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Quirino Majorana

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Quirino Majorana
Quirino Majorana
Born28 October 1871, Catania, Italy
Died31 July 1957, Rieti, Italy
ResidenceBologna, Italy
NationalityItalian
Known forGravity shielding / gravitational absorption, experiments on the constancy of the speed of light, magneto-optics
Scientific career
FieldsPhysics, Gravity, Relativity
InstitutionsUniversities of Rome, Turin (1916-1921) and Bologna (1921-1934)

Quirino Majorana (1871-1957) was an outstanding Italian experimental physicist who investigated a wide range of phenomena during his long career as professor of physics at the Universities of Rome, Turin (1916-1921), and Bologna (1921-1934), Italy. He is remembered above all for a long series of extremely sensitive experiments on gravitational absorption - the claim that a body's weight is measurably reduced when heavy matter is interposed between it and the Earth - and for a parallel programme of optical experiments intended to test Albert Einstein's postulate of the constancy of the speed of light. Openly critical of relativity, Majorana pursued both questions as an experimentalist rather than a theorist, and his gravitational results remain among the most-cited unreplicated experiments in the literature of alternative gravity.

Biography

Quirino Francesco Valentino Majorana was born in Catania, Sicily, on 28 October 1871. He took a degree in engineering in 1891 and a degree in physics in 1893 at Rome, where he worked as assistant to Pietro Blaserna. From 1904 to 1914 he directed the Central Institute of Telephones and Telegraphs in Rome, an appointment that shaped his lifelong interest in applied electricity, radiotelephony and early television.

He then moved to academic chairs, teaching at the Polytechnic of Turin (1916-1921) and then at the University of Bologna (1921-1934), where in 1931 he founded a school for advanced studies in radio and telecommunications. He served as president of the Italian Physical Society (Societa Italiana di Fisica) for many years and was a member of the Accademia Nazionale dei Lincei. In 1927 he organised the Como conference marking the centenary of Alessandro Volta's death - the meeting at which the new quantum mechanics was presented to the international physics community.

His later work at Bologna was influenced by correspondence with his nephew Ettore Majorana (1906-1938), a great physicist in his own right, who disappeared in 1938. Quirino Majorana died at Rieti on 31 July 1957.

Scientific contributions

Gravitational absorption and shielding

Between 1918 and 1922 Majorana performed a long series of very sensitive gravity shielding experiments, which have never been reproduced. Working with a precision balance and a suspended lead test sphere, he surrounded or placed beneath the sphere a large screening mass of mercury or lead and looked for a change in the sphere's apparent weight. Majorana's experiments determined that mercury or lead beneath a suspended lead sphere acted as a screen and slightly decreased the earth's gravitational pull on it.

To describe the effect quantitatively Majorana proposed adding an extinction (absorption) coefficient h to Newton's law, so that gravitational attraction is attenuated exponentially along the path in proportion to the amount of matter traversed. In this picture gravity is not a purely geometric or purely instantaneous attraction but something that can be partially absorbed by intervening matter - which is precisely the behaviour expected of a pushing or kinetic theory of gravity such as that of Georges-Louis Le Sage, in which bodies are driven together by a flux of corpuscles that each body partly screens. Majorana himself set out the theory alongside the measurements in his 1920 Philosophical Magazine paper "On Gravitation: Theoretical and Experimental Researches", and returned to the question in notes to the Paris Academy (1921) and in the Journal de Physique et le Radium (1930).

No attempts have been made to reproduce his results using the same experimental techniques. Other researchers have concluded from other data - including laboratory tests, solar-eclipse gravimetry and lunar laser ranging - that if gravitational absorption does exist it must be many orders of magnitude smaller than Majorana's experiments suggest. The historical episode has been examined in detail by Giorgio Dragoni, who treats it as a case study in the tradition of "misinterpreted experiments", while Coisson, Mambriani and Podini have proposed a different reading of the same data, interpreting the observed weight variations in terms of the sharing of potential energy between interacting masses rather than absorption of gravity, and have suggested a modern test of his results.

The speed of light and the second postulate

Critical of Albert Einstein's relativity theory, Majorana designed and carried out experiments intended to test - and, he hoped, to disprove - Einstein's postulate on the constancy of the speed of light. Using an unequal-arm Michelson-type interferometer of very high sensitivity to wavelength change, he examined light reflected from a rapidly moving mirror (1918) and light emitted by a moving source (1919). In both configurations he found no dependence of the light's velocity on the motion of the mirror or source, and reported that his results were consistent with the second postulate rather than with an emission (ballistic) theory of light. These two experiments remain standard references in the literature on emission theory. Majorana also confirmed Isaac Newton's law of universal gravitation to high precision.

Other work

Majorana worked on the photoelectric properties of selenium and on early schemes for television transmission, on radiotelephony (including a four-electrode ionic valve in 1912), and on the thermal and optical properties of thin metal films. In magneto-optics he discovered the magnetic birefringence of colloidal solutions - since known as the Majorana effect - and reported the magneto-optic Kerr effect in non-ferrous metals such as silver, gold and aluminium, an effect some three orders of magnitude weaker than the usual one.

Discussed in CNPS talks

  • "Dark Matter Versus G" by Bob de Hilster (27 June 2018) - discusses how dark matter was invented to explain the velocities of stars at the edge of our galaxy and to keep Newton's gravity equation valid, reviews Georges-Louis Le Sage's suggestion that gravity has a shielding property, and covers Majorana's experiments on gravitational shielding.

Works

  • "On the Second Postulate of the Theory of Relativity: an Experimental Demonstration," Physical Review, S2, V11, pp. 411-420 (1918).
  • "Experimental Demonstration of the Constancy of the Velocity of Light Emitted by a Moving Source," Philosophical Magazine, S6, V37, pp. 145-150 (1919).
  • "On Gravitation: Theoretical and Experimental Researches," Philosophical Magazine, S6, V39, pp. 488-504 (1920).
  • "Sur l'absorption de la gravitation," Comptes Rendus de l'Academie des Sciences, V173, pp. 478-479 (1921).
  • "Su di un fenomeno fotoelettrico constabile con gli audion," Rendiconti Accademia dei Lincei, V7, pp. 801-806 (1928).
  • "Quelques recherches sur l'absorption de la gravitation par la matiere," Journal de Physique et le Radium, I, pp. 314-324 (1930).
  • "Azione della luce su sottili lamine metalliche," La Ricerca Scientifica, National Research Council, V1 (1935).
  • "Agli albori dell'elettricita. Galvani e la scienza moderna," Sapere, pp. 261-265 (Oct 1937).
  • "Ulteriori ricerche sull'azione della luce su sottili lamine metalliche," Il Nuovo Cimento, V15, pp. 573-593 (1938).

Articles about Majorana

  • Coisson, R.; Mambriani, G.; Podini, P., "A new interpretation of Quirino Majorana's experiments on gravitation and a proposal for testing his results," Il Nuovo Cimento B, V117, N4, p. 469 (2002).
  • Dragoni, Giorgio; Maltese, Giulio; Atti, Luisa, "Quirino Majorana's Experiments on the Speed of Light and Gravitational Absorption," Physics in Perspective, Volume 9, Issue 3, pp. 281-304 (2007).
  • Dragoni, Giorgio, "Quirino Majorana's Research on Gravitational Absorption: A Case Study in the Misinterpreted Experiment Tradition," Centaurus, Volume 39, Issue 2, pp. 141-187 (1997).

External links

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