Julius Plücker | |
|---|---|
 Julius Plücker | |
| Born | (1801-07-16)16 July 1801 |
| Died | 22 May 1868(1868-05-22) (aged 66) |
| Alma mater | University of Bonn University of Heidelberg University of Berlin University of Paris University of Marburg |
| Known for | |
| Awards | Copley Medal (1866) |
| Scientific career | |
| Fields | Mathematics Physics |
| Institutions | University of Bonn University of Berlin University of Halle |
| Doctoral advisor | Christian Ludwig Gerling[1] |
| Doctoral students | Felix Klein August Beer Johann Hittorf Friedrich Lange[1] |
Julius Plücker (16 July 1801 – 22 May 1868) was a Germanmathematician andphysicist. He made fundamental contributions to the field ofanalytical geometry and was a pioneer in the investigations ofcathode rays that led eventually to thediscovery of the electron. He also vastly extended the study ofLamé curves.
Plücker was born atElberfeld (now part ofWuppertal) on July 16th, 1801.[2] After being educated atDüsseldorf and at the universities ofBonn,Heidelberg andBerlin he went toParis in 1823,[3] where he came under the influence of the great school of French geometers, whose founder,Gaspard Monge, had only recently died.
In 1825 he returned to Bonn, and in 1828 was made professor of mathematics.[3]
In the same year he published the first volume of hisAnalytisch-geometrische Entwicklungen, which introduced the method of "abridged notation".
In 1831 he published the second volume, in which he clearly established on a firm and independent basisprojective duality.
In 1836, Plücker was made professor of physics atUniversity of Bonn. In 1858, after a year of working with vacuum tubes of his Bonn colleagueHeinrich Geißler,[4] he published his first 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.[5] It was later shown that the glow was produced by cathode rays.
Plücker, first by himself and afterwards in conjunction withJohann 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 aGeissler tube, by means of which the luminous intensity of feeble electric discharges was raised sufficiently to allow of spectroscopic investigation. He anticipatedRobert Wilhelm Bunsen andGustav 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 asline geometry in the nineteenth century. Inprojective geometry,Plücker coordinates refer to a set ofhomogeneous co-ordinates introduced initially to embed the space of lines in projective space as theKlein quadric in. The construction uses 2×2minor determinants, or equivalently the secondexterior power of the underlyingvector space of dimension 4. It is now part of the theory ofGrassmannians(-dimensional subspaces of an-dimensional vector space), to which the generalization of these co-ordinates to minors of the matrix of homogeneous coordinates, also known asPlücker coordinates, apply. The embedding of the Grassmannian into the projectivization of theth exterior power ofis known as thePlücker embedding.
Plücker was the recipient of theCopley Medal from theRoyal Society in 1866.[7]
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