Richard Rhodes - The Making of the Atomic Bomb

Fermi was prepared because he had been organizing his laboratory for a major expedition into nuclear physics for more than four years. If Italy had been one of the hot centers of physical research he might have been too preoccupied to plan ahead so carefully. But Italian physics was a ruin as sere as Pompeii when he came to it. He had no choice but to push aside the debris and start fresh.

Both Fermi’s biographers—his wife Laura and his protégé and fellow Nobel laureate Emilio Segrè—assign the beginning of his commitment to physics to the period of psychological trauma following the death of his older brother Giulio when Fermi was fourteen years old, in the winter of 1915. 764Only a year apart in age, the two boys had been inseparable; Giulio’s death during minor surgery for a throat abscess left Enrico suddenly bereft.

That same winter young Enrico browsed on market day among the stalls of Rome’s Campo dei Fiori, where a statue commemorates the philosopher Giordano Bruno, Copernicus’ defender, who was burned at the stake there in 1600 by the Inquisition. Fermi found two used volumes in Latin, Elementorum physicae mathematicae, the work of a Jesuit physicist, published in 1840. The desolate boy used his allowance to buy the physics textbooks and carried them home. They excited him enough that he read them straight through. When he was finished he told his older sister Maria he had not even noticed they were written in Latin. “Fermi must have studied the treatise very thoroughly,” Segrè would decide, looking through the old volumes many years later, “because it contains marginal notes, corrections of errors, and several scraps of paper with notes in Fermi’s handwriting.” 765

From that point forward Fermi’s development as a physicist proceeded, with a single significant exception, rapidly and smoothly. A friend of his father, an engineer named Adolfo Amidei, guided his adolescent mathematical and physical studies, lending him texts in algebra, trigonometry, analytical geometry, calculus and theoretical mechanics between 1914 and 1917. When Enrico graduated from the liceo early, skipping his third year, Amidei asked him if he preferred mathematics or physics as a career and made a point of writing down, with emphasis, the young man’s exact reply: “I studied mathematics with passion because I considered it necessary for the study of physics, to which I want to dedicate myself exclusively …. I’ve read all the best-known books of physics.” 766

Amidei then advised Fermi to enroll not at the University of Rome but at the University of Pisa, because he could compete in Pisa to be admitted as a fellow to an affiliated Scuola Normale Superiore of international reputation that would pay his room and board. Among other reasons for the advice, Amidei told Segrè, he wanted to remove Fermi from his family home, where “a very depressing atmosphere prevailed… after Giulio’s death.” 767

When the Scuola Normale examiner saw Fermi’s competition essay on the assigned theme “Characteristics of sound” he was stunned. It set forth, reports Segrè, “the partial differential equation of a vibrating rod, which Fermi solved by Fourier analysis, finding the eigenvalues and the eigenfrequencies… which would have been creditable for a doctoral examination.” 768Calling in the seventeen-year-old liceo graduate, the examiner told him he was extraordinary and predicted he would become an important scientist. By 1920 Fermi could write a friend that he had reached the point of teaching his Pisa teachers: “In the physics department I am slowly becoming the most influential authority. In fact, one of these days I shall hold (in the presence of several magnates) a lecture on quantum theory, of which I’m always a great propagandist.” 769He worked out his first theory of permanent value to physics while he was still a student in Pisa, a predictive deduction in general relativity.

The exception to his rapid progress came in the winter of 1923, when Fermi won a postdoctoral fellowship to travel to Göttingen to study under Max Born. Wolfgang Pauli was there then, and Werner Heisenberg and the brilliant young theoretician Pascual Jordan, but somehow Fermi’s exceptional ability went unnoticed and he found himself ignored. Since he was, in Segrè’s phrase, “shy, proud, and accustomed to solitude,” he may have brought the ostracism on himself. 770Or the Germans may have been prejudiced against him by Italy’s poor reputation in physics. Or, more dynamically, Fermi’s visceral aversion to philosophy may have left him tongue-tied: he “could not penetrate Heisenberg’s early papers on quantum mechanics, not because of any mathematical difficulties, but because the physical concepts were alien to him and seemed somewhat nebulous” and he wrote papers in Göttingen “he could just as well have written in Rome.” 771, 772Segrè has concluded that “Fermi remembered Göttingen as a sort of failure. He was there for a few months. He sat aside at his table and did his work. He didn’t profit. They didn’t recognize him.” 773The following year Paul Ehrenfest sent along praise through the intermediary of a former student who looked up Fermi in Rome. A three-month fellowship then took the young Italian to Leiden for the traditional Ehrenfest tightening. After that Fermi could be sure of his worth.

He was always averse to philosophical physics; a rigorous simplicity, an insistence on concreteness, became the hallmark of his style. Segrè thought him inclined “toward concrete questions verifiable by direct experiment.” 774Wigner noticed that Fermi “disliked complicated theories and avoided them as much as possible.” 775Bethe remarked Fermi’s “enlightening simplicity.” 776Less generously, the sharp-tongued Pauli called him a “quantum engineer”; Victor Weisskopf, though an admirer, saw some truth in Pauli’s canard, a difference in style from more philosophical originals like Bohr. 777“Not a philosopher,” Robert Oppenheimer once sketched him. 778“Passion for clarity. He was simply unable to let things be foggy. Since they always are, this kept him pretty active.” An American physicist who worked with the middle-aged Fermi thought him “cold and clear…. Maybe a little ruthless in the way he would go directly to the facts in deciding any question, tending to disdain or ignore the vague laws of human nature.” 779

Fermi’s passion for clarity was also a passion to quantify. He seems to have attempted to quantify everything within reach, as if he was only comfortable when phenomena and relationships could be classified or numbered. “Fermi’s thumb was his always ready yardstick,” Laura Fermi writes. “By placing it near his left eye and closing his right, he would measure the distance of a range of mountains, the height of a tree, even the speed at which a bird was flying.” 780His love of classification “was inborn,” Laura Fermi concludes, “and I have heard him ‘arrange people’ according to their height, looks, wealth, or even sex appeal.” 781

Fermi was born in Rome on September 29, 1901, into a family that had successfully made the transition during the nineteenth century from peasant agriculture in the Po Valley to career civil service with the Italian national railroad. His father was a capo divisione in the railroad’s administration, a civil rank that corresponded to the military rank of brigadier general. In accord with a common Italian practice of the day, the infant Enrico was sent to live in the country with a wet nurse. So was his brother Giulio, but because Enrico’s health was delicate he did not return to his mother and father until he was two and a half years old. Confronted then with a roomful of strangers purporting to be his family, and “perhaps,” writes Laura Fermi, “missing the rough effusiveness of his nurse,” he began to cry: 782