HE WAS BORN IN ROME, ITALY, ON SEPTEMBER 29, 1901, AND died in Chicago, Illinois, on November 28, 1954. His life spanned two world wars, and though he was too young to participate in the first, his contribution to the outcome of the second was pivotal and made him world famous. His life also spanned the two major intellectual revolutions of the twentieth century—relativity and quantum theory—and though his contributions to the first were notable, his contributions to the second established him as one of the greatest scientists of his day, indeed, one of the greatest scientists of all time.
To no one’s surprise he won a Nobel Prize in 1938.
He made friends easily and inspired passionate loyalty. Those who knew him wept openly when they learned of his premature death at the age of fifty-three. Newspapers around the world carried his death on their front pages, befitting his status as one of the most famous scientists of his day.
His name was Enrico Fermi.
THE ARC OF HIS LIFE IS QUICKLY SUMMARIZED. BORN IN ROME AT the turn of the century, he was a child prodigy, and by the time he arrived at university he had mastered all of classical physics. Because no one in Italy was teaching relativity or quantum theory, Fermi spent his university education teaching himself these subjects; when he graduated he had already published in professional journals. After graduation he studied briefly in Germany and in Holland, returned to the University of Rome for a period as a lecturer, and then won a position at the University of Florence, where he made his first, and some say most important contribution—a method to bring quantum mechanical rules into the field of statistical mechanics. Two years later he won a competition for a professorship in theoretical physics at the University of Rome under his powerful mentor, Orso Mario Corbino. He built one of the major international schools of modern physics and made several extraordinary contributions: a theory that explains a puzzling type of radioactive process called “beta decay”; the discovery that certain elements, when bombarded with neutrons, become radioactive; and the discovery that the intensity of this induced radioactivity increases when the neutrons are slowed down prior to hitting these elements.
He chose the opportunity of his Nobel Prize in 1938 to leave fascist Italy via Stockholm for a faculty position at Columbia University. Shortly thereafter he learned, to his astonishment and embarrassment, that German scientists replicating his 1934 experiments bombarding uranium with neutrons concluded Fermi had been splitting uranium atoms without knowing it. With this knowledge, he and Hungarian émigré Leo Szilard began to explore the possibility of creating a sustained nuclear chain reaction with uranium. After moving the project to the University of Chicago at the request of the US government, Fermi and a large team of fellow physicists and others succeeded in doing so on December 2, 1942, officially ushering in the nuclear age. He was a central figure in the design of plutonium production reactors for the Manhattan Project and in the summer of 1944 moved to Los Alamos, where the first atomic bombs were designed and built. He played a key role in solving the many theoretical and practical problems involved in this final phase of the Manhattan Project. He witnessed the first detonation of an atomic bomb, known as the Trinity test, at Alamogordo, New Mexico, on July 16, 1945.
After the war, Fermi returned to the University of Chicago, where he continued research in nuclear physics and pioneered high-energy physics experiments on Chicago’s new particle accelerator. He spent summers at Los Alamos working on the hydrogen bomb, known as “the Super,” and pioneering the use of computers for simulating complex physics problems. He also studied cosmic rays and astrophysics and took on a full teaching load at the University of Chicago, eventually advising a string of future Nobel laureates and many others who went on to brilliant, high-profile careers. During this period, he advised the US government on all aspects of nuclear technology policy and came to the defense of his Manhattan Project colleague J. Robert Oppenheimer during 1954 hearings on the latter’s security clearance. Fermi died of stomach cancer in November 1954 at the age of fifty-three, leaving behind an indelible mark on virtually every aspect of physics.
THESE ARE THE FACTS ON WHICH ALL AGREE. SEARCHING FOR A richer portrait, one comes across the inevitable outliers. One author portrays him as a “puerile” prankster consumed by jealousy of his more brilliant student Ettore Majorana. Another paints the picture of the greatest scientist in Western history. The consensus not surprisingly lies somewhere in between.
In his youth he was fond of the occasional juvenile prank, but he matured out of this well before he left Rome for the United States. Far from impeding Majorana’s career, Fermi strongly promoted the brilliant introvert’s groundbreaking work.
Fermi was certainly an extraordinary physicist, one of his generation’s greatest, but to argue that he was history’s greatest reflects more the passion he could inspire in those who worked with him than it does his actual place in history.
He had a formidable power of physical intuition and a disciplined, methodical technique that allowed him to crush physics problems in ways that amazed and awed his colleagues. He had a charisma that defies easy analysis—modest, yet fully aware of his superiority over most of the physicists with whom he worked, personally reticent and yet highly gregarious, able to discern the objective and lead others relentlessly toward it, blunt but never nasty, and capable of a self-deprecating wit that immediately put people at ease. No other physicist has ever received such affectionate postdeath tributes. One looks in vain for tributes to other physicists that compare to To Fermi with Love, a two-record set of reminiscences by those who worked with him at Argonne Labs outside Chicago, or The World of Enrico Fermi, the Canadian Broadcasting Company’s lovingly produced documentary of his life and times. Those who worked with him often jostled with each other to secure the mantle of Fermi’s legacy.
He could be collegial but was also highly competitive. Reminiscences from his students paint an inconsistent picture. Those from the early days in Rome speak of a man insensitive to the career difficulties of those around him and completely disinterested in their personal travails. Those who studied with him in Chicago universally comment on his generosity of spirit and ability to connect with those around him and attribute their future successes to his fortuitous interventions.
In other words, the picture is a complex one, hardly surprising given that he was a complex individual in a highly complex world.
SOME WOULD ARGUE, AS DID HIS OLD FRIEND AND COLLEAGUE ISIDOR Isaac (I. I.) Rabi during an interview for the CBC documentary, that the only thing interesting about Fermi was his science, that beyond the science the details of his life are trivial and not worth exploring. Although this is a common view among scientists, who tend to view scientific achievement as distinct from the individual who achieved it, it misses the point. The circumstances of Fermi’s life determined much of what he achieved, and had the chips fallen some other way, his career—and our world—would be different. If Laura had agreed to move to the United States when Fermi first wanted to in 1930, how different would have been the trajectory of his science? We can imagine his coming to the same conclusions regarding beta decay, but would his work on slow neutrons have proceeded the same way with a different, American team? Would that team have discovered fission in 1934, with the benefit of better (or luckier) radiochemists? One can imagine the arc of Fermi’s research altering considerably with an earlier immigration to the States, with unpredictable results. Perhaps he would have delved into high-energy particle physics earlier, although the accelerators available in the 1930s did not have the energy to explore the subatomic world that became the focus of Fermi’s postwar research in Chicago. Even as late as 1939, much of his research agenda seems accidental, particularly the odd set of circumstances that threw Fermi and Szilard together in an historic partnership beginning in early 1939. If in January 1939 Fermi had shown up in Ann Arbor instead of Manhattan, would Szilard have sought him out? Would Fermi have been a central player in the experiments leading to the first chain reaction?
All these questions are essentially imponderables. Still, the very fact that they are imponderable leads to the conclusion that, in common with all scientists of great stature, the specific circumstances of Fermi’s life had an enormous impact on his scientific career. So though one doesn’t need to know much about Fermi’s personal life to study his specific scientific achievements—it is possible, for example, to read the beta decay paper without having any insight whatsoever into the circumstances of its creation—it is incorrect to conclude that an understanding of Fermi’s life is irrelevant to our understanding of his life as a scientist. It is, indeed, essential to grasp the relationship of circumstance to scientific creativity and achievement, to comprehend how history, personality, and circumstance combine to shape the development of any particular scientific achievement. In another context, the British historian of science Charles Percy (C. P.) Snow put it succinctly when he wrote, “If Fermi had been born a few years earlier, one could well imagine him discovering Rutherford’s atomic nucleus, and then developing Bohr’s theory of the hydrogen atom. If this sounds like hyperbole, anything about Fermi is likely to sound like hyperbole.” Snow was alluding to Fermi’s brilliance, but this assessment underscores the importance of circumstance in the development of a scientific career. Yes, Fermi may have discovered the atomic nucleus, he may have thought of the Bohr model of the atom, but he never had the opportunity to do so because he was born two decades too late. We are all are prisoners of the era into which we are born, scientists being no exception.
THE RECEIVED NARRATIVE OF HIS LIFE RINGS TRUE, BUT IT OBSCURES as well as illuminates. Why is there such a difference between the memories of his Italian students and those of his American students, particularly in regard to Fermi’s willingness to encourage them and to promote their careers? Why did he remain so long in Italy, working under a thuggish, essentially evil regime? Was there a part of him that grudgingly supported the fascist dictatorship? Did he really decide to come to the United States only when Mussolini promulgated the anti-Semitic laws that would have targeted his wife? Was he an enthusiastic participant in the Manhattan Project, as so many of the histories of the period suggest? Or was he perhaps somewhat reluctantly pulled along by events out of his control? In October 1949, he was an outspoken opponent of the development of the hydrogen bomb, but by the summer of 1950 he was working intensively on the project. Why? Any biographer must grapple with these questions, even if there are, in the end, no clear-cut answers.
HIS FAME DIMINISHES, EVEN AS HIS LEGACY GROWS.
Perhaps the most enduring of his discoveries as far as the general public is concerned are those relating to his work on the atomic bomb, for which he earned the sobriquet “father of the nuclear age.” Even this, though, raises some important questions. The history of the Manhattan Project is the history of many thousands of scientists, engineers, soldiers, and others who had a hand in bringing about the development of nuclear weapons. Where the epithet most clearly fits is in his role in the development of the first nuclear reactors, devices that demonstrated the possibility of nuclear fission chain reactions that form the basis for nuclear explosions and that served as the production engines for plutonium, the element that formed the core of one of the two atomic bombs that ended World War II. These reactors were built in great haste, under enormous pressure, largely without well-formed engineering plans. Indeed, the first one, at the University of Chicago, emerged more or less fully formed directly from Fermi’s brain. In retrospect, the amazing fact is that they worked as anticipated and that the effort was scalable to a degree that astonishes engineers even today.
His role in the development of the atomic bomb itself is more difficult to assess, being that of a highly valued adviser rather than an architect or designer. In the traditional narratives he is overshadowed by the scientific director of the project, J. Robert Oppenheimer, a physicist as different from Fermi as it is possible to be. But when in the summer of 1944 the work at Los Alamos came to a grinding halt owing to unforeseen technical problems, it was to Fermi that Oppenheimer appealed, asking him to come to the secret city on a New Mexican mesa to help inspire and lead. Fermi did so effectively and without complaint.
For physicists, several of his other achievements rank far higher than those of the Manhattan Project, if not existentially then certainly scientifically. His success in integrating quantum rules into statistical mechanics, in what we now call Fermi-Dirac statistics, is the basis for virtually all condensed matter physics and much else besides. Fermi-Dirac statistics are, if anything, even more useful today than they were when they were proposed in 1926. His 1933 theory of beta radiation, though not considered precisely accurate today, gave rise to an enormous amount of fascinating research in particle physics, resulting in more than a dozen Nobel Prizes to date. After World War II his experimental work in high-energy particle physics helped to lay the groundwork for the quark theory of matter and the Standard Model of particle physics, producing another string of Nobel Prizes. Alone among his true peers, his expertise extended across both theory and experiment, a significant anomaly among world-class physicists. And though he may have had a handful of peers in either theory (Paul Dirac, Werner Heisenberg, Wolfgang Pauli) or experiment (Arthur Compton, James Franck, I. I. Rabi), in the art of teaching, he had none. Some five of his graduate students went on to win Nobel Prizes and several other future Nobel Prize winners thought of him as their primary graduate or postgraduate mentor. In terms of influence as a teacher and mentor, he was truly unique.
IT IS THIS COMBINATION OF LASTING SCIENTIFIC ACHIEVEMENT AND profound influence on several generations of physicists, in the United States and in Italy, that make his story directly relevant to us today. Underlying these achievements was a foundation built on enormous talent, but equally important, on a disciplined, almost terrifyingly comprehensive effort as a young man to teach himself all of known physics. During the period in which he laid down this awe-inspiring foundation, he also developed a unique way of thinking about problems that allowed him to achieve what he did and to inspire those around him. He learned at an early age how to strip a problem to its essentials and structure the solution in a straightforward manner, invariably starting at the right place and avoiding complications that might bedevil others. He used this technique in a wide variety of settings, notably in solving problems that now bear his name. “Fermi problems” can be simplified into a finite set of variables whose values can be estimated to within an order of magnitude. Linking those variables together not only provides a quick, rough-and-ready solution but also forces one to think about the elements of the problem that are essential and those that can be safely discarded. Fermi problems often have at their core estimates of the probability of one event or another occurring. This was the type of problem that Fermi excelled in solving, in part because during that formative period of his intellectual development he mastered probability and statistics as a central part of his scientific repertoire. Calculations of probabilities run like a bright thread throughout his work and at several crucial points in his career provided a focus for his most important breakthroughs—the Fermi-Dirac statistics, for example, or his later fascination with Monte Carlo simulations. This way of thinking, which he passed along to colleagues and students, is one of his greatest legacies. Recruiters at firms like McKinsey and Goldman Sachs pepper potential hires with Fermi problems to see how they think and probably never realize the debt they owe to this giant of modern physics.
Fermi’s ability to grind out solutions to difficult problems using a well-developed toolkit of techniques was paired with an extraordinary sense of what problems were important and an affinity for the quick-and-dirty solution when appropriate to his needs. The former set him apart from most of his contemporaries and ensured that he would be at the forefront of his field throughout his career. The latter was sometimes misinterpreted as laziness or, worse yet, a fear of complex mathematics. He was neither lazy nor afraid—he had enormous reserves of energy that drove him to work longer and harder than many younger colleagues, and he was a fine mathematician, able to hold his own with geniuses like John von Neumann—but he valued his time and chose to work only hard enough to get a practical solution. He once quipped to his daughter, Nella, “Never make something more accurate than necessary.” Offered in the context of some unattractive but functional carpentry for the living room of the family home, it was a philosophy that also guided him in physics.
HE MAY HAVE BEEN A WORLD-CLASS PHYSICIST, BUT HE WAS NOT A world-class family man.
As a husband he could be a frustrating and sometimes infuriating person to live with, as his wife Laura makes clear in her largely affectionate but sometimes arch account of their marriage, Atoms in the Family, published in 1954, just prior to his death. The incessant teasing, the long periods—sometimes months—spent away from her, his unwillingness to take her into his confidence during his work on the Manhattan Project all took their toll. Physics was the most important thing in his life and everything else took second place. Laura knew this when she married him, of course, and if she had any illusions to the contrary, they were shattered the afternoon during their honeymoon when he insisted on teaching her Maxwell’s equations. There is no doubt, however, that they loved each other and eventually accommodated themselves to each other’s idiosyncrasies, as most successful couples do.
He was also not the best of fathers. He helped Laura little in domestic matters relating to raising their children, and Laura seems not to have expected anything different. His daughter, Nella, had great affection for him, although even she admits he could be distant. His son, Giulio, chafed at living in his father’s shadow and ultimately put as much distance as possible between himself and his family legacy. Whether Fermi was any worse a father than other successful, driven men of the time is an open question. Parenting in the 1940s and 1950s was not the art it is today, and the profile we have of Fermi as a father is not substantially different from the profile of many others at that time. In his final years he took his parenting role a bit more seriously, but by then much of the damage had already been done. It was, to say the least, difficult being a child of Enrico Fermi.
THAT HE IS NOT BETTER KNOWN, THAT PHYSICISTS LIKE RICHARD Feynman and Stephen Hawking are more well known to the general public, may simply reflect the circumstances of his death in 1954 at an early age and before the widespread advent of television. Few films of his lectures survive, and his television appearances were rare. In later years he may have resented the adulation of Einstein, but in response he did little in the way of self-promotion. Not that he had any sense of false modesty. One of Fermi’s University of Chicago colleagues reported being told of the following conversation between Fermi and his brilliant but troubled graduate student Majorana:
MAJORANA: There are scientists who “happen” only once in every five hundred years, like Archimedes or Newton. And there are scientists who happen only once or twice in a century, like Einstein or Bohr.
FERMI: But where do I come in, Majorana?
MAJORANA: Be reasonable, Enrico! I am not talking about you or me. I am talking about Einstein and Bohr.
He had an enormous confidence in his own abilities, confidence that was well placed. Perhaps he felt that self-promotion was a bit unseemly. Though he sometimes loved to show off to his colleagues, deriving complex theorems from scratch when he could just as easily have looked them up, he did not have the compulsion, notable in some less secure geniuses, to always make sure that everyone knew he was the smartest guy in the room. His lack of self-promotion, particularly after World War II, may also have resulted from a belief that his proper focus was on his research and teaching and not on his public profile. To the extent that he was a public figure, it was as a private adviser to public bodies such as the US Atomic Energy Commission. He was one of the first major scientists involved in public affairs, but his advice was highly classified and remained so for years after his death. His involvement in these matters was fraught, involving him in controversies that pitted friend against friend. When Oppenheimer asked Fermi to continue advising the Atomic Energy Commission in 1951, Fermi demurred, convinced that he was better suited to a world in which truth was clear and where opinion mattered little.
Another reason for his relative lack of profile may have been his resistance to pronouncements on broader political or philosophical matters. After World War II many physicists raised their voices in public on issues related to the development of nuclear weapons and the accelerating arms race between the United States and the Soviet Union. Fermi rarely spoke publicly about such matters, reserving most of his commentary, such as it was, for private councils of state. Nor was he deeply philosophical, never pondering the underlying reality behind quantum theory, never engaging in the kind of metaphysical debate that characterized the schools of quantum theory that arose in Copenhagen and Göttingen. He confined his intellect to matters of physical reality and to physical problems that could be solved using the physics he so loved. Perhaps for this reason quantum theorist Wolfgang Pauli once quipped, in his typical, acid-tongued way, that Fermi was a mere “quantum engineer.” The general public is fascinated by the philosophical conundrums of quantum theory, but Fermi chose to ignore these in favor of focusing on real physics problems with solutions that could be developed clearly through theory and experiment. He was at core an empiricist, driven by the empirical observations of the world around him. Yet Fermi’s antiphilosophical orientation was shared by some, like Feynman, whose fame has only grown over time. Feynman’s wit, colorful story-telling, and involvement in the Challenger shuttle investigation have contributed to the mystique that still surrounds him. Biographers continue to find him a fascinating subject, as they do Einstein and Oppenheimer. In the case of Fermi, some forty-six years have passed between English-language biographies.
Fermi’s reputation with the public has faded for all these reasons and perhaps others as well. As others have recently realized, a correction is long overdue.
NO ONE REALLY KNOWS HOW GENIUS WORKS, WHY IT MANIFESTS IN some instances and not in others. Even more perplexing, why do some scientists make great discoveries and others do not? Why do some, like Einstein, Wolfgang Pauli, Marie Curie, John Bardeen, or Fermi himself, make several great discoveries, while other scientists with apparently equal talent, like Oppenheimer, have no such discoveries to their name? Fermi used a well-defined set of techniques to attack problems in physics, and if a problem came up that did not seem to fit any of these techniques, he bent the problem to succumb to them. There were, of course, hundreds of physicists who knew these techniques, but almost none of them were able to apply them with Fermi’s effectiveness. At some point early in his career, working almost entirely on his own, Fermi learned how to look at a problem carefully, find the right starting point to address it, and cut through it steadily with an enormously powerful intellect, avoiding all the false starts and dead ends that might trap less talented thinkers, to get at its solution. How he did this, how Fermi became Fermi, is in some sense perhaps an irreducible mystery. Nevertheless, it is one worth trying to solve, because understanding how a young boy from Rome became, in the words of one of his former students, “the last man who knew everything” can help us to appreciate the full potential of the human mind and spirit.