Ettore Majorana, la personalità umana e scientifica

This article is a contribution for celebrating the 100th anniversary of the birth of the Italian theoretical physicist Ettore Majorana, probably the brightest Italian theoretician of the XX century. Enrico Fermi regarded him as the brightest of his time in the world, even if to many people Majorana is still known mainly for his mysterious disappearance, in 1938, when he was 31. In this paper we outline the significance of many publications of his, without forgetting the scientific manuscripts left unpublished by him; as well as his life [the biographical data being based on letters, documents, testimonies discovered or collected by the author during almost 30 years, and contained in the book by Recami, "Il Caso Majorana: Epistolario, Testimonianze, Documenti" (initially published by Mondadori, Milan, and presently published, in 2002, by Di Renzo Editore, Rome)]. We discuss in particular his papers: (i) on spin-flip, the Majorana-Brossel effect, the Majorana’s “sphere”, et alia; (ii) on the infinite-component equation; (iii) on the Heisenberg-Majorana exchange forces inside the atomic nucleus; (iv) on the Majorana neutrino