|Explanation||Hans Christian Ørstedt||Philipp Reis||Alessandro Volta||Enrico Fermi||Mario Corbino|
|Ettore Majorana||Luigi Galvani||Marija Aleksaite-Gimbutiene||Carl Auer von Welsbach|
Ettore Majorana -
Liceo Michele Amari Giarre
Visit the italien Physicans - Site Liceo Michele Amari Giarre
"The Majoranas are like potatoes, the best is underground". This sentence was often heard at the Majoranas house along with a smile.
Fabio Majorana, Ettores father, was born in Catania in Sicily in 1875. He took his first degree, in engineering, quite early and then went on to take another in Physics and Mathematics. Later he would be given the task of educating the child Ettore until he was 9. At this age Ettore was reported as having an above average intelligence. At the age of 7 he was a good chess player and some people say that when he was 4 he was able to do complex calculations. On the walls and the balconies of the family house in the main street there are the figures of his early exercises as a child.
His mother was Dorina Corso, from a well-off family. From the marriage to Fabio Majorana 5 children were born who would grow up to become learned people. Ettore, born in 1906 in Actinia, was the fourth, a very sensitive and introvert person but good-tempered.
He regularly attended and completed his classical studies in 1923. He then moved to Rome to study engineering until, in 1928 he asked for permission to change department and to devote himself to Physics. In 1929 he got his degree in Theoretical Physics under Fermis supervision with a thesis on the quantum theory and radio-active nucleuses, which allowed him to take full marks and a first-class degree.
Of his life it has been said that he sympathised for nazism, but it remains unsure after his letter correspondence. What is certain is that there is a certificate stating his subscription to the PNF, the fascist party in Italy, and that he swore an oath in front of the king and the establishment. On the other side there is an interesting witness by a famous physicist, Rudolf Peierls, who has no hesitations in declaring that Ettore was a convinced anti-fascist.
After that he attended the Physics Institute in Via Panisperna and joined the scientific movement working on several theoretical researches until 1933. He also wrote 9 science papers and some manuscript papers which provide us with evidence of a) how diligent and precise he was in his work. All his achievements are the result of a long series of calculations, done and repeated several times: "even for a genius science is not just a simple matter of intuitions" ;b) among the materials he left us some still distinguish for being current after more than 70 years and are of some interested for modern research; c) that the extant material seems to be written before 1933 and nothing is left from later years ( 1934-38).
His sister Maria used to remember that in those years, after leaving teaching at the end of 1933, he still studied and worked at home several hours a day; he dealt with literature and philosophy, "game theories" or naval strategy, his favourite since he was a child, or medicine and political economics. The crucial question is : did he keep on studying physics ?? We only have a clue: in 1938, in Naples Mr Carelli thought Majorana was working on something important that he did not want to talk about.
Going back to his articles, the first ones are about problems in atomic and molecular physics. They concern matters of atom spectroscopy or chemical bond in the field of quantum mechanics. Lets choose one of these articles, "Oriented Atoms in a Variable Magnetic Field" published in Italian on a science magazine. It was the phenomenon well known today as the Majorana-Brossel effect which allows to predict and calculate the change in the shape of spectral lines as a consequence of an oscillating magnetic field. His results formed the theoretical basis for the experimental method, used to reverse the neutrons spin with a field of radio-frequency.
Another paper, " Relativistic Theory of Particles with Intrinsic Arbitrary Movement" is the typical example of a precursor work which will only be fully understood and appreciated a long time after. At that time it was a common idea or a dogma that it was not possible to write quantum equations compatible with relativity only with zero spin or ½ spin particles. Majorana was not convinced at all and he started building quantum-relativistic equations for the following possible values of spin until he found out that he could write only one equation to represent an infinite series of cases, that is, a whole family of particles with random spin.
Thus he only worked on these infinite-component equations, without under-estimating the fact that they can describe not only ordinary particles but also tachyons.
Moreover Majorana appeals for the first time to the unitary infinite-dimension representations of Lorentz group, representations later revived by Wigner in 1939 and 1948.
In early 1932, as soon as the news was spread in Rome of the experiments by Joliot-Curie, Ettore at once realises they had by chance discovered the "neuter proton". Well before the official presentation of the neutron to the academic world made by Chadwick, Majorana was already able to explain the structure and the stability of atom nucleus by means of protons and neutrons. He also anticipated Ivanenkos pioneer work but he neither said a word nor let Fermi talk about it in Paris in early July of that year. His colleagues still remember how he had gained the basic points of his theories before Easter:
protons and neutrons were bound by quantum forces simply originating by their "undistinguishness", that is by exchange forces from their space positions so that they may have the alpha particle as a saturated system compared with the bond energy.
It was after publishing his studies that Heisenberg convinced Majorana to publish, though a bit later, his own results. And from then on the nucleus exchange forces are called Heisemberg-Majorana forces.
It is also likely, from his manuscripts, that in the same years he was also formulating the guidelines of his symmetric theory for the electron and the anti-electron, when the news was circulating of the discovery of the anti-electron, the positron.
Majorana will present his theory much later in a publication which will be noticed mostly for introducing his famous representation of Diracs matrix in a real form, The first consequence of this hypothesis was that any neuter fermion must coincide with its own anti-particle. Ettore was suggesting that neutrinos may be particles of such a kind.
It is funny that this article was also bound to have some fortune 20 years after its publication, and its reputation has become greater and greater among physicists of relativistic particles and of field theories. Expressions like "Majoranas spinors", Majorana mass or Majorana neutrino are getting routine ones.
Fermi, his more famous colleague, stated that Ettore was the one, among the scientists, who best impressed him. He added: " He is able both to make risky hypotheses and to criticise his work and the others. He is an expert calculator and a profound mathematician who, under the veil of figures and algorithms, never loses sight of the very essence of the physical problem; he has got at its best that set of aptitudes which lead to the first-class physicist". And indeed in a few years his name was known to the scientists all over the world who realised he was one of the greatest wit of contemporary times. Sometimes, we know, Fermi had compared Majorana to Galileo or Newton and to himself, being Majorana superior. Sometimes the two of them stayed behind at school and talked about physics at the blackboard. And sometimes there were big controversies. Confronting calculations - differential equations, definite integrals, etc.- they entered a competition : Fermi armed with his inseparable slide rule which he used with great skill; Ettore just using his mind and standing face to the wall to better concentrate. And when Fermi was ready the other already had the solution!
The details of their first contact are illuminating in some aspects not only scientific ones about Majorana. They were made after Segré told them in public.
Fermis first relevant work, written when in Rome, is today referred to as Thomas-Fermi method. When Fermi discovered that in order to proceed he needed the solution of a non-linear differential equation, Majorana had just joined the Institute and showed his scepticism thinking that the equation was wrong and it would be better to check it once again. He went straight home and turned the original equation into a Riccati one and succeeded in solving it without any calculator just using his great talent for numerical calculation. Back to the Institute he compared his data on a scrap of paper with those on Fermis notebook and when he found they were the same he couldnt help but be astonished.
The revival of Physics in Italy wouldnt have been possible without the presence of Corbino, director of the Institute in 1918. It was when Corbino met Fermi that he understood there was a chance for a quality change in science research in Italy. Actually the turning point was in 1929 when they decided to turn their efforts to nuclear physics. They had enrolled the best intelligence in physics, having Amaldi, Rosetti and Segré. The latter praised Majoranas talent until he convinced him to meet Fermi and to move from Engineering to Physics.
In the words of Amaldi, the biographer for Majorana:
It was then I saw Majorana for the first time. He seemed to be slim, with a shy and uncertain bearing. When closer he had black hair, a dark complexion and lively sparkling eyes: as a whole the physical appearance of a Saracen.
Later the group was joined by Bruno Pontecorvo and the chemist DAgostino. Is is funny how everyone at Via Panisperna was given a nickname so that Corbino was the Allmighty, Fermi was the Pope, Rosetti the Venerable Master, or the Cardinal Vicar, Segré the Basilisk and Majorana the Great Inquisitor, of course because of his critical spirit.
The same revival was in a certain sense flourishing also in Florence. The same competition which allowed Fermi to have his task as a University teacher in Rome, allowed Persico to have the same at Florence University. It was easily acknowledged how there was a good relationship and sincere friendships between the two groups, which produced common activities such as visits and seminars.
Another public competition was held only in 1937 because the University of Palermo needed teachers of Theoretical Physics. There was a great number of candidates among whom Majorana and Giovannino Gentile, the creator of perestatistics in quantum mechanics. The commission was formed with Fermi, Persico and others.
When evaluating the results, after a long and rich debate, the commission was unanimous in acknowledging the remarkable scientific position of Professor Majorana and decided to send a letter to the Minister suggesting the opportunity of his appointment as a Professor of theoretical Physics.
Since the very beginning of his career Prof. Majorana showed depth in his thought and such a great originality and creativeness of scientific ideas to attract the attention of world physics scholars on him. His great contribution given to modern nuclear theories, with the introduction of Majorana forces is commonly accepted among the fundamental ones consenting to understand more closely the reasons for nucleus stability. In Atomic Physics his is the merit of solving some of the most complicated questions on the structure of spectres, thanks to his simple and elegant considerations of symmetry. In addition to his infinite-component equation, in a later work he discovered a brilliant approach, which allows us to deal with the positive and negative electrons in a symmetric way, removing the need of an artful and unsatisfactory hypothesis of an infinitely-great electric charge diffused in the whole space.
We all know that he was a pure theoretician, with no experimental inclination. When he was interested in atomic physics he made some hints at the future revolutionary, perhaps, practical applications to come. Did he know that the construction of nuclear bombs was within reach ??
In 1934 Fermi and his staff start exploring the world of manufacturing artificial radio-active elements through the bombardment of neutrons. Neutron was the ideal bullet to produce the transmutation of elements since, having no electric charge, it is not affected by the nucleus electric repulsion . The common idea was that the neutrons were more effective in inducting reactions in target nucleuses if more energetic. But Fermi was not happy with that. He soon understood the unexpected fact that the "slow" neutrons were hundreds times more effective than the quick ones. From that we have the famous experiments carried out in the " goldfish fountain" just behind the Panisperna Physics Institute in Rome where the water has the function of slowing down the bullet-neutrons. Among the several bullets there was last natural element, uranium, in the hope that the absorption of a neutron by the uranium nucleus will lead to the formation of artificial trans-uranium electrons. A whole generation of physicists was not prepared at that time to realise how some very low-energy neutrons could be successful whereas the most powerful "bullets" failed: in creating the nuclear scission of uranium. In 1934 the Panisperna group had already experienced the fission finding out that the target uranium nucleuses, when splitting into two parts, release a huge amount of energy : hundreds times greater than it is released in common nuclear procedures, and million times bigger than in chemical process.
The public acknowledgement of this discovery was only in 1938 with the experiments by Hahn and Stressmann. Actually it was Hahns assistant , Lise Meitner and his nephew Otto Frisch to be illuminated by the idea that in those experiment uranium fission was produced.
The right explanation was given Otto Hahn says by" Meitner and Frisch , whom we had given our results before the publication". The event was thus public in late Jaunuary 1939, but only the correct interpretation of the 1934 experiments allowed to comprehend how an extra-ordinary source for energy the atomic nucleus might be.
But it wasnt public when Ettore Majorana disappeared. And only in 1939 research started to make it possible the exploitation of nuclear energy, causing the fission-almost simultaneous- of a great amount of nucleuses. Research which will lead Fermi to build the first " atomic pile" in Chicago and , later, to the "H-bomb".
Had Mr Majorana foreseen all that ? And did that contribute to his estrangement from Fermis group , already started in 1933-? It may be but there is no direct or indirect evidence but conjectures .
Sometimes he would say that " physicists or physics were on the wrong way" but tat was possibly more referred to theoretical " speculative" matters than to the ethical implications. Moreover , if Majorana was really afraid of the uncontrolled release of nuclear energy he surely would understand to be more helpful to the just cause being alive rather than dead.
In the attempt at throwing light on the motivations which underlie his sudden disappearance, his letters may help us, and mostly the ones when in Naples, last of his "official" life , at least. In March 1938, at 31 years old, professor of Physics for " alta fama di singolare perizia", for his high reputation of excellent expertise, at the Royal University Physics Institute in Naples since the previous November, he writes the draft of a letter to Antonio Carelli the following letter:
Dear Carelli, I took the decision which was now inevitable . In it there is no To be followed