Enrico Fermi

Enrico Fermi in 1949
Enrico Fermi. By Department of Energy,
Office of Public Affairs,
restored by Yann In Wikipedia.
This month’s essay deals with an important Italian-American physicist who was the creator of the world’s first nuclear reactor, the “Chicago Pile-1,” and Associate Director of the Manhattan Project laboratory at Los Alamos that resulted in the development of the atomic bomb. He has been called the “architect of the nuclear age” and the “architect of the atomic bomb.” He was one of very few physicists to excel in both theoretical physics and experimental physics. His work on inducing radioactivity by neutron bombardment and the discovery of trans-ura- nium elements resulted in his receiving the 1938 Nobel Prize in Physics. With his colleagues, Fermi filed several patents related to the use of nuclear power, all of which were taken over by the US government. He made significant contributions to the development of statistical mechanics, quantum theory, and nuclear and particle physics.
With the critical and popular acclaim of the recent motion picture Oppenheimer, which won seven academy awards, including Best Pic- ture, Best Actor (Cillian Murphy as J. Robert Oppenheimer), and Best Director (Christopher Nolan), I thought it would be appropriate to look at the life of this Italian-American scientist who played such a key role in the whole nuclear project.
Worked closely with Oppenheimer
CELEBRATED: Science, physicist
ASSOCIATIONS: Nobel Prize Winner
Lived 1901 – 1954
COUNTRY OF ORIGIN: Italy
1944 NATURALIZED U.S. CITIZEN

Early Years

Enrico Fermi was born in Rome on September 29, 1901. He was the third and youngest child of Alberto Fermi, who was a chief inspector and a division head in the Ministry of Railways, and Ida de Gattis, an elementary school teacher. His sister, Maria, was two years older; his brother Giulio was a year older than Enrico. After the two boys were sent to a rural community to be wet nursed, Enrico rejoined his family in Rome when he was two and a half years old. Ida was a highly intelligent woman; trained as a teacher, she played a significant role in her children’s education. Although he was baptized a Roman Catholic in accordance with his grandparents’ wishes, his family was not particularly religious. (Enrico was an agnostic throughout his adult life). As a young boy, he shared the same interests as his brother Giulio, building electric motors and playing with electrical and mechanical toys.
Fermi’s intense interest in physics was said to be the result of a family tragedy. When Enrico was 14, his beloved older brother, Giulio, died suddenly during an operation on a throat abscess. Fermi was devastated. To console him, his parents encouraged his studies. At about that time, he came across several physics books written a half century earlier. He became totally enthralled with them and with the problems that they discussed. He and his friends began conducting physics experiments for fun, including building gyroscopes, measuring the acceleration of Earth’s gravity, and testing the density of Rome’s water supply.
Soon after his brother’s death, Fermi met a colleague of his father, Adolfo Amidei. Enrico learned that Adolfo was interested in mathematics and physics, and so he took the opportunity to ask Adolfo a question about geometry. Adolfo understood that the young Fermi was referring to projective geometry and so he gave him a book on the subject written by Theodor Reye. Two months later, Fermi returned the book, having solved all the problems proposed at the end of the book, some of which Adolfo considered difficult. When he saw that Enrico had correctly completed the problems, Adolfo felt that Fermi was “a prodigy, at least with respect to geometry.” Further, he mentored the teenager, providing him with more books on physics and mathematics. Adolfo noted that Fermi had an incredibly good memory and thus could return the books after having read them because he could remember their content very well.
In 1918, Fermi graduated from high school, having skipped the third year entirely. At Amidei’s urging, he learned German in order to be able to read the many scientific papers that were published in that language at the time. After he took first place in the difficult entrance exam, he won a fellowship to the University of Pisa’s prestigious Scuola Normale Superiore, a special university-college for selected gifted students. His entry essay, a required part of the entrance exam, on the theme of Specific characteristics of Sounds was so impressive that he was quickly elevated to the doctoral program in 1920. His doctoral advisor was Prof. Luigi Puccianti, director of the physics laboratory, who said there was little he could teach Fermi and often asked Fermi to teach him something instead. Fermi’s knowledge of quantum physics was so impressive that Puccianti often asked him to organize seminars on the topic. He was awarded his doctor’s degree in physics with honors in 1922.

Early Work in Physics of the Atom

Following graduation, Fermi was awarded a fellowship in 1923 from the Italian government’s Ministry of Public Instruction and spent several months with Professor Max Born in Gottingen, Germany. Born was a German-British physicist and mathematician who was instrumental in the development of quantum mechanics. He also made contributions to solid-state physics and optics and supervised the work of a number of notable physicists besides Fermi in the 1920s and 1930s.
In 1924, Fermi was awarded a Rockefeller Fellowship, and he moved to Leiden University in the Netherlands to work with Paul Ehrenfest, an Austrian theoretical physicist who made major contributions to the field of statistical mechanics and its relations with quantum mechanics, including the theory of phase transition and the Ehrenfest theorem. It was while he was at Leiden that Fermi met Alber Einstein and other prominent figures who were dealing with the evolving theories of quantum mechanics and physics. Later in 1924, Fermi returned to Italy to occupy the post of Lecturer in Mathematical Physics and Mechanics at the University of Florence, a position that he held for two years.
His early research was in general relativity, statistical mechanics, and quantum mechanics. Examples of gas degeneracy (appearance of unexpected phenomena) had previously been known, and some cases were explained by Bose-Einstein statistics, which described the behavior of subatomic particles known as bosons. In 1925 Wolfgang Pauli developed the Pauli Exclusion Principle to account for the observed patterns of light emissions from atoms. The principle asserted that no two electrons in an atom can be at the same time in the same state or configuration. The Exclusion Principle subsequently has been generalized to include a whole class of particles of which the electron is only one member; these include protons, neutrons (that had not yet been discovered in 1925), and other particles. Between 1926 and 1927, Fermi and the English physicist P.A.M. Dirac independently developed new statistics, now known as Fermi Statistics, to manage all the subatomic particles that obeyed Pauli’s Exclusion Principle. These became known as fermions (named for Fermi). This discovery was an extremely important contribution to atomic and nuclear physics, particularly in this period when quantum mechanics was first being developed and applied.
This seminal work brought Fermi an invitation in 1926 to become a full professor at the Institute of Physics at the University of Rome. In 1927, he started his tenure at the University of Rome and was elected Professor of Theoretical Physics. Shortly after Fermi assumed his new position in 1927, Franco Rasetti, a friend from Pisa and another superb experimentalist, joined him in Rome, and they began to gather a group of talented young physicists around them, all of whom eventually had distinguished careers. The group soon nicknamed themselves the “Via Panisperna boys,” named after the street where the Institute of Physics was located. Fermi, who was a charismatic, energetic, and seemingly infallible figure, was clearly their leader— so much so that his colleagues nicknamed him “the Pope.”
In 1928, Fermi married Lalla (Laura) Capon (1907- 1977), the daughter of a respected Jewish family in Rome. She met Fermi while she was a student in general science at the University of Rome. They had a daughter, Nella (1931–1995) and a son, Giulio (1936-1997), named after Fermi’s deceased brother. (Laura became an author and a vocal advocate for the peaceful uses of atomic energy throughout the post- World War II era until her death).

Fermi started splitting uranium atoms by neutron bombardment and, after following this using more than sixty other elements, discovered that nuclear transformation could occur in almost every element that is subjected to neutron bombardment. This work led to the discovery of the process of slowing down neutrons (producing “slow neutrons”), which led to nuclear fission and the production of new elements beyond the traditional natural elements in the Periodic Table.

During the early years of his career in Rome, Fermi engaged in electrodynamic problems and theoretical investigations on various spectroscopic phenomena. But a crucial turning-point came when he began to turn his research interests from the outer electrons in atoms towards the atomic nucleus itself. In 1934, Fermi began his most important work with the atom. He evolved the beta-decay theory, coalescing previous work on radiation theory with Pauli’s idea of the neutrino. Following the discovery by the husband-wife team of Frédéric and Irène Joliot-Curie of artificial radioactivity that year, Fermi started splitting uranium atoms by neutron bombardment and, after following this using more than sixty other elements, discovered that nuclear transformation could occur in almost every element that is subjected to neutron bombardment. This work led to the discovery of the process of slowing down neutrons (producing “slow neutrons”), which led to nuclear fission and the production of new elements beyond the traditional natural elements in the Periodic Table.

Nobel Prize and Atomic Work in US

In 1938, Fermi was without doubt the greatest expert on neutrons in the world. That year he was awarded the Nobel Prize for Physics “for his work with artificial radioactivity produced by neutrons, and for nuclear reactions brought about by slow neutrons.” The award came at an opportune time for Fermi and his family. He had been growing increasingly uncomfortable with the Fascist politics of Benito Mussolini over several years, although he was never particularly interested in politics. When Italy adopted the anti-Semitic policies of its ally, Nazi Germany in 1938, a crisis occurred because Fermi’s wife, Laura, was Jewish. The award of the prize provided the excuse for the family to travel abroad to Stockholm, Sweden to accept it, and then to the US where the prize money helped to establish them.

The award of the (Nobel) prize provided the excuse for the family to travel abroad to Stockholm, Sweden to accept it, and then to the US where the prize money helped to establish them.

After arriving in the US, in 1939 Fermi was appointed Professor of Physics at Columbia University in New York, a position that he held until 1942. While there, Fermi discovered that if uranium neutrons were emitted into fissioning uranium, they could split other uranium atoms, setting off a chain reaction that would release enormous amounts of energy.
His experiments during this time led to the development of an “atomic pile” (nuclear reactor) while at Columbia. Owing to the rate of absorption of neutrons by the hydrogen in water, it was unlikely that a self-sustaining reaction could be achieved with natural uranium and water as a neutron moderator. Fermi suggested, based on his work with neutrons, that the reaction could be achieved with uranium oxide blocks and graphite as a moderator instead of water. This would reduce the neutron capture rate, and in theory make a self-sustaining chain reaction possible. In the end, Fermi and colleagues built an “atomic pile” that consisted of graphite bricks and uranium oxide on the seventh floor of the Pupin Hall laboratory on Columbia’s campus. By August 1941, he had six tons of uranium oxide and thirty tons of graphite, which he used to build a still larger pile in Schermerhorn Hall at Columbia.

World War II and the Manhattan Project

When the United States entered World War II in December 1941, nuclear research became consolidated to some degree. Arthur Compton, a scientist and member of the government’s Office of Scientific Research and Development, as the Advisory Committee on Uranium was known, realized that most of the effort sponsored by the committee had been directed at producing enriched uranium. He determined that a feasible alternative was plutonium, which was a man-made element heavier than uranium that had been discovered in 1940 and would work just as well if not better than enriched uranium in a reactor.
Compton decided to concentrate on the plutonium work at the University of Chicago. Fermi reluctantly moved, and his team became part of the new Metallurgical Laboratory there. He continued to construct piles in the squash court under the stands of the U of Chicago football field, Stagg Field. The final structure of the pile was a flattened sphere about 7.5 meters (25 feet) in diameter, containing 380 tons of graphite blocks as the moderator and 6 tons of uranium metal and 40 tons of uranium oxide as the fuel, distributed in a careful pattern. The pile went “critical” on December 2, 1942, proving that a nuclear reaction could be initiated, controlled, and stopped. This experiment, Chicago Pile-1, as it was called, was a landmark in the quest for nuclear energy, and it was typical of Fermi’s approach. Every step was carefully planned, and every calculation was meticulously done. Thus, the first self-sustained nuclear chain reaction was achieved; it was the first prototype for several large nuclear reactors constructed later at Hanford, Washington, where plutonium was produced. Since plutonium could also fission, it was thus another route to the atomic bomb.
Stagg Field Reactor
Enrico Fermi. (2024, April 22). In Wikipedia. Chicago Pile-1, the first nuclear reactor to achieve a self-sustaining chain reaction. Designed by Fermi, it consisted of uranium and uranium oxide in a cubic lattice embedded in graphite.
In 1944 Fermi and his wife became American citizens. In mid-1944 they moved to Los Alamos, New Mexico when J. Robert Oppenheimer persuaded Fermi to join his Project Y (Manhattan Project) there, whose mission was to fashion weapons out of the rare uranium-235 isotope and plutonium. Arriving in September, Fermi was appointed associate director of the laboratory, and headed one of its 4 divisions, F Division, which was named after him. As head of F Division, he was given broad responsibility for nuclear and theoretical physics. When the first plutonium bomb was tested on July 16, 1945 (The Trinity Test), near Alamogordo, New Mexico, Fermi ingeniously made a rough estimate of the bomb’s explosive energy by dropping strips of paper into the blast wave. He paced off the distance they were blown from the vertical of the blast and calculated the yield as 10 kilotons of TNT (the actual yield was about 18.6 kilotons).

Post- World War II

After the war ended, Fermi accepted the Charles H. Swift Distinguished Professor of Physic position at the Institute for Nuclear Studies of the University of Chicago, a position which he held until the end of his life, where he influenced another distinguished group of physicists. (In 1955, the Institute’s name was changed to the Enrico Fermi Institute for Nuclear Studies, shortened in 1968 to the Enrico Fermi Institute). As in Rome, he began to recognize that his current pursuits, now in nuclear physics, were approaching a condition of maturity. If he continued to pursue these areas, he would no longer have new frontiers of research questions to explore. He thus decided to redirect his research on reactions at higher energies, a new field within physics called elementary particle physics, or high-energy physics. Thus, he especially began to research the subatomic particles pi mesons and muons. In addition, he also led research into the origin of cosmic rays, and worked on developing theories on the fantastic energies present in cosmic ray particles.
The Manhattan Project was replaced by the Atomic Energy Commission (AEC) on January 1, 1947. Fermi was appointed to the AEC General Advisory Committee, an influential scientific committee that was chaired by Oppenheimer. In October 1949, the commission met to discuss the development of the hydrogen bomb. Fermi was appalled at the prospect, however, and later co-authored an addendum to the committee’s report that condemned the H-bomb in the harshest language. When President Harry S. Truman ordered the development of the bomb—ignoring Fermi’s and others’ warnings—Fermi returned to Los Alamos to help with the calculations, hoping to prove that making a superbomb was not possible. (However, much to his chagrin, the bomb was produced under the direction of Edward Teller).

…What is less certain, and what we all fervently hope, is that man will soon grow sufficiently adult to make good use of the powers that he acquires over nature.

Enrico Fermi in a speech on the value of science and technology to advancing and positivly affecting our way of life he did state a single reservation.

Death

Fermi underwent what was termed “exploratory” surgery in October 1954, after which he returned home. He spent the remaining fifty days of his life in Chicago, undergoing various medical procedures. Finally, on November 28, 1954, Enrico Fermi died in his sleep of inoperable stomach cancer at his home in Chicago. He was 53 years old. Fermi suspected working near the nuclear piles involved great physical risk, but he pressed on because he felt the benefits of knowledge outweighed the risks to his personal safety. (Two of his graduate student assistants who had worked near the piles also died of cancer).
A memorial service was held at the University of Chicago’s Rockefeller Chapel. His body was buried at Oak Woods Cemetery in Chicago where a private graveside service for the immediate family took place presided over by a Lutheran chaplain.

Conclusion

Enrico Fermi received numerous awards during his lifetime for his achievements in the study of nuclear physics, the development of the first nuclear reactor (Chicago Pile 1), and his work on the Manhattan Project. He also was elected to numerous professional societies. I have only selected a few of these honors to conclude this essay. He was awarded the Medal for Merit in 1946 for his contribution to the Manhattan Project. He was elected a member of the American Philosophical Society in 1939, a member of the National Academy of Sciences in 1948, and a Foreign Member of the Royal Society (FRS) of Great Britain in 1950. Since 1956, the United States Atomic Energy Commission has named its highest honor, the Fermi Award, after him. A synthetic element isolated from the debris of the 1952 Ivy Mike nuclear test was named fermium (Atomic No. 100), in honor of Fermi’s contributions to the scientific community. (This makes him one of sixteen scientists who have had elements named after them).
The Basilica of Santa Croce in Florence, known for its numerous tombs and memorials of great Italian artists, scientists, and prominent figures, has a plaque commemorating Fermi. Fermi was named by Time magazine as one of the top 100 personalities of the 20th Century. Fermi was widely regarded as an unusual case of a 20th-century physicist since he excelled both in theoretical and experimental physics. Fermi was known as an inspiring teacher and was noted for his attention to detail, simplicity, and careful preparation of his lectures. He disliked complicated theories, and while he had great mathematical ability, he would never use it when the job could be done much more simply. He was famous for getting quick and accurate answers to problems that would stump other people. Later on, his method of getting approximate and quick answers through “back-of-the-envelope” calculations became informally known as the Fermi method.
In closing, I would like to quote Fermi from his essay entitled “The Future of Nuclear Physics,” in which he sums up his view of the importance of scientific study into the atom and the basic structure of matter (It can be found in Cronin, J.W. (ed.). Fermi Remembered. Chicago: University of Chicago Press, 2004). (This excerpt is taken from the Wikipedia article cited in the bibliography below.) “Some of you may ask, what is the good of working so hard merely to collect a few facts which will bring no pleasure except to a few long-haired professors who love to collect such things and will be of no use to anybody because only few specialists at best will be able to understand them? In answer to such question[s] I may venture a fairly safe prediction.
The history of science and technology has consistently taught us that scientific advances in basic understanding have sooner or later led to technical and industrial applications that have revolutionized our way of life. It seems to me improbable that this effort to get at the structure of matter should be an exception to this rule. What is less certain, and what we all fervently hope, is that man will soon grow sufficiently adult to make good use of the powers that he acquires over nature.”

Adapted by James J. Boitano, PhD from:
Badash, Lawrence. “Enrico Fermi: Italian-American Physicist.” Encyclopedia Britannica website, March, 2024
Enrico Fermi: Atomicarchive.com website
Enrico Fermi: Biography.com website, May, 2021
Enrico Fermi: Biographical.” Nobelprize.org website, 1938
Enrico Fermi: Wikipedia website
Featured image: Enrico Fermi: (2024, April 22). By Department of Ener- gy-Office of Public Affairs, restored by Yann In Wikipedia


Additional Resource:
Voice of the Manhattan Project

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