Sir Joseph Larmor (11 July 1857 – 19 May 1942) was an Irish and British
physicist
A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe.
Physicists generally are interested in the root or ultimate cau ...
and mathematician who made breakthroughs in the understanding of electricity,
dynamics,
thermodynamics
Thermodynamics is a branch of physics that deals with heat, work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed by the four laws of th ...
, and the electron theory of matter. His most influential work was ''Aether and Matter'', a theoretical physics book published in 1900.
Biography
He was born in
Magheragall in
County Antrim
County Antrim (named after the town of Antrim, ) is one of six counties of Northern Ireland and one of the thirty-two counties of Ireland. Adjoined to the north-east shore of Lough Neagh, the county covers an area of and has a population o ...
the son of Hugh Larmor, a
Belfast
Belfast ( , ; from ga, Béal Feirste , meaning 'mouth of the sand-bank ford') is the capital and largest city of Northern Ireland, standing on the banks of the River Lagan on the east coast. It is the 12th-largest city in the United Kingdom ...
shopkeeper and his wife, Anna Wright. The family moved to Belfast circa 1860, and he was educated at the
Royal Belfast Academical Institution
The Royal Belfast Academical Institution is an independent grammar school in Belfast, Northern Ireland. With the support of Belfast's leading reformers and democrats, it opened its doors in 1814. Until 1849, when it was superseded by what today is ...
, and then studied mathematics and experimental science at
Queen's College, Belfast
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(BA 1874, MA 1875), where one of his teachers was
John Purser. He subsequently studied at
St John's College, Cambridge, where in 1880 he was
Senior Wrangler
The Senior Frog Wrangler is the top mathematics undergraduate at the University of Cambridge in England, a position which has been described as "the greatest intellectual achievement attainable in Britain."
Specifically, it is the person who a ...
(
J. J. Thomson
Sir Joseph John Thomson (18 December 1856 – 30 August 1940) was a British physicist and Nobel Laureate in Physics, credited with the discovery of the electron, the first subatomic particle to be discovered.
In 1897, Thomson showed that ...
was second wrangler that year) and Smith's Prizeman, getting his MA in 1883. After teaching physics for a few years at
Queen's College, Galway
The University of Galway ( ga, Ollscoil na Gaillimhe) is a public research university located in the city of Galway, Ireland. A tertiary education and research institution, the university was awarded the full five QS stars for excellence in 201 ...
, he accepted a lectureship in mathematics at Cambridge in 1885. In 1892 he was elected a Fellow of the
Royal Society of London
The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national academy of sciences. The society fulfils a number of roles: promoting science and its benefits, re ...
, and he served as one of the Secretaries of the society. He was made an Honorary Fellow of the
Royal Society of Edinburgh in 1910.
In 1903 he was appointed
Lucasian Professor of Mathematics at Cambridge, a post he retained until his retirement in 1932. He never married. He was knighted by King
Edward VII
Edward VII (Albert Edward; 9 November 1841 – 6 May 1910) was King of the United Kingdom of Great Britain and Ireland and Emperor of India, from 22 January 1901 until his death in 1910.
The second child and eldest son of Queen Victoria and ...
in 1909.
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 the honorary
Doctor of Laws (LLD) from the
University of Glasgow
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, motto = la, Via, Veritas, Vita
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in June 1901.
He was awarded the
Poncelet Prize
The Poncelet Prize (french: Prix Poncelet) is awarded by the French Academy of Sciences. The prize was established in 1868 by the widow of General Jean-Victor Poncelet for the advancement of the sciences. It was in the amount of 2,000 francs (as of ...
for 1918 by the
French Academy of Sciences. Larmor was a Plenary Speaker in 1920 at the
ICM at Strasbourg and an Invited Speaker at the ICM in 1924 in Toronto and at the ICM in 1928 in Bologna.
He died in
Holywood, County Down
Holywood ( ) ( Irish: ''Ard Mhic Nasca'', meaning 'Height of the Son of Nasca'. Latin: ''Sanctus Boscus'', meaning 'Holy Wood') is a town in the metropolitan area of Belfast in County Down, Northern Ireland. It is a civil parish and townland of ...
on 19 May 1942.
Work
Larmor proposed that the
aether could be represented as a
homogeneous fluid medium which was perfectly
incompressible
In fluid mechanics or more generally continuum mechanics, incompressible flow ( isochoric flow) refers to a flow in which the material density is constant within a fluid parcel—an infinitesimal volume that moves with the flow velocity. An eq ...
and
elastic. Larmor believed the aether was separate from matter. He united
Lord Kelvin
William Thomson, 1st Baron Kelvin, (26 June 182417 December 1907) was a British mathematician, mathematical physicist and engineer born in Belfast. Professor of Natural Philosophy at the University of Glasgow for 53 years, he did important ...
's model of spinning
gyrostat
A gyroscope (from Ancient Greek γῦρος ''gŷros'', "round" and σκοπέω ''skopéō'', "to look") is a device used for measuring or maintaining orientation and angular velocity. It is a spinning wheel or disc in which the axis of rota ...
s (see
Vortex theory of the atom) with this
theory
A theory is a rational type of abstract thinking about a phenomenon, or the results of such thinking. The process of contemplative and rational thinking is often associated with such processes as observational study or research. Theories may be ...
. Larmor held that
matter
In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ultimately composed of atoms, which are made up of interacting subatomic part ...
consisted of
particles
In the physical sciences, a particle (or corpuscule in older texts) is a small localized object which can be described by several physical or chemical properties, such as volume, density, or mass.
They vary greatly in size or quantity, from s ...
moving in the aether. Larmor believed the source of
electric charge
Electric charge is the physical property of matter that causes charged matter to experience a force when placed in an electromagnetic field. Electric charge can be ''positive'' or ''negative'' (commonly carried by protons and electrons respe ...
was a "''particle''" (which as early as 1894 he was referring to as the
electron
The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family,
and are generally thought to be elementary particles because they have no ...
). Larmor held that the flow of charged particles constitutes the
current
Currents, Current or The Current may refer to:
Science and technology
* Current (fluid), the flow of a liquid or a gas
** Air current, a flow of air
** Ocean current, a current in the ocean
*** Rip current, a kind of water current
** Current (stre ...
of
conduction (but was not part of the
atom
Every atom is composed of a nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons. Only the most common variety of hydrogen has no neutrons.
Every solid, liquid, gas, ...
). Larmor calculated the rate of energy
radiation from an
accelerating
In mechanics, acceleration is the rate of change of the velocity of an object with respect to time. Accelerations are vector quantities (in that they have magnitude and direction). The orientation of an object's acceleration is given by th ...
electron. Larmor explained the splitting of the
spectral line
A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to iden ...
s in a
magnetic field by the
oscillation
Oscillation is the repetitive or periodic variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states. Familiar examples of oscillation include a swinging pendulum ...
of electrons.
Larmor also created the first solar system model of the atom in 1897. He also postulated the proton, calling it a “positive electron.” 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
"Dynamo Electric Machine" (end view, partly section, )
A dynamo is an electrical generator that creates direct current using a commutator. Dynamos were the first electrical generators capable of delivering power for industry, and the foundati ...
action on the
Sun
The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
's surface.
Quotes from one of Larmor's voluminous work include:
* “while atoms of matter are in whole or in part aggregations of electrons in stable orbital motion. In particular, this scheme provides a consistent foundation for the electrodynamic laws, and agrees with the actual relations between radiation and moving matter.”
* “A formula for optical dispersion was obtained in § 11 of the second part of this memoir, on the simple hypothesis that the electric polarization of the molecules vibrated as a whole in unison with the electric field of the radiation.”
* “…that of the transmission of radiation across a medium permeated by molecules, each consisting of a system of electrons in steady orbital motion, and each capable of free oscillations about the steady state of motion with definite free periods analogous to those of the planetary inequalities of the Solar System;”
* “‘A’ will be a positive electron in the medium, and ‘B’ will be the complementary negative one...We shall thus have created two permanent conjugate electrons A and B ; each of them can be moved about through the medium, but they will both persist until they are destroyed by an extraneous process the reverse of that by which they are formed.”
Discovery of Lorentz transformation
Parallel to the development of
Lorentz ether theory
What is now often called Lorentz ether theory (LET) has its roots in Hendrik Lorentz's "theory of electrons", which was the final point in the development of the classical aether theories at the end of the 19th and at the beginning of the 20th cen ...
, Larmor published an approximation to the
Lorentz transformation
In physics, the Lorentz transformations are a six-parameter family of Linear transformation, linear coordinate transformation, transformations from a Frame of Reference, coordinate frame in spacetime to another frame that moves at a constant velo ...
s in the ''
Philosophical Transactions of the Royal Society
''Philosophical Transactions of the Royal Society'' is a scientific journal published by the Royal Society. In its earliest days, it was a private venture of the Royal Society's secretary. It was established in 1665, making it the first journa ...
'' in 1897,
namely
for the spatial part and
for the temporal part, where
and the local time
. He obtained the full Lorentz transformation in 1900 by inserting
into his expression of local time such that
, and as before
and
. This was done around the same time as
Hendrik Lorentz (1899, 1904) and five years before
Albert Einstein
Albert Einstein ( ; ; 14 March 1879 – 18 April 1955) was a German-born theoretical physicist, widely acknowledged to be one of the greatest and most influential physicists of all time. Einstein is best known for developing the theory ...
(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
A phenomenon ( : phenomena) is an observable event. The term came into its modern philosophical usage through Immanuel Kant, who contrasted it with the noumenon, which ''cannot'' be directly observed. Kant was heavily influenced by Gottfried ...
of
time dilation
In physics and relativity, time dilation is the difference in the elapsed time as measured by two clocks. It is either due to a relative velocity between them ( special relativistic "kinetic" time dilation) or to a difference in gravitational ...
, at least for orbiting electrons, by writing (Larmor 1897): "... individual electrons describe corresponding parts of their orbits in times shorter for the
estsystem in the ratio (1 – ''v''
2/''c''
2)
1/2". He also verified that the
FitzGerald–Lorentz contraction
Length contraction is the phenomenon that a moving object's length is measured to be shorter than its proper length, which is the length as measured in the object's own rest frame. It is also known as Lorentz contraction or Lorentz–FitzGerald ...
(
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 was opposed to the
spacetime
In physics, spacetime is a mathematical model that combines the three dimensions of space and one dimension of time into a single four-dimensional manifold. Spacetime diagrams can be used to visualize relativistic effects, such as why differ ...
interpretation of the Lorentz transformation in
special relativity
In physics, the special theory of relativity, or special relativity for short, is a scientific theory regarding the relationship between space and time. In Albert Einstein's original treatment, the theory is based on two postulates:
# The laws ...
because he continued to believe in an absolute aether. He was also critical of the
curvature of space of
general relativity
General relativity, also known as the general theory of relativity and Einstein's theory of gravity, is the geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of gravitation in modern physics ...
, to the extent that he claimed that an absolute time was essential to astronomy (Larmor 1924, 1927).
Publications
* 1884, "Least action as the fundamental formulation in dynamics and physics", ''Proceedings of the London Mathematical Society''.
* 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.
* 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''.
*
* 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''.
* ; Containing the
Lorentz transformation
In physics, the Lorentz transformations are a six-parameter family of Linear transformation, linear coordinate transformation, transformations from a Frame of Reference, coordinate frame in spacetime to another frame that moves at a constant velo ...
s on p. 174.
* 1903, "On the electrodynamic and thermal relations of energy of magnetisation", ''Proceedings of the Royal Society''.
* 1904, "On the mathematical expression of the principle of Huygens" (read 8 Jan. 1903), ''Proceedings of the London Mathematical Society'', Ser.2, vol.1 (1904), pp.1–13.
* 1907, "Aether" in ''
Encyclopædia Britannica
The (Latin for "British Encyclopædia") is a general knowledge English-language encyclopaedia. It is published by Encyclopædia Britannica, Inc.; the company has existed since the 18th century, although it has changed ownership various t ...
'', 11th ed. London.
* 1908, "William Thomson, Baron Kelvin of Largs. 1824–1907" (Obituary). ''Proceedings of the Royal Society''.
* 1921, "On the mathematical expression of the principle of Huygens — " (read 13 Nov. 1919), ''Proceedings of the London Mathematical Society'', Ser.2, vol.19 (1921), pp.169–80.
* 1924, "On Editing Newton", ''Nature''.
* 1927, "Newtonian time essential to astronomy", ''Nature''.
* 1929, ''Mathematical and Physical Papers''. Cambridge Univ. Press.
* 1937, (as editor), ''Origins of Clerk Maxwell's Electric Ideas as Described in Familiar Letters to William Thomson''. Cambridge University Press.
Larmor edited the collected works of
George Stokes,
James Thomson and
William Thomson.
File:Larmor-2.jpg, Title page to a 1900 copy of "Aether and Matter"
File:Larmor-3.jpg, First page of the preface to "Aether and Matter"
File:Larmor-4.jpg, First page of "Aether and Matter"
See also
*
*
History of Lorentz transformations
*
Dynamo theory
In physics, the dynamo theory proposes a mechanism by which a celestial body such as Earth or a star generates a magnetic field. The dynamo theory describes the process through which a rotating, convecting, and electrically conducting fluid can ...
*
Larmor precession
In physics, Larmor precession (named after Joseph Larmor) is the precession of the magnetic moment of an object about an external magnetic field. The phenomenon is conceptually similar to the precession of a tilted classical gyroscope in an extern ...
*
Larmor (crater)
Larmor is a crater on the Moon's far side. It is located to the east-southeast of Shayn and due north of Dante. It is named in honor of the physicist Joseph Larmor.
The rim of Larmor is broken across by the satellite crater Larmor Z. The rem ...
References
Further reading
* Bruce J. Hunt (1991), ''
The Maxwellians
''The Maxwellians'' is a book by Bruce J. Hunt, published in 1991 by Cornell University Press; a paperback edition appeared in 1994, and the book was reissued in 2005. It chronicles the development of electromagnetic theory in the years after the ...
'', 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.
*
* "
A very short biography of Joseph Larmor'"
* "
'" At ''VictorianWeb:'' History of science in the Victorian era
* "
Papers of Sir Joseph Larmor'". Janus, University of Cambridge.
*
External links
*
{{DEFAULTSORT:Larmor, Joseph
1857 births
1942 deaths
Alumni of St John's College, Cambridge
19th-century British mathematicians
20th-century British mathematicians
Conservative Party (UK) MPs for English constituencies
Fellows of the Royal Society
Foreign associates of the National Academy of Sciences
Lucasian Professors of Mathematics
Members of the Parliament of the United Kingdom for the University of Cambridge
People educated at the Royal Belfast Academical Institution
Scientists from Belfast
Physicists from Northern Ireland
British relativity theorists
UK MPs 1910–1918
UK MPs 1918–1922
Recipients of the Copley Medal
Relativity critics
Royal Medal winners
Senior Wranglers
De Morgan Medallists
Mathematicians from Northern Ireland