Ettore Majorana
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-->Ettore Majorana (Catania, Sicily, 05 August 1906 – Tyrrhenian Sea, 27 March 1938 (presumed)) was an Italian theoretical physicist who began promising work on neutrino masses. He disappeared suddenly in mysterious circumstances.
Life and Work
Majorana was mathematically extremely gifted, and 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. 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 Arthur 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 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 marks Majorana's centenary, and a book of his (nine) collected papers, with commentary and English translations, is scheduled to be 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.
"MAJORANA LEGACY IN CONTEMPORARY PHYSICS". Volume 3, Issue 10 (April 2006), Majorana Issue (Editor: Ignazio Licata).
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).
Disappearance
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.Hypotheses include that
- 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.
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" (Mondadori, 1991) 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.589ff. (1975)). In the above-mentioned book and article, Recami discusses critically the various rival explanations concerning Majorana's disapparance, including those advanced by Sciascia in his short book, and presents highly suggestive evidence to the effect that Majorana absconded to Argentina.
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
See also
- Majorana equation
- Majorana neutrino
External links:
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