Explanation Hans Christian Ørstedt Philipp Reis Alessandro Volta Enrico Fermi Mario Corbino
Ettore Majorana Luigi Galvani Marija Aleksaite-Gimbutiene Carl Auer von Welsbach

 

Enrico Fermi - Liceo Michele Amari Giarre
1901 - 1954

Visit the italien Physicans - Site Liceo Michele Amari Giarre

With Enrico Fermi the world was blessed with a prodigy, who by his unparalleled works carved a niche for himself in the realm of Physics.

Enrico Fermi was born in Rome on 29th September

1901. The Fermis were a family of farmers coming from the most fertile countryside in Italy, around Piacenza in the valley of the Po River, in the north of Italy.

Enrico's father, Alberto, began his career as a railroad official, progressed to a senior position in government service; His work meant he travelled all over Italy for several years, after which he settled in Rome.

At the age of 41, he married Ida De Gattis, a woman fourteen years his junior, a teacher in an elementary school. The first-born in the Fermi family was a girl, Maria, born in 1899; she was followed by a male child, Giulio, in 1900, and then by another boy, Enrich.
Enrich was sent as a child to live in the countryside and went back home only when he was two and a half years old. His return into the family was quick and easy and his relationship with his family soon returned to normal.

Some say that his mother was rather strict but also smart, lovely and tender. Enrich was quick in learning to read and write, probably with the help of his older sister. We know that he went to school at the age of six.

The little Enrich, although he was baptised, had no religious teaching from the school he attended, which was, according to the standards of that time, a non religious school. His family did not profess any religious practice and were indifferent to all religions. They remained philosophically agnostic for the rest of their lives. The three siblings were very bright, however their parents did not evaluate their intellects beyond their school marks. From early childhood, Giulio and Enrich had grown close to each other, shared their games and spent their leisure hours together inseparably. As the two boys grew into adulthood, they became extremely talented.

It is a puzzling mystery how he approached mathematics. He was probably used to listening to conversations of his father's friends and colleagues, who were mostly engineers.
When he was ten he went to the " Umberto" gymnasium, the traditional classical lyceum where a major emphasis was put on humanities such as Latin, Greek and Italian, etc.
Thank to his wit and hard work he only needed a little time to do his homework. The rest of the day was devoted to his personal intellectual interests, which were mostly scientific. During this phase of his life his closest friends were his siblings, Giulio and Maria. The two brothers used to play together, where they created a small world of their own, closed to other people but sufficient to their needs. Together with Giulio they built electric motors, designed, constructed and operated by them. They also drew plans of airplane engines, (all children were fascinated by the new invention, then a novelty) so well that experts were of the opinion that it could not be the handiwork of children. They were indistinguishable in their achievements.

A hard stroke fell upon the Fermi family in 1915 when Enrich was just 14. A serious throat disease caused a fatal infection in Giulio. A routine surgical operation took place but unexpectedly the young boy died. The tragedy shocked the Fermi family, the mother and Enrich , above all, who lost a brother and his most treasured companion. For a long time his mother was given to protracted crying spells which was understandable, as Giulio was her favourite.

Enrich too mourned his loss, but in a quietened sorrow that may have been deeper than hers. His brother had been his sole companion and steady friend. There had been no need for others because the two completed each other to form a unit, as two atoms unite to form a molecule. A week after his brother's death he walked alone
by the hospital where Giulio had passed away. He wanted to prove to himself that he was capable of overcoming the emotion that the sight of the hospital would arouse in him. Later, he found a way to deal with the lonesome and melancholic hours: Study.
Fermi developed a passion for mathematics and physics in particular. Browsing through the bookstalls in Rome's Campo dei Fiori, he found two antique volumes of elementary physics, ("Elementarum physicae matematicae volumen primum et secundum") carried them home and read them, sometimes correcting the mathematics. These volumes were a revelation to him and over the next few days, Fermi relished the wonderful manner in which the book explained the movement of the waves, the motions of the planets and the
tides. He had failed to notice that they were written in Latin, not his mother tongue. It was the basis for his next studies.

It was in those years that he met and made friends with Enrich Persico ( who would later become Professor of Physics at university ). They soon realised that they had more in common than mere first names. Their tastes, scientific aptitude and proclivity to speculation were all familiar. They differed in temperament, however their friendship held them together through the years. They used to visit Campo dei Fiori every Wednesday and after acquiring books, used to take turns in reading them. As they built up their knowledge of physics, the two friends looked to apply it to experimental problems. With the rudimentary equipment that they could procure, they made some accurate measurements; that of the magnetic field of the earth, for instance. They also tried to explain some other natural phenomena.

An important event, often quoted when talking about his intelligence, occurred when he was 23. When he knew that his father's friend, Ingegner Amidei , was very fond of
Physics, he took the chance to ask him a few questions. The latter lent him a book on Geometry which contained problems and theorems which the young student gave back after only two months with more than 200 solved problems and theorems. Amidei was shocked because he found some of them very difficult when he was Enrico's age.

After he discovered that Enrich studied Physics and Maths from old books found at bookstalls in Campo de' Fiori he provided him with the best books to give him a sound, solid mathematical and physical foundation. Fermi, on his side, supplemented the books borrowed from Amidei with those he purchased randomly at Campo de' Fiori.
Thus, the idea of becoming a physicist, helped and tended with care by Amidei, grew in Enrich.
At 17, Fermi was awarded a scholarship at the Reale Scuola Normale Superiore, associated with the University of Pisa. He left Rome for Pisa. Here his precocity often led him to teach his teachers. The following summer he went back to Rome where he was happy to see his old friend Persico. It was during the summer holidays that he decided to put more order into his notes and, as a result, a leather-bound book was made, which was jealously kept for the rest of his life.
This small book gives us a clear picture of Fermi's cultural formation and intellectual maturity between 18 and 19. It is full of notes about analytical dynamics, about the electronic theory of matter, about Lorentz theory, on restricted relativity, the black body theory, the diamagnetism and paramagnetism. Bohr's first attempts at the hydrogen spectrum are also mentioned, still little known at the time, and Boltzmann law on the Kinetic theory of gas, a few notions on gas electric properties, on photoelectricity, from Townsend's work.

An important feature which comes out from Fermi's work is that, though he never had any fear about mathematical difficulties, he was not obsessed by them. It didn't matter whether a mathematical theory was easy or not, what really mattered to him was the opportunity it offered to throw more light on essential laws of Physics. His extraordinary talent was soon acknowledged by most of the teachers at Scuola Normale in Pisa and by his companions. All the students at Normale, both in humanities and sciences, were well aware of having someone around whose intelligence was well beyond normal standards.
Fermi too, was aware of his prominence, and without any false modesty, he wrote to Persico in January 1920: " At the department of Physics I'm getting the most influential authority. Indeed one of these days I'll have to give a lecture in front of some professors on the quantum theory which I have always been a keen supporter of". He was only 19. At Pisa Fermi continued studying in depth Sommerfeld's " Autobau und Spektrallinien" and better than anyone else he mastered Bohr and Sommerfeld's old quantum theory.
Then, at 21 he earned his doctorate with a research thesis on x- rays. Part of 1922 was spent working on his thesis on x-ray diffraction for curved crystals, and the image which can be obtained using this method. At the same time he was asked to complete another research thesis to qualify at Scuola Normale. As a topic he chose a theorem on probability calculations and some of its applications in astronomy. The degree which he was awarded on July 7th 1922, was accompanied with the academic praise " magna cum lode".
Menwhile Fermi had achieved better results in the field of relativity than in the subjects he dealt with in his thesis. He succeeded in demonstrating in the easiest way how in proximity of a time line Space behaves like it was Euclidean. This important law is expressed in his work :"Sopra i fenomeni che avvengono in vicinanza di una linea oraria""
After a short visit to Rome, Fermi left for Germany on the Italian Ministry of Public Instruction fellowship to study at the University of Gottingen, under the physicist Max Born. Fermi then returned to teach mathematics at the University of Florence. In July 1922, his paper concerning behaviour of a perfect, hypothetical gas impressed the physics department of the University of Rome, which invited him to become a professor of theoretical physics.

When Fermi left Pisa in 1922 he had already developed his own personal style. As we have seen, he was almost completely self-taught, all he knew and learned was due to books he had read, but more importantly, on the re-discovery of the notions he himself went through. A personal feature of his was to privilege analysis of the real/ concrete problems which required the application of well-known principles, imagination and subtlety. He was fond of experiments and most all he loved combining theory with his experiences. Fermi did not have a special taste for abstract ideas, in fact he felt a need for absolute clarity when analysing and understanding them.

Maybe this is one of the main reasons which later prevented him from joining the first developments of Heisemberg's quantum mechanics . In reality he was not fascinated at all by the philosophical trends of Bohr and Heisenberg. And if he was not able to "penetrate" in depth Heisenberg's first speculation on quantum mechanics it was not because of mathematical difficulties but probably due to the fact that the physics concepts seemed to be quite nebulous to his eyes.

On the other hand, he was attracted by Schroedinger studies. Thus he learned quantum mechanics and, when he felt familiar enough with the new ideas, he became quite confident in them. He also approached Dirac's efforts and often re-formulated them in a more accessible way.

In 1922 relativity studies were at the centre of scientists' attentions, thanks to the pioneer activity of such scientists as Ricci Curbastro and Tullio Levi-Civita. It is no wonder then, that Fermi's first work was within the field of general relativity, by means of which he soon gained a great reputation among the experts.

In 1924 Fermi wrote an essay, "Masses in the Theory of Relativity" which was soon published. Fermi deals with the possibility of release of nuclear energy, discussing it as the most spectacular potential output of relativity. Moreover he hints at some experiments by Rutherford on disintegration. It was clear to him that between relativity and quantum
theory it was the latter which would have greater applications, and would allow to reveal the mysteries of atom structure. Indeed quantistics was imbued of the new physics and so was closer to Fermi's interests.

After getting his degree Fermi went back to his family in Rome. The normal routine for a young Italian graduate who wanted to devote himself to university teaching was to gain a scholarship first, an assistantship later, to take the university teaching qualification, find some work as a supply teacher, and eventually to find the position of a permanent university teacher by open competition.

Winning a post by open competition before the age of 30 was something very seldom. A teacher in his first years was often sent, culturally outcast, to cover minor posts at minor universities, and only many years later could he teach in major universities as Milan, Turin, Naples, Pisa, Bologna etc.

Once a post was won to enter university, the future career depended on the length of service/ seniority. There could also be academic awards for the most brilliant teachers and some could even be appointed Senators of the Kingdom. This was usually after a proposal by the government in favour of professors who also had a political life, apart from science, even if it was not uncommon to have senators appointed from other fields of human activities. Fermi was well aware of how it all worked; he was sure of his
ambitions and was determined to climb the ladder of success in a short time but he was also sure he wouldn't sacrifice his intellectual honesty to progress in his career.

In 1923 Fermi had used his scholarship to take a position at Max Born's Institute in Gottingen. It was the golden age at Gottingen, for Physics was at its best. Max Born taught Theoretical Physics while James Franck was engaged in Experimental Physics, and close to them was a group of young people who were bound to change physics within a few years in a radical way.

In Gottingen Fermi met brilliant researchers such as Werner Heisenberg and Pasqual Jordan, two top rank scientists. Unfortunately Fermi seemed neither to feel at ease in this productive milieu nor to interact with his colleagues. Therefore his stay in Gottingen was not as productive as it could have been. Fermi wrote some papers on analytical mechanics which he could write with the same results without moving from Rome, as he was not positively influenced by the Gottingen avant-garde atmosphere. Some say that Heisenberg and Jordan were so deeply focused on their important works that they underestimated his great talent.

On may 8th his mother died. And yet this loss was not unexpected, since she had been sick for a long time. Little is known about Enrich and his parents’ relationship. He seldom showed his inner emotions. Undoubtedly Fermi beloved his mother and he reportedly praised her intelligence and skill to his wife Laura. After his brother Giulio’s death , his mother turned from a lively person into a sad character and Enrich realised that his family world was too depressing to him and decided to move away. In 1927 his father Alberto died , too.

Meanwhile his paper on the theorem "Ergotigo" written while in Gottingen, was noticed by Prof. Paul Ehrenfest, famous physicist and friend to Einstein. He asked his student George Uhlenbeck to go and search for Fermi and to become an acquaintance of his. And as a result a friendship was born which was to last forever.

In the summer of 1924 during an excursion on the Dolomite Alps , Fermi worked out a theory about the atom clash against electrically-charged particles, in which he introduced some new ideas which are basic to what is today referred to as Weizsaecker and Williams’s method.

The article on the atom clash was sent to "Zeitschrift fur Physik" and some time after its publication Bohr remarked that Fermi’s method provided no distribution of the emitted electrons’ speed, coherent with the experiment. Fermi suffered from Bohr’s criticism which he considered unjustified and, above all, at a time during which he struggled to be acknowledged as a good physicist.

On the first of September of that year he went to Leyden where , at last , he found the best appropriate and congenial atmosphere as well as his friend Uhlenbeck and a new one , Samuel Goundsmith, . The two scientists discovered the electron spin which a few years later turned atomic physics upside down. The aspects of physics which were usually studied at Leyden………….mechanics and spectroscopy…. Suited in a special way to Fermi’s intelligence.it is likely that it was at that time that Fermi’s long and stubborn meditations on the perfect monoatomic gas’entropy had their origins.

He was very close to the discovery of what would be famous as Fermi’ statistics. It is now clear that he was searching for the fundamental principle still lacking and determining the number of representative points in a system which could fit in any cell of the phase space. This is well known today as Pauli-Fermi exclusion principle. Some years after he said that he himself would have discovered the principle in a few months if Pauli had not.

At the end of 1924 he went back to Florence where , thanks to presence of Rasetti, he gave new vigour to his experimental work. The cooperation between them soon proved to be a mutual influence. Rosetti’s great ability as a researcher allowed Fermi to carry out important and modern tests using up-to-date equipment. The best experiment the two friends made in 1925 was on the effect of an alternate magnetic field on the polarization of mercury resonance light, which was a precursor study of many important applications of radio-frequencies to atom spectroscopy.

In 1926 Schroedinger’s first memoirs on wave mechanics started circulating. In Florence Fermi was attracted at once and after a closer examination he was positively impressed. He was already familiar with the weak or critical points of quantum theory, with its contradictions and paradoxes on one side and the undeniable new elements on the other. Fermi did not know De Broglia’s studies and his hypothesis on material waves. And when Schroedinger’s first paper on the quantization as a problem of eigenvalue was published Fermi was astonished. Quite different from Dirac’s and Heisemberg, Schroedinger’s ideas were very intelligible, he had been using techniques for years and could provide results which could be easily verified through experiences. Fermi rapidly absorbed these new methods from Schroedinger but he was for some time uncertain about the interpretation of the wave function and the time scalar.

On July 19, 1928, Fermi married Laura Capon, daughter of an admiral in the Italian Navy. The couple had two children, Nella (1931) and Giulio (named after Fermi's brother) (1936).

Second part

At 26 Fermi had his chair of Physics at Rome university and in a certain sense he could look at himself as a self-realised man. In Rome he was in touch with a group of famous mathematicians , much older than him, and though they were in good terms with Enrich they did not cooperate in any joint work.

A new generation of scholars was felt as necessary and Fermi was bound to be the leader.

Since Pisa , Fermi made al lot of attempts at introducing his new views on Physics in Italy. But it was hard work, as an example there were not Italian books of Physics for university students. The basic text through which a whole generation of students had learned the new doctrines was Sommerfeld’s "Atombau und Spektrallinien" in German and it was too detailed to be considered an introductory text . It was mainly for this reason that Fermi decided to devote himself to write a text book, which he did in the summer 1927 spent on Dolomites. He wrote it at once without the support of reference books and with few deletions/erasures. The manuscript was sent to the Bologna- based publishing company Zanichelli and soon printed . It was a special tool for a long time to Italian students.

His most decisive move , though, was to open/ found a school. Since his arrival in Rome , Fermi realised that the teaching of Physics was neither based on relativity nor on quantum theory. He wanted to turn the Physics Institute in Rome in a modern centre which could stand comparison with the best ones in Europe.

One of his first objectives was to reinforce the foundations of experimental Physics. On this matter he fully agreed with Corbino, the institute director. Next step in order to consolidate the Physics Institute in Rome was to enrol good quality students, which was quite a hard task at that time. The studies of Physics at university often ended in the teaching profession at secondary school because the chairs at university were rather limited. The perspective university teacher should be endowed with ability and self-confidence besides a certain financial independence. And most of all he should be very keen on Physics notwithstanding the financial disadvantages offered by the teaching profession.

Despite all this , Fermi’s reputation soon widespread outside the Institute. In September 1927 at the International Physics Conference in Como participated some among the best known scientists: Lorentz, Rutherford, Planck, Bohr and others, and a small group of young people such as Heisenberg, Pauli and Fermi himself . They al represented the new frontier of modern Physics. Fermi’s was the most influential voice among the Italians , and some authoritative foreigners as Bohr and Sommerfeld listened to what Fermi stated with his talks.

Fermi’s first follower was Emilio Segre who, after joining the Conference in Como, decided to follow his inclination to study Physics. A couple of months later he left the Engineering Faculty to enter the Department of Physics, thus becoming officially his first student and opening Rome Physics School. In June 1928 Corbino visited some of his classes in the Course for engineers and informed that a few positions were still available in Pure Physics in the Institute for brilliant and motivated students, stressing the need for gifted students . The only one who accepted his invitation was Edoardo Amaldi ; he joined the restricted circle of students to be directly taught by Fermi in the hope to form a good team of researchers and collaborators. A few weeks later another student joined the group: Ettore Majorana who moved from Engineering to Physics, as Segré had previously done.

Meanwhile other students, who attended regular courses in electro-logy or atomic physics, sometimes joined Fermi’s "private" lessons which should sound rather improvised and informal ones. Later in the afternoon his students met in his studio and the conversation soon turned unwillingly into an academic lesson. This proved a good way to discuss/ deal with a lot of subjects using an elementary register, accessible to anyone. Yet sometimes the tone of the conversation was higher and Fermi himself explained or commented some articles or papers he had just read. This was how Schroedinger and Dirac’s latest works were presented , only a few weeks after their publication. The privileged place for such activity was the old building of the Physics Institute in Via Panisperna. The old building was good enough for the limited number of students and could stand well the comparison with other European centres in the 20’s. On the contrary the equipment was rather obsolete, and above all the spectroscopes and the optical instruments were rather bad with few exceptions.

The mechanic workshop/ lab was rather old as far as the equipment was concerned ; it was not good enough for the task it had to fulfil ; the library was on the other hand very good and up-to-date. The building was on three floors and a basement; the first lodged the research laboratories and the teachers’ studios, Mr Corbino’s, Suardo’s and Fermi’s, and the library. The ground floor was for the workshop, the class-rooms and the laboratories for the students; in the basement was electric generators and other services.

Fermi’ first major work in Rome was "A statistical method for determining some atom properties", known today as Thomas-Fermi method, because he was not aware that Thomas himself had already employed the same method four years before. When Fermi found out that in order to go on with the method he needed the solution of a non linear differential equation, characterised by unusual conditions al contorno , thanks to his legendary energy he calculated the solution using a simple hand calculator in a week’s hard work. Majorana, a newcomer in the Institute, was usually skeptical, and also on that occasion he thought that the numerical analysis by Fermy was not correct and it would be better to check it. Majorana went back home, changed the original equation in a Riccati-type equation and solved it without the aid of any calculator, using his great ability in numerical calculations.

Fermi went on to apply his method several times to different practical problems and he himself suggested Rasetti and his students with other applications. The basic idea of this statistical method became one of Fermi’s greatest ideas and he applied it as a rule in the next years. It consisted in regarding the electrons moving around the nucleus as the atmosphere of a fermion gas at absolute zero to which the limit case of Fermi’s statistics for high degeneration is applied.

In another field of statistical concepts there was the application, of the same kind, to high-energy nuclear events.

Fermi’s interests and knowledge covered/embraced the whole physics and he was often busy in reading the best science reviews to keep himself updated on the new developments. He had an inclination for complete problems and mistrusted of too abstract or general/ vague theories but every specific problem, in any field of classical Physics-mechanics, spectroscopy, thermodynamics, solid state and many other more, appealed to him and made him sharpen his wits to solve it until the numerical control and the matching with the experiment. His work proceeded as in a teaching lesson, although in a slower way, and at the end the equations were written on the blackboard ready to be transcribed and published with few slight changes. A good example of such a way of working was the carrying out of the works on the quantum theory of irradiation . Fermi had already seen Dirac’s papers on the same topic and understood/ realised the results he had achieved. Yet he was not sympathetic with his colleague’s method and he decided to re-write the theory in a more familiar formula.

Something very curious about Fermi’s working method was the uniform speed he applied in his calculations. Even when the mathematical passages were relatively easy he wouldn’t speed up and a ingenuo observer would wonder how he was so slow in such easy algebraic calculations; but when he met some obstacles which would stop anyone he was able to overcome them without any problems. An example of his technique is the evolution of the "diffusion length" concept which was first published in the spectroscopy study "Sopra lo spostamento per pressione delle righe delle serie spettrali" and then in "Artificial radioactivity produced by neutron bombardment" and later several times in studies on the diffusion of slow neutrons.

The speed with which it was possible to "form" a young physicist at Fermi’s school was quite unbelievable. No doubt this was partly due to the great enthusiasm he was able to stir/ arouse in his students, not through long speeches or blamings, with he invincible force of his example .

Fermi was used to treat his students and staff in a friendly and direct way, without any superfluous formality or complications. He was never rude to them yet he was not too premuroso and only rarely he made long personal speeches. At the end of this academic experience, a friendship developed among the participants to the Institute life which turned out to be strong and everlasting. There was a slight difference in age, being the oldest Fermi and Rosetti 26 and the youngest Amaldi 19.

It was only seldom that Corbino attended the seminars in the afternoon yet he was much interested in the scientific work at the Institute and the career perspectives and shortcomings of the members of the group.

It was more or less in the same period that we assist to a flourishing of Physics in Florence as well, and Prof. Persico exerted a strong and beneficial influence on this new movement. He was the only permanent teacher of the new generation and his teachings were successful.

Also the Florence group was formed by people in their early twenties. Persico’s boys were mostly self-taught except for his own teachings but were full of enthusiasm, energy and brilliant and original ideas.

The two groups , both in Florence and Rome shared a sincere friendship and often exchanged visits or seminars.

Very soon rumours of what happened in Rome and Florence were spread among young physicists in several cities. One of the most constant visitors of Rome Institute was Giovanni Gentile Jr, the son of the Fascist Minister, who had recently completed his studies at the Scuola Normale in Pisa .

In 1929 it was clear to anyone that, while/if the status of theory was pretty good, on the contrary the experimental side of their works was still unsatisfactory. It was essential that the members of the group should go and practice in foreign labs to learn and import new techniques. Tat is why Rasetti went to California Institute of Technology in Pasadena which was directed by Millikan and had the opportunity to carry out some tests on the Raman test; Segrè went to Prof. Zeeman’s lab in Amsterdam to study on forbidden research and Amaldi moved to Leipzig at Prof. Debye’s lab where he worked on the X-ray diffraction in the liquids/fluids. At first they all agreed on the convenience of choosing places where they could continue the research they had started in Rome , with better and more advanced experimental means. Later they went anywhere to extend the range of their research to new fields. It was in this second phase that Rasetti devoted his efforts to the study of radio- activity. On the whole the plan was successful because, otherwise without all that training abroad it wouldn’t be possible to go complete rapidly and effectively the complex study on neutrons.

Even during their stay abroad the Panisperna boys they kept in close touch by mail , and when on holidays they usually met and spent some time together to talk about the progresses in the jobs they were engaged in. In this period Fermi only went abroad for short visits. He was then used to a kind of intellectual isolation as in Rome Majorana was the only one he could talk of physics on the same grounds. But at the beginning of the 30’s a lot of young physicists, worried about the German menace , came to Rome and many of them were bound to leave lasting tracks in Physics. Their long stay and presence in Rome gave new life/ vigour to the Institute. Now the group was provided with the lucky chance to communicate with some among the best champs of the German science, and the latter in turn learnt something new from Fermi entourage. It was in Rome at that time that Bethe, one of the Germans, said referring to Fermi: "What really impressed me about Fermi was his way of dealing physics issues with simplicity. He could analyse any problem, no matter how difficult it was, reducing it to the essential points. He stripped away any maths complication and unnecessary formalism, and that way he was able to find the main problem and its solution in less than half an hour". The physic aspect was easy to get thanks to an analysis of the essential and some evaluation of the degrees of order. His method of approach to the problem was absolutely pragmatic.

Life in Via Panisperna was calm and repetitive. The working day was from nine to half past twelve and then back in the afternoon from four to about eight. Of course the timing was approximate and was not compulsory at all. Actually some people worked according a different timetable. No work was authorized after dinner and it was common to have a long walk in Rome surroundings or on the mountains where they went skiing during winter holidays. In summer they went to the Alps or abroad.

The most remarkable event in Fermi’s life was his marriage: on July 19, 1928, Fermi married Laura Capon, daughter of an admiral in the Italian Navy. The couple had two children, Nella (1931) and Giulio (named after Fermi's brother) (1936).

In 1929 Duce Mussolini appointed Fermi as " Accademico d’Italia". His nomination, which was made by the Prime Minister himself and not by election, has an interesting backstage. In 1928 Corbino had been on business to the States, and was not, therefore , in Rome for the election to the Accademia dei Lincei. He wanted Fermi to be elected and had left a letter to Lo Sordo in which he proposed the name of Fermi to the Accademia, with the prayer to read it when appropriate. When Corbino was back from the States he found out that Fermi hadn’t been elected !

Mussolini distrusted the Accademia dei Lincei since he was convinced that its members were mainly anti-fascists. He thought it was better to have a super-academy , Accademia d’Italia, which should overshadowed Lincei . The appointment of its member was by co-optation and Fermi was the only physicist chosen on that round.

Fermi rejoiced at this public acknowledgement , although he was , then and for the rest of his life, extraordinarily devoid of vanity, which was quite common in the academic world.

This nomination as a member to the Academy would have a beneficial effect, indeed, on the future development of Physics in Italy since this science was represented, maybe for the first time, by a very eminent person: Fermi became almost automatically a famous and influential man. However, even after his appointment, he had no political role or weight as he was not willing to devote his time to non-scientific matters. Moreover his intellect was more disposed to scientific speculation than administration or politics. His cultural advancement brought him some real advantages: it improved his financial status since his life pension as academic was much more relevant than his wage as a professor. It was probably for economic reasons that he had accepted the position of Secretary for the Physics section at the CNR ( Consiglio Nazionale delle Ricerche) which required him to examine inventions and evaluate the applications for funds to research.

Fermi visited the States for the first time during the summer holidays of 1930. And it is true that when University of Michigan offered him to keep a summer course on theoretical physics at Ann Arbor he enthusiastically accepted . There he met two old friends of his: Uhlenbeck and Goudsmit. On that occasion Fermi discussed on the quantum theory and had a memorable course talking about this new complex subject in a very simple but effective way.

This experience at Ann Arbor was a great scientific success and , at the same time, such a very pleasant holiday that Fermi would become one of the most faithful visitors of the summer courses; he went again in 1933 and in 1935 from Italy and later from New York. It was thanks to these visits that Fermi developed a strong sympathetic feeling for the USA. He was fascinated by rich laboratories, by the generous financial resources supplied for research, the enthusiasm which he could perceive in the new generation of physicists and the hearty welcome by the senior physicists. All the observations and considerations coming out of this professional experience as well as the ones concerning the American political and social life opened a path in his mind to his later emigration, so that when he eventually moved to the States it was more the conclusion a long-thought project than the result of a sudden decision, determined by some given circumstances.

Although Fermi had given a great contribution to the practical applications in physics, the Italian scientists as a whole made a relatively little efforts as far as the development of theoretical principles was concerned , in the most crucial period of the formation of a quantum theory. Actually Fermi’ s statistics had been elaborated well before his getting familiar with the new theories or independently of them. The studies on wave mechanics by Schroedinger were the first ones to be understood and appreciated by Fermi who soon enthusiastically decided to teach/explain them to his closest friends first and then to Corbino. The latter was for some time rather sceptical.

Fermi greatly suffered from the fact that people he admired and respected around him , as Corbino was, should be exaggeratedly sceptical about the new quantum mechanics and its interpretation. He considered this matter as a lack of comprehension and confidence. It is honest to say that fermi himself in the previous years ( more than once ) had seemed to be less confident or sure than ever of the interpretation of the quantum mechanics according to the orthodox/classical scheme. Of course he never questioned the validity of the formulas yet he was never sure that everything was done with /the last word had been said on their right interpretation. The opposition or the resistance to the quantum theory was mainly coming from the old generation of researchers who did not want to or couldn’t make the efforts which were necessary to seize/to master the new ideas , and tried to hide their incompetence by attacking them.

The coming of quantum mechanics, according to Fermi ,Rasetti and to some extent, to Corbino, marked the definite completion of atomic physics. Now that the fundamental questions had been settled, it was time for the physics of future to head towards the exploration of the nucleus and the atom’s most complex structures, following a route which maybe could flow into biology.

But , no doubt, a new approach to physics was depending on a radical change in the Institute’s plans. The transition to nuclear physics meant a significant effort on different grounds. It was not a mere whim or fancy, the simple desire/ wish to follow a fashion in science but the consequence of mature reflections and of a plan by Fermi and his staff, which was discussed, and often argued upon, in the smallest details .

Corbino expressed this point of view in a magniloquent speech. He listed the objectives which the physicists had proposed to achieve. The first one consisted in the discovery of new unpredicted phenomena , which was not easy to explain by means of the existing theories at the time of the investigations, such as the production of electric current by the Volta pile, the x-rays and the radio-active transformations. The second field of research was based on the qualitative and quantitative testing/control/ verification of the reactions/consequences which might be derived from the theories of that time. A third category of research concerned the determination of the mechanic constant, the thermal constant, etc., of various substances: it was the physics of precise measurements which include the measurement of the (universal) gas constants. Corbino went on providing criteria to evaluate the importance of studies which may assure theoretical previsions. He quotes typical examples as the Raman effect and the experiments made by Davisson and Germer, discussing the positive influence they had on the future development of physics.

This speech by Corbino is a special document which gives us a clear image of what was common opinion in Rome in late 1929. The first step towards the practical achievement/ fulfilment of those hopes/ideas, which needed a radical change in the group’s experimental trends, was Rasetti’s attendance/ acquaintance with Lisa Meither at Berlin-Dahlem Kaiser Wilhelm Institute where he could become familiar with the nuclear techniques .

The study on the hyperfine structures of spectral lines was a suitable topic for the transition from the atom to the nucleus and Fermi and Segré devoted themselves to it.

A Volta Conference, promoted by the Accademia d’Italia , on the atom nucleus, help them to realise the current problems in nuclear physics. Forty-five physicists joined the one-week Rome workings opened by Marconi and closed with Mussolini’s visit.

In July 1933 another important conference was held, in Paris, on the occasion of a great international electronics conference. Fermi was charged/invited to present a report/statement on the state of the art of nuclear physics. Fermi enounced the weak points of the long-established and commonly accepted proton-electron nuclear model and for the first time hinted at Pauli’s neutrin hypothesis.

From 1930 on Walther Bethe and H.Becker had been bombarding beryllium with alpha particles and had found out an extremely penetrating radiation which they attributed to gamma rays.

At the end of 1931 Irène Curie and her husband, Fréderic Joliot, continued that research and showed, as in Wilson’s cloud chamber, how this piercing radiation projects high-energy protons, when hitting hydrogenated substances. The explanation given by Joliot, the Compton effect on protons, was not acceptable in the traditional scheme of electro-dynamics and atomic physics, and some time later James Chadwick demonstrated that that radiation contained neuter corpuscles having a mass very similar to the proton’s, and he called them neutrons.

Chadwick’s findings, demonstrating the existence of the neutrons, had been published just before Fermi’s report at Paris conference. Out of this report it was evident a certain uneasiness by scientists towards the electron-proton nuclear model and some confusion about the neutron. When Fermi dealt with such problems the Polish physicist Wertenstein asked if there could be a non-detectable neuter radiation which could express the conservation of energy in beta radiation. Pauli had been proposing the neutrino since 1930 to try and solve the big difficulties shown by beta decay which was apparently in contradiction with the principle of energy conservation, as a nucleus, starting from a determined state of energy or arriving at a determined state of energy seemed it could emit electrons of various energy.. Therefore in oreder to save the principle of energy conservation and other fundamental laws, Pauli postulated the existence of a particle, the neutrino, whose detection was rather impossible but yet able to carry energy away.

The word neutrino was suggested for the first time by Fermi during informal conversations . He used the augmentative/ accretive neutron referring to the heavy particle and the diminutive neutrino to the light one. This terminology was soon adopted at the Institute and from Rome it would diffuse among the world physicists.

The scientists were already certain about the existence of the neutron and the way it acted ; and the nuclear model based on protons and neutrons had been deeply examined , thanks to the work of Heisemberg, Ivanenko and Majorana .

Although Fermi’s role in Brussels was limited to some observations on nuclear forces, he learned and made his own some of the new materials which were circulated. He heard again about the neutrino hypothesis and, back to Italy , he must have been thinking on as, in two months’ time, he wrote down his fundamental work on the beta-rays theory. Before Pauli, for the first time, proposed the neutrino theory, it was believed that the nucleus should contain electrons, and Pauli thought that the neutrino was another nuclear component with a tiny yet finite mass. Fermi had further studied the problem of the electro-magnetic radiation applying Dirac’s theory. Later he went deeper in this study and when he could master it she said he would train/ practice using the beta decay. That is why he wrote his famous paper "Attempt at a theory of the <<beta>> rays". In this research it is described how he changed Pauli’s qualitative hypothesis in a quantitative theory, how he introduced a fundamental constant, today called "Fermi’s constant". This step in Fermi’s life, in 1933, embodied all the basic ideas which ruled the field of weak interactions and had an enormous influence/importance on the future development both of nuclear physics and particle physics. Besides it remarkably resisted to the passing of time being as fresh as ever. Nowadays it would only demand few slight changes to be perfectly update. It is true that it is not complete but the essential elements are still valid.

Fermi was well aware of his work’s relevance: he was sure that it would be his masterpiece.

Fermi left Italy in 1938 to receive the Nobel Prize for Physics, for Sweden. He and his wife then moved to the United States to escape Italy’s increasing fascism and anti-Semitism. In 1944, after having satisfied the residence requirements, the US became Fermis’ permanent residence. In 1946, Fermi became Distinguished Service Professor for Nuclear Studies at the University of Chicago and also received the Congressional Medal of Merit.

He argued against US development of the hydrogen bomb when the project was debated, in 1949. In 1950, he was elected foreign member of the Royal Society of London. Fermi died an untimely death of stomach cancer in Chicago in 1954. Fermi is recognized as one of the greatest scientists of the 20th century. He always worked at the forefront of knowledge and loved the excitement of being involved in breakthroughs in physics.

While announcing the plan to establish the Formula in honor of Fermi in 1969, Glenn T. Seaborg, the then chairman of the US Atomic Energy Commission remarked, "It is particularly fitting that we honor Dr. Fermi in this manner, for in doing so we further acknowledge his many contributions to the progress of nuclear science, particularly his work on nuclear processes."

In Fermi, the world witnessed a man whose quest for knowledge was insatiable. A huge void was left unfulfilled in the world of science, in the loss