Fermi Remembered

James W. Cronin, James W. Cronin

• Publisher: University of Chicago Press
• Year: 2013
• ISBN:
  9780226109954
• Topic: Technology & Engineering
• Subtopic: Science & Technology Biographies
• Index: Technology & Engineering

Nobel laureate and scientific luminary Enrico Fermi (1901-54) was a pioneering nuclear physicist whose contributions to the field were numerous, profound, and lasting. Best known for his involvement with the Manhattan Project and his work at Los Alamos that led to the first self-sustained nuclear reaction and ultimately to the production of electric power and plutonium for atomic weapons, Fermi's legacy continues to color the character of the sciences at the University of Chicago. During his tenure as professor of physics at the Institute for Nuclear Studies, Fermi attracted an extraordinary scientific faculty and many talented students—ten Nobel Prizes were awarded to faculty or students under his tutelage.Born out of a symposium held to commemorate the hundredth anniversary of Fermi's birth, Fermi Remembered combines essays and newly commissioned reminiscences with private material from Fermi's research notebooks, correspondence, speech outlines, and teaching to document the profound and enduring significance of Fermi's life and labors. The volume also features extensives archival material—including correspondence between Fermi and biophysicist Leo Szilard and a letter from Harry Truman—with new introductions that provide context for both the history of physics and the academic tradition at the University of Chicago.Edited by James W. Cronin, a University of Chicago physicist and Nobel laureate himself, Fermi Remembered is a tender tribute to one of the greatest scientists of the twentieth century.Contributors:
Harold Agnew
Nina Byers
Owen Chamberlain
Geoffrey F. Chew
James W. Cronin
George W. Farwell
Jerome I. Friedman
Richard L. Garwin
Murray Gell-Mann
Maurice Glicksman
Marvin L. Goldberger
Uri Haber-Schaim
Roger Hildebrand
Tsung Dao Lee
Darragh Nagle
Jay Orear
Marshall N. Rosenbluth
Arthur Rosenfeld
Robert Schluter
Jack Steinberger
Valentine Telegdi
Al Wattenberg
Frank Wilczek
Lincoln Wolfenstein
Courtenay Wright
Chen Ning Yang
Gaurang Yodh

Chapter One

Biographical Introduction

This first chapter presents a brief biography of Enrico Fermi which was written by Emilio Segrè for Fermi’s Collected Papers (1962). While this volume is concerned with Fermi’s life in the United States with much emphasis on his years at the University of Chicago, more than half of his scientific life was spent in Italy. To gain an appreciation of Fermi’s total impact on physics, we have chosen to reprint the biography. The references given at the end of this chapter conform to the numbering in Fermi’s collected papers.

. . .

Emilio Segre

BIOGRAPHICAL INTRODUCTION

Enrico Fermi was born September 29, 1901, in Rome at Via Gaeta N° 17, the third child of Alberto Fermi and Ida De Gattis. His family originally came from the North Italian town of Piacenza. He grew up in Rome, where he attended grammar school and later the Ginnasio Liceo Umberto I. He then studied at the University of Pisa as a Fellow of the Scuola Normale Superiore, and in 1922 he received his doctorate in physics. In 1923, with a Fellowship of the Italian government, he went to Göttingen to work under Max Born; and in 1924 he moved to Leyden to work under P. Ehrenfest. He returned to Rome the same year and in 1925 became “Libero Docente”. He then held a lectureship at the University of Florence, and finally, in 1926, he was appointed Professor of Theoretical Physics at the University of Rome, where he remained until 1938.

In 1938 the Fascist racial laws, which affected his wife Laura Capon and her relatives and moreover deeply offended his sense of fairness, induced him to emigrate to the United States of America. Here, he was at first Professor of Physics at Columbia University in New York; then, during the Second World War he devoted all his activity to the development of nuclear energy on a large scale at Chicago, Illinois and at Los Alamos, New Mexico. At the end of the war, in 1946 he moved to the new Institute for Nuclear Studies at the University of Chicago, where he remained until his early and unexpected death on November 29, 1954.

These are the bare, external facts of Fermi’s life. As is often the case with a man of science, they do not seem especially dramatic, although in his case the development of nuclear energy, more than emigration to America, certainly represented an event comparable in adventure to the discovery of a continent for an explorer.

The lamented circumstance of his early death has as a consequence that many of his contemporaries, collaborators, and friends remember him well. In recounting their experiences with him they can try to reconstruct a living image of the man. This is highly desirable because many scientists have the natural desire to know personally, as it were, the major worthies of their craft. What physicist has not had the curiosity to learn what kind of a man Galileo, Newton or Maxwell was? How did he work? How did his ideas originate? These questions are not easily answered by the ordinary biographies, generally written by authors with little personal and scientific contact with their subject. In Fermi’s case, however, the fact that he collaborated extensively with other scientists, who were often his own pupils, makes it easier to reconstruct his scientific portrait. For this reason, while the single papers here collected speak for themselves scientifically and give the finished product of his work, we have tried as often as possible to provide for each of them an introduction written by whoever is in a position to be well informed of the circumstances which led to that specific investigation. While these introductions can add but little to the scientific interest of the papers, we hope that they may contribute to a reconstruction of the picture of the scientist as we knew him.

If we examine Fermi’s works as a whole, we find them still fresh and interesting, often written with rare pedagogical skill. In a certain sense, the papers make easy reading, so that an able student can profit greatly from their study, even as a beginner; at the same time, they often have such deep implications that they have inspired very difficult and recondite investigations. The typical style of Fermi’s writings is a close reflection of his personal and intellectual history. We see it evolve as time goes on from the early papers written at Pisa, in almost complete isolation, on a variety of disconnected problems, to the late papers in Chicago when he was a mature physicist and a great leader in the field, investigating theoretically and experimentally, with numerous co-workers, a whole new chapter of physics.

In the following pages I shall try to render Fermi’s image as it appears to me.

Fermi’s interest in mathematics and physics manifested itself very early. He told me that when he was about ten years old he had seriously struggled to try to understand why a circle was represented by the equation x² + y² = R², and had finally succeeded only after great efforts. This episode gives us a measure of his development at that age.

A little later he must have made considerable progress because while still an adolescent he read, in Latin, a book entitled “Elementa Physicae Mathematicae” by “Andrea Caraffa e Societate Jesu, in Collegio Romano”. This is an ample treatise of mathematical physics published by a Jesuit in 1840. Its two volumes comprise approximately 900 pages and they cover mechanics, optics and astronomy, using the resources of analysis. Fermi acquired the book in a used-book stall and must have studied it quite diligently because the book has numerous marginal notes and developments of the calculations in his handwriting.

We know that what little outside help Fermi received came mostly from Ingegnere A. Amidei who was among the first to notice the boy’s extraordinary ability. In this connection we have the invaluable first-hand testimonial of Ing. Amidei as set forth in a letter by him to E. Segrè. He states that sentences quoted verbatim were noted by him in writing at the time of his conversations with Fermi. We quote here Ing. Amidei’s letter:

“Antignano (Livorno).

“November 25^th, 1958.

“Having had the opportunity of guiding and counseling Enrico Fermi in his studies during his youth from his 13th to the end of his 17th year, I deem it appropriate to hereby summarize his course of study during the above-mentioned period, which was from the autumn of 1914 to the autumn of 1918.

“In 1914 I was Principal Inspector of the Ministry of Railways, and my colleague was Chief Inspector Alberto Fermi. When we left the office we walked together part of the way home, almost always accompanied by the lad Enrico Fermi (my colleague’s son), who was in the habit of meeting his father in front of the office. The lad, having learned that I was an avid student of mathematics and physics, took the opportunity of questioning me. He was 13 and I was 37.

“I remember very clearly that the first question he asked me was: ‘Is it true that there is a branch of geometry in which important geometric properties are found without making use of the notion of measure?’ I replied that this was very true, and that such geometry was known as ‘Projective Geometry’. Then Enrico added, ‘But how can such properties be used in practice, for example by surveyors or engineers?’ I found this question thoroughly justified, and after having tried to explain some properties that had very useful applications, I told him that the next day I would bring him—as I did—a book on projective geometry by Professor Theodor Reye⁽¹⁾ that included an introduction which, in a masterful, artistic style succeeds, by itself, in explaining the usefulness of the results of this science.

“After a few days Enrico told me that besides the introduction he had already read the first three lessons and that as soon as he finished the book he would return it to me. After about two months he brought it back, and to my inquiry whether he had encountered any difficulties, replied ‘none’, and added that he had also demonstrated all the theorems and quickly solved all the problems at the end of the book (there are more than two hundred).

“I was very surprised and since I remembered that I had found certain problems quite difficult and given up trying to solve them since they would have taken too much time, I wanted to verify that Enrico had also solved those. He gave me the evidence.

“Thus it was certainly true that the boy, during the little free time that was left to him after he had fulfilled the requirements of his high school studies, had learned projective geometry perfectly and had quickly solved many advanced problems without encountering any difficulties.

“I became convinced that Enrico was truly a prodigy, at least with respect to geometry. I expressed this opinion to Enrico’s father and his reply was, yes, at school his son was a good student, but none of his professors had realized that the boy was a prodigy.

“I then learned that Enrico studied mathematics and physics in secondhand books that he bought at Campo dei Fiori, hoping to find one treatise that would scientifically explain the motion of tops and gyroscopes, but he could never find an explanation, and so, mulling the problem over and over again in his mind, he succeeded in reaching an explanation of the various characteristics of the mysterious movements by himself. Then I suggested to him that to obtain a rigorous explanation, it was necessary to master a science known as ‘Theoretical mechanics’; but in order to learn it he would have to study trigonometry, algebra, analytical geometry and calculus, and I advised him not to try the problems of tops and gyroscopes, since he would be able to solve them easily once he had mastered the field that I had outlined. Enrico was convinced of the soundness of my advice and I supplied him with the books that I thought were most suitable for giving him clear ideas and a solid mathematical base.

“The books which I loaned him and the date of the loan are as follows:

“In 1914, for trigonometry, the treatise on plane and spherical trigonometry by Serret.

“In 1915, for algebra, the course on algebraic analysis by Ernesto Cesàro and, for analytic geometry, notes from lectures by L. Bianchi at the University of Pisa.

“In 1916, for calculus, the lectures by Ulisse Dini at the University of Pisa.

“In 1917, for theoretical mechanics, the ‘Traité de mécanique’ by S. D. Poisson.

“I also deemed it appropriate for him to study the ‘Ausdehnungslehre’ by H. Grassmann which has an introduction on the operations of deductive logic by Giuseppe Peano. These books were loaned to him in 1918.

“I thought it appropriate because it was my opinion that the Ausdehnungslehre (similar to vector analysis) is the most suitable tool for the study of different branches of geometry and theoretical mechanics. . . .

“Enrico found vector analysis very interesting, useful and not difficult. From September, 1917, to July, 1918, he also studied certain aspects of engineering in books that I lent him.

“In July, 1918, Enrico received his diploma from the Liceo (skipping the third year) and thus the question arose whether he should enroll at the University in Rome. Enrico and I had some long discussions on this subject.

“First of all I asked him whether he preferred to dedicate himself to mathematics or to physics. I remember his reply and I transcribe it here literally: ‘I studied mathematics with passion because I considered it necessary for the study of physics, to which I want to dedicate myself exclusively’. Then I asked him if his knowledge of physics was as vast and profound as his knowledge of mathematics and he replied: ‘It is much wider and, I think, equally profound, because I’ve read all the best known books of physics’ ^(*). I had already ascertained that when he read a book, even once, he knew it perfectly and didn’t forget it. For instance, I remember that when he returned the calculus book by Dini, I told him that he could keep it for another year or so in case he needed to refer to it again. I received this surprising reply: ‘Thank you, but that won’t be necessary because I’m certain to remember it. As a matter of fact, after a few years I’ll see the concepts in it even more clearly, and if I need a formula, I’ll know how to derive it easily enough’.

“In fact, Enrico, together with a marvelous aptitude for the sciences, possessed an exceptional memory.

“I then considered that the proper moment had arrived to present a project that I had already considered in his behalf for a year, that is from the time when I advised him—and he immediately followed my suggestion—to study the German language, since I foresaw that it would be very useful for reading scientific publications printed in German without having to wait until they were translated into French or Italian. My plan was this: Enrico ought to enroll not at the University of Rome, but at the one in Pisa. First, however, he would have to win a competition to be admitted to the Scuola Normale at Pisa and attend (besides the courses in the School) the University of Pisa.

“Enrico recognized at once the soundness of my plan and decided to follow it, even though he knew that his parents would be opposed to it. Then I immediately went to Pisa to obtain the necessary information and the program for the competition to the Scuola Normale Superiore and immediately returned to Rome to examine it minutely with Enrico. I ascertained that he knew the subjects in the group of mathematics and physics perfectly, and I expressed my conviction that he would not only win the competition, but would also be the first among the applicants—as in fact he was.

“Enrico’s parents did not approve of my plan, for understandable and human reasons. They said: ‘We lost Giulio (Enrico’s older brother, who died after a short illness in 1915) and now we are to allow Enrico to leave us to study at Pisa for four years while there is an excellent university here in Rome. Is this right?’

“I used the necessary tact to persuade them, a little at a time, that their sacrifice would open a brilliant career for their son and they finally agreed that my program should be carried out. Thus, as Enrico’s wife wrote in her book ‘Atoms in the Family’, ‘at the end, the two allies—Fermi and Amidei—carried the day”.

Thus far goes the Amidei letter.

Persico tells of experiments undertaken together with Fermi at about the same time as that covered by the Amidei letter ⁽²⁾. They are noteworthy especially for the choice of problems, such as to determine with high precision the density of Rome’s drinking water (Acqua Marcia). This is a rather different problem from the more common one of a boy wanting to build some sort of an electric motor or apparatus: today this would be most probably a radio; at the time we are considering, it would have been a wireless telegraph. This does not preclude the fact that, at the time, Fermi was an expert builder of electric motors, but obviously he was also interested in more sophisticated problems such as the investigation of the behaviour of gyroscopes.

The point reached by his scientific development at the age of 17, when he finished his secondary schools, is clearly demonstrated by the entrance examination for the “Scuola Normale Superiore” at Pisa. The theme was “Distinctive properties of sounds” and is dated November 14, 1918. Certainly the examiners expected an essay at a high school level as one reasonably would. Instead, after a few introductory sentences, we find in his examination sheet the partial differential equation of a vibrating reed and its solution with the help of a Fourier series. The examiner, Professor G. Pittarelli, a very kindhearted man and a good mathematician in his own right, must certainly have been stunned by the little essay. Fermi himself told me that Pittarelli, after having read the examination paper, called him to ascertain whether the candidate really understood what he had written. After questioning him, Pittarelli said that during his long teaching career he had never met anybody like Fermi and that certainly the boy had extraordinary talents. Fermi remembered these occurrences many years later with obvious pleasure and deep gratitude towards Pittarelli.

In his other studies it is clear that at the Ginnasio and Liceo he progressed brilliantly and without effort. He was the sort of model student who succeeds in everything. His professor of Italian was Giovanni Federzoni, and Fermi who had an exceptional memory, knew long excerpts from the “Divine Comedy” and other Italian poems by heart and for the rest of his life was able to quote them on appropriate occasions. “Orlando Furioso” by Ariosto apparently was one of his favorite readings even before he had to read it at school; already when he was about 12 years old he could recite entire cantos by heart. For him one reading was sufficient to commit a section to memory. He must have been bothered by Greek, which was compulsory in Italian schools. At Los Alamos I once complained that in a sort of nightmare I had dreamed of a Greek final examination at the Liceo: Fermi confessed that he had been subject to the same nightmare.

His literary tastes were very simple; his own writings, including popular lectures, are not noteworthy for elegant literary style, especially in his early years. He had little sensitivity to literary form; to him the content was the only thing that mattered. On the other hand he was extremely careful, almost pedantic, as far as scientific precision was concerned. This care for precision increased steadily with time and one notices a remarkable difference in style between the early papers and those of his more mature years.

With regard to his knowledge of languages, he learned German as a boy, as Ing. Amidei mentions. The complexities of German grammar fascinated him. I think in his youth he could sit down and write an article in German without any mistakes, and he spoke it fluently; he knew French as many Italians do, using it easily but not always correctly. More than any other language except Italian he used English. He learned everything that one can by application and study, but the muscles of his mouth never became accustomed to English sounds, and he always retained a strong Italian accent, which occasionally irritated him. In America, Fermi devoted more effort to his English pronunciation than most immigrants are wont to do, but the result always remained imperfect.

Fermi registered at the University of Pisa as a Fellow of the Scuola Normale Superiore in the fall of 1918. This school was founded by Napoleon in 1813 as a branch of the École Normale Supérieure of Paris. Its original purpose was the preparation of high-school teachers and the promotion of higher studies and research. Its pupils attend the University of Pisa, but in addition have special courses, mostly of the character of seminars. The pupils and professors live in the school as in a British college. Admission is by competition only and there are no fees of any kind. Several of the most distinguished literary and scientific figures of modern Italy studied there, and the roster of its alumni add...

Table of contents

• Cover
• Copyright
• Title Page
• Contents
• Preface
• Chapter 1. Biographical Introduction
• Chapter 2. Fermi and the Elucidation of Matter
• Chapter 3. Letters and Documents Relating to the Development of Nuclear Energy
• Chapter 4. Correspondence between Fermi and Colleagues: Scientific, Political, Personal
• Chapter 5. Research and Teaching: Selections from the Archives
• Chapter 6. Reminiscences of Fermi’s Faculty and Research Colleagues, 1945–1954
• Chapter 7. Reminiscences of Fermi’s Students, 1945–1954
• Chapter 8. Reminiscences of Students of the Fermi Period, 1945–1954
• Chapter 9. What Can We Learn with High Energy Accelerators?
• Notes
• Further Reading
• List of Contributors
• Index