Joseph Larmor

Sir Joseph Larmor FRS^[2] (11 July 1857 – 19 May 1942) was a Northern Irish^[3] physicist and mathematician who made innovations in the understanding of electricity, dynamics, thermodynamics, and the electron theory of matter. His most influential work was Aether and Matter, a theoretical physics book published in 1900.

Biography

He grew up in Belfast, the son of a shopkeeper. He was a student at Royal Belfast Academical Institution, Queen's University Belfast, and St John's College, Cambridge where he was Senior Wrangler.^[4] After teaching physics for a few years at Queen's College, Galway, he accepted a lectureship in mathematics at Cambridge in 1885. In 1903 he was appointed Lucasian Professor of Mathematics at Cambridge, a post he retained until his retirement in 1932. He never married.

Larmor proposed that the aether could be represented as a homogeneous fluid medium which was perfectly incompressible and elastic. Larmor believed the aether was separate from matter. He united Lord Kelvin's model of spinning gyrostats (see Vortex theory of the atom) with this theory.

Parallel to the development of Lorentz ether theory, Larmor published the Lorentz transformations in the Philosophical Transactions of the Royal Society in 1897 some two years before Hendrik Lorentz (1899, 1904) and eight years before Albert Einstein (1905). Larmor however did not possess the correct velocity transformations, which include the addition of velocities law, which were later discovered by Henri Poincaré. Larmor predicted the phenomenon of time dilation, at least for orbiting electrons, and verified that the FitzGerald–Lorentz contraction (length contraction) should occur for bodies whose atoms were held together by electromagnetic forces. In his book Aether and Matter (1900), he again presented the Lorentz transformations, time dilation and length contraction (treating these as dynamic rather than kinematic effects). Larmor opposed Albert Einstein's theory of relativity, though he supported it for a short time. Larmor rejected both the curvature of space and the special theory of relativity, to the extent that he claimed that an absolute time was essential to astronomy (Larmor 1924, 1927).

Larmor held that matter consisted of particles moving in the aether. Larmor believed the source of electric charge was a "particle" (which as early as 1894 he was referring to as the electron). Thus, in what was apparently the first specific prediction of time dilation, he wrote "... individual electrons describe corresponding parts of their orbits in times shorter for the [rest] system in the ratio (1 – v²/c²)^1/2" (Larmor 1897). Larmor held that the flow of charged particles constitutes the current of conduction (but was not part of the atom). Larmor calculated the rate of energy radiation from an accelerating electron. Larmor explained the splitting of the spectral lines in a magnetic field by the oscillation of electrons.

In 1919, Larmor proposed sunspots are self-regenerative dynamo action on the Sun's surface.

Motivated by his strong opposition to Home Rule for Ireland, in February 1911 Larmor ran for and was elected as Member of Parliament for Cambridge University (UK Parliament constituency) with the Liberal Unionist party. He remained in parliament until the 1922 general election, at which point the Irish question had been settled. Upon his retirement from Cambridge in 1932 Larmor moved back to County Down in Northern Ireland.

He received the honorary Doctor of Laws (LL.D) from the University of Glasgow in June 1901.^[5] He was awarded the Poncelet Prize for 1918 by the French Academy of Sciences.^[6]

Publications

• 1887, "On the direct applications of first principles in the theory of partial differential equations", Proceedings of the Royal Society.
• 1891, "On the theory of electrodynamics", Proceedings of the Royal Society.
• 1892, "On the theory of electrodynamics, as affected by the nature of the mechanical stresses in excited dielectrics", Proceedings of the Royal Society.
• 1893–97, "Dynamical Theory of the Electric and Luminiferous Medium", Proceedings of the Royal Society; Philosophical Transactions of the Royal Society. Series of 3 papers containing Larmor's physical theory of the universe.
• 1894, "Least action as the fundamental formulation in dynamics and physics", Proceedings of the London Mathematical Society.
• 1896, "The influence of a magnetic field on radiation frequency", Proceedings of the Royal Society.
• 1896, "On the absolute minimum of optical deviation by a prism", Proceedings of the Cambridge Philosophical Society.
• Larmor, J. (1897). "A Dynamical Theory of the Electric and Luminiferous Medium. Part III. Relations with Material Media". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 190: 205. Bibcode:1897RSPTA.190..205L. doi:10.1098/rsta.1897.0020. 
• 1898, "Note on the complete scheme of electrodynamic equations of a moving material medium, and electrostriction", Proceedings of the Royal Society.
• 1898, "On the origin of magneto-optic rotation", Proceedings of the Cambridge Philosophical Society.
• Larmor, J. (1900), Aether and Matter, Cambridge University Press ; Containing the Lorentz transformations on p. 174.
• 1903, "On the electrodynamic and thermal relations of energy of magnetisation", Proceedings of the Royal Society.
• 1907, "Aether" in Encyclopædia Britannica, 11th ed. London.
• 1908, "William Thomson, Baron Kelvin of Largs. 1824–1907" (Obituary). Proceedings of the Royal Society.
• 1924, "On Editing Newton", Nature.
• 1927, "Newtonian time essential to astronomy", Nature.
• 1929, Mathematical and Physical Papers. Cambridge Univ. Press.^[7]
• 1937, (as editor), Origins of Clerk Maxwell's Electric Ideas as Described in Familiar Letters to William Thomson. Cambridge University Press.^[8]

Larmor edited the collected works of George Stokes, James Thomson and William Thomson.

See also

Wikisource has original works written by or about: Joseph Larmor

• History of Lorentz transformations
• Larmor precession
• Larmor (crater)

References

Further reading

• Bruce J. Hunt (1991) The Maxwellians, Cornell University Press
• Macrossan, M. N. "A note on relativity before Einstein", British Journal for the Philosophy of Science, 37 (1986): 232–234.
• Warwick, Andrew, "On the Role of the FitzGerald–Lorentz Contraction Hypothesis in the Development of Joseph Larmor's Electronic Theory of Matter". Archive for History of Exact Sciences 43 (1991): 29–91.
• Darrigol, O. (1994), "The Electron Theories of Larmor and Lorentz: A Comparative Study", Historical Studies in the Physical and Biological Sciences, 24 (2): 265–336, doi:10.2307/27757725, JSTOR 27757725 
• "A very short biography of Joseph Larmor"
• "Ether and field theories in the late 19th century" At VictorianWeb: History of science in the Victorian era
• "Papers of Sir Joseph Larmor". Janus, University of Cambridge.