Joseph Larmor
Encyclopedia
Sir Joseph Larmor a 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.
, 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. 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
(e.g., vortex
es) with this theory
.
Parallel to the development of Lorentz ether theory
, Larmor published the Lorentz transformation
s 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 line
s in a magnetic field
by the oscillation
of electrons.
In 1919, Larmor proposed sunspot
s 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
.
Larmor edited the collected works of George Stokes
, James Thomson
and William Thomson
.
Physicist
A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...
and mathematician
Mathematician
A mathematician is a person whose primary area of study is the field of mathematics. Mathematicians are concerned with quantity, structure, space, and change....
who made innovations in the understanding of electricity
Electricity
Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...
, dynamics
Dynamics (mechanics)
In the field of physics, the study of the causes of motion and changes in motion is dynamics. In other words the study of forces and why objects are in motion. Dynamics includes the study of the effect of torques on motion...
, thermodynamics
Thermodynamics
Thermodynamics is a physical science that studies the effects on material bodies, and on radiation in regions of space, of transfer of heat and of work done on or by the bodies or radiation...
, 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 BelfastBelfast
Belfast is the capital of and largest city in Northern Ireland. By population, it is the 14th biggest city in the United Kingdom and second biggest on the island of Ireland . It is the seat of the devolved government and legislative Northern Ireland Assembly...
, the son of a shopkeeper. He was a student at Royal Belfast Academical Institution
Royal Belfast Academical Institution
The Royal Belfast Academical Institution, is a Grammar School in Belfast, Northern Ireland. Locally referred to as Inst, the school educates boys from ages 11–18...
, Queen's University Belfast, and St John's College, Cambridge
St John's College, Cambridge
St John's College is a constituent college of the University of Cambridge. The college's alumni include nine Nobel Prize winners, six Prime Ministers, three archbishops, at least two princes, and three Saints....
where he was Senior Wrangler. 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
Luminiferous aether
In the late 19th century, luminiferous aether or ether, meaning light-bearing aether, was the term used to describe a medium for the propagation of light....
could be represented as a homogeneous
Homogeneous (chemistry)
A substance that is uniform in composition is a definition of homogeneous. This is in contrast to a substance that is heterogeneous.The definition of homogeneous strongly depends on the context used. In Chemistry, a homogeneous suspension of material means that when dividing the volume in half, the...
fluid
Fluid
In physics, a fluid is a substance that continually deforms under an applied shear stress. Fluids are a subset of the phases of matter and include liquids, gases, plasmas and, to some extent, plastic solids....
medium
Material
Material is anything made of matter, constituted of one or more substances. Wood, cement, hydrogen, air and water are all examples of materials. Sometimes the term "material" is used more narrowly to refer to substances or components with certain physical properties that are used as inputs to...
which was perfectly incompressible and elastic
Elasticity (physics)
In physics, elasticity is the physical property of a material that returns to its original shape after the stress that made it deform or distort is removed. The relative amount of deformation is called the strain....
. Larmor believed the aether was separate from matter. He united Lord Kelvin
William Thomson, 1st Baron Kelvin
William Thomson, 1st Baron Kelvin OM, GCVO, PC, PRS, PRSE, was a mathematical physicist and engineer. At the University of Glasgow he did important work in the mathematical analysis of electricity and formulation of the first and second laws of thermodynamics, and did much to unify the emerging...
's model of spinning gyrostats
Gyroscope
A gyroscope is a device for measuring or maintaining orientation, based on the principles of angular momentum. In essence, a mechanical gyroscope is a spinning wheel or disk whose axle is free to take any orientation...
(e.g., vortex
Vortex
A vortex is a spinning, often turbulent,flow of fluid. Any spiral motion with closed streamlines is vortex flow. The motion of the fluid swirling rapidly around a center is called a vortex...
es) with this theory
Theory
The English word theory was derived from a technical term in Ancient Greek philosophy. The word theoria, , meant "a looking at, viewing, beholding", and referring to contemplation or speculation, as opposed to action...
.
Parallel to the development of Lorentz ether theory
Lorentz ether theory
What is now often called Lorentz Ether theory 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 century....
, Larmor published the Lorentz transformation
Lorentz transformation
In physics, the Lorentz transformation or Lorentz-Fitzgerald transformation describes how, according to the theory of special relativity, two observers' varying measurements of space and time can be converted into each other's frames of reference. It is named after the Dutch physicist Hendrik...
s in the Philosophical Transactions of the Royal Society
Philosophical Transactions of the Royal Society
The Philosophical Transactions of the Royal Society is a scientific journal published by the Royal Society of London. It was established in 1665, making it the first journal in the world exclusively devoted to science, and it has remained in continuous publication ever since, making it the world's...
in 1897 some two years before Hendrik Lorentz
Hendrik Lorentz
Hendrik Antoon Lorentz was a Dutch physicist who shared the 1902 Nobel Prize in Physics with Pieter Zeeman for the discovery and theoretical explanation of the Zeeman effect...
(1899, 1904) and eight years before Albert Einstein
Albert Einstein
Albert Einstein was a German-born theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics and one of the most prolific intellects in human history...
(1905). Larmor however did not possess the correct velocity transformations, which include the addition of velocities law, which were later discovered by Henri Poincaré
Henri Poincaré
Jules Henri Poincaré was a French mathematician, theoretical physicist, engineer, and a philosopher of science...
. Larmor predicted the phenomenon
Phenomenon
A phenomenon , plural phenomena, is any observable occurrence. Phenomena are often, but not always, understood as 'appearances' or 'experiences'...
of time dilation
Time dilation
In the theory of relativity, time dilation is an observed difference of elapsed time between two events as measured by observers either moving relative to each other or differently situated from gravitational masses. An accurate clock at rest with respect to one observer may be measured to tick at...
, at least for orbiting electrons, and verified that the FitzGerald-Lorentz contraction (length contraction
Length contraction
In physics, length contraction – according to Hendrik Lorentz – is the physical phenomenon of a decrease in length detected by an observer of objects that travel at any non-zero velocity relative to that observer...
) 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
Albert Einstein
Albert Einstein was a German-born theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics and one of the most prolific intellects in human history...
's theory of relativity
Theory of relativity
The theory of relativity, or simply relativity, encompasses two theories of Albert Einstein: special relativity and general relativity. However, the word relativity is sometimes used in reference to Galilean invariance....
(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
Matter
Matter is a general term for the substance of which all physical objects consist. Typically, matter includes atoms and other particles which have mass. A common way of defining matter is as anything that has mass and occupies volume...
consisted of particles
Elementary particle
In particle physics, an elementary particle or fundamental particle is a particle not known to have substructure; that is, it is not known to be made up of smaller particles. If an elementary particle truly has no substructure, then it is one of the basic building blocks of the universe from which...
moving in the aether. Larmor believed the source of electric charge
Electric charge
Electric charge is a physical property of matter that causes it to experience a force when near other electrically charged matter. Electric charge comes in two types, called positive and negative. Two positively charged substances, or objects, experience a mutual repulsive force, as do two...
was a "particle" (which as early as 1894 he was referring to as the electron
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
). Thus, in what was apparently the first specific prediction of time dilation
Time dilation
In the theory of relativity, time dilation is an observed difference of elapsed time between two events as measured by observers either moving relative to each other or differently situated from gravitational masses. An accurate clock at rest with respect to one observer may be measured to tick at...
, 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
Atom
The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...
). Larmor calculated the rate of energy
Energy
In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...
radiation
Radiation
In physics, radiation is a process in which energetic particles or energetic waves travel through a medium or space. There are two distinct types of radiation; ionizing and non-ionizing...
from an accelerating
Acceleration
In physics, acceleration is the rate of change of velocity with time. In one dimension, acceleration is the rate at which something speeds up or slows down. However, since velocity is a vector, acceleration describes the rate of change of both the magnitude and the direction of velocity. ...
electron. Larmor explained the splitting of the spectral line
Spectral line
A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from a deficiency or excess of photons in a narrow frequency range, compared with the nearby frequencies.- Types of line spectra :...
s in a magnetic field
Magnetic field
A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...
by the oscillation
Oscillation
Oscillation is the repetitive variation, typically in time, of some measure about a central value or between two or more different states. Familiar examples include a swinging pendulum and AC power. The term vibration is sometimes used more narrowly to mean a mechanical oscillation but sometimes...
of electrons.
In 1919, Larmor proposed sunspot
Sunspot
Sunspots are temporary phenomena on the photosphere of the Sun that appear visibly as dark spots compared to surrounding regions. They are caused by intense magnetic activity, which inhibits convection by an effect comparable to the eddy current brake, forming areas of reduced surface temperature....
s are self-regenerative
Regenerative circuit
The regenerative circuit or "autodyne" allows an electronic signal to be amplified many times by the same vacuum tube or other active component such as a field effect transistor. It consists of an amplifying vacuum tube or transistor with its output connected to its input through a feedback...
dynamo
Dynamo
- Engineering :* Dynamo, a magnetic device originally used as an electric generator* Dynamo theory, a theory relating to magnetic fields of celestial bodies* Solar dynamo, the physical process that generates the Sun's magnetic field- Software :...
action on the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
's surface.
Motivated by his strong opposition to Home Rule for Ireland
Devolution
Devolution is the statutory granting of powers from the central government of a sovereign state to government at a subnational level, such as a regional, local, or state level. Devolution can be mainly financial, e.g. giving areas a budget which was formerly administered by central government...
, in February 1911 Larmor ran for and was elected as Member of Parliament for Cambridge University (UK Parliament constituency)
Cambridge University (UK Parliament constituency)
Cambridge University was a university constituency electing two members to the British House of Commons, from 1603 to 1950.-Boundaries, Electorate and Election Systems:...
with the Liberal Unionist party. He remained in parliament until the 1922 general election
United Kingdom general election, 1922
The United Kingdom general election of 1922 was held on 15 November 1922. It was the first election held after most of the Irish counties left the United Kingdom to form the Irish Free State, and was won by Andrew Bonar Law's Conservatives, who gained an overall majority over Labour, led by John...
, at which point the Irish question had been settled. Upon his retirement from Cambridge in 1932 Larmor moved back to County Down
County Down
-Cities:*Belfast *Newry -Large towns:*Dundonald*Newtownards*Bangor-Medium towns:...
in Northern Ireland
Northern Ireland
Northern Ireland is one of the four countries of the United Kingdom. Situated in the north-east of the island of Ireland, it shares a border with the Republic of Ireland to the south and west...
.
Writings
- 1887, "On the direct applications of first principles in the theory of partial differential equations," Proceedings of the Royal SocietyProceedings of the Royal SocietyProceedings of the Royal Society is the parent title of two scientific journals published by the Royal Society, whereas its initial journal, Philosophical Transactions, is now devoted to special thematic issues...
. - 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.; Containing the Lorentz transformationLorentz transformationIn physics, the Lorentz transformation or Lorentz-Fitzgerald transformation describes how, according to the theory of special relativity, two observers' varying measurements of space and time can be converted into each other's frames of reference. It is named after the Dutch physicist Hendrik...
s on p. 229. - 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 transformationLorentz transformationIn physics, the Lorentz transformation or Lorentz-Fitzgerald transformation describes how, according to the theory of special relativity, two observers' varying measurements of space and time can be converted into each other's frames of reference. It is named after the Dutch physicist Hendrik...
s on p. 174. - 1903, "On the electrodynamic and thermal relations of energy of magnetisation," Proceedings of the Royal Society.
- 1907, "Aether" in Encyclopædia BritannicaEncyclopædia BritannicaThe Encyclopædia Britannica , published by Encyclopædia Britannica, Inc., is a general knowledge English-language encyclopaedia that is available in print, as a DVD, and on the Internet. It is written and continuously updated by about 100 full-time editors and more than 4,000 expert...
, 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.
Larmor edited the collected works of George Stokes
George Stokes
George Stokes is the name of:* Sir George Stokes, 1st Baronet , Irish mathematician and physicist* George Henry Stokes , Member of Canadian Parliament* George Thomas Stokes , Irish historian...
, James Thomson
James Thomson (engineer)
right|300px|James Thomson was an engineer and physicist whose reputation is substantial though it is overshadowed by that of his younger brother William Thomson .-Biography:Born in Belfast, he grew up mostly in Glasgow...
and William Thomson
William Thomson, 1st Baron Kelvin
William Thomson, 1st Baron Kelvin OM, GCVO, PC, PRS, PRSE, was a mathematical physicist and engineer. At the University of Glasgow he did important work in the mathematical analysis of electricity and formulation of the first and second laws of thermodynamics, and did much to unify the emerging...
.
See also
- History of Lorentz transformationsHistory of lorentz transformationsThe Lorentz transformations relate the space-time coordinates, relative to a particular inertial frame of reference , and the coordinates of the same event relative to another coordinate system moving in the positive x-direction at a constant speed v, relative to the rest system...
- Larmor precessionLarmor precessionIn physics, Larmor precession is the precession of the magnetic moments of electrons, atomic nuclei, and atoms about an external magnetic field...
- Larmor formulaLarmor formulaIn physics, in the area of electrodynamics, the Larmor formula is used to calculate the total power radiated by a nonrelativistic point charge as it accelerates. It was first derived by J. J...
- Larmor (crater)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....