Ettore Majorana

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Ettore Majorana (5 August 1906 – 27 March 1938 presumed dead) was an Italian theoretical physicist who began promising work on neutrino masses. He disappeared suddenly in mysterious circumstances.

Life and work

Gifted in Mathematics

Majorana was born in Catania, Sicily. Mathematically extremely gifted, he was very young when he joined Enrico Fermi's team in Rome as one of the "Via Panisperna boys", who took their name from the street address of their laboratory. His first papers dealt with problems in atomic spectroscopy.

First published academic papers

His first paper, published in 1928, was written when he was an undergraduate and was coauthored by Giovanni Gentile Jr., a junior professor in the Institute of Physics in Rome. This work was an early quantitative application to atomic spectroscopy of Fermi's statistical model of atomic structure (now known as the Thomas-Fermi model, due to its contemporaneous description by Llewellyn Thomas).

In this paper, Majorana and Gentile performed first-principles calculations within the context of this model that gave a good account of experimentally observed core electron energies of gadolinium and uranium, and of the fine structure splitting of cesium lines observed in optical spectra. In 1931, Majorana published the first paper describing the phenomenon of autoionization in atomic spectra, designated by him as "spontaneous ionization"; an independent paper in the same year, published by Allen Shenstone of Princeton University, first used the term "auto-ionization", which has since become conventional, without the hyphen.

An important paper (1932) in the field of atomic spectroscopy concerned the behaviour of aligned atoms in time-varying magnetic fields. This problem, also studied by I. I. Rabi and others, led to an important sub-branch of atomic physics, that of radio-frequency spectroscopy. Also in 1932, Majorana published his paper on a relativistic theory of particles with arbitrary intrinsic momentum, in which he developed and applied infinite dimensional representations of the Lorentz group, and gave a theoretical basis for the mass spectrum of elementary particles. Like most of Majorana's papers in Italian, this paper languished in relative obscurity for several decades. (It is discussed in detail by D. M. Fradkin, Amer. J. Phys., vol. 34, pp.314-318 (1966)). Subsequently, he studied with Heisenberg in Leipzig and worked on a theory of the nucleus (published in German in 1933) which, in its treatment of exchange forces, represented a further development of Heisenberg's theory of the nucleus. Majorana's last-published paper, in 1937, again in Italian, concerned his elaboration of a symmetrical theory of electrons and positrons.

Majorana, during these same years in which he published these few articles, wrote many small works about several topics: from Earth Physics, to Electrical Engineering , from Mathematics to Relativity. These unpublished papers, preserved in Domus galileiana in Pisa, have been recently edited by Erasmo Recami and Salvatore Esposito.

He became full professor of theoretical physics in Naples University in 1937 without needing to take examination because, as certified by official documents, competition board suggested “ to appoint Majorana as full professor of Theoretical Physics in a University of the Italian kingdom, for high and well-deserved repute, independently of the competition rules”.

The competition board suggestion was accepted and Majorana taught the chair of Theoretical Physics in Naples. After a few months of teaching, however, it ended with his well-known disappearance.

Work with neutrino masses

Majorana did prescient theoretical work on neutrino masses, a currently active subject of research. He also worked on an idea that mass may exert a small shielding effect on gravitational waves, which did not gain much traction.

His uncle Quirino Majorana was also a physicist.

The year 2006 marked Majorana's centenary, and a book of his (nine) collected papers, with commentary and English translations, was published by the Italian Physical Society.

For the Centenary of Ettore Majorana (1906-1938) Electronic Journal of Theoretical Physics' (EJTP) has published a special issue (20 articles) dedicated to the modern development of Majorana’s legacy.

On the occasion of the Majorana Centenary in 2006 and the editing of the Special Issue about his Legacy in Contemporary Physics, the Electronic Journal of Theoretical Physics has established a prize in memory of the great Sicilian physicist Ettore Majorana (1906 - 1938). The " Majorana Medal" is an annual prize of excellence for the researchers who showed peculiar creativity, critical sense and mathematical rigour in theoretical physics - in its broadest sense. The recipients of the 2006 Majorana prize were Erasmo Recami (University of Bergamo and INFN) and George Sudarshan (University of Texas).

Disappearance at sea and theories

Traveling to Naples

Majorana disappeared in unknown circumstances during a boat trip from Palermo to Naples. Despite several investigations, the truth about his fate is still uncertain. His body has not been found.

Immediately after his disappearance, several people theorized about what could have happened; major hypotheses have included:

He could have committed suicide (he left two letters which contained a sort of farewell).
He could have been kidnapped by foreign powers.
He could have voluntarily disappeared, changed his identity and possibly left Italy.

Voluntary disappearance theory detailed

Some argue for this last hypothesis, conjecturing that after having envisioned the destructive power of atomic energy, Majorana did not want to contribute to its deployment in a fascist state (at that time, Italy was governed by Benito Mussolini). There have been sporadic rumors that he may have been sighted in South America in the 1950s. Also in Italy a story appeared in the news when a man living on the street claimed that he once was a famous physicist.

The Sciascia hypothesis

The Italian writer Leonardo Sciascia has summarized some of the results of these investigations and these hypotheses in his passionate book La Scomparsa di Majorana (Einaudi, 1975 - English translation: The Moro Affair and The Mystery of Majorana, Carcanet, 1987, ISBN 0-85635-700-6). However, some of Sciascia's conclusions were refuted by certain of Majorana's former colleagues, including E. Amaldi and E. Segrè. The various hypotheses on Majorana's disappearance have been extensively discussed by Erasmo Recami in his book "Il caso Majorana: Lettere, testimonianze, documenti" (Di Renzo Editore, Roma, 2000) and in a journal article (E. Recami, "I nuovi documenti sulla scomparsa del fisico Ettore Majorana", Scientia, vol. 110, pp.577-588 (1975); English version titled "New Evidence on the Disappearance of the Physicist Ettore Majorana", Scientia, vol. 110, p. 589 ff. (1975)). In the above-mentioned book and article, Recami discusses critically the various rival explanations concerning Majorana's disappearance, including those advanced by Sciascia in his short book, and presents highly suggestive evidence to the effect that Majorana absconded to Argentina.

The theories about Majorana’s disappearance can be summarized as follows:

Hypothesis of suicide by Amaldi, Segrè and others
Hypothesis of escape to Argentina by Recami and Artemi (who has developed a detailed if hypothetical reconstruction of the possible escape and in life Argentina of Majorana)
Hypothesis of escape to a monastery by Sciascia
Hypothesis of kidnapping or killing to avoid his participation in the construction of an atomic weapon by Bella, Bartocci and others
Hypothesis of escape to become a beggar ("omu cani" hypothesis) by Bascone

References

E.Recami , Il caso Majorana , Di Renzo Ed. , Roma , 2001
Carlo Artemi , Il piano majorana : una fuga perfetta (The majorana plan : a perfect escape ) , De Rocco press , Rome , 2007
E.Amaldi , Ricordo di Ettore Majorana , Giornale di fisica , 9 , 1968 ,
U.Bartocci La scomparsa di Majorana : un affare di stato ? ed. Andromeda 1999
L. Sciascia , La scomparsa di Majorana ,Adelphi ed. 1975
I.Bascone , Tommaso l’omu cani amara e miserabile ipotesi sulla scomparsa di Ettore Majorana fisico siciliano al tempo del fascismo , ed. Ananke , 1999
S.Bella , Rivelazioni sulla scomparsa di uno scienziato : Ettore Majorana , Italia letteraria , 1975
Edited by E.recami and S.Esposito Appunti inediti di Fisica teorica , Zanichelli , 2006
L.Castellani , Dossier Majorana , Fratelli Fabbri , 1974 (edited again in 2006 )

Quotes

There are many categories of scientists, people of second and third rank, who do their best, but do not go very far. There are also people of first class, who make great discoveries, fundamental for the development of science. But then there are the geniuses, like Galilei and Newton. Well, Ettore Majorana was one of them ...

Enrico Fermi

Sources

For a summary of Majorana's scientific output, see the following article (in Italian): E. Amaldi, "L'opera scientifica di Ettore Majorana", Physis, vol. X, pp.173-187 (1968).

Majorana's collected papers, accompanied by English translations and commentaries, were published in Ettore Majorana Scientific Papers on the occasion of the centenary of the birth

External links

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