The Pope of Physics

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The Pope of Physics Page 7

by Gino Segrè


  Everybody, parents included, trusted him to make the best decisions about excursions. He would pick the day’s route, make sure all the hikers had what they needed, and see to it that the youngest hikers were not too heavily burdened. Fermi’s knapsack was always by far the heaviest. Acting the role of mountain guide, he invariably took the lead and watched for trouble spots, not an infrequent circumstance on the Dolomites’ tricky scree slopes. When one came along, he helped whoever needed a hand.

  After that summer, Laura was delighted to learn that Fermi had been appointed to a professorship in Rome. The two could continue to see each other in the environs of the busy city. When summer again came in 1927, Laura returned with her family to the Dolomites, the scene of her budding courtship with Enrico. He returned as well.

  Fermi fit nicely into the Capon family mix. The Capons were upper-class, but their standing was based on achievement, not inherited wealth or rank. Fermi felt at ease with them and they, in turn, were not skeptical of Laura’s choice of a suitor, although he was not Jewish and not raised in their socioeconomic bracket.

  Though both Fermi and Laura had grown up in Rome, their circumstances differed considerably. The Capons lived in a house located not far from the Fermis’, but their beautiful garden-enclosed villa had little in common with the apartments Enrico had inhabited. The Capons had servants to take care of household affairs, slept on ironed linen sheets, went on expensive vacations, and always spent a few weeks in the fall at Laura’s aunt and uncle’s imposing country residence in the hills above Florence.

  At the end of the summer, Laura began her customary stay with her Florence relatives. It afforded her on this occasion a chance to quietly study for university exams later that fall, a time when many Italian university examinations were given. Laura had just finished her second year in Rome’s university, having chosen general science as a major. Though the major did not involve an intensive study of physics, it did require attending Orso Corbino’s introductory course and gave her at least some feeling for Fermi’s vocation.

  In early September, Fermi had departed for the Como conference that became so pivotal to his international recognition. Both of them sensed that their separation would not be for long. After more than a year of knowing each other, their romance had blossomed. Later that month, Laura remembered, she was disappointed upon learning that Fermi had purchased an automobile, since he had laughingly told friends he intended to do something crazy, either get married or buy a car. But just as with his decision to be either a theorist or an experimentalist, he soon did both.

  The car, an egg-yolk-colored Bébé Peugeot two-seater convertible with a rumble seat, added a certain zest to Laura and Enrico’s courtship as well as a degree of uncertainty, because the Bébé was unreliable. Fermi always kept the hand crank by his seat to start the car and hesitated to take it for long trips. For Sunday excursions in the countryside, Franco Rasetti, who had a similar car, provided backup for automotive mishaps. It was fun for everyone.

  Laura appreciated the closeness of the bond between Fermi and Rasetti though she could not help but notice their dissimilarities. While Fermi delighted in female company, Rasetti seemed not to care much about girls even though they were attracted to him. Laura commented that he examined girls with “dispassionate detachment, bending his head to one side for a better view, with narrowed eyes behind his glasses. He examined them, dissected them with his piercing look, as if they were rare butterflies or strange plants.” Fermi’s musings on the female species were more forthright. He had told Laura that he sought a wife who was blond, tall and strong, and from “country stock.” Laura met no part of that profile.

  Although close, Fermi and Rasetti diverged in other ways as well. Fermi was rapidly moving toward bourgeois values; Rasetti continued to be something of a loner, still living with his mother. For Fermi, the days of throwing cats in the air during a lecture or of setting geckos free to scare a cook were over. His penchant for pranks had changed into a kind of good-natured humor.

  Undoubtedly Laura affected Fermi’s demeanor and contributed to his general happiness. He much admired her wit, intelligence, and casual elegance. Nor was he insensitive to her beauty. Leona Marshall, a co-worker of Fermi’s fifteen years later, remembered her own reaction to meeting Laura: “When I first met her in 1942, I thought her the most beautiful lady I had ever met.” When Marshall commented to Fermi on his wife’s beauty, she writes: “Enrico caught his breath and told me I could have no idea how beautiful the teen-age Laura was.”

  Laura had been seventeen years old when she and Enrico first briefly met. He was obviously smitten. Those feelings began to be reciprocated two years later, in the summer of 1926. Admittedly Fermi did not come from a prestigious background, but that was more than made up for by the brilliant future toward which he was obviously heading. As Gina Castelnuovo had first said to Laura, everybody knew he was “the hope of Italian physics.” When Enrico proposed marriage, Laura accepted.

  Although enamored of him, Laura found one trait of his annoying. It was her husband-to-be’s insistence on repairing everything he thought needed repairing without asking for help from anybody else. Fermi ascribed the attribute to his mother. He told Laura about how his mother had contrived to fix a pressure cooker, creating her own version in the process. As he explained to Laura, “If she wanted something, she would make it for herself.” Having observed this at an early age, the son followed in his mother’s footsteps.

  This trait emerged inconveniently on Enrico and Laura’s wedding day. Fermi was late for their departure for City Hall, located on top of the Capitoline steps. When Laura nervously asked about what had delayed him, the groom told her that when he unpacked a new shirt, he discovered the sleeves were too long. Instead of quickly pinning them up, he had painstakingly sewn a fold in them.

  A photo of the wedding party includes friends and family: Corbino and Rasetti were among the twenty-five stylishly attired witnesses attending the ceremony. On an oppressively hot day, women wore fashionable hats and flapper-style dresses. Laura, in a scalloped dress, stood elegantly next to her beloved, their arms locked, revealing Fermi’s long white shirt covering his wrist. His efforts at shortening his sleeves had not been altogether successful. But the dominant figure in the photo is Laura’s father, the admiral, whose height and dashing uniform set him apart from the others. He is clad from head to toe in white, from a jaunty officer’s hat to spotless white shoes.

  Fermi could not help thinking of when, less than a year earlier, he had been atop the Capitoline steps. At that time, he was among those greeted by Mussolini after the Como Congress, where he had been in effect anointed as a physics genius. His marriage to Laura was an anointing of another kind. The only cloud in the sky on that July day in 1928 was the dark cloud of Il Duce on those same Capitoline steps in September 1927. Little did the wedding party realize how the Fascist dictator would soon change their lives.

  The ceremony had gone smoothly. There was only a civil wedding, since the Capons were secular Jews and Fermi a nonbeliever like his parents. Only Fermi’s sister, Maria, a deeply pious Catholic, minded the lack of a religious rite. As soon as Laura and Enrico were declared man and wife, Fermi’s best man, Corbino, came over to Laura, kissed her hand, and said, “Congratulations, Mrs. Fermi.”

  That afternoon Laura and Enrico boarded a two-engine seaplane that flew to Genoa. Commercial aviation had started in Italy only two years earlier, so this was an adventure. From there they boarded a train and were off for their honeymoon in an Alpine valley lying between the Matterhorn and Monte Rosa. Not quite twenty-seven, Fermi now had a wonderful wife, a professorship in Rome, a thriving career, and even a semifunctional car. It was remarkable to think that only six years earlier he had been an impoverished Pisa student with an indeterminate future.

  PART 2

  PASSAGES

  10

  THE BOYS OF VIA PANISPERNA

  The Colle Viminale (Viminal Hill), one of ancient Rome’s pro
verbial seven hills, rises gently from the flat expanse linking the Forum to the Colosseum. Via Panisperna, one of the many streets that wind their way up the hill, housed the Rome physics department when Fermi became a professor there in 1927. The department, its address at number 89A, lay in the midst of the rapidly growing capital. Rome had almost quadrupled in population since 1870, the year of Italy’s unification, a time when the city had only two hundred thousand inhabitants. The university had expanded accordingly, with most of the students locally based.

  The villa at 89A Via Panisperna, with three floors and a basement, was spacious enough to accommodate the physics department. Orso Corbino and his family lived on the third floor. The second floor held a well-stocked library and the research laboratories of the department’s three professors and their students. Classrooms and the shop occupied the first floor. The building had a serene atmosphere, in large part due to the palm trees and the bamboo thickets in the extensive garden surrounding it. A high wall shielded the plantings and villa from the noisy and dusty street and added to the semblance of an oasis of tranquility. As Emilio Segrè wrote, “I believe that everybody who ever worked there kept an affectionate regard for the old place and had poetic feelings about it.”

  Segrè, not a sentimental man, was clearly taken by this setting and all that it encompassed. At age twenty-two, he became part of an ambitious endeavor, nothing less than establishing Italian physics for the future. Fermi and Rasetti, both only twenty-six, had set the stage; they were building a unique research institute that would attract a top cadre of students. Segrè, a fourth-year engineering major at the university, would be the first to join them.

  The recruitment of Segrè was not sheer happenstance; it came about because of mountain climbing. This was an avocation he shared, it turned out, with Rasetti. When Segrè heard that Rasetti had come to Rome, he contacted him immediately. The man quickly came to fascinate the younger climber. Aside from being a first-rate mountaineer, Rasetti spoke many languages, was widely read, knew everything about insects and plants, was doing serious research in a burgeoning field, and was the best friend and co-worker of the reportedly extraordinary Enrico Fermi. Listening to Rasetti talk made physics seem much more enticing than engineering. But Segrè was cautious. Was there really a future in Italy for physics?

  An event in the summer of 1927 convinced him that there was. After having done a number of climbs together, Rasetti and Segrè set off in August for the Matterhorn, or the Cervino, as Italians call it. They ascended a ridge on the Italian side, known as a difficult route, and descended down the easier Hornli Ridge on the Swiss side. While on this expedition, Rasetti told Segrè he was planning to go afterward to a physics conference nearby at Lake Como. The conference, with many of the world’s eminent physicists present, promised to be a festive occasion, one honoring the hundredth anniversary of the death of Alessandro Volta. Rasetti, still a youngster, had not been invited but he didn’t anticipate problems in attending, at least the plenary sessions.

  The thought of seeing all the great men of physics excited Segrè and he decided that “by tailing Rasetti, who in turn was tailing Fermi, I might be able to go to some of the lectures and see what was going on.” For Segrè, “what was going on” became a turning point. He made up his mind to become a physicist, in no small part because of the prospect of an apprenticeship under Fermi and Rasetti.

  Fermi was hoping to draw other promising researchers to Via Panisperna, but didn’t quite know how to proceed. The indefatigable Orso Corbino helped him. During the previous spring he had paused in one of his lectures to second-year engineering students and a few general science students, including the future Mrs. Fermi. He announced that he was recruiting a brilliant young man named Enrico Fermi to the physics faculty in a few months. If any of them felt up to the challenge, Corbino was inviting them to participate in a field that was in the midst of a revolution. Great things were happening.

  One of the students who felt ready to accept the challenge was Edoardo Amaldi, age eighteen. Two years earlier Amaldi’s father, a well-regarded Rome mathematician, had taken the family for summer vacation to the Dolomites. There they joined the Castelnuovo circle of university mathematicians, including the Capons and Fermi. During that summer young Amaldi had gone on a number of hikes with Fermi and even on a long bicycle tour with him. Amaldi had been enormously attracted by the energy and joie de vivre of the new physics professor. Now, a little older and encouraged by Corbino, he was eager to shift from engineering to physics. The pattern of switching to physics that had begun with Rasetti after meeting Fermi was repeating itself.

  These four, Fermi, Rasetti, Segrè, and Amaldi, formed the nucleus of what came to be known as the Boys of Via Panisperna. The Boys stuck to the same basic Italian schedule: working five days a week from early in the morning until one, taking a two-hour break for lunch at home, returning to work at three, and then staying until seven or eight in the evening.

  There was one point of the workday that was sacrosanct. It occurred in the late afternoon, when the Boys would gather for an informal discourse by Fermi on a topic he chose or one that was perplexing the group. In his methodical way, Fermi would proceed, without consulting texts, to obtain all the formulas that might apply, solve the problem, and consider further questions. Fermi enjoyed this informal method of teaching and would continue to employ it throughout his life. His delivery was so smooth and seemingly effortless that students frequently did not realize how impromptu the session really was.

  On Saturday mornings, plans were made for the next week’s activities. Sunday was reserved for play: sometimes excursions into the Roman countryside, other times longer hikes in the nearby hills or trips to the beach at Ostia once the weather turned warm. Sunday outings were always group affairs for Fermi, but the members of the group varied according to who was in Rome and available for a daylong jaunt. In the early days, before he became a professor, the group might be his sister, Maria, Enrico Persico, and a few mutual friends. Later Laura, one or more of the Boys, and new friends might join. Arrangements were always flexible.

  The many photographs of the changing group have a common look: smiling men dressed in casual clothes and similarly smiling young women in skirts and fashionable 1920s cloche hats, wearing hiking boots instead of elegant shoes. Conversations during the outings often had a cheerful teasing tone as they urged one another on as to who could be sillier. Occasionally the subject turned to physics, though never related directly to the research the Boys were engaged in. That was reserved for the rest of the week.

  Playtime was not limited to Sunday day trips. During summer vacations, the Boys and their friends hiked in the Dolomites, and in the winter they skied in the Alps or the Dolomites, despite the scarcity of ski tows or lifts. Fermi, who loved all these activities, was an easy and sought-after companion. His piercing eyes shone with the intensity of his intellect, but his easy smile invited close friendships.

  A merry mood and close camaraderie prevailed in Via Panisperna. One aspect of this was the bestowing of nicknames. This being Rome, several of them received ecclesiastical monikers. Fermi, regarded as infallible, was Il Papa (the Pope), and Rasetti was addressed as Cardinal Vicario (Cardinal Vicar), a nod to his position as Fermi’s right-hand man. Segrè’s judgmental disposition led to his being known as Basilisco (Basilisk), the legendary reptile capable of causing death with a single glance. Amaldi, with his youthful, cherubic, rosy face, was Fanciulletto (Young Boy). And then there was Corbino, whose ability to perform miracles, chiefly the raising of funds and the creation of assistantships for his young protégés, earned him the title of Padreterno (God Almighty).

  The Boys of Via Panisperna, originally a four-member group, soon grew to include an unusual fifth, Ettore Majorana. Majorana’s brilliance had become obvious to his fellow students while he was studying for an engineering degree at the university. Segrè befriended the shy and self-deprecating young man and encouraged him to switch to physics. A short intervie
w with Fermi convinced Majorana. A relative loner among the Boys, Majorana became known as Il Gran Inquisitore (the Grand Inquisitor) for his terse and critical manner, applied to the research of others, but particularly to his own work.

  Il Gran Inquisitore rivaled Il Papa in the rapidity of his calculations. One day, at Fermi’s request, Majorana had examined a complicated equation to determine how much energy it would take to ionize an atom, that is, to remove its electrons. Fermi was trying to approximate it numerically. Over the next few days Majorana retreated and then returned to Via Panisperna to compare his answers to Fermi’s. To the astonishment of the Boys, Majorana had solved the equation analytically, his answer agreeing with Fermi’s numerical conclusions. Until then, they had thought nobody could rival Enrico.

  The paper Fermi wrote on this topic, applying statistical mechanics to atomic physics, was greeted with considerable approval. However, its acclaim was not as high as Fermi had expected. He soon learned that that was because almost identical results had been derived a year earlier by an Englishman named Llewellyn Thomas. Since Thomas’s paper had been published in the Proceedings of the Cambridge Philosophical Society, a journal unavailable in Italy, Fermi had not seen it. And so, just as he had previously scooped Dirac, Fermi was now the one to be scooped.

  Since the phenomenon of independent findings was common before the age of rapid communication, the discovery was credited to both men and hence goes by the name “Thomas-Fermi equation.” Having been scooped on this one occasion had a relatively small impact on Fermi, whose international reputation was growing. His career beginnings in Rome had been off to a strong start. Soon there would be other reasons to recognize the Pope.

  11

  THE ROYAL ACADEMY

  Though Fermi’s main emphasis was on research and teaching, he knew that he should reach out beyond the confines of Via Panisperna if he hoped to promote the growth of physics in Italy. He became active in the government’s National Research Council and served as an editorial consultant to the Enciclopedia Treccani, the Italian rival to the Britannica.

 

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