Welcome to the building on Via Panisperna, home now to the Historical Museum of Physics and the Enrico Fermi Study and Research Center. This building housed the historic “Higher Royal Institute of Physics” where a group of young scientists gathered around the figure of Enrico Fermi in the 1930’s, conducting the famous experiments on neutron-induced radioactivity, fundamental to the development of atomic energy.
Einstein’s theory, which completely redefines the structure of space-time and the relationship between mass and energy, has many different consequences; one of the most fascinating is the intuition that mass and energy are two aspects of the same entity and that it’s possible to convert one into the other and vice versa. Everyone knows the famous equation E=mc2, energy is equal to mass multiplied by the speed of light squared: an extraordinary concept that, it’s said, ruined Einstein’s sleep because of the possible military implications.
Max Planck theorized that energy exchange in emission phenomena and electromagnetic radiation absorption occurred separately, proportional to the oscillatory frequency of the radiation and not continuously as classical electromagnetic theory sustained. In this hypothesis, calculating the blackbody emissions spectrum, experimental results were correctly replicated, as long as a constant value of proportionality between energy and frequency in accord with the experiments was chosen.
In 1913 Neils Bohr theorized that in every atom there would exist a minimum orbit called the fundamental state, under which the electrons couldn’t descend; otherwise, given their negative charge, they’d be attracted by the positive charge of the nucleus, they would have fallen into it and all matter would explode. Electrons could, however, “jump” from one orbit to another and these jumps were accompanied by an absorption or an emission of light particles, in other words, the photons or light quanta that Einstein had theorized to explain the photoelectric effect.
Fermi moved his research in 1929 in the experimental realm towards nuclear physics. This new line of inquiry would be the theme of an international physics conference in Rome precisely at the Institute at Via Panisperna in October of 1931. In 1934 the possibility of producing artificial radioactive elements by bombarding different elements with charged particles became a reality thanks to Irene Curie and Frédéric Juliot. Fermi and his boys threw themselves into this new pursuit using some newly discovered particles—neutrons—that had the advantage of not being affected by the electrostatic repulsion of the nucleus.
Fermions obey to the Pauli’s Principle of Exclusion: it is impossible for two atoms in a solid to be in the same state and therefore have the same energy. All known matter consists of fermions, which are responsible for the mass that is detectable in nature. Pauli’s exclusion principle is responsible for the fact that ordinary matter is stable and occupies volume
Fermi wrote to Dirac to claim the priority of the discovery and Dirac immediately sent Fermi a message of apology and from then on he always referred to the discovery as the Fermi-Dirac statistic, generously attributing much of the authorship to Fermi. If we now call particles that obey the exclusion principle “fermions” it is precisely because Dirac recognised Fermi’s precedence in the discovery.
In December of 1933 Fermi wrote the article “A possible theory for the emission of beta rays”, published in the Italian magazine Nuovo Cimento: with the neutrino theory, Fermi built upon the idea that a neutron could transform into a proton with the subsequent creation of an electron and a neutrino. During the beta emission process a neutrino would be emitted along with an electron and the two particles would have shared the available energy. What’s more, according to the conservation of mass, the neutrino would be a very light neutral particle and because of its minimum interaction with matter would be difficult to observe.
Fermi called in Rasetti and all the young men of his group, Edoardo Amaldi, Emilio Segrè and Oscar D’Agostino, “the chemist of Via Panisperna”, to make a systematic examination of the entire periodic table to try and activate as many elements as possible. Fermi and Rasetti did the calculations and measuremnts, Segrè had the job of finding the equipment and substances to irradiate, Amaldi built the Geiger counters and d’Agostino analyzed the byproducts of the bombardment with the most advanced radiochemical techniques. In just a few months they discovered many new radioisotopes.
Fermi goes to Stockholm to receive the Nobel Prize. Sweden will be only a stop along the way towards the United States of America. In spite of their scientific successes, the survival of Fermi’s group in the cultural and political climate of fascist Italy has become ever more difficult due to the lack of adequate research opportunities and financing; the passage of the anitsemitic laws removes even the most elementary of civil rights from Italian citizens of Jewish origin. Not only is Fermi’s wife Jewish but so are some of the Boys including Bruno Pontecorvo and Emilio Segrè. So, at the station on December 6, the day of departure for Sweden, there are only Rasetti and Amaldi with his wife, Ginestra. The send-off can only mean one thing: the end of an era.
Fermi’s arrival in the United States of America coincided with news of the discovery of nuclear fission by a small group of German physicists. Fermi realized that he and the Boys of Via Panisperna had split the nucleus of uranium into two large pieces during their experiments, even though they hadn’t known it at the time. It was evident that the enormous amount of energy predicted by Einstein could be released by the process of fission of uranium. The beginning of WWII and the dangerous advance of nazi-fascism put great pressure on research into the use of nuclear energy for military purposes. The news came out of Germany that the greatest German physicist at the time was working on a nuclear fission weapon. All the physicists who had escaped to the US, Fermi included, were alarmed. Albert Einstein wrote a letter to President Roosevelt, warning him of the danger that would be created by the probable construction of a German nuclear weapon, giving Hitler the possibility of conquering the world.
Fermi was not only a great theoretical physicist but a great experimental physicist as well, a quality that is practically unique in this century and the last one. In the case of cosmic rays, Fermi didn’t conduct any experiments but gave an enormous theoretical contribution. In 1949, he wrote an article in which he proposed a theory of how these particles, which are either protons or nuclei, become accelerated to such high energies:
After the war, Fermi encouraged the building of a cyclotron capable of accelerating relatively heavy protons to reach an energy of 60 million electronvolts sufficient to produce mesons. It would be 5 years before Fermi’s dream of a large accelerator would become reality and in 1951, most of Fermi’s experimentation would center around an “upgraded” cyclotron.
Around 1947, John von Neumann developed one of the first programmable electronic calculators which raised a lot of interest over at Los Alamos. Fermi jumped at the chance to insert his own equations into the computer and worked with Ulam and another computational physicist, John Pasta, to study the problem he had come across during his application for the Normal School in 1918. They inserted the equations of a vibrating string into the Los Alamos computer and simulated its behavior. Numerical simulations were done by Mary Tsingou. The paper they wrote was the first fundamental contribution to Chaos Theory.
Fermi’s collaborators include a very long list of the greatest American and European physicists of the first half of the 20th century, many of them Nobel Prize winners. Five of Fermi’s direct students were awarded the Nobel Prize: Chamberlain, Friedman, Lee, Segrè and Steinberger. Two others, Cronin and Yang also won the Nobel Prize and, although they were not officially Fermi’s students, both credit him with inspiring and guiding them. Many other students and collaborators went on to important and influential careers in the same field.
In this room you can find a desk that is a faithful reproduction of the one Enrico Fermi used in his study in this building in the 1930s. An installation contains the names associated with Enrico Fermi that are currently used to describe the physical phenomena he helped to identify. In addition, there are names that have been introduced to celebrate Fermi.
Another installation contains Enrico Fermi’s scientific articles written in the Italian period up to 1938. Finally, there is a note, written during his stay in Stockholm in December 1938, where he had gone for the Nobel Prize award ceremony, showing Fermi’s interest in interdisciplinarity.
Fermi’s name became famous in the nuclear field when he became secretary general of the first International Congress of Nuclear Physics, organized by the Volta Foundation and held from 11 to 18 October 1931 at the Institute of Physics of the Royal University of Rome. The most influential physicists of the time, such as Niels Bohr, Marie Curie and Warner Heisenberg, were invited to Rome. Out of 50 participants, seven Nobel Laureates plus many future winners were present.
The virtual reality room being built represents the core of a new way of disseminating science, using the emotional and entertainment aspect, which only highly sophisticated modern technology can provide by projecting the spectator into a totally virtual world, and combining it with the opportunity to illustrate in simple and appealing terms the scientific concepts underlying the experiments carried out in this building by Fermi and his group.
Emilio Segrè, “the Basilisk”, in 1932 was appointed Fermi’s assistant in Rome, a post he held until 1935, when he won the competition for professorships and moved to the University of Palermo. In 1943, he was called to Los Alamos to work on the Manhattan Project. In 1933 Oscar D’Agostino “the Chemist”, was called to the Institute in Via Panisperna, characterising artificial radioisotopes. Pontecorvo, together with Amaldi, became involved in the discovery of neutron-induced radioactivity. In the summer of 1950, after a short stay in Italy, Bruno Pontecorvo’s entire family disappeared, after they had made a tortuous journey to the Soviet Union.
Enrico Fermi said, “There are various categories of scientists in the world; second and third-rate people who do their best and don’t get very far. There are also first-rate people who make discoveries of great importance, fundamental for the development of science. But then there are the geniuses like Galileo and Newton. Ettore Majorana was one of them. Majorana had what no one else in the world has; unfortunately he lacked what is common to find in other men, simple common sense.”
Translated with www.DeepL.com/Translator (free version)
When simple elements interact, they form complex structures and develop collective motions that have little to do with the properties of the individual isolated elements whose interactions lead to new emerging phenomena. This is why the behaviour of the whole is fundamentally different from any of its elementary sub-parts. We can represent this situation as the study of the ‘architecture’ of matter and nature, which depends in some way on the properties of the ‘building blocks’, but which then displays fundamental characteristics and laws that cannot be linked to those of the individual elements. Translated with www.DeepL.com/Translator (free version)
“Scientific progress is an essential key to our security as a nation, to our better health, to more jobs, to a higher standard of living, and to our cultural advancement…. Science can only be useful to the nation’s well-being as a member of a team, whether the conditions are of peace or war. But without scientific progress no progress in other directions can ensure our health, prosperity and security as a nation in the modern world…”