Julius Plücker

Infobox_Scientist
name = Julius Plücker

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image_width = 300px
caption = Julius Plücker
birth_date = birth date|1801|6|16|mf=y
birth_place = Elberfeld, Duchy of Berg
death_date = death date and age|1868|5|22|1801|6|16|mf=y
death_place = Bonn, Germany
residence =
nationality =
field = Mathematician
work_institution = University of Bonn
University of Berlin
University of Halle
alma_mater = University of Bonn
University of Heidelberg
University of Berlin
University of Paris
University of Marburg
doctoral_advisor = Christian Ludwig Gerling
doctoral_students = Felix Klein
August Beer
known_for = Plücker formula
prizes = Copley Medal (1866)
religion =
footnotes =

Julius Plücker (June 16, 1801 – May 22, 1868) was a German mathematician and physicist. He made fundamental contributions to the field of analytical geometry and was a pioneer in the investigations of cathode rays that led eventually to the discovery of the electron. He also vastly extended the study of Lamé curves.

Life and work

Plücker was born at Elberfeld (now part of Wuppertal). After being educated at Düsseldorf and at the universities of Bonn, Heidelberg and Berlin he went to Paris in 1823, where he came under the influence of the great school of French geometers, whose founder, Gaspard Monge, was only recently dead. In 1825 he returned to Bonn, and in 1828 was made professor of mathematics. In the same year he published the first volume of his "Analytisch-geometrische Entwickelungen", which introduced for the first time the method of abridged notation. In 1831 he published the second volume, in which he clearly established on a firm and independent basis projective duality.

In 1847 Plücker was made professor of physics at Bonn. In 1858 he published the first of his classical researches on the action of the magnet on the electric discharge in rarefied gases. He found that the discharge caused a fluorescent glow to form on the glass walls of the vacuum tube, and that the glow could be made to shift by applying an electromagnet to the tube, thus creating a magnetic field. It was later shown that the glow was produced by cathode rays.

Plücker, first by himself and afterwards in conjunction with Johann Hittorf, made many important discoveries in the spectroscopy of gases. He was the first to use the vacuum tube with the capillary part now called a Geissler's tube, by means of which the luminous intensity of feeble electric discharges was raised sufficiently to allow of spectroscopic investigation. He anticipated Robert Wilhelm Bunsen and Gustav Kirchhoff in announcing that the lines of the spectrum were characteristic of the chemical substance which emitted them, and in indicating the value of this discovery in chemical analysis. According to Hittorf he was the first who saw the three lines of the hydrogen spectrum, which a few months after his death were recognized in the spectrum of the solar protuberances.

In 1865 Plücker returned to the field of geometry and invented what was known as "line geometry" in the nineteenth century. In projective geometry, Plücker co-ordinates refer to a set of homogeneous co-ordinates introduced initially to embed the set of lines in three dimensions as a quadric in five dimensions. The construction uses 2×2 minor determinants, or equivalently the second exterior power of the underlying vector space of dimension 4. It is now part of the theory of Grassmannians, to which these co-ordinates apply in generality ("k"-dimensional subspaces of "n"-dimensional space).

Plücker was the recipient of the Copley Medal from the Royal Society in 1866.

*Plücker formula
*Timeline of low-temperature technology

External links

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* [http://members.chello.nl/~h.dijkstra19/page7.html The Cathode Ray Tube site]
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Persondata
NAME= Plücker, Julius
ALTERNATIVE NAMES=
SHORT DESCRIPTION= Mathematician
DATE OF BIRTH= June 16, 1801
PLACE OF BIRTH= Elberfeld, Duchy of Berg
DATE OF DEATH= May 22, 1868
PLACE OF DEATH= Bonn, Germany