George Johnstone Stoney

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George Johnstone Stoney bigraphy, stories - Anglo-Irish physicist

George Johnstone Stoney : biography

15 February 1826 – 5 July 1911

George Johnstone Stoney (15 February 1826 – 5 July 1911) was an Anglo-Irish physicist. He is 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. 

Stoney, G.J. (1881). "On the Physical Units of Nature." Phil. Mag. [5] 11, 381. He published around 75 scientific papers during his lifetime.

Education and employment positions

Stoney was born at Oakley Park, near Birr, 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.

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 molecules 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 Specimens 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 scale 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):

m_S=sqrt{frac} = sqrt{alpha}, m_P

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:

ell_P=sqrt{frac{hbar}cdotfrac}
ell_S=sqrt{fraccdotfrac}

where hbar 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.