The Pope of Physics

by Gino Segrè

  Three years later, Enrico went back to Italy as well. It was an emotional trip for him. Although he was firmly embedded in America, Italy would forever be close to his heart, the country where his roots were. He had seen his homeland go astray and then be devastated by a war in which he fervently hoped Mussolini’s government would be defeated. But he had also been apprehensive about what might happen there in the immediate postwar period. Accordingly, in a rare act of self-motivated political concern, Fermi had written in October 1946 to the United States secretary of state James Byrnes regarding his worry that in Italy “forces that tend to make the situation unstable are dangerously strong.”

  Though this was unstated, Fermi had clearly been troubled that the Communist Party, then part of the coalition government, might take control of the country. Fermi modestly added that he doubted this threat would be news to Byrnes, “but my knowledge of Italy where I was born and where I lived until seven years ago may make it of some interest to you to hear my views” and urged the secretary of state to “encourage the democratic forces in Italy.” In the same letter, he made a plea for ascertaining the fate of Italian Jews who had been rounded up in 1943, deported to Germany, and never heard from. That referred to—among others—Laura’s father. Fermi concluded his letter by saying, “I believe that any help that the United States can give Italy … would strengthen enormously the chances that Italy may settle in a stable democratic form of government.”

  When Fermi went back to his homeland in 1949, he felt the gravest danger was over. Though Italy would not be admitted to the United Nations until 1955, it had returned to relative stability, making Fermi eager to support its rebuilding of physics.

  His first Italian stop was the tranquil retreat of Como, showing no scars of the brutal war, its beauty preserved. Hillsides dropped steeply down, joining the thirty-mile-long lake, strikingly blue against a backdrop of the Alps. Memories flooded Fermi’s consciousness when he thought back about the international Volta conference, a turning point in his career. Enrico had been thrilled to hear talks by iconic physicists of that time, Niels Bohr and Arnold Sommerfeld, the latter recognizing the young Fermi’s promise. After faint acknowledgment on the Italian stage, Enrico’s confidence had been seriously boosted by this explicit endorsement on the international stage. Sommerfeld’s approval had been reinforced many times over by Enrico’s extraordinary contributions to physics.

  The 1949 conference focused on cosmic rays, of considerable interest to Fermi and an Italian specialty in the immediate postwar years. The literal high point of the conference was a special excursion to the new Italian cosmic ray observatory located on a high plateau between the Cervino (the Italian name of the Matterhorn) and Monte Rosa. Furthermore, reaching it required going through Champoluc, the village he and Laura had chosen for their honeymoon twenty-one years earlier.

  The conference also provided an almost complete reunion of the Boys of Via Panisperna since Edoardo Amaldi, Bruno Pontecorvo, and Emilio Segrè were attending. This gave them a chance to discuss a nagging question. They, along with Franco Rasetti, had discovered in 1934 the effect of using slow neutrons to study nuclear structure. The Boys, at the urging of their mentor Orso Corbino, had filed an Italian patent on the technique they developed, subsequently extending the patent to other countries including the United States. After the war, slow neutrons had proved to be central to nuclear power production and had significant military applications. The patent was valuable.

  Fermi, who had been the chief inventor, was the paramount figure in patent negotiations over just compensation. To his considerable annoyance, U.S. government lawyers asserted that Fermi’s presence on the Atomic Energy Commission’s GAC, even though unpaid, created a conflict of interest for him and the other patent claimants. Negotiations were drawn out and arduous. Fermi would have been content to let the matter drop. He had not taken patents out on any of his later discoveries at Columbia or Chicago. But he felt obligated to assert the rights of his Italian co-inventors of the slow neutron technique. And he resented the tactics of zealous lawyers who maneuvered their way around mandated patent laws.

  The claim was further complicated in 1950 when the story took on a new twist. Pontecorvo mysteriously disappeared, apparently having fled to the Soviet Union. Since he had always seemed apolitical, this came as a total surprise. A patent claim being argued in the United States legal system was made even more convoluted by one of the claimants being a defector, a presumed Communist. After much legalistic wrangling, the claim was finally settled in 1953 with the distribution of modest compensations. A spinoff of the whole unpleasant process was Fermi’s renewed disillusionment with politics, especially with serving on government advisory boards. On August 1, 1950, he declined reappointment to the GAC, a post he had held since January 1, 1947.

  Once the Como conference was over, Fermi traveled to Rome to reunite with his sister, Maria, now a widow with three children. He learned more about the attempts she had made to save Admiral Capon and also how, during the horrendous Nazi raids of October 1943, she had hidden six Jews in her small house: two teenage boys, a mother with a small child, a middle-aged lady, and an old man. Enrico admired her greatly. He also took the opportunity to explain his involvement in making the bomb. Her issue, as she had articulated in a 1945 letter to him, was that it was dropped on innocent populations. Enrico seemed inured to the criticism and tried, with limited success, to minimize his role in that decision.

  The highlight of Fermi’s Italian visit was a two-week cycle of nine lectures, the first six delivered in Rome and the last three in Milan. His impending visit was publicized extensively and enthusiastically in the press and newsreels. The prodigal son was returning. Emotions ran high in the large audience attending his first talk on October 3 at the University of Rome’s huge lecture hall, the Aula Magna. When Guido Castelnuovo, old and frail, rose to his feet to introduce Fermi, the animated crowd quieted.

  Castelnuovo was the last survivor of the four great Rome mathematics professors who had offered a strong welcome to Fermi when he arrived in Rome in the early 1920s. The warm reception had been important for the young Pisa graduate’s morale. And Castelnuovo had been a good friend of Admiral Capon, Fermi’s father-in-law and a fellow Venetian: it was Castelnuovo’s daughter Gina who had introduced her friend Laura to young Enrico.

  During the Nazi occupation of Rome, Castelnuovo had barely escaped Capon’s fate, doing so by hiding under an alias. In 1938, the four Roman mathematicians from that earlier day, and all other Jewish members, had been expelled from the century-old Accademia dei Lincei, the Italian society of notable intellectuals Mussolini had proceeded to abolish. With the war over, the Accademia was reestablished and Castelnuovo, pointedly, was chosen as its head. His task was to officially greet Fermi after an absence of more than a decade.

  Castelnuovo’s 1949 message to the physicists underscored that Fermi’s visit was “demonstrating his interest in the young school of Italian physics to which he had given its first impulse.” It was time to rebuild Italian physics. Rising to the occasion, Fermi gave a brilliant series of lectures on contemporary topics in physics. It was a remarkable display of omniscience and virtuosity. All the more impressive was that Fermi had worked in recent years on each of the topics, unfailingly opening windows to the future.

  Fermi gave the last of his cycle of nine lectures on the twenty-first of October. His reentry to Italy had been a resounding success by any measure. But it also underlined his deep-seated Americanization, despite the country’s flaws. He was happy to return to Chicago. Five summers would pass before he came back to Italy. Meanwhile, he resumed his yearly summer visits to Los Alamos.

  The Atomic City on the mesa had changed in tenor. No longer an army post, temporary housing was being replaced by permanent structures. A state-of-the-art high school was built in 1946. Grocery stores were well stocked, and an ice cream parlor proudly advertised thirty-seven different flavors. It was beginning to look like a typical American
town.

  After the war, the laboratory had undergone a period of crisis. Most of the key personnel who had worked on the bomb had left, although many of them—like Fermi—had returned for summers. The lab had diversified somewhat, but its mandate to build an arsenal of nuclear weapons was primary. As the Soviet threat deepened and the Cold War took shape, this mission intensified.

  Fermi was matter-of-fact about the laboratory’s purposes. Unlike other elite scientists who had worked on the bomb, he did not subsequently join—much less establish—any antinuclear groups. Fermi was not opposed to weapon development, even though he advocated for further efforts at international control of nuclear weapons.

  The year 1953, Fermi’s last summer in Los Alamos, was bookmarked by two significant but seemingly unrelated occurrences. Toward its beginning, he had been once again reluctantly dragged into the political arena, elected to a one-year term as president of the American Physical Society. He expected the role to be largely ceremonial but, with America at the height of the McCarthy frenzy, he found himself repeatedly defending physicists against witch hunts. The best known of these began toward the end of 1953.

  On December 21, J. Robert Oppenheimer, while he was director of the Princeton Institute for Advanced Studies—although still a government consultant—was shaken by the news that his security clearance had been suspended, presumably because of his earlier left-wing and Communist affiliations and his opposition to the development of the H-bomb. Confident of his loyalty to America and of his record of leadership, Oppenheimer requested hearings be held by the Atomic Energy Commission. He felt that otherwise his reputation would be tarnished. Fermi knew that were he called to testify at the hearings, he would do so unequivocally in Oppenheimer’s favor. However, a colleague in Chicago who was having lunch with Fermi on the day they heard the news recalled Fermi’s saying, “What a pity that they attacked him and not some nice guy like Bethe. Now we all have to be on Oppenheimer’s side.”

  Although appreciative of Oppenheimer’s contributions, Fermi—a self-made physicist from modest stock—was not a fan of the man he referred to as “born with a golden spoon in his mouth.” The reasons for Fermi’s coolness toward Oppenheimer are easy to imagine. The physicist Robert Wilson, who knew both, once compared the two. He described Oppenheimer as having a “personality crisis” every five years: “When I knew him at Berkeley he was the romantic, radical bohemian sort of person, a thorough scholar. Then at Los Alamos, he was the responsible, passionate leader that we all knew so well and was so effective. Later on he had another metamorphosis, becoming the high-level statesman who would call Acheson by his first name.”

  Wilson’s description of Fermi conveys a very different persona: “Fermi, on the other hand, I never knew him to change, from the time I, as a student had seen him, to the time at Columbia, when I was involved in a collaboration with him, to the time at Los Alamos, to the time after that. It always seemed that Fermi was Fermi!” Oppenheimer and Fermi were both inspirational leaders, albeit in different ways. And, while certainly respectful, they were never comfortable with the other’s approach to life or to physics.

  The physics community reacted to the news of the hearings with shock. Oppenheimer was highly regarded by most of his peers, but within that group he had enemies, none more insistent and influential than Edward Teller. Teller had long been jealous of Oppenheimer’s popularity and by 1954 wanted to “defrock him in his own church.”

  The hearings began on April 12 and lasted four weeks. Fermi’s testimony, on April 20, expressed no ambiguity in his defense of Oppenheimer. Teller was another matter, giving damaging testimony on the twenty-eighth. At first he intoned, “I would like to see the vital interests of this country in hands which I understand better, and therefore trust more.” When pressed, Teller asserted that “it would be wiser not to grant clearance.” The ruling was announced by the AEC on June 30: Oppenheimer’s security clearance was revoked. The physics community was aghast and largely ostracized Teller from then on. Their supportive feelings toward Oppenheimer were reflected in a quip by the rocket scientist Wernher von Braun: “In England they would have knighted him.”

  More was at stake than the fate of one man. Fallout from the hearings led to a new chapter on the relationship of scientists to government. Fermi had always sought to narrowly define his participation in government by focusing on technical matters. But others had quite comfortably bridged scientific and political spheres, seeing themselves as ordained to the “public-policy priesthood.” That time had come to an end.

  39

  LAST GIFT TO ITALY

  (Ultimo Regalo all’Italia)

  In his role as president of the American Physical Society as well as on a personal level, Fermi was extremely upset by the Oppenheimer proceedings. America seemed to be taking a turn for the worse, McCarthyite hysteria conjuring up echoes of Fascist Italy. And he saw the emotional and physical price that the debacle had exacted from Oppenheimer. Adding to his distress was that Fermi regarded himself as a good friend of Teller’s and bemoaned Edward’s damning testimony.

  Fermi welcomed the fact that coincidentally he had made plans to return to Europe in the summer of 1954. Luckily for him, Los Alamos would not be his usual destination; it was inevitable that conversations there would be dominated by what happened at the Oppenheimer hearings. He and Laura arrived in Paris on July 1 and spent a few days with their old Los Alamos neighbors Stan and FranÇoise Ulam in southern France. Ulam noted that his friend did not look well and was having trouble with his digestion. Laura thought it was probably due to overwork and tensions from the Oppenheimer hearings. She was hoping a break would do him good.

  Fermi’s plans for the summer were to teach at two physics schools, both times giving lectures to thirty or forty advanced students or recent Ph.Ds. The first lecture was held at the Les Houches school, located in a village perched on a high Alpine meadow at the foot of Mont Blanc. The site afforded a magnificent view of the mountains and the whole valley of Chamonix, the busy resort center four miles away. The housing was in simple mountain chalets and the lectures were delivered in a converted barn.

  The work schedule was intense but fortunately there was time for hiking. On the fourteenth of July, the French national holiday commemorating the storming of the Bastille, there were no lectures. Knowing of Fermi’s interest in cosmic rays and his appreciation of the local scenery, the school’s directors arranged for him and three others to have a special excursion to the French observatory near the top of the Aiguille du Midi, one of the needle-like peaks in the Mont Blanc massif.

  The journey upward was an adventure: the present enclosed cable car lift had not yet been built. All that was available was a bucketlike carrier used for hauling supplies and construction workers. It was barely large enough for the four passengers crouched on its floor. As they entered the clouds, Fermi “smiled archly, saying he understood how angels felt.” The Pope then “began singing the only hymn he knew: ‘Mine eyes have seen the glory…’” Both the ascent and descent went smoothly, and the group returned safely to Les Houches.

  Leaving the French Alps for Italy, the Fermis arrived on the eighteenth of July in Varenna on the familiar shores of Lake Como, where the second summer school took place. Today it is known as the Enrico Fermi International School of Physics. Meetings are held in the beautiful Villa Monastero, whose grounds are enchanting. A carefully tended formal garden has wide steps leading directly to the water’s edge, inviting attendees for an afternoon swim. Fermi regarded it as perfect.

  Fermi acted as teacher and critic. This was particularly important in the school’s final lectures, devoted to the topic of future particle accelerators. Recovered from the ravages of World War II, European economies were beginning to thrive. The continent was preparing itself for a renaissance in science, with high-energy physics a paramount focus.

  CERN, a symbol of European unity for nuclear research based in Geneva, was taking the lead. Edoardo Amaldi was one of its prin
cipal proponents and ardently spoke in Varenna about its progress. Hearing him, Fermi fondly remembered his good friend’s visit to Chicago in 1946, when he offered Amaldi a professorship at the university. A serious lure had been the prospect of building a large cyclotron, the kind the two of them had envisaged in Rome years before. Now Europe was embarking on the quest to build bigger, more powerful accelerators. Fermi even joked about a giant one that would circle the entire earth, calling it a Globatron. Had he lived to see CERN’s Large Hadron Collider, the world’s largest particle accelerator, he would not have been altogether daunted by it or its discoveries of new particles, such as the Higgs boson.

  But in 1954, accelerators were still relatively small, their future often the subject of rival national interests. Within Italy, the competition for a potential site to build an accelerator had been whittled down to either Frascati, just outside Rome, or to Milan. After Frascati was chosen, Pisa, an initial competitor, found itself with unallocated funds that had been earmarked. That is where Fermi came in.

  When asked by leading Italian physicists how to spend the funds, Fermi advised developing a large computer. Having witnessed the computer’s capabilities in Los Alamos, he considered this the wave of the future. Fermi also wrote a letter to the Rector of Pisa assuring him that such a computer “would constitute a means of research from which all the sciences and all avenues of research would gain in an inestimable way.” This pivotal recommendation was referred to as Fermi’s “ultimo regalo all’Italia” (last gift to Italy).