Enrico Fermi

Enrico Fermi was born in Rome, Italy, on September 29, 1901, to Alberto Fermi, a chief inspector of the Ministry of Communications, and Ida de Gattis.⁠[1]

In 1918 Fermi won a fellowship at the Scuola Normale Superiore in Pisa, and in 1922 he received his doctorate in physics from the University of Pisa under Professor Puccianti. In 1923 an Italian government scholarship took him to Göttingen for several months with Max Born, and in 1924 a Rockefeller Fellowship took him to Leiden to work with P. Ehrenfest.⁠[1][2]

From 1924 to 1926 Fermi was a lecturer in mathematical physics and mechanics at the University of Florence, and in 1926 he discovered the statistics, now called Fermi statistics, that govern particles obeying Pauli’s exclusion principle. In 1927 he became professor of theoretical physics at the University of Rome, a post he held until 1938. In 1929 he was appointed by Benito Mussolini as one of the first 30 members of the Royal Academy of Italy.⁠[1][2]

In 1934 Fermi developed his theory of beta decay and discovered the effects of slow neutrons, work that helped pave the way to the discovery of nuclear fission. In May that year his Rome team bombarded elements with neutrons and split uranium without realizing it.⁠[1][2][3]

Fermi received the whole 1938 Nobel Prize in Physics as a scholar of Rome University, “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.⁠[4]

His wife, Laura Fermi, came from a prominent Jewish family, and Italy had adopted anti-Semitic policies. In late 1938 Fermi left Italy with his wife and their two children for the Nobel ceremony in Stockholm and then quietly moved to the United StatesUnited StatesThe United States is a federal country in North America made up of 50 states, the District of Columbia as the seat of government, and territories such as Puerto Rico and Guam; its capital is Washington, D.C. The Continental Congress adopted the Declaration of Independence on July 4, 1776. The 2020 census (April 1, 2020) counted a resident population of 331,449,281, and the 435 seats of the House of Representatives are apportioned among the states on the basis of the census.Open the full entry. Encyclopaedia BritannicaEncyclopædia BritannicaEncyclopædia Britannica is a general English-language encyclopedia first published in Edinburgh, Scotland, in 1768; the name also refers to its publisher, Chicago-based Encyclopædia Britannica, Inc. (which presents itself as The Britannica Group). The print edition ended in 2012, and the company’s main businesses since then have been the online encyclopedia Britannica.com, digital education products for schools and libraries, and Merriam-Webster dictionaries.Open the full entry judges that the award gave the family an excuse to travel abroad and that the prize money helped establish them in the United States.⁠[5][6][2]

From 1939 to 1942 Fermi was professor of physics at Columbia UniversityColumbia UniversityColumbia University, formally Columbia University in the City of New York, is a private research university in New York City and a member of the Ivy League. Founded in 1754 by royal charter from King George II as King's College, it is the oldest institution of higher education in New York State and the fifth oldest in the United States. It was renamed Columbia College in 1784 and adopted the university name and moved to Manhattan's Morningside Heights in 1896. It has 17 schools and four affiliated colleges, with 35,978 students enrolled in fall 2025. Legal scholar Jennifer L. Mnookin became president on July 1, 2026.Open the full entry. The family lived first in New York City and then in Leonia, New JerseyNew JerseyNew Jersey is a state in the eastern United States on the Atlantic Ocean, bordered by New York State, Delaware, and Pennsylvania, with the Hudson River forming its northeastern boundary and the Delaware River its western boundary; its capital is Trenton and its largest city is Newark. One of the original 13 colonies, it became the third state to ratify the U.S. Constitution on December 18, 1787, and its population in the 2020 census (April 1, 2020) was 9,288,994.Open the full entry. He began work at the Pupin Laboratories in January 1939 and, shortly afterward, with Booth and Dunning verified the fission experiment of Hahn and Strassmann; the Atomic Heritage Foundation records him as part of the team that conducted the first fission experiment in the United States on January 25, 1939.⁠[1][6][7][2]

At Columbia University, Fermi and Herbert Anderson worked in parallel with Walter Zinn and Leo Szilard. He began building his first nuclear pile at Pupin, and it was later moved to and completed in Schermerhorn Hall; in 1941 he built a graphite-brick pile at Columbia. After Pearl Harbor he commuted between Chicago and New York for a few months and then moved to Chicago.⁠[7][2]

In 1942 Fermi joined the University of Chicago’s Metallurgical Laboratory. Construction of the main pile began in November 1942 in a former squash court beneath the West Stands of Stagg Field; it was built of graphite blocks, some containing small pieces of uranium, and regulated with cadmium-coated control rods.⁠[2][8][9][10]

On December 2, 1942, before 49 scientists led by Fermi, George Weil withdrew the control rod and Chicago Pile-1 (CP-1) achieved the first self-sustaining, controlled nuclear chain reaction, at an accepted official time of 3:36 p.m.; Leona Marshall was the only woman researcher present. After the group had watched the reaction for twenty-eight minutes, Fermi ordered the safety rod back in at 3:53 p.m. and the reaction stopped. The energy produced was enough to power one small lightbulb.⁠[9][8][10]

Arthur Compton then telephoned James B. Conant at HarvardHarvard UniversityHarvard University is a private research university in Massachusetts, established by the Massachusetts Bay Colony legislature in 1636 and named in 1639 for early benefactor John Harvard. Its principal campuses are in Cambridge and the Allston and Longwood neighborhoods of Boston. It includes Harvard College, graduate and professional schools, and the Radcliffe Institute for Advanced Study. Two governing boards share oversight. Alan M. Garber was president as of October 2026, and the endowment stood at $56.9 billion at the end of fiscal 2025.Open the full entry with the coded message “The Italian navigator has landed in the New World.” The participants celebrated with Chianti in paper cups and signed the bottle’s label, the only written record of who took part. Encyclopaedia Britannica judges that CP-1 proved a controlled nuclear reaction was possible and served as the prototype for the later reactors at Hanford. In early 1943 CP-1 was dismantled and rebuilt as the larger Chicago Pile No. 2 (CP-2) at Site A in the Argonne Forest Preserve south of Chicago.⁠[8][9][6]

On November 4, 1943, Fermi witnessed the X-10 Graphite Reactor at Oak Ridge, TennesseeTennesseeTennessee is a U.S. state in the southeast-central United States, with its capital at Nashville. It was admitted to the Union on June 1, 1796, as the 16th state, and the 2020 census (April 1, 2020) counted 6,910,840 residents.Open the full entry, go critical. In September 1944 he became a U.S. citizen. On September 27, 1944, at Hanford, Washington, he inserted the first uranium slug into the B Reactor, and he helped identify xenon-135 as the cause of the reactor’s shutdown.⁠[2][1][3]

J. Robert OppenheimerJ. Robert OppenheimerJ. Robert Oppenheimer (1904–1967) was an American theoretical physicist and science administrator who directed the Los Alamos laboratory that developed the atomic bomb during World War II.Open the full entry recruited Fermi as associate director of the Los Alamos laboratory. The Fermi family arrived at Los Alamos in September 1944, and F Division, which he headed, was established that month. On July 16, 1945, he observed the Trinity test and estimated the yield of the first plutonium bomb from how far slips of paper were blown. F Division was dissolved in October 1945, and he left the laboratory in December 1945.⁠[3][5][6]

On July 1, 1945, Fermi was named professor of physics at the University of Chicago; from 1946 until his death he was a professor at its Institute for Nuclear Studies, turning to high-energy particle physics and pion–nucleon interactions. He served on the General Advisory Committee of the Atomic Energy Commission and was president of the American Physical Society, giving his retiring address at Columbia University on January 30, 1954.⁠[2][1][6][7]

Fermi and Isidor Rabi opposed building a thermonuclear bomb, arguing on ethical grounds that it would be “necessarily an evil thing considered in any light.” President Harry S. TrumanHarry S. TrumanHarry S. Truman (1884–1972) was an American politician who served as a U.S. senator from Missouri and as vice president in 1945, succeeding Franklin D. Roosevelt on his death that year and serving as the 33rd president of the United States from 1945 to 1953, a period spanning the end of World War II and the early Cold War.Open the full entry decided otherwise, and Fermi briefly returned to Los Alamos to assist with work on fusion weapons.⁠[6]

Fermi died of stomach cancer in Chicago, IllinoisIllinoisIllinois is a state of the United States that borders Lake Michigan and the states of Wisconsin, Indiana, Kentucky, Missouri and Iowa; its capital is Springfield and its largest city is Chicago. It was admitted to the Union on December 3, 1818, as the 21st state, and its population in the 2020 census (April 1, 2020) was 12,812,508.Open the full entry, on November 28, 1954, at the age of 53, and was buried in Oak Woods Cemetery in Chicago. He was the first recipient of a $50,000 award that now bears his name.⁠[3][6][1]

Fermi married Laura Capon in 1928; they had a son, Giulio, and a daughter, Nella.⁠[1]

The U.S. Department of Energy’s Enrico Fermi Award, the Fermi National Accelerator Laboratory (Fermilab) in Illinois and fermium, element 100, are named for him. The Department of Energy’s Office of Nuclear Energy notes that Fermilab’s name honors his contributions to nuclear physics and his work at the University of Chicago.⁠[6][9]

Columbia University: Official website: https://www.columbia.edu/ (opens in a new window).⁠[7]

University of Chicago: Official website: https://www.uchicago.edu/ (opens in a new window).⁠[11]

Los Alamos National Laboratory: Official website: https://www.lanl.gov/ (opens in a new window).⁠[12]