George Johnstone Stoney
Encyclopedia
George Johnstone Stoney (15 February 1826 – 5 July 1911) was an Irish
physicist most famous for introducing the term electron
as the "fundamental unit quantity of electricity".
He had introduced the concept, though not the word, as early as 1874 and 1881, and the word came in 1891.
He published around 75 scientific papers during his lifetime.
, County Offaly
, in the Irish Midlands, in an old-established Anglo-Irish family. He attended Trinity College, Dublin
, graduating with a B.A. in 1848. From 1848 to 1852 he worked as an astronomy assistant to William Parsons, 3rd Earl of Rosse
at Birr Castle, County Offaly, where Parsons had built the world's largest telescope, the 72-inch Leviathan of Parsonstown
. Simultaneously Stoney continued to study physics and mathematics and was awarded an M.A. by Trinity College Dublin in 1852.
From 1852 to 1857 he was professor of physics at Queen's College Galway. From 1857 to 1882 he was employed as Secretary of the Queen's University of Ireland
, an administrative job based in Dublin. In the early 1880s he moved to the post of superintendent of Civil Service Examinations in Ireland, a post he held until his retirement in 1893. In that year, he took up residence in London. Stoney died in 1911 at his home in Notting Hill
, London
. During his decades of non-scientific employment responsibilities in Dublin, Stoney continued to do scientific research on his own. He also served for decades as honorary secretary and then vice-president of the Royal Dublin Society
, a scientific society modelled after the Royal Society of London, and after his move to London Stoney served on the council of that society too. Additionally he intermittently served on scientific review committees of the British Association for the Advancement of Science
from the early 1860s on.
s in a cubic millimetre of gas, at room temperature and pressure, from data obtained from the kinetic theory of gases. Stoney's most important scientific work was the conception and calculation of the magnitude of the "atom of electricity". In 1891, he proposed the term 'electron
' to describe the fundamental unit of electrical charge, and his contributions to research in this area laid the foundations for the eventual discovery of the particle by J.J. Thomson in 1897.
He was elected a Fellow of the Royal Society in June 1861 on the basis of being the author of papers on "The Propagation of Waves," – "On the Rings seen in Fibrous Speciamens of Calc Spar," and Molecular Physics, published in the Transactions of the Royal Irish Academy, et cetera, Distinguished for his acquaintance with the science of Astronomy & General Physics.
as the most suitable scale for a unified theory. The Planck scale was, however, anticipated by George Stoney. Like Planck after him, Stoney realized that large-scale effects such as gravity and small-scale effects such as electromagnetism naturally imply an intermediate scale where physical differences might be rationalized. This intermediate scale comprises units (Stoney scale units
) of mass, length, time etc., yet mass is the cornerstone.
The Stoney mass mS (expressed in contemporary terms):
where ε0 is the permittivity of free space, e is the elementary charge
and G is the gravitational constant
, and where α is the fine-structure constant
and mP is the Planck mass.
Like the Planck scale, the Stoney scale functions as a symmetrical link between microcosmic and macrocosmic processes in general and yet it appears uniquely oriented towards the unification of electromagnetism and gravity . Thus for example whereas the Planck length is the mean square root of the reduced Compton wavelength
and half the gravitational radius of any mass, the Stoney length is the mean square root of the 'electromagnetic radius' (see Classical electron radius
) and half the gravitational radius of any mass, m:
where
is the reduced Planck's constant and c is the speed of light
. It should be noted however that these are only mathematical constructs since there must be some practical limit to how small a length can get. If the Stoney length is the minimum length then either a body's electromagnetic radius or its half gravitational radius is a physical impossibility, since one of these must be smaller than the Stoney length. If Planck length is the minimum then either a body's reduced Compton wavelength or its half gravitational radius is a physical impossibility since one of these must be smaller than the Planck length. Moreover, the Stoney length and Planck length cannot both be the minimum length.
According to contemporary convention, Planck scale is the scale of vacuum energy
, below which space and time do not retain any physical significance. This prescription mandates a general neglect of the Stoney scale within the scientific community today. Previous to this mandate, Hermann Weyl
made a notable attempt to construct a unified theory by associating a gravitational unit of charge with the Stoney length. Weyl's theory led to significant mathematical innovations but his theory is generally thought to lack physical significance.
neighbourhood. The street that he lived on was later re-named Stoney Road in his memory. After Stoney died in London, his cremated ashes were buried in Dundrum, Dublin.
One of Stoney's sons, George Gerald Stoney, was a scientist. But a more scientifically notable relative was Stoney's nephew, the Dublin-based physicist George FitzGerald
(1851–1901). Stoney and FitzGearld were in regular communication on scientific matters. In addition, on political matters, both Stoney and FitzGearld were active opponents of the Irish Home Rule Movement
. In their political opinion, the spirit of Irish Home Rule and later Irish nationalism was contrary to the spirit of science. Stoney resigned from his job as Secretary of Queen's University of Ireland in 1882 in objection to a government decision to introduce "sectarianism" into the system; i.e., Stoney wanted to keep the system non-denominational, but the government acceded to Irish Catholic demands for Catholic institutions.
Craters
on Mars
and the Moon
are named in his honour.
Irish
Irish may refer to:*Irish cuisine* Ireland, an island in north-western Europe, on which are located:** Northern Ireland, a constituent country of the United Kingdom** Republic of Ireland, a sovereign state...
physicist most famous for introducing the term 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...
as the "fundamental unit quantity of electricity".
He had introduced the concept, though not the word, as early as 1874 and 1881, and the word came in 1891.
He published around 75 scientific papers during his lifetime.
Education and employment positions
Stoney was born at Oakley Park, near BirrBirr
Birr is a town in County Offaly, Ireland. Once called Parsonstown, after the Parsons family who were local landowners and hereditary Earls of Rosse. It is also a parish in the Roman Catholic Diocese of Killaloe....
, County Offaly
County Offaly
County Offaly is a county in Ireland. It is part of the Midlands Region and is also located in the province of Leinster. It is named after the ancient Kingdom of Uí Failghe and was formerly known as King's County until the establishment of the Irish Free State in 1922. Offaly County Council is...
, in the Irish Midlands, in an old-established Anglo-Irish family. He attended Trinity College, Dublin
Trinity College, Dublin
Trinity College, Dublin , formally known as the College of the Holy and Undivided Trinity of Queen Elizabeth near Dublin, was founded in 1592 by letters patent from Queen Elizabeth I as the "mother of a university", Extracts from Letters Patent of Elizabeth I, 1592: "...we...found and...
, graduating with a B.A. in 1848. From 1848 to 1852 he worked as an astronomy assistant to William Parsons, 3rd Earl of Rosse
William Parsons, 3rd Earl of Rosse
William Parsons, 3rd Earl of Rosse, Knight of the Order of St Patrick was an Irish astronomer who had several telescopes built. His 72-inch telescope "Leviathan", built 1845, was the world's largest telescope until the early 20th century.-Life:He was born in Yorkshire, England, in the city of...
at Birr Castle, County Offaly, where Parsons had built the world's largest telescope, the 72-inch Leviathan of Parsonstown
Leviathan of Parsonstown
Leviathan of Parsonstown is the unofficial name of the Rosse six foot telescope. This is a historic reflecting telescope of 72 in aperture, which was the largest telescope in the world from 1845 until the construction of the 100 in Hooker Telescope in 1917...
. Simultaneously Stoney continued to study physics and mathematics and was awarded an M.A. by Trinity College Dublin in 1852.
From 1852 to 1857 he was professor of physics at Queen's College Galway. From 1857 to 1882 he was employed as Secretary of the Queen's University of Ireland
Queen's University of Ireland
The Queen's University of Ireland was established formally by Royal Charter on 3 September 1850, as the degree-awarding university of the Queen's Colleges of Belfast, Cork, and Galway that were established in 1845 "to afford a university education to members of all religious denominations" in...
, an administrative job based in Dublin. In the early 1880s he moved to the post of superintendent of Civil Service Examinations in Ireland, a post he held until his retirement in 1893. In that year, he took up residence in London. Stoney died in 1911 at his home in Notting Hill
Notting Hill
Notting Hill is an area in London, England, close to the north-western corner of Kensington Gardens, in the Royal Borough of Kensington and Chelsea...
, London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...
. During his decades of non-scientific employment responsibilities in Dublin, Stoney continued to do scientific research on his own. He also served for decades as honorary secretary and then vice-president of the Royal Dublin Society
Royal Dublin Society
The Royal Dublin Society was founded on 25 June 1731 to "to promote and develop agriculture, arts, industry, and science in Ireland". The RDS is synonymous with its main premises in Ballsbridge in Dublin, Ireland...
, a scientific society modelled after the Royal Society of London, and after his move to London Stoney served on the council of that society too. Additionally he intermittently served on scientific review committees of the British Association for the Advancement of Science
British Association for the Advancement of Science
frame|right|"The BA" logoThe British Association for the Advancement of Science or the British Science Association, formerly known as the BA, is a learned society with the object of promoting science, directing general attention to scientific matters, and facilitating interaction between...
from the early 1860s on.
Stoney's scientific output
Stoney published seventy-five scientific papers in a variety of journals, but chiefly in the journals of the Royal Dublin Society. He made significant contributions to cosmic physics and to the theory of gases. He estimated the number of moleculeMolecule
A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...
s in a cubic millimetre of gas, at room temperature and pressure, from data obtained from the kinetic theory of gases. Stoney's most important scientific work was the conception and calculation of the magnitude of the "atom of electricity". In 1891, he proposed the term '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...
' to describe the fundamental unit of electrical charge, and his contributions to research in this area laid the foundations for the eventual discovery of the particle by J.J. Thomson in 1897.
He was elected a Fellow of the Royal Society in June 1861 on the basis of being the author of papers on "The Propagation of Waves," – "On the Rings seen in Fibrous Speciamens of Calc Spar," and Molecular Physics, published in the Transactions of the Royal Irish Academy, et cetera, Distinguished for his acquaintance with the science of Astronomy & General Physics.
The Stoney scale
Contemporary physics has settled on the Planck scalePlanck scale
In particle physics and physical cosmology, the Planck scale is an energy scale around 1.22 × 1019 GeV at which quantum effects of gravity become strong...
as the most suitable scale for a unified theory. The Planck scale was, however, anticipated by George Stoney. Like Planck after him, Stoney realized that large-scale effects such as gravity and small-scale effects such as electromagnetism naturally imply an intermediate scale where physical differences might be rationalized. This intermediate scale comprises units (Stoney scale units
Stoney scale units
In physics the Stoney units form a system of units named after the Irish physicist George Johnstone Stoney, who first proposed them in 1881. They are the first historical example of natural units, i.e. units of measurement designed so that certain fundamental physical constants serve as base units...
) of mass, length, time etc., yet mass is the cornerstone.
The Stoney mass mS (expressed in contemporary terms):
where ε0 is the permittivity of free space, e is the elementary charge
Elementary charge
The elementary charge, usually denoted as e, is the electric charge carried by a single proton, or equivalently, the absolute value of the electric charge carried by a single electron. This elementary charge is a fundamental physical constant. To avoid confusion over its sign, e is sometimes called...
and G is the gravitational constant
Gravitational constant
The gravitational constant, denoted G, is an empirical physical constant involved in the calculation of the gravitational attraction between objects with mass. It appears in Newton's law of universal gravitation and in Einstein's theory of general relativity. It is also known as the universal...
, and where α is the fine-structure constant
Fine-structure constant
In physics, the fine-structure constant is a fundamental physical constant, namely the coupling constant characterizing the strength of the electromagnetic interaction. Being a dimensionless quantity, it has constant numerical value in all systems of units...
and mP is the Planck mass.
Like the Planck scale, the Stoney scale functions as a symmetrical link between microcosmic and macrocosmic processes in general and yet it appears uniquely oriented towards the unification of electromagnetism and gravity . Thus for example whereas the Planck length is the mean square root of the reduced Compton wavelength
Compton wavelength
The Compton wavelength is a quantum mechanical property of a particle. It was introduced by Arthur Compton in his explanation of the scattering of photons by electrons...
and half the gravitational radius of any mass, the Stoney length is the mean square root of the 'electromagnetic radius' (see Classical electron radius
Classical electron radius
The classical electron radius, also known as the Lorentz radius or the Thomson scattering length, is based on a classical relativistic model of the electron...
) and half the gravitational radius of any mass, m:
where
is the reduced Planck's constant and c is the speed of lightSpeed of light
The speed of light in vacuum, usually denoted by c, is a physical constant important in many areas of physics. Its value is 299,792,458 metres per second, a figure that is exact since the length of the metre is defined from this constant and the international standard for time...
. It should be noted however that these are only mathematical constructs since there must be some practical limit to how small a length can get. If the Stoney length is the minimum length then either a body's electromagnetic radius or its half gravitational radius is a physical impossibility, since one of these must be smaller than the Stoney length. If Planck length is the minimum then either a body's reduced Compton wavelength or its half gravitational radius is a physical impossibility since one of these must be smaller than the Planck length. Moreover, the Stoney length and Planck length cannot both be the minimum length.
According to contemporary convention, Planck scale is the scale of vacuum energy
Vacuum energy
Vacuum energy is an underlying background energy that exists in space even when the space is devoid of matter . The concept of vacuum energy has been deduced from the concept of virtual particles, which is itself derived from the energy-time uncertainty principle...
, below which space and time do not retain any physical significance. This prescription mandates a general neglect of the Stoney scale within the scientific community today. Previous to this mandate, Hermann Weyl
Hermann Weyl
Hermann Klaus Hugo Weyl was a German mathematician and theoretical physicist. Although much of his working life was spent in Zürich, Switzerland and then Princeton, he is associated with the University of Göttingen tradition of mathematics, represented by David Hilbert and Hermann Minkowski.His...
made a notable attempt to construct a unified theory by associating a gravitational unit of charge with the Stoney length. Weyl's theory led to significant mathematical innovations but his theory is generally thought to lack physical significance.
Other
The woman Stoney married was one of his cousins. They had two sons and three daughters. For most of his decades in Dublin, Stoney resided in the Dundrum, DublinDundrum, Dublin
Dundrum , originally a town in its own right, is now a suburb of Dublin in Dún Laoghaire-Rathdown, Ireland.The area is located in the postal districts of Dublin 14 and Dublin 16.-History:...
neighbourhood. The street that he lived on was later re-named Stoney Road in his memory. After Stoney died in London, his cremated ashes were buried in Dundrum, Dublin.
One of Stoney's sons, George Gerald Stoney, was a scientist. But a more scientifically notable relative was Stoney's nephew, the Dublin-based physicist George FitzGerald
George FitzGerald
George Francis FitzGerald was an Irish professor of "natural and experimental philosophy" at Trinity College in Dublin, Ireland, during the last quarter of the 19th century....
(1851–1901). Stoney and FitzGearld were in regular communication on scientific matters. In addition, on political matters, both Stoney and FitzGearld were active opponents of the Irish Home Rule Movement
Irish Home Rule Movement
The Irish Home Rule Movement articulated a longstanding Irish desire for the repeal of the Act of Union of 1800 by a demand for self-government within the United Kingdom of Great Britain and Ireland. The movement drew upon a legacy of patriotic thought that dated back at least to the late 17th...
. In their political opinion, the spirit of Irish Home Rule and later Irish nationalism was contrary to the spirit of science. Stoney resigned from his job as Secretary of Queen's University of Ireland in 1882 in objection to a government decision to introduce "sectarianism" into the system; i.e., Stoney wanted to keep the system non-denominational, but the government acceded to Irish Catholic demands for Catholic institutions.
Craters
Impact crater
In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...
on Mars
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...
and the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
are named in his honour.