Enrico Fermi was an Italian-American nuclear physicist who created the first self-sustaining nuclear chain reaction in 1942. He played a key role in developing the first atomic bomb and has been described as the architect of the nuclear age. Fermi excelled in both theoretical physics and experimental physics and was awarded the Nobel Prize in physics in 1938, for his work on induced radioactivity. He made contributions to quantum theory, statistical analysis, nuclear physics and particle physics.
Enrico Fermi was born in Rome on 29 September 1901. From a young age, he displayed an aptitude for mathematics and physics. Largely self-taught, he became knowledgable in quantum mechanics and atomic physics – two subjects which at the time were in their infancy. At the age of only 20, he gained his submitted his Laurea – Italian degree, after submitting his thesis on X-ray diffraction images. He travelled around Germany and Italy meeting leading physicists. This included meeting the famed Albert Einstein. Fermi was the first to take Einstein’s famous equation (E = mc2) and be aware of the enormous potential nuclear energy contained in the formula. In 1923, Fermi wrote
“It does not seem possible, at least in the near future to find a way to release these dreadful amounts of energy—which is all to the good because the first effect of an explosion of such a dreadful amount of energy would be to smash into smithereens the physicist who had the misfortune to find a way to do it.”
It was a prophetic statement as that unfortunate scientist would prove to be Fermi himself.
His first major work was publishing a paper on statistical theory to describe the behaviour of large numbers of particles, such as electrons, protons and neutrons. Although this branch of physics was obscure at the time, it became of increasing value as the sub-atomic level of physics was developed. The particles are now named fermions about Fermi
By 1926, he was a full professor at the University of Rome. Despite being a leading physicist, he was also noted for being an excellent teacher, who would present topics in a clear and easy understandable way. Fermi had tremendous intellect, but he would also try to simplify and use uncomplicated methods. Where possible he would use simple calculations first, before using more complicated maths. When scientists try a rough and ready predictions from the ‘back of an envelope’ calculation – it is known as the ‘Fermi Method’.
In 1928, he married Laura Capon, a science student at the university. They had two children, Nella and Giulio.
In 1933, Fermi published a paper on the puzzling behaviour of beta decay – which involved electrons being emitted from the nucleus of an atom. This behaviour was puzzling from the perspective of the law of conservation of energy. His paper became a key aspect of particle physics and later became known as Fermi’s interaction. It was also the precursor to the theory of weak interaction where the interaction between the proton–neutron and electron–antineutrino is mediated by a virtual W− boson.
The 1920s and 30s was a period of rapid discoveries in sub-atomic physics. In 1932, the British physicist James Chadwick discovered the neutron (a sub-atomic particle with no electric charge constituting the nuclei of atoms) Fermi experimented with bombarding chemical elements with neutrons. Fermi’s experiments showed that if neutrons could be slowed down (by water or paraffin), then they could be more easily absorbed by chemical elements. This became an important component of a nuclear reactor – the moderator where fast-moving protons are slowed down. For this research, he was awarded the Nobel Prize in 1938.
In 1929, the fascist dictator Mussolini appointed Fermi to the Royal Academy of Italy; Fermi joined the Fascist party shortly after – probably as something he was expected to do, rather than with any enthusiasm. However, by 1938, Mussolini introduced severe anti-semitic laws to please Hitler – which prohibited Jewish people from working in state-owned institutions. It put many of Fermi’s assistants out of work and threatened his wife who was Jewish. In December he travelled with his family to Stockholm to accept the Nobel Prize, he never returned to Italy, but quietly travelled to the US, where Colombia University was happy to welcome the famous physicist.
Atomic research in the US
For several reasons – both personal and scientific – it was fortunate timing to leave fascist Italy and arrive in the US. Shortly after arriving in the US in 1938, he came to learn there had been an important scientific breakthrough with the first cases of nuclear fission. Nuclear fission is a nuclear reaction which occurs when the nucleus of an atom splits into smaller lighter nuclei. The experiment was carried out by the German scientists Otto Hahn and Fritz Strassman who had bombarded uranium with neutrons.
In the US, leading scientists such as Niels Bohr and Enrico Fermi became excited at the possibilities of harnessing the power of nuclear fission and the potential energy locked within.
Shortly after on 25 January 1939, a team of scientists at Columbia University including Enrico Fermi conducted the first nuclear fission in the US. They were also able to show that the uranium emitted more neutrons than were sent towards the uranium – showing a chain reaction was occurring. Aware of the potential military value of this science, in March 1939, Fermi gave a lecture to the navy department on the potential of nuclear energy. It had little immediate effect. However, when scientists sent a letter signed by Albert Einstein to US president Roosevelt that Germany was likely to be developing an atomic bomb, the US attitude changed. As a result, Roosevelt approved substantial resources to a top-secret project – the Advisory Committee on Uranium – to develop the military capabilities of nuclear fission.
Fermi’s first task was to build an atomic pile – using enriched uranium and graphite, where a self-sustaining nuclear chain reaction could occur. Using Fermi’s theoretical and experimental knowledge, he built the Chicago Pile I – in a location 20 miles from the University of Chicago. The pioneering nuclear reactor was housed in a disused squash court underneath the University of Chicago’s abandoned football stadium.
With Fermi’s meticulous calculations and planning, the nuclear reactor was successfully built becoming the world’s first nuclear reactor and marking the coming of the nuclear age. As the project was top secret a coded message was sent to the chairman, James B. Conant of the National Defence Research Committee.
“you’ll be interested to know that the Italian navigator has just landed in the new world.
Conant replied “Is that so, were the natives friendly?”
“Everyone landed safe and happy.”
The success of this atomic reactor led to the American government pursuing the Manhattan project with unlimited resources and as a top priority. For a while, Fermi stayed in Chicago where he proceeded to pursue several groundbreaking nuclear experiments which were now possible because of the Chicago reactor.
However, in mid-1944, Robert Oppenheimer persuaded Fermi to directly join his project in Los Alamos, New Mexico.
After the war, he continued his research into a variety of physics, such as the origin of cosmic rays. He also postulated on the possibilities of alien life creating the Fermi paradox – that despite a probability there is alien life, we have not become aware of it yet. He also warned about the dangers of atomic and hydrogen bombs. After the Soviet Union developed a hydrogen bomb in 1949, he wrote:
“Such a weapon (hydrogen bomb) goes far beyond any military objective and enters the range of very great natural catastrophes. By its very nature it cannot be confined to a military objective but becomes a weapon which in practical effect is almost one of genocide.”
(report for the Atomic Energy Commission 30 October 1949)
However, he still took part in the project to develop the US hydrogen bomb. He believed that it was almost impossible to stop scientific development.
“One might be led to question whether the scientists acted wisely in presenting the statesmen of the world with this appalling problem. Actually there was no choice. Once basic knowledge is acquired, any attempt at preventing its fruition would be as futile as hoping to stop the earth from revolving around the sun.”
Collected Papers of Enrico Fermi: The United States, 1939-54
Fermi often pointed out that when Alessandro Volta studied electricity, he had no idea where it would lead. For Fermi, like many atomic scientists, he remained uncomfortable with the development of atomic bombs. One year before his death, he remained concerned about the potential dangers of this technology in the hands of the powerful.
“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 revolutionised 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.”
Enrico Fermi, The Future of Nuclear Physics, unpublished address, Rochester, NY, January 10, 1953, EFP, box 53.
In 1954, he died from stomach cancer, aged only 53.
Outside of physics, his favourite pastimes were walking, mountaineering, and winter sports. He was born a Roman Catholic, but his family were not particularly religious and he remained agnostic throughout his life. He was a member of the American Philosophical Society, the American Physical Society and Sigma XI, honorary scientific fraternity.
The Last Man Who Knew Everything: The Life and Times of Enrico Fermi, Father of the Nuclear Age
The Last Man Who Knew Everything: The Life and Times of Enrico Fermi, Father of the Nuclear Age
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