Plucker
NAME: Plucker, Julius
ACHIEVEMENT(S): Cathode ray work
NICKNAME/ALIAS: None
DATE/PLACE OF BIRTH: 16 June 1801, at Elberfeld (now Wuppertal), Duchy of
Berg (now Germany)
DATE/PLACE/AGE AT DEATH: 22 May 1868, in Bonn, Germany. Aged 66
DISCIPLINE: Mathematician and physicist
FIELD: Mathematics and physics
LANGUAGE: German
PARENTS: ?
SIBLINGS: ?
SPOUSE: ? Altstatten, married 1837
CHILDREN: One son
EDUCATION: Dusseldorf Gymnasium, 1813-19; Universities of Bonn, Heidelberg,
Berlin and Paris, 1819-24
MAJOR WORK: 'Theory of Algebraic Curves,' 1839
LIFE AND TIMES: Plucker’s first important work appeared in 1828. Volume I of ‘The Development of Analytic Geometry’ was followed in 1831 by volume II. This work established him as an important new mathematician.
In 1829, Plücker introduced a revolutionary idea into analytic geometry: that the fundamental geometric element need not be the point, but could be the straight line. Describing the so-called triangular coordinates as three values that are proportional to the distances of a point from three given lines, Plucker developed a new way of specifying coordinates in which a point has a linear equation (that of all lines through the point), while a line has a pair of numbers (the x and y coordinates of where it cuts the axes). From this concept, Plucker then extrapolated the principle of reciprocity, now called the principle of duality.
He gave a detailed explanation at the end of volume II of his 'Analytisch-geometrie', and which initiated the investigation of geometrical configurations associated with line complexes.
In 1833 Plucker moved to Berlin, where he held simultaneous posts as extraordinary professor at the University of Berlin, and as a teacher at the Friedrich Wilhelm Gymnasium. The following year he was appointed to the chair of mathematics at the University of Halle.
At Halle, Plucker published his second important work, 'System of Analytic Geometry' (1835), which discussed general point and line coordinates for treating conic sections, introducing the use of linear functions in place of the usual coordinate points, and presented an extensive treatment of plane cubic curves.
In 1836, Plucker then returned to Bonn, where he was appointed full professor of mathematics, and three years later he published his greatest work, 'Theory of Algebraic Curves,' which contained equations - known as "Plucker's equations" - detailing the number of singularities (points at which there is no unique tangent line) on algebraic curves, and corrected some errors made by <revised work of> Euler* in his 'Introductio in analysis infinitorum' (1748).
Seven years later, in 1846, he produced his 'System of the Geometry of Space in a New Analytical Treatment,' which studied the problem of focal points of algebraic curves, the osculation of two surfaces, and wave surface (important contributions to the analytical geometry of space).
After 1846 Plucker abandoned his geometrical studies and began conducting experiments in physics, and in the following year he transferred to the chair of physics at Bonn. Soon after this Plucker began research on the behaviour of crystals in a magnetic field and then investigated the properties of magnetic bodies, in 1847 discovering the magnetic nature of tourmaline crystal.
During the late 1840s and early 1850s he also studied optics and gas spectroscopy, and was an early investigator of gas spectrum analysis, recognizing that spectral lines were characteristic for each chemical substance, and indicating the value of this discovery to chemical analysis.
He was also the first to see the three lines of the hydrogen spectrum (well before <anticipated> Bunsen* and <anticipated> Kirchhoff* at Heidelberg had begun their experiments in this field), which were recognized a few months after Plucker's death in the spectrum of the solar prominences, solving a mystery of modern astronomy.
In 1862 he discovered that the same element may show different spectra at different temperatures.
Meanwhile, in 1852 Plucker had begun collaborating with <collaborated with> Geissler*, an exceptionally talented manufacturer of scientific instruments, in constructing a standard thermometer, a great improvement on the thermometers currently in use as it was made of thinner glass, utilized capillary action, and was highly accurate.
He had also, via a lengthy correspondence with the English physicist <corresponded with> Faraday*(who in the 1830s had experimented with electrical discharge in gases at very low pressures), become interested in the phenomena of electrical discharges in evacuated gases, and during the 1850s he took up this work.
After 1855 he had the added advantage, unlike Faraday, of being able to use the new, highly-effective vacuum tube developed by Geissler at Bonn, and in 1858 he found that the electrical discharge caused a fluorescent glow to form on the glass walls of the vacuum tube, and that the glow could be deflected by a strong magnetic field.
<taught> Hittorf*, one of Plucker's students, continued this work, and in 1869 showed that the glow was produced by cathode rays formed in the tube, which in 1897 <influenced> J.J. Thomson* demonstrated were made up of electrons.
Plucker spent his last years introducing six equations of higher plane curves, which have
since been named "Plucker's coordinates", but he died in 1868, at the age of 66, before this project was completed.
ASSESSMENT: Plucker made important contributions to analytic geometry and physics. In mathematics, his work suggested the far-reaching principle of duality, which states the equivalence of certain related types of theorems.
EXTRA CONNECTIONS: His work related to that of <work related to> Goldstein* and <work related to> Lenard*
ONELINER: Julius Plucker, cathode ray pioneer
BIBLIOGRAPHY:
DSB, EB Biographical Dictionary of Physicists