one’s name permanently attached to an important physical concept
or unit bestows a kind of immortality. It is hard to imagine any
discussion of modern physics in which Fermi’s name does not
come up at least once, in terms of such as fermion, Fermi gas, Fermi
momentum, Fermi temperature, Fermi surface, Fermi coupling, Fermi
transition, and Fermi length. Still, because Fermi died so young—and
so long ago—he has become, for the current generation of physicists,
a somewhat mystical figure.”
Valentine L. Telegdi
“Fermi devoted a great deal of his time
to the graduate students…his teaching was exemplary, minutely
prepared, clear, with emphasis on simplicity and understanding of
the basic ideas, rather than generalities and complications…We
would knock at his office door, and if free, he would take us in,
and then he would be ours until the question was resolved.”
“Fermi had the widest scope of all the
founders of quantum physics. As a theorist, he contributed decisively
to quantum mechanics (Fermi-Dirac statistics) and nuclear physics
(theory of beta decay). As an experimentalist, he introduced the
technique of neutron bombardment to study artificial radioactivity,
opening the way to the discovery of nuclear fission.”
Enrico Fermi is regarded as father of nuclear physics. In the history
of modern physics there is none who matched the versatility of Fermi.
His contributions in pure theoretical physics and concrete experimental
work were equally great. He could design and build, with his own
hands, astonishingly useful experimental tools. He developed the
mathematical statistics required to describe a large class of sub-atomic
particles. He discovered neutron-induced radioactivity.In 1938,
Fermi was awarded Nobel Prize in physics “for his identification
of new radioactive elements produced by neutron bombardment and
for his discovery of nuclear reaction effected by slow neutrons.”
In 1942 Fermi constructed the first nuclear reactor. He directed
the first controlled chain reaction involving nuclear fission. Fermi
was a great teacher and through the influence of his eminent students,
in Italy and the US, Fermi effectively revolutionized the training
of physicists. Fermi established a famous school (The Rome School)
of nuclear physics in Rome. In Chicago also he established a vibrating
school. Fermi was a central figure in the Manhattan project to build
the first atomic bomb. The element with atomic number 100, discovered
one year after his death, was named Fermium (Fm) in Fermi’s
Fermi was born on September 29, 1901 in Rome.
His father Alberto Fermi was a railroad engineer and his mother
Ida de Gattis was a school teacher. He was the youngest of three
children of his parents. Fermi learned to read and write from his
mother. He studied at the local high schools. Fermi as a child displayed
unusual mathematical ability and prodigious memory. His school records
were excellent. Fermi was much influenced by a colleague of his
father, Adolfo Amidei, who lent him books on mathematics. At the
age of 17, Fermi entered the highly selective Reale Scuola Normale
Superiore, an Italian advanced study and research institution. It
was Amidei who advised Fermi to go for this elit institution. The
institution was established by Napoleon in 1810 as a branch of the
Ecole Normale Superieure of Paris. It was associated with the University
Fermi obtained his PhD at the age of 21 from the
University of Pisa. His PhD thesis was on his research on X-rays.
After his PhD he made a short visit to Rome and then left for Germany
with the Fellowship from the Italian Ministry of Public Instruction
to study at the University of Gottingen under Max Born. From Germany
he went to Leiden in the Netherlands, where he worked with P. Ehrenfest
(1880-1933). After returning in Italy in 1924, Fermi joined the
University of Florence, where he lectured on mathematical physics
In 1926, Fermi started to study statistical mechanics
of particles that obey Pauli exclusion principle, such as electrons.
Fermi was the first to apply Pauli exclusion principle to systems
of multiple electrons not attached to atoms.The result was the so-called
Fermi-Dirac Statistics, as Dirac also obtained the same conclusion.
In 1927 Fermi was appointed Professor of Theoretical
Physics at the University of Rome, the post he held for 12 years.
At the time of his appointment he was just 25 years old. He became
the youngest full professor in Italy. He also became the first person
to occupy a chair in theoretical physics. This was no mean achievement
for a person of Fermi’s age particularly considering the traditional
and bureaucratic nature of the Italian Universities in those days.
It was true that Fermi had established his reputation by publishing
30 substantial research papers. But perhaps this was not the only
reason for Pauli’s success in climbing the ladder of Italian
science. Fermi was patronized by Orso Mario Corbino, the most distinguished
Italian physicist of his time and also a senator. Corbino was all
for modernizing Italian physics and thought that Fermi, in spite
of his youth, was ideal man to advance his ideas. With Corbino’s
support Fermi organized his group of young experimental and theoretical
physicists. The group, which later came to be called as the Rome
School, included Edoardo Amaldi, Franco Rasetti, Bruno Pontecorvo,
Emilio Segre, Oscar D’Agostino and Ettore Majorana. The Rome
school changed the landscape of Italian physics, and indeed world
Fermi and his group followed up the then-new phenomenon
artificial radioactivity. In 1934, Irene and Frederic Joliot-Curie
had announced the production of artificial radioactive isotopes
by the bombardment of boron and aluminium with helium nuclei or
alpha particles. Fermi realized that neutron discovered by James
Chadwick in 1932 would be a better candidate than alpha particle
for creating new radio isotopes. Though neutron is less massive
but because of its neutrality it could overcome the positive charge
of a target nucleus. In 1934 Fermi found that neutrons slowed down
in passing through light elements and if neutrons are suitably retarded
they become extremely effective in carrying out nuclear transmutation.
Actually Fermi had stumbled on the slow neutrons. Fermi without
any advance warning, or conscious prior reasoning took some odd
piece of paraffin and placed it in front of the incident neutrons.
As the result of the collisions with the light hydrocarbon molecules
the neutrons slowed down and as they slowed down they remained in
the vicinity of the target nucleus sufficiently long to increase
In the summer of 1938, the fascist government
of Mussolini introduced racial laws modeled after the notorious
German Nurenberg laws. Under the provision of these laws scientists
and scholars of Jewish origin working in Italian universities were
to be dismissed. Fermi was affected because his wife Laura was a
Jewish. He was also publicly accused by fascist extremists of “having
transformed the physics institute into a synagogue.” Fermi
and his family decided to leave Italy. They went to America.
Before emigrating to America in January 1939,
Fermi had already visited the America several times. In 1933, he
had taught a course in quantum electrodynamics at the University
of Michigan. His celebrated article “Reviews of Modern Physics”
was based on this course. In 1936, he was a visiting professor at
Columbia University, where he taught a course on thermodynamics.
Lloyd Motz edited Fermi’s lecture notes into book form and
which is still in use. During his visit to Columbia University in
1936, George Pegram, the Chairman of the Physics Department, offered
him a permanent appointment at the Columbia University. However,
at that time Fermi did not feel the urgency of leaving Italy.
Fermi was a great teacher. Commenting on Fermi’s
understanding of theoretical physics, the German born American physicist,
Hans Bethe (1906-2005) wrote: “My greatest impression of Fermi’s
method of teaching in theoretical physics was its simplicity. He
was able to analyse into its essential point every problem, however
complicated it seemed to be. He stripped it of mathematical complications
and of unnecessary formalism. In this way, often in half an hour
or less, he could solve the essential physical problem involved….His
approach was pragmatic….He was master of achieving important
results with a minimum of effort and mathematical apparatus.”
The Italian born American physicist Emilio Segre
(1905-1989) wrote: “The speed at which it was possible to
train a young physicist at the ‘Fermi school’ was incredible.
Naturally a good deal of the success was due to the immense enthusiasm
that had been aroused in the young people—never by exhortations
or ‘sermons’ but by the eloquence of example. After
having spent time in the institute in Via Panisperna, one became
completely absorbed in physics.”
To know personal attributes of Fermi let us quote
Valentine Telegdi, who was associated with Fermi in Chicago in the
early 1950s. Telegdi wrote: “It was not easy to know Fermi
intimately, in the sense of understanding his deeper motivations.
Professionally, he was always accessible, but he stayed aloof on
the personal level. When I knew him at Chicago, he did not seem
to develop bonds of friendship with colleagues at the university.
Herb Anderson and Leona Marshall were perhaps the only exceptions.
Fermi avoided gossip and rarely expressed his opinions, high or
low, about the practices of others. All this gave him an air of
modesty that belied his full awareness of his own capabilities.
Fermi rarely made mistakes when he was talking about physics. A
public mistake was a painful experience for him. The story is told
that once, when writing on the blackboard in front of a class, he
realized that he had gotten a certain factor wrong. He faced the
audience to make some interesting remarks and, at the same time—without
interrupting his delivery—he wiped out the wrong formula with
his left elbow. Another story tells of a student who pointed out
that Fermi had written a ‘c’ in the numerator rather
than in the denominator where it belonged. ‘Who told you’,
responded the great teacher, ‘that I use ‘c’ and
not ‘1/c’ for the velocity of light?’
Fermi had very regular working habits and a frugal
lifestyle. He usually came to work before 8 AM, either walking or
biking when weather permitted. He had already been working for several
hours at home. He was totally secure in his own physics talent and
almost never displayed jealousy of another scientist. The only exception
was Einstein. More than one, Fermi expressed annoyance at the attention
Einstein received from the press.”
Fermi jointly with Leo Szilard and Eugene Wigner,
drafted an important letter for Einstein to send to President Roosevelt
explaining the dangerous military potentialities offered by nuclear
fission and warning him that Germany might develop these weapons.
The letter itself has become important part of history. This letter
played an important role in initiating American efforts that finally
produced the nuclear reactor and the fission bomb. On December 06,
1941, President Roosevelt authorized the organization of the secret
project, named as “Manhattan Project”. The programme,
the final aim was to produce the atomic bomb, included work on chain
reaction, research to develop ways of producing plutonium-239 and
to find methods of obtaining enriched uranium-235. The first step
of the project was to try to create a chain reaction. A fission
chain reaction experiment was first performed at Columbia University
under the leadership of Fermi. The project was then transferred
to Chicago. But Fermi was not involved with this initiative. Fermi
being an émigré Italian was considered enemy alien
and he was confined to New York. Fermi’s mail was subject
to censorship. But then the situation was changed in 1942 when President
Roosevelt declared that Italians would no longer be considered enemy
aliens. Fermi was allowed to join other scientists working in the
project for the atomic bomb. However, his letters were still censored.
At Chicago, Fermi and his team, succeeded in constructing
the world’s first nuclear reactor. On December 02, 1942, the
reactor went critical. An account of the historic event was given
in this way. “The clicks [of the counter] came more and more
rapidly, and after a while they began to merge into a roar, the
counter couldn’t follow any more. That was the moment to switch
to the chart recorder. Everyone watched in the sudden silence the
mounting deflection of the recorder’s pen. It was an awesome
silence. Everyone realized the significance of that switch; we were
in the high intensity regime. Again and again, the scale of the
recorder had to be changed to accommodate the neutron intensity
which was increasing more and more rapidly. Suddenly Fermi raised
his hand. ‘The pile has gone critical’, he announced.
No one present had any doubt about it.”
Arthur Compton informed the managing committee
by saying “the Italian navigator has just landed in the new
world and that the natives were friendly.’’
After completing the chain reaction Fermi continued
to work on the project. In the preparation of the testing of the
first atomic bomb named, Trinity, Fermi’s role was instrumental.
Segre wrote: “This was one of those occasions when Fermi’s
dominion over all physics, one of his most startling characteristics,
came into its own. The problems involved in the Trinity test ranged
from hydrodynamics to nuclear physics, from optics to thermodynamics,
from geophysics to nuclear chemistry. Often they were closely interrelated,
and to solve one it was necessary to understand all the others.
Even though the purpose was grim and terrifying, it was one of the
greatest physics experiments of all time. Fermi completely immersed
himself in the task. At the time of the test he was one of the very
few persons (or perhaps the only one) who understood all the technical
ramifications of the activities at Alamogordo.”
In 1952, Fermi was elected President of the American Physical Society.
On November 16, 1954, President Eisenhower presented the Atomic
Energy Commission’s special award for his lifetime of accomplishments
in physics and in particular for the development of atomic energy.
Fermi died on November 28, 1954 in Chicago, just after his fifty-third
birthday. He was survived by his wife Laura and their two children.
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