Enrico Fermi!

Enrico Fermi!

 

 

 

[Edit] Biography [edit] Childhood and adolescenzaFiglio of Alberto Fermi, a native of Piacenza and chief inspector at the Ministry of Communications, and Ida de Gattis, an elementary school teacher, was the third of three children (his sister Maria and her brother Julius, two and one year respectively larger). Enrico Fermi showed, since young, that they have an exceptional memory, as well as a great intelligence, that allowed him to excel in their studies.

From childhood he was inseparable from his older brother Giulio. Julius died in 1915 during surgery to remove an abscess of the throat. Henry, to soothe his deep sorrow, threw himself into the study of physics to high school and completed one year in advance (Liceo Umberto Primo in Rome, today the State High School Pilo Albertelli).

One of the first sources to satisfy his hunger for knowledge was found to market a treaty of Campo de 'Fiori in Rome, entitled Elementorum physicae Mathematicae. This treaty included subjects such as mathematics, classical mechanics, astronomy, optics and acoustics. His nine hundred pages, in Latin, written by the Jesuit Father Andrea Pitcher, professor of the Roman College, were thoroughly investigated by the young Fermi, as evidenced by the discovery of many leaflets and notes in the two volumes of the Treaty.

In addition to the Treaty of Carafe, Enrico Fermi had the opportunity to learn Persian Henry who was a friend of his brother Julius, and thus a year older than him. Developed together with ongoing discussions and further correspondence with college enrollment, their knowledge in physics and mathematics. The two friends in 1926 won the first two chairs of theoretical physics created in Italy.

During the years of high school, he met Enrico Fermi, a family friend and business colleague of her father, an engineer Adolfo Amidei, who led the formation of Fermi in algebra, trigonometry, analytical geometry, calculus and mechanics. Also in 1918 Amidei also suggested to Fermi not to attend the University of Rome, but rather to enroll at the University of Pisa and participate in the competition to enter the prestigious Scuola Normale Superiore di Pisa.

[Edit] Scuola Normale Superiore di PisaPer admitted to the prestigious University, Enrico Fermi had to overcome a contest to play with the following theme: The distinctive characteristics of sounds and their causes. The theme was done by Fermi with extraordinary safety and absolute possession of the means mathematicians. Based on lessons learned in the Treaty of mechanics using Poisson and concepts such as differential equations and Fourier series expansion, exhaustively described the character of the sound analysis of specific cases. The level of his performance was amazing to get so large the jury. Following an oral interview conducted by Professor Julie Pitta, it was confirmed the excellence of the preparation of seventeen Fermi, who won first place in the ranking. During the interview, Professor Pitt exposed, foretelling, the young student from Rome, who would become an important scientist.

During his university years, Enrico Fermi found time to pursue extra-curricular activities. This activity actively involved his friend Enrico Persico, a student at the University of Rome.

Between 1919 and 1923 he studied general relativity, quantum mechanics and atomic physics. Her background in quantum mechanics reached levels so high that Puccianti Louis, director of the Institute of Physics at the Normal School, asked him to organize seminars on the subject. In this period he learned the tensor calculus, mathematical tool invented by Gregorio Ricci-Curbastro and Tullio Levi-Civita, which is essential in order to demonstrate the principles of general relativity.

In 1921, the third year of university, he published his first two papers in the journal Il Nuovo Cimento: On the dynamics of a rigid system of electric charges in a transitional Sull'elettrostatica a uniform gravitational field and the weight of the masses measured. The first of these works led to a conclusion that contradicts put the calculation of the mass as part of the theory of Lorentz the principle of energy equivalence Einstein. This apparent contradiction was clarified in the following year by the same Fermi correction in a serious discrepancy between the theory of relativistic electrodynamics and the electromagnetic mass. Weight and inertia of electricity, which first appeared in the journal The statements and then the prestigious German journal Physikalische Zeitschrift.

Also in 1922 he published his first important work in the journal Proceedings of the Accademia dei Lincei, entitled On the phenomena that occur in the vicinity of an hour line, where he introduced for the first time those who are subsequently referred to as the Fermi coordinates, and showed that close to one hour line, space behaves as if it were Euclidean.

In 1922 he started his dissertation on the experimental X-ray diffraction images produced by curved glass. It should be noted that the X-ray tubes were manufactured by Fermi and two other students and Franco Rasetti Nello Carrara, part of their experiments "free" in the physics laboratory at the Institute of Physics Normal . The three boys were given free access to the laboratory and the library with the permission of the head of the institution itself. According to Franco Rasetti, Fermi, well known as a theoretical physicist, developed a thesis because it was a full physical.

However, it seems that Fermi's theory, however, preferred to those experiments. In a letter to his Persian, dated March 1922, Fermi understand that it was eager to finish the thesis in order to devote to quantum mechanics.

On 4 July the same year he graduated from the University and the Fermi later graduated from the Normal, July 7, in both cases got the magna cum laude.

In 1923, after writing the Appendix of the book Foundations of Einstein's relativity by August Kopff, Enrico Fermi, specialized in the further study of general relativity with Giuseppe Armellini and Tullio Levi-Civita for the first time puts the emphasis on ' enormous amount of energy embodied in the famous equation (E = mc2). Assertion that can be seen as the first real step towards the generation of atomic energy.

[Edit] Period to GöttingenSubito after graduation, he appeared at Orso Mario Corbino, professor of experimental physics, and in 1923, thanks to a scholarship, he went for six months in Göttingen at the school of Max Born. The period in Göttingen not proved very successful, and seem to be various reasons: some say that is not comfortable with the style too theoretical and formal primary school of quantum physics at the time, who, like Emilio Segrè, Fermi was argued that on the one hand and on one side so too proud, and who even though his colleagues (Born, Heisenberg, Pauli and Jordan) were too busy with their research.

During these six months, rather than looking to solve the contradictions of so-called old quantum physics, introduced by Bohr and Sommerfeld, and on which they were venturing his colleagues in Göttingen, preferred to study the limits of application to atomic systems of the so-called principle of adiabatic spelled out by Paul Ehrenfest, who formulated one of the leading ideas to derive the quantization conditions of the old quantum physics.

Although not the perfect environment, the scientific production of Fermi in Göttingen was intense. After a month of arrival published an article titled "The principle of adiabatic and the systems that do not allow the angular coordinates, article in which it was proposed to determine the limits of validity of the principle of Ehrenfest, showing that for particular adiabatic transformations were to lose its base.

Two months later he published a second article in the journal Zeitschrift Physkalische, titled show that overall, a mechanical system is almost normal ergodic, that article attracted the attention of Ehrenfest.

In this article, titled Some important theorems of analytical mechanics to quantum theory, Enrico Fermi demonstrated the validity of the Ehrenfest principle to determine the orbits of a quantum three-body atomic system. Also show that systems with more of a constant motion of the Ehrenfest principle is not valid.

[Edit] Return from Göttingen and Göttingen from LeidaTornato period, he wrote his first important contribution to quantum mechanics called the probability of quantum states, the work presented by the Academy of the Lincei Corbino December 16, 1923. This work shows the paradox of classical statistics in relation to the calculation of the probability of different quantum states of a gas of atoms at high temperature. According to classical statistics, the different quantum states of an atom have the same probability, a hypothesis that brings the sum of the probabilities of all possible quantum states to infinity. In fact, the maximum probability of any system is by definition equal to 1. The formal solution to this contradiction was that of ad hoc hypothesis in order to establish as not all possible orbits of quantum states for which the radius of the atom is greater than the average distance between atom and atom. Fermi elegantly solved this paradox by calculating the thermodynamic law that contains a factor that makes a negligible contribution to the series with high quantum numbers. This approach is known in literature as Fermi-Urey.

In January 1924, Fermi publish a work entitled On the reflection and diffusion of resonance, in which he develops the theory of optical resonance. In the same month he also wrote Considerations on the quantization of systems that contain identical elements, which represents the first real step towards what will be one of its main findings here in two years: the new quantum statistics, which is called the Fermi-Dirac .

Thanks to the interest of the famous mathematician Vito Volterra, Fermi won a scholarship from the Rockefeller Foundation for a study period in the autumn of 1924 in Leiden at the institute directed by Paul Ehrenfest. This choice is partly based on lack of presence in Italy at the time of personnel involved in research on quantum mechanics.

In the summer of 1924, published an article titled "On the theory of impact between atoms and electric corpuscles, first published in Italian on" Nuovo Cimento "and then in German on" Zeitschrift für Physik. This study represents the first major contribution of the so-called Fermi old quantum physics. In the article mentioned, Fermi developed a method, later known as a method of how virtual photons or equivalent method, based on the similarity between the ionization of an atom produced by a light at an appropriate frequency and that produced by electrons with sufficient speed. In his own words:

"When an atom is in its normal state is illuminated with light of appropriate frequency can excite it, namely a quantum state switch to more energy, absorbing a quantum of light. If the light has more energy than the energy needed to ionize the atom, it can ionize a loss, the frequency of light, an electron or those belonging to the deep layers of the atom. [...] Phenomena in nature very similar to these occur also in the excitement by shock. In fact, if you bombard the atoms of a gas of electrons with sufficient speed, they may get excited or ionized, and if the velocity of exciting electrons is very large, they can also lose electrons belonging to the deep layers of the atom. The purpose of this study was to clarify further the similarities between these two classes of phenomena, namely, to deduce quantitatively the phenomena of excitation for shock absorption than optical. "

The work, although it was experimentally tested and found strong criticism by Bohr. Fermi was adversely affected by this incident, and according to Emilio Segre this could be the reason why Enrico Fermi later showed a negative attitude towards the theories developed by physicists in Göttingen and Copenhagen. Emilio Segrè himself points out that once established in a precise manner the laws of quantum mechanics, the work mentioned above is fully justified by the time dependent perturbation theory developed by Dirac.

At Leiden, as well as take advantage of the scientific guidance of Ehrenfest, Fermi also had to know the physical world authorities such as Einstein and Lorentz, and became friends with Samuel Goudsmit and Niko Tinberg.

The first impression of the period in Leiden are listed in a letter dated October 23, 1924 to his friend Enrico Persico:

"Because, contrary to your predictions I am not dead nor asleep, I'll send some of my news. The environment is known here in Leiden is very nice and pleasant. I have known: that Einstein has been here for about twenty days, although very nice person carries the wide-brimmed hat to give the air of a misunderstood genius. He was taken by a lively sympathy for me could not help but declare every time I met (pity it is not a nice girl!) Ehrenfest, who was also very nice and polite, though not out of place in a clothing store used the ghetto. [...] Lorentz, essential though blue eyes of fire. Then I met several others, including several young people who do not have a name yet, but that probably if they do. "

The period was particularly fruitful in Leiden. In the correspondence between Fermi and Persian speaking of the many discoveries made by Fermi in Leiden. An all was described in a paper published under the title On the strength 'of multiple lines, where Fermi derives the expressions of the intensity of the various components of the multiple lines of atomic spectra of different elements. The agreement found with experimental data was better than that of Heisenberg and Sommerfeld in the theoretical treatment of the problem.

[Edit] Return from Leiden and the beginning of his career universitariaFra 1924 and 1925 Fermi was named, at the invitation of the mayor of Florence and director of the Institute of Physics Garbasso Antonio, to occupy the chair of mathematical physics at the University of the city. During this time he started some research in atomic physics with Franco Rasetti found friend. The two friends carried out important experimental work on atomic spectra by means of radiofrequency fields, and with the same words Rasetti:

"They describe the second adventure in the experimental Fermi after several years of theoretical work, showing his ability in dealing with unfamiliar techniques, and constitute the first example of a research on the atomic spectra by means of radiofrequency fields, a technique that would have numerous applications later. "

The research was also somewhat adventurous, always with the words of Rasetti:

"Without calculate the characteristics of a simple oscillator circuit that would produce fields with the intensity and frequency corrections. Fortunately they were discovered in a closet and some triodes Fermi ruled that they were suitable to carry out the circuit designed by him. The workshop also had several hot-wire ammeters to measure current in the coils, and thus could determine the intensity of the magnetic field. If these tools were not available the experiment could not be made because the research funds available to the school were extremely thin and did not allow the purchase of expensive equipment. [...] The coil inductance and some minor components were built by us and when the circuit was installed it worked instantly as expected Fermi. [...] The results showed that the frequency of precession of the atom was in agreement with the prediction based on the factor of land. "

Between 1924 and 1925 Without trying to make a university career, well aware of his ability. Before you enter a contest in Florence chair without success. Later, along with Volterra, Civita and Corbin, seeks to establish the first chair of theoretical physics in Italy in Rome. But he will have to wait another year and a half to succeed in this endeavor.

Via Panisperna boys. Enrico Fermi was the first to the right. At the center of Edward AmaldiNel meantime try to win the contest for mathematical physics in Cagliari, but the favorite is Giovanni Giorgi, a mathematical physicist of the old guard, known for having brought the international system of units. Among the commissioners were Volterra and Levi-Civita who voted to stop them. The anger over the failure to appoint not last long. In the fall of 1926, Fermi won the competition for the post of the first chair of theoretical physics in Italy, on appointment of Corbino and Garbasso. In the final decision of the judging committee stated:

"The Committee examined the large and complex scientific work of Professor Fermi, has found unanimous in recognizing the exceptional qualities, and he noted that, even at such a young age and few years of scientific work, already highly honors Italian physics . While fully owns the finest resources of mathematics, you know doing is sober and discreet, never losing sight of the physical problem in seeking the solution. [...] While they are perfectly familiar concepts of the most delicate classical mechanics and mathematical physics, he can move with complete mastery of the most difficult issues of modern theoretical physics, so he is the most prepared and most worthy to represent our country in this field of so high and feverish scientific activity worldwide. "

[Edit] The discovery of Statistics particelleNel previous period and prior to this appointment, Fermi went to get interested in quantum mechanics, but as reported by himself in a letter to the 1925 Persian, was not convinced of the new quantum mechanics, or so-called matrices, developed by Bohr, Heisenberg and Jordan.

Fermi rather, as reported by Emilio Segrè, let himself impressed by the work of Schrödinger on wave mechanics. In this period from a work of Born, in which the Schrödinger formalism was used to understand impact and diffusion between the particles together with a first probabilistic interpretation of the wave function, Fermi published a work entitled On the wave mechanics of the processes of 'impact. Finally in December 1925, Fermi wrote his famous work On the quantization of the monatomic ideal gas, which was presented by the Accademia dei Lincei Corbino and expanded version published in Zeitschrift für Physik and thorough.

In this work, Fermi formula for the first time his famous equation of the Fermi-Dirac particles which obey the elementary spin semintero (named in his honor fermions), which is now known as the antisymmetric Fermi-Dirac statistics, by the name of British scientist Paul Dirac, which, although delayed by about six months, compared to Fermi, came to similar conclusions. In a letter sent by a Fermi Dirac, reads:

"Dear Lord! In his interesting work, On the theory of quantum mechanics, proposed a theory of ideal gas based on the Pauli exclusion principle. Now a theory about the ideal gas which is virtually identical to his was published by me in early 1926 (Zs. f. Phys. 36, p. 902, Lincei Rend. February 1926). Because I guess she has not seen my article I would like to draw your attention to it. Yours sincerely, Enrico Fermi. "

[Edit] Genesis of Statistics particelleFermi began to look for the first time in Leiden in 1923 when he faced the determination of the absolute constancy of entropy for a monatomic ideal gas. This problem had already seen the first involved Sackun Otto and H. Tetrode, and then Otto Stern. Fermi published in 1923 on Rendiconti Accademia dei Lincei an article entitled "On the theory of Stern's constant absolute entropy rejecting the basic structure of his theory, and with his words:

"In this paper I propose to show that this assumption is not unnatural at all necessary, because you can alter the kinetic deduction [...] taking into account that the molecules of the solid body can move only on quantum orbits. "

The following year he published on Nuovo Cimento article entitled Considerations on the quantization of systems that contain identical elements. This article shows how the Fermi Sommerfeld quantization rules so perfectly predict the frequency spectrum of the hydrogen atom, but do not give any security for the spectra of atoms more complex. He says:

"Such a failure is usually attributed to the fact that these more complex systems do not allow separation of variables. [...] In this paper I propose to show that there are reasons that lead us to believe that failure is due rather to the inadequacy of the Sommerfeld conditions to calculate the orbits of stability, those systems that, independently from admitting or not the separation of variables, contain some identical parts (in the case of helium atom, for example, the two electrons are indistinguishable from each other). "

Fermi concluded that the Sommerfeld quantization rules are not enough to derive the formula for the Sackur-Tetrode entropy:

"The failure of Sommerfeld rules in calculating the quantity of atoms of atomic number greater than one [...] is due to the fact that these atoms contain at least two electrons are not distinguishable, and that the rules of Sommerfeld, even If the possibility of separation of variables, are not applicable in the case that some parts of the system are completely identical to each other. "

In 1925 Wolfgang Pauli enunciated what is known as the Pauli exclusion principle. Fermi points as Rasetti

"I understood that now had all the elements for a theory of ideal gas that would satisfy the principle of Walther Nernst at absolute zero, would give the correct formula of Sackur-Tetrode entropy for the absolute limit of low density and high temperature, and were free from various arbitrary assumptions that had to be introduced into statistical mechanics to derive the correct value of entropy. "

The objective of Fermi was clear: he wanted

"Find a method for the quantitation of the ideal gas as much as possible independent of arbitrary assumptions about the statistical behavior of the gas molecule. "

In order to apply the Pauli exclusion principle for electrons orbit the atom to the molecules of an ideal gas, Fermi had to face the problem of quantization of their motion. In this regard, demanded that the Fermi gas molecules subjected to a range of attractive three-dimensional elastic forces on the harmonic oscillator model. Remember Rasetti

"It should be noted that Fermi did not express her ideal gas in a box, according to the usual approach, but placed the particles in a potential three-dimensional harmonic oscillator. In this way he could get a density of gas in spherically symmetric and monotonically decreasing. For large radii the density was still low enough to ensure the validity of the approximation of classical Boltzmann. [...] The artifice of the molecules have potential in this kind of course later led to the statistical theory of the atom as a degenerate gas of electrons. "

As a result of the use of the harmonic potential, Fermi, using the principle of adiabatic Ehrenfest, was able to establish that there is a critical temperature below which the statistics of a gas of particles deviates significantly from the classical Boltzmann statistics. Later he obtained the expressions for a strongly degenerate gas (below the critical temperature) pressure and zero-point energy, and a formula for the specific heat at constant volume, which tends to zero linearly with temperature. Regained the equation of a classical ideal gas entropy and a value coincident with that of Sackur-Tetrode.

The discovery by Fermi statistics is quite general in that it applies to a large number of particles. The particles discovered so far can be grouped into two groups: neutron, proton and electron) or μ meson (now known as fermions) which obey the Fermi-Dirac statistics. Photon or π meson (boson) which obey the Bose-Einstein statistics.

The difference between bosons / fermions is related to the value of the corresponding spin. This number assumes a semi full spin for fermions and bosons for a whole wave function and leads to a totally asymmetric fermions and a totally symmetrical for bosons. The relations between the two quantum statistics were highlighted by Dirac. A Fermi instead we must acknowledge that he made the Pauli principle is a principle of general physics.

[Edit] Application of statistics and recognition of its importanzaNel December 1926 the British physicist Ralph Howard Fowler applied the Fermi-Dirac for a problem of astrophysics on the so-called white dwarfs. Pauli applied the same statistics for a study on paramagnetic substances. In 1927, the centenary of the death of Alessandro Volta, Como was organized in a major international conference that took part in all the main scientists in the world. During the Congress, Sommerfeld showed how a series of thermal and electrical phenomena not interpretable with the classical theories, find immediate explanation by the new Fermi-Dirac. Rasetti recalled:

"It was a real triumph for Fermi, Italian and many professors were amazed that a young twenty-six, barely known in Italy, was already so famous in Germany. "

In 1927, the same Fermi statistics applied his own so-called Thomas-Fermi atomic model. In this model the electrons are assumed to be like a degenerate Fermi gas, maintained around the nucleus by the Coulomb force. Fermi and his students used this model to study the properties of atoms vary regularly with the variation of atomic number. About this period and in general working method of Fermi Amaldi's words are interesting:

In the summer of 1935, the group began to disperse. Rasetti went to Columbia University. Segre was also in the U.S., and when he returned to Italy, won the chair of experimental physics at Palermo. D'Agostino left the group to go to the newly formed Institute of Chemistry of CNR. Pontecorvo went to Paris to work with the Joliot-Curie. Majorana finally disappeared. In the words of Amaldi

"Responsibility for what was the general political situation in Italy, as the country was preparing for war with Ethiopia.                                

As a reaction to the heavy political climate, the pace of work became frenzied. Amaldi recalls:

"I start at eight in the morning and measurements almost without interruption until six or seven in the evening, and often even later. Been measured according to a schedule time clock, since we studied the minimum time required to perform all operations. The repeated every three or four minutes to hours and hours and all days to reach a conclusion on any particular point. After resolving a given problem, they immediately attack another without any disruption or uncertainty. Physics as a "burden" was the expression we used to talk about our work and the general situation in Italy was becoming more grim. "

Towards the end of 1936 the political situation in Italy deteriorated further following the Pact of Steel between Italy's Fascist Mussolini and Hitler's Nazi Germany. The blow of the KO group arrived on January 23, 1937, when Corbino died suddenly of pneumonia. Fermi was its natural successor as head of the institute via Panisperna but through political maneuvering, Professor Lo Surdo managed to take the place of the deceased Corbino

The paraffin block used by Fermi for his experiment of October 20, 1934, bearing the initials "Royal Institute of Physics" (RIF), is still preserved in the museum of the Department of Physics, University La Sapienza of Rome.

[Edit] The end of the group and the flight to the States UnitiLa discovery of slow neutrons firmly established the reputation of Fermi's group in the world.

Already in 1935, the group had realized that the sources of radon - beryllium were very weak and that only a particle accelerator would have made more intense. Fermi, sensing its importance, the group wanted to provide a machine of this type. In the summer of 1935, Rasetti was sent to visit the laboratory of Robert Millikan Pasadena and the Radiation Laboratory at Berkeley to study the performance of systems installed at these workshops if you ever decide to build one in Italy. A Pasadena, Rasetti studied a high-voltage accelerator developed by a student of Millikan, and studied at the Berkeley cyclotron invented by Ernest Lawrence.

The production of neutrons of the cyclotron was in the order of 1010 neutrons per second, equivalent to neutrons can be obtained with a kilogram of radon mixed with beryllium. After a year's visit Rasetti, Segrè also went to Berkeley and noticed that the cyclotron had meanwhile been greatly improved. Back in Italy, together with Fermi abandoned the idea of ​​building a cyclotron in Italy because of the high cost. In November 1936, Fermi and Domenico Marotta, Director of the Institute of Public Health, presented the proposal to create a type Cockcraft-Walton accelerator from 1MeV, which would be obtained at the Institute of Public Health, only a few months after the drain Fermi fascist Italy. In order to maintain the international position reached, Fermi introduced January 29, 1937, a detailed proposal for the establishment of a National Institute of radioactivity:

"The research on radioactivity had in recent years, in all civilized nations, an exceptionally intense and fruitful development. This movement is not mentioned in any way to decline, but rather tends to spread to new and vast fields of not only physical but also of chemistry and biology. Italy has so far had a prominent role in this research [...]. On the other hand, the radiological technique has been used largely as primary sources of natural radioactive substances, so that the ordinary means of a physical laboratory university could, with limited external support, be sufficient to develop the research. Besides the technique of natural sources has been developing in all major foreign countries than the artificial sources. [...] These sources have intensity a thousand times higher than starting from naturally occurring substances. It is clear that these circumstances make it vain to think of an effective competition with foreign countries, even if Italy does not find a way to organize research on a proper plan. "

and kept emphasizing that

"In the field of physics has just begun a study to survey the properties of a hundred new radioactive bodies (about half discovered in Italy). [...] In addition to this field of systematic research, which alone could take several years for the work of various researchers, there are still many unsolved problems related to nuclear structure and properties of the neutron, the study of which is natural to assume a remarkable harvest of results. "

Fermi was not limited to stress the importance of basic research but also highlights the possible practical consequences:

"Another important field of study, for which you have already promettentissimi beginning, is the application of artificial radioactive substances as indicators for the analysis of chemical reactions. No less important facing applications in biology and medicine. This importance has been recognized in various countries in which research on artificial radioactivity are widely supported by medical institutions. Some applications involve the replacement of the natural radioactive substances for therapeutic purposes.

The final request by Fermi was 300,000 lire more than 230,000 for the costs of staffing and management. In 1937, the same Fermi went to Berkeley to study the economic way of building a cyclotron, but this plan did not bring anything to the increasing political isolation and scientific Fermi began to suffer after the death of Corbino and that was accentuated further with the 'sudden death of Guglielmo Marconi, who as president of the CNR and the Academy of Italy, was an influential patron of the group and listened. In May 1938, the proposed Fermi was definitive failure on the grounds that there was enough money. He was just awarded a grant of 150,000 pounds for the year 1938-1939. This decision marked the end of the dream of a cyclotron and the death of Italian Italian nuclear physics, just a few months prior to the granting of the Nobel Prize for physics. [Citation needed]

During this time she reached the decision (even after the constant journeys to the USA) to leave Italy to fly overseas, because in the U.S. there were adequate funding for research. As recalled by Segrè:

"I enticed equipped laboratories, the abundant resources for research, the enthusiasm felt in the new generation of physicists, the cordial welcome the Americans. [...] The American ideals, unlike those fascists were echoed in a deep Fermi. All comments and considerations that followed the spiritually prepared to leave, and when he finally moved to America was more the execution of a long-meditated that a sudden decision given the circumstances. "

However the situation in Europe, with the annexation of Austria by Nazi Germany, began to degenerate rapidly. In July 1938 he also began the anti-Semitic campaign in Italy with the publication of the manifesto of the race and the subsequent racial laws, for which Fermi had to give up the collaboration of some of his assistants. The same Fermi's wife, Laura Capon (Capon daughter of Admiral Augustus), being Jewish, was subject to racial persecution imposed by the regime, together with their children. Fermi's wife, recalls in his book Atoms in the family, the couple decided to leave Italy following the implementation Of this law. Fermi himself was subject to export controls of any kind.

On 10 November 1938. Prof. Enrico Fermi received, at the age of thirty-seven, the official announcement of the Nobel prize. The famous Italian scientist decided that after the award ceremony in Stockholm, he sailed with his family to the United States, where the Columbia University in New York, invited him to a series of lessons. Edoardo Amaldi, thus restoring the atmosphere that preceded the official announcement of the allocation to Fermi's Nobel

"In the days following the award of the Nobel Prize to Fermi, the press was limited to giving the news in an extremely short part had come to express a cautious satisfaction with the international recognition he had received the Enrico Fermi's work done in an Italian university, rather than in the capital, and sometimes tried to do the climb on the regime [...]. But at the same time leaked here and there, some concern about the imperfection of racial family Fermi, Italian physics institute and the environment in general and to the suspicion that Stockholm had to stop the first stage of a journey well longer. "

An interesting story about the climate around the figure of the famous physicist Roman comes to us from a routine check by an informant made the Minister of the Interior. Following the ceremony that Magneti Marelli, a company which Fermi was scientific adviser, organized to celebrate the new Nobel laureate, were invited every major city authorities in the region. From the informant's story:

"I'm told that at the ceremony to celebrate the academic [...] Enrico Fermi, the Nobel Prize for physics in 1938, were invited all the city authorities. By HRH the Duke of Bergamo, the prefect, General Secretary, States and Fascist leaders, mayor, superintendent, etc.. It seems that at the last moment, with the exception of the Duke of Bergamo, none of those authorities, and especially political, he wished to speak. It is said that the cause is due to the fact that the birthday boy, married to an Israel, he repeatedly expressed his disapproval of the anti Jewish, instead declaring himself happy to have a Jewish partner. "

On December 6, 1938 Fermi went by train to Stockholm. At Termini station, the family was accompanied by Rasetti and Fermi Amaldi, showing the last moments with the master:

"I know, indeed knew, that night finally ended a period, brief, history of culture in Italy that could be spread and grow larger and perhaps have an influence on the environment and education, over the years, maybe even the entire country. Our little world was shattered, almost certainly destroyed by forces and circumstances completely beyond our scope. A careful observer might say that he had been naive to think of constructing a building on the slopes of a volcano that showed such clear signs of increasing activity. But on those slopes were born and raised, and we had always thought that what we were doing was much more durable political phase that the country was going through. "

On 10 December 1938, the Academy of Sciences in Stockholm awarded the Nobel Prize for Enrico Fermi

'The discovery of new radioactive elements belonging to the whole field and for the discovery of the selective power [...] of slow neutrons. "

Enrico Fermi's behavior during the award presentation became a sensation inside information of the fascist regime [2]. As recalled by Amaldi:

"The fact that Fermi instead of wearing the uniform or the Academy of fascist Italy and bring the tails instead of making the fascist salute stringesse hands with the Swedish king led to a real wave of indignation. "

In the days after Otto Hahn and Fritz Strassmann noted that, as a result of bombarding uranium with neutrons, the presence of radioactive barium, which is an intermediate element with atomic number (similar to the discovery of Fermi's group of elements with higher atomic number called experienced and Ausonius). The two German scientists speculated for the first time the possible fission of uranium.

After receiving the Nobel Prize, Fermi went to Bohr in Copenhagen, December 24, 1938 to embark on an ocean liner Franconia to New York.

[Edit] Top searches statunitensiCome above, Fermi was at first at Columbia University. Here occurred the initial experiments of Hahn and Strassmann on nuclear fission, and with the help of Booth and Dunning began to build the first nuclear pile (which will reach the critical first 2 December 1942).

In a speech in 1954, when it was decided by the President of the American Physical Society, Fermi recalled the beginning of the project:

"I remember vividly the first month, January 1939, I started working at the Pupin Laboratories and everything began to happen very quickly. At that time, Niels Bohr had been called for a series of lectures at Princeton and I remember one afternoon Willis Lamb came back from one of them really excited and said that Bohr had escaped from his mouth very important news: the discovery of nuclear fission and large lines its interpretation of the phenomenon. Then again later the same month, there was a meeting in Washington where he was assessed the possible application of the newly discovered phenomenon of fission as a nuclear weapon. "

After Einstein's famous letter of 1939 (written by Leo Szilard) to President Roosevelt in which, faced with the threat posed by the Nazi regime, that highlighted the possibility of an atomic bomb, the Navy established a fund of $ 6,000 for Columbia University, which was increased to fund the Manhattan Project and the work of Fermi.

ter Germany's surrender, the doubts of the scientists involved in the Manhattan Project grew in intensity. In Chicago, in the days immediately following the end of the war in Europe, Arthur Compton appointed a committee to address the question of the use of the bomb, made up of various scientists in the Metallurgical Laboratory, including the same Szilard, and chaired by James Franck, a German physicist of great value, immigrated to the United States to escape persecution of anti-Semitism of the Nazis. In early June 1945 the final report, known as the Franck Report although drawn largely from Szilard, was delivered urgently to the Minister of War Henry Stimson because he sent to President Truman. The report advised against the use of atomic bombs against Japan, and suggested a bloodless demonstration of the new weapon.

Not having reached any findings to report Franck, Szilard decided to write a petition to President Truman, and had circulated among scientists at the Metallurgical Laboratory, collecting 53 signatures. It then sent copies to the laboratories of Oak Ridge and Los Alamos, with a covering letter in which he wrote: "As far as limited and the possibility that our petition will affect the course of events, I personally feel that it would be important if a large number of scientists who have worked in this field has publicly expressed with clarity and confidence on the opposition on moral grounds the use of these bombs in the current phase of the war, "but Los Alamos Szilard's petition was not circulated. Posted by Szilard through institutional channels, the petition never reached Truman that "the question of the use of the bomb had already been fully addressed and resolved by the competent authorities."

The decision was taken at the highest political level, but Fermi and other scientific leaders of the Manhattan Project played a key role in decision-making: two months earlier, in May of 1945, Truman had in fact created a special commission, known as the Interim Committee to address the issue of the use of the atomic bomb. The Interim Committee was assisted by a scientific committee composed of four leading scientists of the Manhattan Project: Oppenheimer, Fermi, Lawrence, and Compton, who had the delicate responsibility of giving technical advice on the use of nuclear weapons against Japan. The four scientists were given by the Stimson Report Franck did not find him convincing.

The recommendation of Fermi and other leading members of the project convinced that dell'lnterim Committee unanimously approved the following measures:

1) the bomb should be used against Japan as soon as possible; 2) will be used on a dual target, namely the war on military installations or facilities surrounded or adjacent to homes, and 3) to be used without prior warning about the nature of the weapon.

In his address to ODA, Fermi also said:

"Well, we arrived at Pearl Harbor. At the time I left Columbia University, and after several months of back and forth between Chicago and New York, I settled in Chicago to continue the work, and from then on, with rare exceptions, the work at Columbia focused on the phase of the project Atomic Energy initiated by Booth, Dunning and Urey around 1940 concerning the separation of isotopes. "

[Edit] Fermi forerunner of his time

The way to RomaFermi Enrico Fermi was a man of extremely bright, unusually open mind and common sense. It was a truly gifted theorist, as evidenced by his theory of beta decay. Had the same talent also on laboratory work, proceeding quickly and with great intuition. He argued that his speed in the laboratory led him to the Nobel Prize, saying that they discovered that he had arrived early were made by someone else, and that he had just arrived before us

In 1933 he proposed his famous paper on beta decay to the prestigious journal Nature, but the journal's editors rejected it because "it contained speculations which were too distant from reality." For this, Brace published his theory in Italian and German.

Immediately understood the importance of computers. [2] He never forgot to be a precursor of his day, and he used to tell his students' favorite: "Never be first, try to be second."

On November 29, 1954 Fermi died of stomach cancer in Chicago, Illinois. He was fifty-three years. Eugene Wigner wrote of him: "Ten days before Fermi died I said I hope it does not last long. It is perfectly reconciled with his fate."

Prof. Edoardo Amaldi had to say during the commemoration held in classes Joined March 12, 1955 by the Accademia dei Lincei:

"His scientific work is so powerful and brilliant, the practical consequences of some of his work are so important and serious than those who do not easily have had the good fortune to know him and led him to be a very different image from the truth. Only the relatives and friends, only those who knew him know that, while it was difficult to separate the various aspects of Enrico Fermi scientist, researcher, teacher and man, as intimately fused together, d ' other hand, its simplicity of taste and way of life, its quiet serene in the face of problems in life, its lack of any installation or quirk of nature human qualities were even more remarkable for the contrast with his exceptional qualities as a scientist . "