The Pope of Physics: Enrico Fermi and the Birth of the Atomic Age

The Pope of Physics: Enrico Fermi and the Birth of the Atomic Age

by Gino Segrè, Bettina Hoerlin


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Enrico Fermi is unquestionably among the greats of the world's physicists, the most famous Italian scientist since Galileo. Called the Pope by his peers, he was regarded as infallible in his instincts and research. His discoveries changed our world; they led to weapons of mass destruction and conversely to life-saving medical interventions.

This unassuming man struggled with issues relevant today, such as the threat of nuclear annihilation and the relationship of science to politics. Fleeing Fascism and anti-Semitism, Fermi became a leading figure in America's most secret project: building the atomic bomb. The last physicist who mastered all branches of the discipline, Fermi was a rare mixture of theorist and experimentalist. His rich legacy encompasses key advances in fields as diverse as comic rays, nuclear technology, and early computers.

In their revealing book, The Pope of Physics, Gino Segré and Bettina Hoerlin bring this scientific visionary to life. An examination of the human dramas that touched Fermi’s life as well as a thrilling history of scientific innovation in the twentieth century, this is the comprehensive biography that Fermi deserves.

Product Details

ISBN-13: 9781627790055
Publisher: Holt, Henry & Company, Inc.
Publication date: 10/18/2016
Pages: 368
Product dimensions: 6.20(w) x 9.40(h) x 1.70(d)

About the Author

Gino Segrè is a professor of Physics and Astronomy at the University of Pennsylvania. He has been a visiting professor at M.I.T. and Oxford University, chair of the Department of Physics and Astronomy at the University of Pennsylvania, and director of theoretical physics at the National Science Foundation. He is the author of several books of scientific history, Ordinary Geniuses, Faust in Copenhagen, and A Matter of Degrees.

Bettina Hoerlin taught healthcare disparities at the University of Pennsylvania for sixteen years. She also has been a visiting lecturer at Haverford College and Oxford University. Her career in health policy and administration included serving as Health Commissioner of Philadelphia. The author of Steps of Courage: My Parents’ Journey from Nazi Germany to America, she grew up in the Atomic City of Los Alamos.

Read an Excerpt

The Pope of Physics

Enrico Fermi and the Birth of the Atomic Age

By Gino Segrè, Bettina Hoerlin

Henry Holt and Company

Copyright © 2016 Gino Segrè and Bettina Hoerlin
All rights reserved.
ISBN: 978-1-62779-006-2



Enrico Fermi's ancestral roots can be traced to the valley of Italy's greatest river, the Po, whose origins lie in the western Alps. It flows from west to east, neatly bisecting Northern Italy, and finally empties into the Adriatic Sea. As it travels its four-hundred-mile course, it grows steadily in volume, fed by rivers coursing down from the Alps and from ones born in the central Apennine mountain chain.

The Po Valley, defined by its river, is agriculturally fertile and culturally vibrant. It is also Italy's economic center, thanks to large industries, but enriched by a wealth of small businesses that have adapted an older tradition of craftsmanship to the demands of the new commerce. Turin, the automotive home of Fiat, is located directly on the river. As it winds further, Milan, a center of style and fashion, is a little north, and Bologna, known for its culinary treats, a little south, of its course. Venice, an architectural wonder, is not far from the delta where the Po empties into the sea. These are the region's dominant cities, but there are a number of midsized ones with their own history and institutions.

In most cases this diversity comes from their ancient founding during the Roman Empire and sometimes even earlier, followed by an evolution during the Renaissance into independent city-states. What we currently call Italy, a country that came together only in 1870, was until shortly before then little more than a hodgepodge of smaller fiefdoms wavering opportunistically to and fro in their allegiances to larger European powers.

Piacenza, the ancestral home of the Fermis, lies in the midst of the Po Valley. It has a particularly impressive thirteenth-century city hall, but the town is largely neglected as a tourist attraction because it lies almost directly in the middle of a triangle formed by the better-known Parma, Cremona, and Pavia. Founded by the Romans in 218 B.C.E., the settlement was given the name Placentia, from the Latin placere, "to please." Through the following centuries, it did indeed please, and in doing so underwent the same cyclical sacking and rebuilding that its neighbors suffered.

In 1545 the Duchy of Parma and Piacenza was established. Except for a brief interlude during Napoleon's short-lived conquest of Northern Italy, it controlled the region surrounding those two cities until the formation of modern Italy. Shortly before that, the Fermis, a local family, made the transition away from tilling the soil. The man who would become Enrico's grandfather, Stefano Fermi, entered the employment of the state and rose to be administrative head of a small municipality adjacent to Piacenza.

Enrico Fermi's grandfather married Giulia Bergonzi, a woman thirteen years his junior, and began a large family; their second son, Alberto, would one day become Enrico's father. The fluid national identities that characterized the Italian peninsula in the first years after Alberto's birth in 1857 were such that he entered the world as a subject of the Duke of Parma and Piacenza, became a resident of the free territory of Emilia two years later and a citizen of the Kingdom of Sardinia a year after that, and finally, at age four, became an Italian. All this without ever leaving the vicinity of Piacenza.

In the 1840s, Alberto's father, Stefano, had settled with his wife in Caorso, a small municipality that lay eight miles east of Piacenza. Their life was a simple one, centering on family, work, and church. He and his wife, Giulia, almost certainly went occasionally to Piacenza, but they probably did not venture as far as Cremona, for though it was only eight miles west of Caorso, going there required crossing the Po and entering a different country.

Those borders vanished in 1861 with the emergence of the Kingdom of Italy. Stefano and Giulia hoped there would be opportunities for advancement in this new country, still woefully underdeveloped by comparison to those of Northern Europe. The Industrial Revolution had for all practical purposes bypassed the peninsula, and most of Italy's workers either labored on the land as they had for centuries or engaged in minor commerce. Nor was transportation very different from what it had been since Roman times, for there was little more than fifteen hundred miles of rail lines in the whole country, almost all of it north of the Po.

Education was viewed as providing a first step to bettering oneself. More than three quarters of Italy's population was still functionally illiterate. Many could read a little but, like Enrico's grandmother Giulia, had not learned to write, much less how to deal with arithmetic problems beyond a simple shopping list.

The newly formed Italian government instituted a set of reforms designed to change this state of affairs. An innovative law called for universal enrollment in elementary school starting at age six. Attendance in the first four years was compulsory, though in practice the rule was often broken. The poor considered it a luxury to have their offspring removed from the workforce. The rich educated theirs at home.

Stefano and Giulia, despite their modest circumstances, insisted on having their children attend school, and Alberto, who seemed to be the most scholastically gifted of them, advanced beyond an elementary education. But given the Fermi family's financial situation, attending university was never considered. When he reached the age of sixteen, Alberto's schooling was finished and it was time for him to seek employment.

By then Rome was the capital of Italy. The city and its surrounding region had been an independent state under papal rule until 1870, when the Kingdom of Italy had annexed the territory. Pope Pius IX had declared the occupation violent, unjust, and invalid. Retreating into the Vatican, he refused to recognize the existence, much less the legitimacy, of the new Italy.

Alberto Fermi, thirteen at the time, must have followed the story with keen interest. His parents, especially his mother, were devout Catholics, but he was already having the doubts that would later turn him into an agnostic, if not an atheist.

Alberto knew that he would have to leave Caorso if he was to advance in the world. Working for a company that built and managed rail lines seemed to be a particularly interesting choice in the early 1870s. At the time of his birth Italy had more than two dozen independent railway companies, each operating separate lines. Many of the lines had been founded with foreign capital, making them dependent on events outside Italy's control. Each attempted to maximize its profits with no concern for helping to forge a national identity.

By the age of twenty-four, Alberto was employed in the service of the company that managed the northern Italian railroads, one of the four that had emerged from consolidation. Through various reorganizations, the railroads continued to employ him until his retirement. In 1905 he became a civil servant for the Italian railroads, nationalized and combined into a single company, the Ferrovie dello Stato.

During all the years of employment, Alberto's willingness to work harder than anybody else, combined with his organizational ability, perseverance, and native intelligence, had led to his steady rise in the ranks. These personality traits would be very much imprinted on his only surviving son, Enrico.

Like his father, Alberto did not marry until he was forty-one. Ida de Gattis was fourteen years his junior. The daughter of an army officer, she was born in Bari, a city in Puglia, commonly known as the heel of Italy. Ida had been orphaned at a young age and raised by relatives in Milan. Like Alberto, she strongly advocated self-sufficiency and self-reliance. She began teaching after a three-year course for elementary school teachers, her ambitious trajectory a relative rarity at a time when women were still discouraged from entering a profession.

Ida and Alberto were both intelligent and upwardly mobile. They were not cultured in the traditional sense of appreciating art, music, and literature, though Alberto, a rather taciturn man, was known to occasionally break into song in the privacy of his home when shaving or bathing. His choice was almost always a Verdi aria, probably because the composer was born in Busseto, a small town only a few miles from Piacenza.

When Ida and Alberto married, they settled in Rome on Via Gaeta, a street that lay a short distance from the central railroad station. Their apartment was in one of the newer buildings that had sprung up during the thirty years since Italian unification, a period during which the city's population had roughly doubled to some four hundred thousand. Their neighbors were much like the Fermis, upwardly mobile middle-class people, the husbands typically employees of the government or of a quasigovernmental agency.

The Fermis lived on Via Gaeta for ten years, then moved to a nearby apartment in 1908. Slightly more spacious, but still far from luxurious, it had no central heating and its bathroom, as was not unusual at that time, was equipped with only a sink and a toilet. Baths were taken in two zinc tubs, a smaller one for children and a larger one on casters for the parents. By then Ida and Alberto had three children. Maria was born in 1899, Giulio in 1900, and Enrico on the twenty-ninth of September, 1901.

The closeness in age of the children and Ida's desire to continue teaching resulted in Enrico's being placed in a farm family. The tradition of having wet nurses for infants was centuries old in Italy, usually only adopted by the upper classes. A young woman who had recently given birth would be brought in from the countryside to nurse and care for the baby, living with the family at least until the child was weaned.

Toward the end of the nineteenth century, the reverse was becoming common for middle-class couples living in big cities: their children were sent to the countryside. With three children in less than three years, the Fermis made such arrangements for Enrico, the youngest. At the time farms still existed close to Rome; it was not too hard to find a suitable family willing — for a fee, of course — to take on a little boy for a few years.

A child psychologist, ruminating on where such a beginning would lead, might conclude that in adulthood the person would be either very self-reliant and controlled or overly needy and dependent. Enrico was obviously an example of the former.

One can speculate that the farm family provided a loving environment and a place where he could observe, explore, and enjoy nature. The security that Fermi exuded, as well as his love of the outdoors, might be related to those farm years. Yet the pain of separation from his family of birth must have affected his development, too, and is probably related to why Fermi kept emotions to himself and never complained. This is how he learned to cope.

And those coping skills served him well in later life.



(Il Piccolo Fiammifero)

Enrico's sister remembers him being "small, dark and frail-looking" when he rejoined the family at age two and a half. She also recalled how, probably worried by the sudden appearance of all the strangers, he immediately began crying, only to be told by his mother "to stop at once; in this home naughty boys are not tolerated." Little Enrico did stop crying. But with bottled-up frustrations, he was known to occasionally break into flaming rages, earning him the family nickname of Piccolo Fiammifero (Little Match).

Rages were not tolerated any more than an untidy appearance. Perhaps rules had been slacker in a farm environment. In a city setting, his mother apparently would insist that his face always be clean, stopping at fountains to wash up during their excursions. Despite Alberto and Ida's strictness in child rearing, the Fermi family appears to have been close, with a special bond developing between the two brothers, Giulio and Enrico, only a year apart in age.

Alberto and Ida had advanced in their careers despite not having university degrees; but, like many upwardly mobile parents, they wanted more for their children. All three of those children, through a combination of natural ability and the self-discipline learned from their parents, excelled in their studies, each of them consistently at the top of his or her class.

At the beginning of the twentieth century the advanced school curriculum was still oriented toward a classical education, emphasizing Latin and Italian literature with Greek added in the final five years. Mathematics, history, and science were also taught, but regarded as secondary. In particular a student preparing for the culminating graduation exam, the so-called Maturità, was expected to know practically by heart Dante's Divina Commedia, Italy's national literary treasure. Fermi had little interest in music or visual arts, but a love of poetry, and not only Dante, remained with him. On long hikes he could occasionally be heard reciting under his breath verses he had learned in his youth.

Maria, who eventually would become a high-school literature teacher, was drawn to the humanistic side of the studies. By contrast, Giulio and Enrico were more interested in science or at least in the technical skills they acquired by building models and little electrical motors.

The first recognition that Enrico was exceptional occurred shortly after he turned thirteen. Alberto Fermi, nearing sixty, had continued to rise in his profession and had become a chief inspector in the Ministry of Maritime and Railroads. Its offices were located in a building a little less than a mile from the Fermi apartment, and Enrico had started meeting his father at the building's door after work and walking home with him. Adolfo Amidei, a thirty-seven-year-old engineer employed in the same office as Enrico's father, often joined them for part of the way since his apartment was in the same direction as theirs.

When Enrico discovered that Amidei had an interest in mathematics, he asked him a few questions about geometry that his father had been unable to answer. To help his colleague's son, Amidei lent Enrico a geometry book. The young boy quickly worked out the solutions to the problems it contained, some of which even Amidei had not been able to solve. Impressed, Amidei inquired of his senior colleague whether anybody else had commented on his son's skill and precocity. Alberto told him that Enrico had always done well in school, but none of his teachers had noted anything out of the ordinary.

At about the same time, early January 1915, tragedy struck the family. Giulio had developed a throat abscess that was interfering with his breathing, not an uncommon consequence of a severe tonsil infection. Today, treatment is by massive doses of antibiotics, thereby usually avoiding any surgical intervention. The standard procedure in 1915 was an incision and drainage of the abscess under a local anesthetic. This surgery was performed on Giulio in a clinic, his mother and sister waiting to take him home after the anesthetic wore off. But Giulio had a dramatic adverse reaction to its administration, went into anaphylactic shock, and died on the operating table.

The family was devastated. Alberto became even more taciturn and Ida fell into a deep depression; Giulio, warmer and more outgoing than Enrico, had been her favorite. Ida's fits of inconsolable crying lasted for hours and she was in no shape to help alleviate the pain of others. Enrico was left to grieve on his own. To prove to himself that he was not a total wreck, a week later he deliberately walked by the clinic where his brother died. It was a striking example of Fermi's early need for emotional control.

One way for thirteen-year-old Enrico to fill the traumatic and heartbreaking void was by hard work. Amidei, recognizing both the boy's loneliness and his eagerness to learn, tried to do what he could by continuing to lend him books; the more he did, the more impressed he was by Enrico's intelligence and thoroughness. When Amidei once asked his young protégé if he wanted to keep a calculus book he had lent him, he was told that it wasn't necessary because he had thoroughly assimilated the material. As people would repeatedly say over the next forty years, "When Fermi knew something, he really knew it."

Another precious balm for Enrico was having a schoolmate of Giulio's become his close friend. Enrico Persico shared his interests in science and in building mechanical objects. The two of them soon began taking long walks together, discussing their common dreams. Fifteen years later, the two Enricos would be Italy's first two professors of theoretical physics. And almost forty years later, they would still take long walks together and share dreams.

The young Fermi, insatiable in his quest to learn more about science, found his first real physics book in Rome's Campo dei Fiori (literally Field of Flowers). This square, located between the Tiber and the ruins of Pompey's Theatre, the site of Caesar's assassination, remains to this day one of Rome's liveliest areas. Now a popular outdoor food market, during Enrico's childhood it was a horse market two days a week and once a week held stalls where one could purchase new and old books. Most of them were novels or, this being Rome, theological treatises. Occasionally one might find something else.


Excerpted from The Pope of Physics by Gino Segrè, Bettina Hoerlin. Copyright © 2016 Gino Segrè and Bettina Hoerlin. Excerpted by permission of Henry Holt and Company.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.

Table of Contents


Prologue: Trinity 1


1. Family Roots 7

2. The Little Match (Il Piccolo Fiammifero) 13

3. Leaning In: Physics and Pisa 18

4. Student Days 24

5. The Young Protégé 28

6. The Summer of 1924 35

7. Florence 41

8. Quantum Leaps 49

9. Enrico and Laura 56


10. The Boys of Via Panisperna 65

11. The Royal Acad emy 70

12. Crossing the Atlantic 76

13. Bombarding the Nucleus 81

14. Decay 87

15. The Neutron Comes to Rome 93

16. The Rise and Fall of the Boys 102

17. Transitions 110

18. Stockholm Calls 116


19. Fission 127

20. News Travels 135

21. Chain Reaction 144

22. The Race Begins 151

23. New Americans 159

24. The Sleeping Giant 167

25. Chicago Bound 176

26. Critical Pile (CP-1) 184

27. The Day the Atomic Age Was Born 193


28. The Manhattan Project: A Three-Legged Stool 201

29. Signor Fermi Becomes Mister Farmer 209

30. Götterdämmerung 219

31. The Hill 226

32. “No Acceptable Alternative” 234

33. Aftershock 244

34. Goodbye, Mr. Farmer 253


35. Physicist with a Capital F 261

36. The Fermi Method 268

37. The Super 275

38. Circling Back 283

39. Last Gift to Italy (Ultimo Regalo all’Italia) 291

40. Farewell to the Navigator 296

Afterword 303

Notes 309

Bibliography 326

Acknowledgments 334

Index 337

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