Sir Joseph Larmor (/ˈlɑːrmɒr/; 11 July 1857 – 19 May 1942) was an Irish[2] mathematician and physicist who made breakthroughs 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.

He was born in Magheragall in County Antrim, the son of Hugh Larmor, a Belfast shopkeeper and his wife, Anna Wright.

[5] After teaching physics for a few years at Queen's College, Galway, he accepted a lectureship in mathematics at Cambridge in 1885.

[7] In 1903 he was appointed Lucasian Professor of Mathematics at Cambridge, a post he retained until his retirement in 1932.

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 Conservative 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 an honorary Doctor of Laws (LLD) from the University of Glasgow in June 1901.

[9][10] He received an honorary Doctor in Science from Trinity College Dublin in 1903.

Larmor proposed that the aether could be represented as a homogeneous fluid medium which was perfectly incompressible and elastic.

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).

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.

He said the destruction of this type of atom making up matter "is an occurrence of infinitely small probability".

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

Quotes from one of Larmor's voluminous work include: Parallel to the development of Lorentz ether theory, Larmor published an approximation to the Lorentz transformations in the Philosophical Transactions of the Royal Society in 1897,[22] namely

Larmor predicted the phenomenon of time dilation, at least for orbiting electrons, by writing (Larmor 1897): "... individual electrons describe corresponding parts of their orbits in times shorter for the [rest] system in the ratio (1 – v2/c2)1/2".

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 was opposed to the spacetime interpretation of the Lorentz transformation in special relativity because he continued to believe in an absolute aether.

He was also critical of the curvature of space of general relativity, to the extent that he claimed that an absolute time was essential to astronomy (Larmor 1924, 1927).