Among the 20th century physicists, there were people more creative than Enrico Fermi; One or two of them thought more deeply, and a few were more skilled in mathematics. But Enrico Fermi was the best problem solver in them, with his amazing ability to see the essence of any physics problem. He was also the last person that reached the highest level in both theoretical and experimental fields.
The invention of the atomic bomb
His reaction to the explosion test of the first atomic bomb shows these qualities. Fermi was the responsible scientist for the physical concepts derived in the Los Alamos National Laboratory in New Mexico, the research and design center for the nuclear weapon development program, codenamed "the Manhattan Project". He played an important role both in these concepts that led to the making of the atomic bomb and also in the construction of the actual bomb. Many of those at Los Alamos saw him as a prophet to be consulted in any difficult problem of theory, experiment, or computation. Nevertheless, he never made an engraved quote for the memories of the test explosion of the atomic bomb on July 16, 1945. However, there is an interesting story.
J. Robert Oppenheimer's immediate response to this event, the director of the Manhattan Project, is the most well-known. Seeing the explosion illuminating the sky, a line from the Hindu inscription Bhagavad Gita came to his mind; Vishnu said to the Princess: "Now I am become Death, the destroyer of worlds." On the other hand, the head of the test, Kenneth Bainbridge, summarized the same event differently: "Now, we are all sons of bitches." While those present at the test side were in emotions ranging from fear to pride, the always pragmatic Fermi was seen breaking down a sheet of paper to find a quick and simple way to measure the impact of the explosion.
When the shock wave reached his location after 40 seconds, it blew the pieces around. He calmly observed how far the pieces flew, then, referred to a simple chart he had previously prepared, took out the spreadsheet, and made his prediction about the size of the atomic explosion. Fermi's ability to calculate the dimensions of any physical phenomenon was legendary, as the detailed measurements show later, this was no exception.
Who is Enrico Fermi?
Enrico Fermi was born on September 29, 1901, in Rome and grew up in an ordinary family. His father worked on state railways, his mother was a teacher. Fermi's extraordinary abilities were quickly noticed and he was awarded a scholarship to study at Scuola Normale Superiore at the elite university of Italy, Pisa. Here he quickly overshadowed not only other students but also teachers. At that time, Italy was relatively weak in physics. This means that Fermi was a self-taught student. He has developed his own style, focusing on seeking a simple solution by sorting out the key points of a problem.
This approach was opposed to the dominant German school of that time, which was based heavily on mathematics. After graduation, Fermi quickly solved many important problems in theoretical physics, one of which was the subject of statistical mechanics, which incorporated the approaches of the new quantum mechanics. This success attracted the attention of the physics professor Orso Corbino in Rome. He was a much older man than Fermi, who was looking for the person of his dreams to run the world-class physics institute.
Corbino, a politically strong man, saw his dreams come true in Fermi. In an unprecedented fashion in Italy, Fermi helped him join the theoretical physics chair in Rome when he was 26 years old.
Enrico Fermi went far beyond Corbino's dreams by attracting visitors from all over Europe and developing young Italian talents. Fermi's best-known contribution to theoretical physics made in 1934 when he entered the theory of weak interactions in particle physics. It has been known for several years that nuclear decays that release electrons do not seem to comply with the energy conservation law. This principle was an important enigma as it was the cornerstone of physics at the time. Niels Bohr argued that conservation may not be so absolute. On the other hand, Wolfgang Pauli thought that it was absolute and the lost energy was carried by a new particle called the neutrino. But how?
Theory and experiments
In 1934, Fermi showed how this phenomenon could occur. He called Pauli's unknown particle the neutrino and suggested the existence of a new kind of interaction in which a neutron decays and dissociates into protons, electrons, and neutrinos. He showed the way the interaction could take, calculated its size and explained the results. At a time when the only two known forces were gravity and electromagnetism, this was a revolutionary concept; it is still seen as a milestone in physics.
While continuing to work as a theoretician, he formed a tightly connected group of experiments, most of whom will continue on their way in distinguished careers. The original group of Edoardo Amaldi, Bruno Pontecorvo, Franco Rasetti, and Emilio Segre took part in the most important experimental initiative of Fermi. Until the early 1930s, scattering from nuclear targets was done by bombarding the rays of alpha particles (i.e., helium nuclei) from radioactive decay using a technique led by Ernest Rutherford.
But in 1932, James Chadwick's discovery of the neutron in Cambridge offered a new opportunity for bombardment. Focusing on the neutron beam was more difficult, but the fact that the electrical charges were neutral meant that neutrons would not be pushed away in the nuclear bombardment. Therefore, they were more likely to reach the target. Fermi now had an important insight.
The possibility of a nuclear transformation was expected to increase with the increasing energy of the bombarding neutron, but he realized that the opposite was true. The slower the incoming neutrons are, the more time it takes for them to pass through the target nucleus, and the greater the chances of a reaction. This new system has led to several important discoveries, some by his group and some by other scientists. One of them was the invention of nuclear fission in 1938.
Enrico Fermi was awarded the Nobel in physics for this work in 1938 and went directly from Sweden to the USA. The decision to migrate was wise, as his wife was Jewish, and brutal race laws were introduced in Italy under Mussolini. The departure of Fermi determined the end of an era in Italian physics, but now this area was taken its place in the mainstream of the country, even though it lost its biggest practitioner.
Enrico Fermi and the world's first nuclear reactor
Enrico Fermi's neutrino research was increasingly turning to military purposes, but he continued it in his new homeland. He led the construction of the first nuclear reactor built at the University of Chicago in 1942; He was at work even when the criticality — the point where a reactor sustains a fission chain reaction by itself — was obtained. He then transferred his work to Los Alamos, but at the end of the war, he returned to the University of Chicago and performed activities in other fields, such as astrophysics. He also became the leading name in emerging high energy physics.
He continued his legendary career with both a theoretician and an experimental work habit. He attracted many talented young American physicists to Chicago. In 1954, Fermi was diagnosed with stomach cancer while he was at the summit of his power and died shortly after the exploratory surgery, which showed how the cancer was spread. His death caused sadness all over the world. The largest high energy facility in the USA was named Fermi National Accelerator Laboratory (Fermilab). More importantly, all the particles with a half odd integer spin (neutron, proton, electron, and neutrino) were now called a fermion particle.
Enrico Fermi quotes
- "It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge."
- "There are two possible outcomes: if the result confirms the hypothesis, then you've made a measurement. If the result is contrary to the hypothesis, then you've made a discovery."
- "If I could remember the names of all these particles, I'd be a botanist."
- "Before I came here I was confused about this subject. Having listened to your lecture I am still confused. But on a higher level."
- "The fundamental point in fabricating a chain reacting machine is of course to see to it that each fission produces a certain number of neutrons and some of these neutrons will again produce fission."