The Pope of Physics

by Gino Segrè

  Amaldi and Fermi were both ferocious workers. Amaldi recalled how the two “worked with incredible stubbornness. We would begin at eight o’clock in the morning and take measurements without a break until six or seven in the evening and often later … Having solved one problem we immediately attacked another without a break or feelings of uncertainty. ‘Physics as soma’ was the phrase we used to refer to our work performed while the situation in Italy grew more and more bleak, first as a result of the Ethiopian campaign and then as Italy took part in the Spanish Civil War.” Amaldi borrowed the metaphor of soma from Aldous Huxley’s Brave New World (1932), in which soma is a mythical drug of self-medication that eliminates feelings of stress and discomfort. Through physics as soma, the two researchers were able to block out the turmoil happening in the surrounding world.

  The upshot of their year of labors between the summers of 1935 and 1936 is detailed in a fifty-page paper they published in La Ricerca at the end of May and republished in November 1936 in America’s leading physics journal, Physical Review. Another paper, this time a mere forty pages, was also written by Fermi. It provided the theoretical physics underpinnings to experiments he and Amaldi conducted. Amaldi commented on its foresight: “The paper contains the seeds of nearly all of the important ideas on neutrons that Fermi developed in succeeding years.”

  It was an incredible effort and at the same time characteristic of Fermi. He was seemingly impervious to fatigue, frustration, or dissatisfaction.

  Fermi’s passion for physics flowered during 1934, 1935, and 1936, the years of his transformative accomplishments in neutron physics and beta decay. This had made those happy years for him despite the grim political climate.

  In February 1936, another event added to those happy years. There was a new arrival: Laura gave birth to a baby boy. The tradition in Italian families was to name a son after his grandfather, but in this case Enrico wanted to honor the memory of his much-loved brother, who had died at age fourteen. The baby was given the name Giulio.

  Fatherhood was again welcomed by Fermi, although, not uncharacteristically for those times, he was relatively uninvolved in the role. In her candid book, Laura has a chapter “How Not to Raise Children” that starts by describing how when Nella was born Enrico did not “dare to take his first born in his arms or even touch her. He looked at her from a distance with bewilderment and misgivings.” By the time of Giulio’s birth five years later, Enrico’s behavior was only slightly less awkward. It was not that he did not love his children, but his devotion to physics—although not religious—had aspects of a higher calling: explaining the laws of nature.

  17

  TRANSITIONS

  Toward the end of 1936, views of the future were looking bleaker and bleaker. The tightening vise of Fascism, the rumblings of anti-Semitism, and the drums of war affected Fermi’s work. After a period of incredible creativity, it was as though the light of Fermi’s genius was dimming. As noted by Emilio Segrè, “Fermi had developed a certain reticence.” His commentary goes on to say that there seemed to be no special reasons for this. If one examines what was happening at the time, however, the reasons become discernible. The world as Fermi knew it was falling apart.

  In January 1937, tragedy struck both personally and professionally. Following a brief bout of pneumonia, Orso Corbino died; he was only sixty-one. The Padreterno, Fermi’s guide and protector, was gone. Fermi wrote a heartfelt eulogy of his mentor beginning with a description of their first meeting, Fermi a nervous twenty-year-old recent university graduate and Corbino an illustrious professor and a Senator of the Realm. The warm reception Fermi was given that day began an enduring friendship.

  The personal loss Fermi felt was heightened by a bureaucratic decision to move the physics department to the new University City. The Boys, or what was left of them in Rome, would no longer work in an inviting and intimate villa surrounded by palm trees, an island of calm surrounded by a bustling city life. The Boys also would no longer feel the embrace of the Corbino family, who lived one floor above their working space. Instead they were shuttled off to a complex erected at the city’s edge, built in the mock-imperial style that came to be known as fascist architecture, ostentatious and seemingly grand on the outside but unwelcoming in its interior. The era of Via Panisperna had truly come to a close.

  Luckily, Amaldi was chosen to fill Corbino’s chair at the university. However, there was still trouble, because Lo Surdo, never a fan of Fermi and his group, was named to replace Corbino as director of the physics institute. Fermi had been the obvious successor for the position, but without Corbino watching out for him, political machinations triumphed. The Fascists could count on Lo Surdo. Fermi’s prestige was such that Lo Surdo could do little to harm him, but he certainly would not go out of his way to help him and Amaldi.

  The Rome physics upheaval in 1936 and 1937 was about more than Corbino’s death and the move away from Via Panisperna. Major shifts were taking place in the field of nuclear physics, especially in respect to where the most vital research was being conducted and who was conducting it. Rome, struggling to keep up, was running the risk of obsolescence.

  The glory days of Cambridge’s Cavendish Laboratory, a leader in nuclear physics ever since the field’s founding, were already over, its ingenious small-scale experiments a thing of the past. Lord Rutherford’s death in October 1937 following a botched hernia operation was the coup de grâce. And the German centers in Munich, Göttingen, and Berlin, having to teach “Aryan” physics, were shadows of their former selves.

  Nuclear physics was reaching a new level of sophistication. The old analogy of an electron’s passage through a complex atom was discarded. Neutrons and protons were packed too tightly within the nucleus and interacted too strongly with one another for that picture to be useful. Niels Bohr and his Copenhagen associates, in part guided by the results of Amaldi and Fermi’s 1935–36 experiments, were developing a new model of the nucleus. Making headway on the experimental front required new tools. Without them little progress would be achieved.

  Fermi knew this. He had been a driving force in nuclear physics from 1934 to 1937, but his output in the next two years had little impact. It was unclear how productive he might be unless he moved to the United States, the country he repeatedly looked to as the likely future leader of physics. His visits there during the summers of 1930, 1933, 1935, 1936, and 1937 had made obvious to him the personal freedom America offered, and the work opportunities. A group of young men who had learned quantum mechanics in Europe were establishing schools of theoretical physics and chemistry in America, and they were being joined by a large number of refugees.

  Talented and versatile young experimental physicists such as Luis Alvarez, Carl Anderson, and Edwin McMillan were also emerging in the United States. Then there was Fermi’s contemporary, Ernest Lawrence, already famous for his development of the cyclotron. The praises of this machine’s capabilities were being sung worldwide. Its beams of electrically charged particles were more intense than any other laboratory could achieve and the energies they reached were unprecedented. The consequence was that bombarding targets with the cyclotron’s projectiles produced radioactive samples in previously unimagined abundance.

  Fortunately for others, Lawrence was unusually generous with the riches spewing forth from Berkeley’s cyclotron. Segrè remembers Fermi receiving a letter from Lawrence in the summer of 1935, asking him if he might find it useful to have a sample of radiosodium, a radioactive isotope of sodium. Lawrence suggested sending him a millicurie, an amount a thousand times greater than Fermi would have expected. After thanking Lawrence, Fermi pointed out that there must have been a mistake; Lawrence had surely intended a microcurie, not a millicurie. The reply was an envelope containing a millicurie of radiosodium. There had been no mistake.

  But the Boys all knew that Lawrence’s charity was not a substitute for having a cyclotron. Wanting to advance Rome’s experimental capabilities, Amaldi, Fermi, and Rasetti spent the summer
of 1936 in the United States. All three came back to Italy in the fall enthusiastic about the prospect of building one in Rome.

  Applying pressure to the Consiglio to fund the venture, Fermi wrote them in January 1937 that it would be “hopeless to think of an effective competitiveness with laboratories abroad, unless even in Italy a way is found to organize these researches on an adequate basis.” Rasetti followed up that letter in an address to the Italian Society for the Advancement of Science. He pointed out to its members that the rest of the world had accelerators “that are functioning or in an advanced state of construction, twelve exemplars in the United States, one in France, two in England and one in Denmark.”

  The Consiglio’s response was a grant of thirty thousand lire to develop a prototype of a cyclotron, a pittance compared to the million or more it would take to build a real one. Though the amount was not out of line with previous grants, it showed that Italy was unwilling or unable to provide the funds necessary for a major undertaking.

  Still harboring hope, Fermi went back to the United States in the summer of 1937, this time to the West Coast. The cyclotron that had started functioning in Berkeley five years earlier was already being phased out and replaced by a larger and more powerful one. This progress was encouraging from the point of view of physics, but discouraging for what it presaged for Italy’s future in the field.

  While Fermi was in California, he received news that made chances of Italy having a cyclotron even more distant. Guglielmo Marconi, president of the Consiglio, had died of a sudden heart attack. The unexpected deaths of Corbino and Marconi left Fermi without his two special sources of support. Making matters even worse, Pietro Badoglio, the army general and former commander of the Italian troops in Ethiopia, was named as Marconi’s replacement. The man who had ordered that mustard gas be used on the enemy was now in charge of Italian science.

  One glimmer of light flickered amid the enveloping darkness in the fall of 1937. It made Fermi feel that perhaps what he had so carefully and successfully built to assure Italy’s place as a center of exciting physics was not altogether lost. Without a real prospect of a cyclotron for experimental research, at least theoretical physics could prosper. The much-admired theoretician Ettore Majorana reappeared after a mysterious four-year withdrawal from physics. The man whom the Boys nicknamed the Gran Inquisitore had retreated to his Rome apartment in 1934, seldom emerging from its door. In essence, he had vanished.

  Majorana’s reentry was in the form of a brilliant article about neutrinos. Almost certainly Majorana’s new publication was related to his unexpected declaration that he wished to be a candidate for a theoretical physics professorship. Professorships were scarce in Italy. Not since 1926 had there been a competition for these coveted posts. The announcement was heralded with a great deal of publicity. As was the norm in such cases, three candidates would be selected in priority order and three professorships awarded; in 1926 Fermi, Enrico Persico, and their friend Aldo Pontremoli had been the winners.

  The 1937 appointment committee, which included Fermi and Persico, had essentially decided beforehand who the three would be, all deemed eminently suitable. That was before Majorana, clearly preeminent, announced his candidacy. Listing Majorana as first choice would mean dropping the third candidate, whose father was an extremely influential politician, called by Mussolini the “philosopher of Fascism.” Denying this man’s son the expected professorship might have ugly repercussions.

  The answer, in one of those not altogether infrequent Italian accommodations, was to break from tradition. The appointment committee held a special session and managed to appoint all four candidates. Citing his exceptional merits, they awarded Majorana a special professorship in theoretical physics at the University of Naples.

  Serendipitously, while Fermi’s professional world was shifting, Laura’s was settling. In 1936, she, along with Ginestra Amaldi, had published Alchimia del Nostro Tempo (Alchemy of Our Time), a popular treatise on atomic and nuclear physics. The two women had collaborated successfully on their favorably reviewed book. In 1937, they were enjoying its enthusiastic reception. This sealed a friendship that already was linked by physicist husbands, small children, and a love for Italy. Neither Laura nor Ginestra wanted to move from her homeland. Ginestra was sympathetic to Laura’s reluctance to leave her frail, elderly father, who had retired from his post as an admiral in the Italian navy. He was alone after her mother’s death in December 1935.

  Yet Laura’s fantasies about Italy somehow escaping fascism were rattled in the fall of 1937. Just weeks after Fermi’s return from California, Il Duce undertook his first trip off Italian soil in more than a decade. Germany was his destination. Received with great pomp by the Führer, Mussolini was impressed by the sight of marching German soldiers, by a visit to the Krupp steel foundries, and by lavish receptions accorded him in both Munich and Berlin. Il Duce concluded his speech in the German capital by telling a crowd of close to a million that his and their country had to be united “in one single unshakable determination.”

  Mussolini stressed that commitment in December by having Italy follow Germany’s lead in withdrawing from the League of Nations. This sent a clear signal to other nations that he and Hitler, already bound through their support of Franco’s forces in Spain, would be acting together from now on. That unity was tested less than four months later by Germany’s annexation of Austria, accomplished without Mussolini even being notified beforehand. Il Duce did not protest the deed: he obviously no longer felt the need for a buffer between his country and Hitler’s.

  18

  STOCKHOLM CALLS

  In hindsight it seems inevitable that Italy would follow Germany in enacting anti-Semitic legislation, but for the time being this trajectory did not appear to worry the Fermis. In January 1938, they moved into a new and larger dwelling near Rome’s Villa Borghese Park. The Fermis had bought the apartment because, as Laura writes somewhat drolly, “I had been attracted by the idea of a green-marble-lined bathroom. It satisfied my ambitions of grandeur, which had been rising as Enrico’s position had steadily grown better.” She could now say, “I felt rich, well established, and firmly rooted in Rome.”

  These lines, written fifteen years after the events in question, reflect a much wiser woman thinking back about her naïveté at that time. It also indicates the degree of denial that permeated the Fermi household. Although there was some trepidation, neither Enrico, the child of civil servants, nor Laura, growing up in a loyal military family, was inclined to do anything other than support a government in power, even if they did not approve of its actions. Furthermore, given Fermi’s status, there was no reason to believe his position would be threatened.

  Fermi was shaken, however, in the spring of 1938, by both personal tragedy and political developments. On the twenty-fifth of March, Majorana took the overnight ferry from Naples to Palermo. Before leaving he sent a suicide note to Antonio Carelli, the head of the Naples physics department. The next day Majorana wrote Carelli again, saying he had changed his mind and would be returning to Naples. He appears to have boarded the ferry, but that’s where the trail ends.

  All subsequent efforts to find traces of Majorana failed. The most plausible answer is that he committed suicide by jumping from the boat. But the body was never found and his family always insisted that no matter how desperate he had been, his strong religious beliefs would have precluded his taking such a step. The result has been a continuing debate in Italy, some suggesting that Majorana preferred anonymity, retired to a monastery, left Italy altogether, or even that he foresaw the advent of a nuclear bomb and escaped from having anything to do with it.

  Assuming he had in fact committed suicide, his Via Panisperna companions mourned him. They regarded Il Gran Inquisitore’s talents as sadly compromised by an overly critical personality that made him undervalue others’ achievements and in particular his own.

  The previous twelve months had seen many transitions in Fermi’s life, all of them pointi
ng to a darker professional and personal future in Italy. The moment was fast approaching when staying in their homeland would be untenable for the Fermis.

  In May, Hitler and his entourage reciprocated Mussolini’s visit to the Third Reich by traveling to what Il Duce was now referring to as the Second Roman Empire. Mussolini tried to match the might of the military prowess he had witnessed during his visit to Germany. The Italian navy mounted a grandiose display in the Gulf of Naples, ships leaving the harbor with airplanes flying overhead in formation. It was showy, but the visitors saw clearly that Italy’s industrial output was in no way comparable to theirs. The Führer did, however, greatly admire the works in Florence’s Uffizi Gallery, perhaps even thinking about the artworks he would collect after dominating Europe.

  Germany’s anti-Semitism had been very much alive even before Hitler came to power. There were few signs of such sentiments in Italy, generally regarded as the least anti-Semitic of all large European countries. Part of this may be due to the general tolerance exhibited by Italians, but it is also true that Italy’s Jews, who numbered approximately fifty thousand, represented a far smaller percentage of the population than in most of those other countries, a tenth of what it was in Germany.

  Mussolini’s launching of an anti-Semitic campaign in July 1938 therefore took his compatriots by surprise. Many thought he was simply bowing to pressure by the Führer, but there is little evidence of this; it appears to have been entirely Il Duce’s initiative.

  His initial salvo came in the form of an order from the Ministry of the Interior: the Central Demography Office was to change its name to the Office of Demography and Race and to immediately take a census of all Jews in Italy. The Manifesto degli Scienziati Razzisti (Manifesto of the Racial Scientists) appeared in mid-July 1938. This document, claiming that a pure Italian race did not include Jews, was apparently mainly written by Mussolini. It was followed a month later by the first publication of a slanderous national biweekly, Difesa della Razza (Defense of the Race), a small but virulent anti-Semitic publication.