Julius Plücker
Julius Plücker (June 16th, 1801 - May 22nd, 1868) was a Mathématicien and a German Physicien . He obtained fundamental results in analytical Geometry and was a pioneer in research on the Cathode rays which led to discovered of the electron. He worked also much on the curves of Lamé.
Plücker was born with Elberfeld (incorporated today in Wuppertal). After studies with Düsseldorf and in the universities of Bonn, Heidelberg and Berlin, it goes to Paris in 1823, where it is influenced by the university of the French geometricians, from which the founder Gaspard Monge just came to die. In 1825, it goes back to Bonn and in 1828 he becomes mathematics professor. The same year, it publishes the first volume of sound Analytisch-geometrische Entwickelungen (analytico-geometrical Developments), which introduces for the first time its method of the shortened notation. In 1831, it publishes the second volume, in which it clearly establishes the foundations of the great principle of duality.
In 1847, Plücker becomes professor of physics in Bonn. In 1858, it publishes the first of its traditional research on the action of the magnets on the electric shock in rarefied gases. It shows that the discharge causes the formation of a fluorescent gleam on the walls of glass of the vacuum tube, and that one can force the gleam to shift by applying a magnet to the tube, thus creating a magnetic field. Later, it was shown that the gleam came from the cathode rays.
Plücker, initially only, then in collaboration with Johann Hittorf, made many important discoveries in the Spectroscopy of the gas. It is the first to use the vacuum tube with a capillary part (tube of Geissler) which makes it possible sufficiently to increase the low intensity of the electric shocks to allow the spectroscopic study. It precedes Robert Wilhelm Bunsen and Gustav Kirchhoff by announcing that the lines of the spectrum are characteristic of the substance which emitted them, and by showing the value of this discovery in chemical Analysis. According to Hittorf, it was the first to see the three lines of the spectrum of hydrogen, which were found a few months after its death in the spectrum of the solar protuberances.
In 1865, Plücker turns over to the Géométrie and then invents what one called the geometry of the lines at the 19th century. In projective Geometry, the Coordonnées of Plücker are a whole of homogeneous Coordonnées introduced initially to plunge the whole of the lines of the projective space of dimension three in a Quadrique in the projective space of dimension five. Their construction uses the minor 2×2, or in an equivalent way, the second power external of the vector space of dimension 4 subjacent. The coordinates of Plücker now form part of the theory of the grassmanniennes, which describe the whole of the subspaces of dimension K in a space of dimension N in any general information.
Plücker received the Médaille Copley of the Royal Society in 1866.
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