Enrico Fermi
 |
Enrico Fermi in the 1940s |
Enrico Fermi (
September 29,
1901–
November 28,
1954) was an
Italian physicist most noted for his work on
beta decay, the development of the first
nuclear reactor, and for the development of
quantum theory. Fermi won the
1938 Nobel Prize in Physics for his work on induced radioactivity.
Physics in Rome
Enrico Fermi was born in
Rome,
Italy. As a young boy he enjoyed physics and mathematics. He also had a brother named Giulio with whom he shared his scientific interests. When Giulio died unexpectedly of a throat abscess in 1915, Enrico was distraught, and immersed himself into scientific study to distract himself. According to his own account, he would walk in front of the hospital where Giulio died each day, until he became inured to the pain. Later, Enrico befriended another scientifically inclined student named
Enrico Persico, and the two together engaged in scientific projects such as building
gyroscopes, and measuring the
magnetic field of the
earth. Fermi's interest in physics was further encouraged when a friend of his father's gave him several books on
physics and
mathematics, which he read and assimilated.
Fermi recieved his undergraduate and doctoral degree from the
Scuola Normale Superiore in
Pisa. There was an entrance exam which candidates had to take in order to enter the prestigious insitute, which included an essay. For his essay, the seventeen year old Fermi chose to derive and solve the
Fourier analysis based partial differential equation for waves on a string. The examiner interviewed Fermi and concluded that his essay would have been commendable even for a doctoral degree. At the
Scuola Normale Superiore, Fermi teamed up with a fellow student named
Franco Rasetti and used to indulge in light hearted pranks with him. Later, Rasetti became his close friend and collaborator.
Fermi's
Ph.D advisor was
Luigi Puccianti. In 1924 Fermi spent a semester in
Göttingen, then stayed for a few months in
Leiden with
Paul Ehrenfest. When he was only 24 years old, Fermi took a
professorship in
Rome (the first for
theoretical physics in Italy, created for him by professor
Orso Maria Corbino, director of the Institute of Physics).
Corbino helped Fermi in selecting his team, which soon was joined by notable minds like
Edoardo Amaldi,
Bruno Pontecorvo,
Franco Rasetti and
Emilio Segrè. For the theoretical studies only,
Ettore Majorana also took part in what was soon nicknamed "the
Via Panisperna boys" (after the name of the road in which the Institute had its labs).The group went on with its now famous experiments, but in
1933 Rasetti left Italy for
Canada and the
United States, Pontecorvo went to
France and Segrè left to teach in
Palermo.
During their time in Rome, Fermi and his group made important contributions to many practical and theoretical aspects of physics. Some of these include
Fermi-Dirac statistics, the theory of
beta decay, and the discovery of slow neutrons, which was to prove pivotal for the working of
nuclear reactors. His group also systematically bombarded elements with
neutrons, and during their experiments with
Uranium, narrowly missed observing
nuclear fission. At that time, fission was thought to be improbable, if not impossible, mostly on theoretical grounds. While people expected elements with higher
atomic number to form from neutron bombardment of lighter elements, nobody expected neutrons to have enough energy to actually split a heavier
atom into two light element fragments. However, the
chemist Ira Noddack had criticised Fermi's work and had suggested that some of his experiments could have produced lighter elements. At the time, Fermi dismissed this possibility on the basis of calculations.
When Fermi submitted his famous paper on
beta decay to the prestigious journal
Nature, the journal's
editor turned it down because "it contained speculations which were too remote from reality". Thus, Fermi saw the theory published in
Italian and in
German before it was published in
English.
He never forgot this experience of being ahead of his time, and used to tell his
protégés: "Never be first; try to be second".
Nobel Prize and the Manhattan Project
Fermi remained in Rome until
1938.
In
1938, Fermi won the
Nobel Prize in Physics for his "demonstrations of the existence of new
radioactive elements produced by neutron
irradiation, and for his related discovery of
nuclear reactions brought about by slow neutrons".
|
Fermi (bottom left), Szilárd (second from right on bottom), and the rest of the pile team. |
After Fermi received the
Nobel prize in
Stockholm, he, his wife Laura, and their children immigrated to
New York. By this time, the
Fascist government in Italy had instituted
anti-Semitic laws, and Fermi's wife,
Laura Capon, was Jewish. Soon after his arrival in New York, Fermi began working at
Columbia University.
At Columbia, Fermi verified the initial
nuclear fission experiment of
Hahn and
Fritz Strassmann (with the help of Booth and Dunning). Fermi then began studies that led to the construction of the first
nuclear pile.
Fermi recalled the beginning of the project in a speech given in
1954 when he retired as President of the
American Physical Society:
"I remember very vividly the first month, January,
1939, that I started working at the
Pupin Laboratories because things began happening very fast. In that period,
Niels Bohr was on a lecture engagement at the
Princeton University and I remember one afternoon
Willis Lamb came back very excited and said that Bohr had leaked out great news. The great news that had leaked out was the discovery of
fission and at least the outline of its interpretation. Then, somewhat later that same month, there was a meeting in
Washington where the possible importance of the newly discovered phenomenon of fission was first discussed in
semi-jocular earnest as a possible source of
nuclear power."
|
An image from the Fermi-Szilárd "neutronic reactor" patent. |
In August of
1939 Leó Szilárd prepared and
Albert Einstein signed the
famous letter warning President
Franklin D. Roosevelt of the probability that the Nazis were planning to build an atomic bomb. Because of
Hitler's September 1st
invasion of
Poland, it was October before they could arrange for the letter to be personally delivered. Roosevelt was concerned enough that the
Uranium Committee was assembled and awarded
Columbia University the first
atomic energy funding of US$ 6,000. However, due to bureaucrat's fears of foreigners doing secret research, the money was not actually issued until Szilárd implored Einstein to send a second letter to the president in the spring of 1940. The money was used in studies which led to the first
nuclear reactor â€"
Chicago Pile-1, a massive "
atomic pile" of
graphite bricks and
uranium fuel which went
critical on
December 2,
1942, built in a
squash court under
Stagg Field, the
football stadium at the
University of Chicago. This experiment was a landmark in the quest for energy, and it was typical of Fermi's brilliance. Every step had been carefully planned, every calculation meticulously done by him. When man first achieved the first self sustained nuclear chain reaction, a coded phone call was made to one of the leaders of the Manhattan Project,
James Conant: 'The Italian navigator has landed in the new world... The natives were very friendly'. The chain-reacting pile was important not only for its help in assessing the properties of fission â€" needed for understanding the internal workings of an
atomic bomb â€" but because it would serve as a pilot plant for the massive reactors which would be created in
Hanford, Washington, which would then be used to "
breed" the
plutonium needed for the bombs used at the
Trinity test and
Nagasaki. Eventually Fermi and Szilárd's reactor work was folded into the
Manhattan Project.
Fermi moved to
Los Alamos in the later stages of the Manhattan Project to serve as a general
consultant. His broad knowledge of many field of physics was useful in solving problems that were of an interdisciplinary nature.
He became a
naturalized citizen of the United States of America in
1944.
Post-war work
In Fermi's
1954 address to the APS he also said, "Well, this brings us to
Pearl Harbor. That is the time when I left Columbia University, and after a few months of commuting between Chicago and New York, eventually moved to Chicago to keep up the work there, and from then on, with a few notable exceptions, the work at Columbia was concentrated on the
isotope separation phase of the atomic energy project, initiated by Booth, Dunning and Urey about
1940".
Fermi was widely regarded as the only physicist of the twentieth century who excelled both theoretically and experimentally (Snow, 1981) (see
link below in 'References'). The well-known historian of physics,
C. P. Snow, says about him, "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". Fermi's ability and success stemmed as much from his appraisal of the art of the possible, as from his innate skill and intelligence. 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 which would stump other people. An instance of this was seen during the first atomic bomb test in
New Mexico on July 16, 1945. As the blast wave reached him, Fermi dropped bits of paper. By measuring the distance they were blown, he could compare to a previously computed table and thus estimate the bomb energy yield. He estimated that the blast was greater than 10
kilotons of
TNT, the measured result was 18.6. (Rhodes, page 674). Later on, this method of getting approximate and quick answers through back of the envelope calculations became informally known as the 'Fermi method'.
|
The Enrico Fermi street in Rome |
Fermi's most disarming trait was his great modesty, and his ability to do any kind of work, whether creative or routine. It was this quality that made him popular and liked among people of all strata, from other Nobel Laureates to technicians.
Henry DeWolf Smyth, who was Chairman of the Princeton Physics department, had once invited Fermi over to do some experiments with the Princeton
cyclotron. Walking into the lab one day, Smyth saw the distinguished scientist helping a graduate student move a table, under another student's directions. Another time, a
Du Pont executive made a visit to see him at Columbia. Not finding him either in his lab or his office, the executive was surprised to find the
Nobel Laureate in the machine shop, cutting sheets of tin with a big pair of shears.
After the war, Fermi served for a short time on the General Advisory Committee of the
Atomic Energy Commission, a
scientific committee chaired by Oppenheimer which advised the commission on nuclear matters and policy. After the detonation of the first Soviet
fission bomb in August
1949, he, along with
Isidor Rabi, wrote a strongly worded report for the committee which opposed the development of a hydrogen bomb on moral and technical grounds. But Fermi also participated in preliminary work on the hydrogen bomb at Los Alamos as a consultant, and along with
Stanislaw Ulam, calculated that the amount of
tritium needed for
Edward Teller's model of a
thermonuclear weapon would be prohibitive, and a
fusion reaction could not be assured to propagate even with this large quantity of tritium.
In his later years, Fermi did important work in particle physics, especially related to pions and muons. He was also known to be an inspiring teacher at the
University of Chicago, and was known for his attention to detail, simplicity, and careful preparation for a lecture. Later, his lecture notes, especially those for
quantum mechanics,
nuclear physics, and
thermodynamics, were transcribed into books which are still in print.
On
November 28,
1954, Fermi died at the age of 53 of
stomach cancer in
Chicago, Illinois and was interred there in
Oak Woods Cemetery. As
Eugene Wigner wrote: "Ten days before Fermi had died he told me, 'I hope it won't take long.' He had reconciled himself perfectly to his fate".
A recent poll by
Time magazine listed Fermi among the top twenty scientists of the century.
*
Fermi paradox*
Fermi problem*
Fermion field*
Fermi's golden rule*
Scuola Normale Superiore*
Laura Fermi,
Atoms in the Family: My Life with Enrico Fermi (Chicago: University of Chicago Press, 1954) ISBN 0226243672
*
Richard Rhodes,
The Making of the Atomic Bomb (New York: Simon and Schuster, 1986).
*
C. P. Snow, "The Physicists" (Toronto: Little, Brown, 1981)
*
Emilio Segrè,
Enrico Fermi - Physicist* Fermi's audio biography at the University of Chicago website. (http://www-news.uchicago.edu/fermi/resources.html)
*
pdf* Roberto Mignani e Fabio Cardone,
I Secchi della Sora Cesarina: metodo, pregiudizio e caso in fisica,
Di Renzo Editore, Roma
Information*
A photographic archive of Fermi and "the Panisperna boys"*
About Enrico Fermi*
Life and works of Enrico Fermi (in Italian)
*
Annotated bibliography on Enrico Fermi from the Alsos Digital Library*
The Story of the First Pile*
E-Book Enrico Fermi: The Master Scientist *
Goudsmit on the
discovery of electron spin*
Fermi Commemorative Events* —
Process for the Production of Radioactive Substances, filed October, 1935, issued July, 1940
* —
Neutron Velocity Selector, filed September, 1945, issued October, 1950
* —
Neutronic reactor, with
Leo Szilard, filed December, 1944, issued May, 1955
* —
Testing Material in a Neutronic Reactor, filed August, 1945, issued October, 1956
* —
Test Exponential Pile, filed May, 1944, issued February 1957
* —
Method of Operating a Neutronic Reactor, filed December 1944, issued July, 1957
* —
Neutronic Reactor, filed October 1945, issued September, 1957
* —
Neutronic Reactor Shield, filed January 1946, issued September, 1957
* —
Method of Sustaining a Neutronic Chain Reacting System, filed November, 1945, issued November, 1957
* —
Air Cooled Neutronic Reactor* —
Chain Reacting System* —
Neutronic Reactor* —
Neutronic Reactor* —
Method of Testing Thermal Neutron Fissionable Material for Purity, filed November 1945, issued January 1961
