino Majorana, who was a respected experimental physicist at the University of Bologna. Quirino was also a member of the panel of judges for the Rome concorso that Fermi won. Ettore was an engineering student and had become friendly with Segrè. Segrè believed that Majorana’s mathematical brilliance would be wasted in the engineering field and persuaded him to join the group at Via Panisperna.

Corbino brought Rasetti to Rome earlier in the year as his own special assistant and as the physicist best able to add to the experimental expertise of the Rome group. Rasetti was particularly strong in spectroscopic experimentation, at that point the central concern of experimental physics. Persico, who came in second in the concorso for the Rome position, went to Florence. Fermi found himself, to his delight, reunited with Rasetti, his old friend from his days in Pisa. He missed Persico, of course, who was an even older friend, but Persico frequently traveled to Rome to visit the team at Via Panisperna.

The core of the Rome School was now more or less fully formed: Fermi, Rasetti, Segrè, Amaldi, and Majorana. Others joined the group over time, and the group would eventually dissolve as each member went his own separate way, but by late 1927–early 1928 the Rome School was born.

SEGRÈ, MAJORANA, AND AMALDI ALL HAD A PASSION FOR PHYSICS and were each brilliant in their own way. The three students also understood just how special this opportunity was, to work with one of the greatest minds in physics. There was no question as to who led the group. Aside from these elements in common, the three could not have been more different.

Segrè was a profoundly practical man, with a knack for business inherited from his father. He also had a fiery temper, resulting in his nickname “Basilisk,” after a mythical creature who could kill with a single glance. He was, in addition, a gifted experimental physicist who in later years shared a Nobel Prize with an American student of Fermi, Owen Chamberlain, for the discovery of the antiproton.

Majorana was by all accounts the brightest of the group, in some ways even brighter than Fermi. His greatest strength was in mathematics; he would often complete a complex calculation quicker than Fermi. Unique among the Rome group, Majorana was a quiet introvert, who spent many solitary hours with his work. The general ambience of the Rome School was highly social. In this he stood apart from the rest.

Amaldi was the youngest of the group, sociable and outgoing, like Segrè an enthusiastic outdoorsman, a strong physicist with a preference for experimental work who readily stepped into the role of Fermi’s experimental assistant when the time came. He knew Fermi from childhood and his subsequent 1933 marriage to Ginestra Giovene brought him even closer to the Fermis, because Ginestra was rapidly becoming Laura Fermi’s closest friend.

The curriculum these students embarked on was unlike that at any other university and was itself one of the hallmarks of the Rome School. The method of teaching ensured that Fermi made his mark directly on each student. Though there were university lectures on all the standard topics of physics, Fermi’s physics students were not required to attend these. Instead, they attended private seminars in Fermi’s office. Fermi’s formal lectures were reserved for students required to take physics as part of some other degree requirement. The ones who attended the private seminars with Fermi in the afternoon were mainly physics students, although others were occasionally invited. Ginestra Giovene, a general science student at the university, was one such attendee. It was here that she met her future husband, Edoardo. Another was a young man named Gabriello Giannini, who became a successful industrialist and businessman in the United States and later led the Rome group through the complex international patent process for the discovery of induced radiation.

These private seminars were the centerpiece of a Rome physics education. Segrè’s description tells us much about the way in which Fermi taught and the secret behind keeping the group as coherent and tightly bound as it was:

Fermi’s seminar was always improvised and informal. In the late afternoon we would meet in his office, and our conversations might give rise to a lecture—for example, if we asked what was known about capillarity, Fermi would improvise a beautiful lecture on its theory. One had the impression that he had been studying capillarity up to that moment and had carefully prepared the lecture. I find in one of my notebooks on the discussions of those years the following topics: blackbody radiation, viscosity of gases, wave mechanics (the establishment of Schrödinger’s equation), tensor analysis, optical dispersion theory, gaussian [sic] error curve, more quantum mechanics, and Dirac’s theory of spin.

In this fashion we reviewed many subjects at a level that corresponded to a beginning graduate course in an American university. Sometimes, however, discussion was on a higher level, and Fermi might explain a paper he had just read. In this way we became conversant with some of the famous papers by Schrödinger and Dirac as they appeared. We never had a regular course. [Italics added.] If there was an entire field of which we knew nothing and about which we asked Fermi, he would limit himself to mentioning a good book to read. Thus, when I asked him for some instruction on thermodynamics, he told me to read the book by Planck. But the readings were not always the best, perhaps because he mentioned only the books he himself had studied, which were not necessarily the best pedagogically but simply those he had found in the library at Pisa. After his lecture we would write our notes on it and solve (or try hard to solve) the problems he had given us, or others we thought of.

Ginestra wrote that students learned so much from these sessions because Fermi “brought his problems to the others and worked at them on the blackboard, aloud, with chalk and voice, thus showing how a rational mind reasons, how accidental factors can be discarded and essential ones taken into light; how analogies with known facts help to clear the unknown.”

In these seminars Fermi was teaching more than physics. He was teaching his students to think the way he thought, to address problems the way he did, by cutting away all irrelevant factors and focusing on the heart of the matter in order to arrive at the simplest solution. Segrè notes that Fermi would work his way through a problem slowly and steadily, never speeding up when the mathematics was simple, never slowing down when the equations became thornier, much like a steamroller “that moved slowly but knew no obstacles. The final result was always clear, and often one was tempted to ask why it had not been found long ago inasmuch as everything was so simple and natural.” This deliberative, almost plodding style of working through a problem almost always resulted in a much deeper understanding of the solution than an approach used by many of Fermi’s contemporaries, which glossed over the easier steps and focused all the energy on the more difficult steps.

Fermi, Rasetti, Segrè, and Amaldi also became close socially. Years later Laura Fermi wrote:

When the four came together, two teachers and two students, they were all young—there were seven years’ [sic] difference between the oldest and the youngest. They shared a love for physical exercise, a swim in the near-by sea, a climb in the mountains, a long hike, and a game of tennis.

They also shared a “certain playfulness, a naïve love of jokes and silly acting that they brought into their serious work.” When Ginestra first encountered the private seminar, Fermi explained that they liked to play a game called “two lire.” Anyone in the group could ask anyone else a question. If the person could not answer the question, then that person owed one lire to the one who asked it. If, however, the person who asked the question could not answer the question himself, then he owed two lire to the one whom he had originally challenged. Edoardo Amaldi came up with a question for the bewildered, unnerved Ginestra: if tin has a lower boiling point than olive oil, how can you possibly boil olive oil in a tin-lined skillet? Ginestra was clearly flustered but composed herself sufficiently to think through the solution. She explained that when one cooks with olive oil, the oil is not boiling; rather, it is the water in the food that boils. This was the correct answer and no money changed hands that day.

By this time the ragazzi di Via Panisperna (boys of Via Panisperna), as they were known, had each adopted a nickname, giving them a specific relationship to the infallible Fermi, il Papa (the Pope). Corbino became il Padreterno (Eternal Father) owing to his munificent sponsorship of the group. Rasetti was the Cardinale Vicario, il Papa’s right-hand man. Persico was Prefetto di Propaganda Fede, Prefect of Propaganda of the Faith, responsible for spreading the gospel of quantum physics wherever he could. Il Basilisco (the Basilisk) was the name given to Segrè. Amaldi was l’Abate (the Abbot), reflecting his junior position within the team. When young Bruno Pontecorvo came on board in 1933, he too took on a nickname appropriate for his status—il Cucciolo (the Puppy).

Eventually, the members of the group (generally excepting Majorana) spent weekends together hiking in the hills around Rome or sunning themselves on the beach at Ostia; they took ski holidays together in the Italian Alps; they dined with each other regularly. Like the “logarithms” before them, they became an intimate circle of friends, Fermi always leading with an easy informality and familiarity that increased group cohesion. They were “family.” They became so close, reportedly, that they all began to speak in the same slow, deep, unusually cadenced Italian that Fermi and Rasetti had developed when they were students together. Segrè tells the story of a member of the group who once struck up a conversation with a fellow railway passenger, who immediately asked whether he was a physicist from Rome. The Fermi protégé confirmed that he indeed was and asked how the passenger could tell. The passenger had guessed it from the way he spoke.

In this way, physics in Rome became fun. It is almost as if Fermi, having experienced the dry austerity of physics at Göttingen some five years earlier, had decided that he would build a school along very different principles. It was also a group endeavor, a social endeavor, one in which each person had a role. Even when Fermi was doing theory, he would bring his thoughts to the private seminars and work through them in front of an audience of students and fellow researchers. They might argue over physics by day, but evenings and weekends were spent together, and the group became very close indeed.

In Florence, Garbasso was developing his own group of strong, young physicists. The two groups exchanged visits and met often to discuss their mutual research interests. In addition to Persico, the group included Bruno Rossi, who later became the world’s leading expert on cosmic rays; Giuseppe Occhialini, who would go on to major contributions to particle physics, including an important role in the discovery of a particle called the pion; Gilberto Bernardini, a brilliant experimentalist who led the effort to build Italy’s first major accelerator lab after the war and later became director of the Scuola Normale; and theorist Giulio Racah, who after the war established modern physics in Israel.

Italian visitors were not the only ones who were at home at Via Panisperna. As word spread that Fermi’s group was doing interesting things and having fun doing them, young physicists from around Europe sought post-doc appointments or short visiting stints with Fermi and his colleagues. Sommerfeld’s student Hans Bethe stayed for a year and became a good friend of Fermi. Other visitors who ultimately made important contributions included George Placzek, Felix Bloch, Rudolf Peierls, Sam Goudsmit, and Eugene Feenberg. Young Hungarian physicist Edward Teller visited and challenged Fermi to table tennis. Teller was quite good at the game in spite of having a prosthetic foot and always won handily, to Fermi’s inevitable frustration.

ONE PROBLEM THAT CORBINO AND FERMI FACED TOGETHER EARLY on, as Fermi settled in to his new position in Rome, was how to raise the profile of Italian physics on the international scene. Modern physics always relied on international conferences for the development of new ideas, exchange of information, and thrashing out of major debates and disputes. In the first half of the twentieth century, no series of conferences was as important, or prestigious, as the Solvay conferences. When Fermi arrived back in Rome, no Italian had ever been invited to attend.

The conferences were the idea of Ernest Solvay, a successful Belgian industrial chemist and philanthropist. Beginning in October 1911 and every three years hence, the conferences, under the direction of Dutch physicist Hendrik Lorentz, attracted the greatest names in physics of the day—Planck, Einstein, Sommerfeld, Rutherford, Marie Curie, and Poincaré, among others. Many of the original issues associated with relativity and quantum theory were hashed out at these historic meetings. The fifth Solvay conference, scheduled for late October 1927, would focus on the topic of “Electrons and Photons,” involving a variety of complex developments, including Dirac’s recent, brilliant work on the quantum theory of the electron. Among the “who’s who” of international physicists invited to attend, totaling some thirty-two scientists, not one was Italian.

The absence of any Italian was a source of continuing irritation for the leaders of Italian physics. Not even the famous Guglielmo Marconi received an invitation, probably because he was considered more of an inventor than a scientist. Other distinguished Italians might have merited inclusion, such as Corbino in Rome, Garbasso in Florence, and even Levi-Civita, who, though not a physicist, had developed much of the mathematical framework for Einstein’s theory of general relativity. Lorentz ignored them all. Italian physicists were simply not part of the highest-level dialogues in the field.

Feeling shunned, Corbino came up with an idea that he thought would alter the playing field. If Italians could not get invited to Solvay, he would hold a conference of his own. He had two major assets on his side. First, of course, was Fermi, already known to many of those invited to Solvay. The other was the natural beauty of Italy’s Lake District. Breathtaking lakes nestled in the valleys of the Italian Alps could, he imagined, provide an attractive place for Italy’s own conference on physics. He chose the town of Como for the site of his conference. The hundredth anniversary of the death of famed Italian physicist Alessandro Volta, who invented the electric battery, provided a credible reason to bring the world’s great physicists together.

And so it did. Among those who attended the conference in mid-September 1927, just one month before the fifth Solvay conference, were Niels Bohr, Max Born, Walter Bragg, Maurice de Broglie, Werner Heisenberg, Wolfgang Pauli, Max Planck, Ernest Rutherford, Arnold Sommerfeld, Pieter Zeeman, and even Solvay director Hendrik Lorentz himself. The Italians were there in full force, of course, with Corbino and Fermi acting as hosts for the events.

From an historical perspective, the most important presentation was that of Bohr, who took the opportunity to share some initial thoughts on his concept of complementarity, thoughts that he developed in greater detail a month later at the Solvay conference. Fermi, Heisenberg, and Pauli presented no papers of their own, but they did comment on Bohr’s paper and on a variety of other issues relating to quantum theory.

On a social level, it was an opportunity for Fermi to meet and greet many of the great names of the field. It was the first time Fermi met Pauli in person. Heisenberg introduced the two of them by saying something to the effect of “May I introduce the applications of the exclusion principle to each other.” Rasetti memorialized the moment in a photograph he took of the three young quantum theorists sharing a boat ride on Lake Como. In the photo Heisenberg is clearly the happiest, arms folded and beaming. He had just made an historic introduction and was probably quite pleased with himself. Pauli looks happy enough as well. It is Fermi who looks the most awkward; perhaps because Rasetti caught him just at a moment when the wind was whipping his thinning hair up and away from his head. Or perhaps it was the conflict he felt as host, colleague, and competitor with respect to his companions on the boat. Rasetti’s photo is one of the iconic images of twentieth-century physics, showing three of its greatest minds at the height of their intellectual powers.

FIGURE 7.3. Left to right: Fermi, Heisenberg, and Pauli, Lake Como, 1927. Photograph by Franco Rasetti. Courtesy of AIP Emilio Segrè Visual Archives, Segrè Collection.

Years later, Rasetti, reflecting on the importance of the Como conference, noted that in general Italian physicists were not aware of Fermi’s significance until Sommerfeld underscored the impact of Fermi’s work on statistical mechanics at this conference, in particular, pointing to its ability to explain the behavior of electrons in metals. The conference also made clear to the Italian physics community just how far behind it was because many of its senior physicists refused to adopt the new quantum theories of 1925–1926. It was, in Rasetti’s view, the moment when Italy began to recognize Fermi’s standing.

It was too late to invite Fermi to the fifth Solvay conference just a month later, and it is not clear just how much the Como conference influenced the organizers of Solvay, but they invited Fermi to attend the conferences in 1930, 1933, 1936, and 1939 (although the last one was canceled owing to the outbreak of World War II).

FERMI’S ARRIVAL IN ROME WAS NOT MET WITH UNIVERSAL WELCOME in the corridors of Via Panisperna. In particular, Antonino Lo Surdo, an older experimentalist with offices at Via Panisperna, resented the newcomer. Corbino and Lo Surdo were personal rivals and had been feuding for years before Fermi arrived on the scene. Lo Surdo had made some important discoveries but was overlooked for a Nobel Prize in 1919, perhaps in part because Corbino had worked hard to undermine his scientific reputation in Italy. By the time Fermi arrived in Rome Lo Surdo was a bitter man who resented the appointment of this prodigy to a new professorship at the institute.

Lo Surdo may not have won a Nobel Prize, but he was a member of the distinguished Accademia dei Lincei (Academy of Lynxes), the oldest scientific society in the Western world. Founded in 1603, among its earliest members was Galileo. By the early twentieth century, its status as Italy’s most prestigious scientific organization was unquestioned. At this point in Fermi’s career, it would have been natural for Corbino to nominate his protégé to the Accademia, and it would also have been natural for Lo Surdo to block the nomination. But the accepted narrative of these events, as told by Laura Fermi, does not cohere. As she would have us believe, Corbino prepared a nominating letter on behalf of Fermi and, because he would be traveling during the annual election meeting, entrusted this letter to Lo Surdo, who promised to submit it in Corbino’s absence. When Corbino returned, however, Fermi was not on the list of those elected. When he confronted Lo Surdo, the latter insisted he had forgotten to submit the nomination letter—an unlikely excuse, to say the least.

It is genuinely difficult to believe that, given their historic enmity, Corbino would have entrusted Fermi’s nomination to Lo Surdo. Their feud had lasted over a decade, and Corbino was highly sophisticated and politically adept. Further, the process of nomination was a complex, lengthy one, and many people would have been involved by the time an election was held; members would have been aware that Fermi was up for election well before the election date. The story does not hold up. Corbino probably had a different agenda.

Mussolini had long been planning to establish his own institution to rival the Accademia dei Lincei in prestige and importance. The Reale Accademia d’Italia (Royal Academy of Italy) was Mussolini’s brainchild, and the bill to establish it passed the Senate in 1926. Setting it up was complicated because the fascist dictator wanted to include the greatest cultural and intellectual figures in all of Italy, across all disciplines. He also wanted, somewhat naïvely, to include individuals who were not completely enamored with his fascist regime. Under the circumstances, it took until March 1929 for the government to compile a slate of inaugural candidates for the new academy. Corbino, no fan of the dictator, was nevertheless able to persuade Mussolini to place Fermi on the list of academicians.

Lo Surdo had expected to be named and was deeply disappointed to have been passed over. Corbino had in fact won a double victory. Not only had he influenced the naming of Fermi over Lo Surdo; he had done so at a time when he must have known that, owing to Mussolini’s new high-profile academy, the Accademia dei Lincei would soon fade in importance. Fermi was delighted. On that date he wrote in large capital letters in his notebook: “INCIPIT VITA NOVA—GAUDEAMUS IGITUR!” (Now begins a new life—let us rejoice!).

Newly appointed members of the Accademia d’Italia were celebrated in the press, and ceremonies of great pomp and elegance were held to honor them. Of far greater importance to Fermi, membership included a significant annual stipend of 36,000 lire for life, more than doubling his salary from the university. This enabled him to drop other distracting commitments he had made to supplement his income, most notably an editorship in Treccani’s Enciclopedia. It entitled him to be known as “His Excellency,” a title whose pretentions endlessly amused him. It also included a new uniform designed especially for the honor, with flowing robes and faintly ridiculous headgear. Self-conscious of appearing in public so dressed, Fermi would drive himself in the bébé Peugeot to the meetings of the Accademia d’Italia and dress when he got there. On one occasion, he was challenged by a guard who was certain that such a car did not belong at an august meeting of the Reale Accademia. Fermi explained—truthfully, he would later recount with a smile—that he was the driver of His Excellency, Enrico Fermi. The guard waved him through.

The public was fascinated. Fermi was by far the youngest academician. Before his induction he was known by physicists throughout Europe for his work in quantum physics. His fame within Italian physics spread as a result of Sommerfeld and others’ comments at Como. As a result of his elevation to the Accademia, he was now known more broadly. He had become, as he would later say, “a great man.”

He was certainly willing to play Mussolini’s game, lending his name and his scientific prestige to the new fascist institution. He may well have thought that it was essential for continuing government funding for Italian physics. Corbino, no Fascist himself, probably felt the same way. Although the honors fed Fermi’s ego, he considered the various functions and receptions a waste of time. Every hour spent at the Reale Accademia was an hour away from his work at Via Panisperna. There was never any doubt about his priorities.

In this way an uneasy symbiosis was established between Fermi and the fascist regime. However readily he accepted the radical ideas of the new physics, he was personally conservative and may at some level have approved of the stability that Mussolini brought to Italy, despite the regime’s use of thuggery and violence. Fermi played the game and was trotted out as an example of the brilliant science sponsored by the regime. In return, his work was supported without interference. It was, to be sure, a deal done with the devil, but it served Fermi’s purpose. His trips to America, beginning in 1930 and continuing throughout the decade, showed him what opportunities lay abroad under a freer, more prosperous form of government, and he fully appreciated those opportunities. Laura’s resistance, however, prevented him from making a move.

IN THE END, THE IMPORTANCE OF THE ROME PERIOD HAD NOTHING to do with Fermi’s election to the Accademia d’Italia, nor to his growing celebrity, nor even to his ability to attract the best young talent to Via Panisperna. The importance of these years can only be measured by the discoveries made by Fermi and his little group perched on a hill overlooking Via Panisperna. The work in Florence had made him famous among physicists. The work in Rome would make him a legend.