Emil Warburg

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Emil Warburg. Photo from 1900.

Emil Gabriel Warburg (born March 9, 1846 in Altona ; † July 28, 1931 in Grunau (now part of Bayreuth )) was a German physicist .

Life

family

Warburg's ancestors originally came from Bologna . They finally settled in Altona via the Westphalian Warburg , since there was freedom of belief and Jews were also allowed to trade and build ships. Emil Warburg later converted to the Protestant denomination.

The biochemist, cell physiologist and Nobel Prize winner Otto Warburg is his son.

Education

In 1863 Warburg began studying chemistry at Heidelberg University and attended lectures by Robert Wilhelm Bunsen , Hermann von Helmholtz and Gustav Robert Kirchhoff . Not least under the impression of Kirchhoff's clear and well thought-out lectures, Warburg switched to physics, as this subject corresponded more to his mathematical interests. During his studies he became a member of the Allemannia Heidelberg fraternity . In 1865 he continued his studies in Berlin. Heinrich Gustav Magnus's laboratory located there was one of the few in Germany at the time that offered students the opportunity to experiment independently. Under the guidance of laboratory assistant August Kundt , he first dealt with acoustic issues. In 1867 Warburg received his doctorate with the dissertation De systematis corporum vibrantium, which was then still to be written in Latin . This deals with a special vibration system with a fourth order differential equation .

Emil Warburg completed his habilitation in May 1870. Due to the general mobilization , he was called up in July and took part as an officer in the Franco-German War .

Strasbourg

As the loser , France had to cede Alsace-Lorraine to the newly founded German Empire after it had belonged to France for a long time . As a result, the University of Strasbourg was re-established in 1872 . It was supposed to win the Alsatians for Germany and was therefore provided with appropriate financial resources. August Kundt took over the construction of the physics faculty. To relieve himself of the work involved in setting up the institute, he was able to secure an additional position for the theoretical aspects of physics, which, according to his wishes, Warburg received in the winter semester of 1872/73. At this point in time, there was no separation between experimental physics and theoretical physics. Emil Warburg is considered to be one of the last physicists to master and teach both aspects.

The collaboration over the next four years has been extremely fruitful. They published two major papers on kinetic gas theory . According to this theory, which was still controversial at the time, internal friction ( viscosity ) and thermal conductivity of gases are constant up to a limit pressure, i.e. H. independent of pressure. They were able to verify this experimentally up to a pressure of 10 −2 Torr. The deviation calculated by Warburg at an even lower pressure, he was able to confirm experimentally 24 years later thanks to the vacuum technology that has now been improved.

Kundt and Warburg provided further confirmation of the kinetic gas theory by measuring the adiabatic exponent κ = c p / c v of diluted mercury gas using the dust figure method developed by Kundt. (c p or c v is the specific heat capacity at constant pressure or constant volume). The experimentally determined value of 5/3 was higher than for all other gases. This value is understandable according to the kinetic gas theory, but only under the condition that the gas particles behave like real mass points, i.e. cannot rotate around their own axis or perform internal oscillations. Not least through Kundt and Warburg's measurements, the concept of the kinetic gas theory was retained and developed further.

Freiburg

In 1876, at the age of just 29, Warburg took over the professorship for physics at the University of Freiburg . Here he devoted himself to electromagnetic phenomena. The discovery and theoretical interpretation of magnetic hysteresis (1880) is one of the most scientifically significant achievements of Warburg.

Hysteresis, from: Annalen der Physik und Chemie, 20, pp. 814-835, 1881, Fig. 5

The illustration comes from the publication of the results in the Annalen der Physik und Chemie from 1881 and shows the magnetic moment as a function of the magnetizing force. The area enclosed by the curve is a measure of the work that is done during magnetization and converted into heat. The term hysteresis curve was coined later. In today's usual representations of the hysteresis curve, the magnetic moment M is shown as a function of the magnetic field strength H.

Berlin

In 1894 Warburg succeeded Kundt in Berlin. Previously, Friedrich Wilhelm Kohlrausch , who was favored for this post, had declined the call because of the expected workload. Warburg was able to prevail against his rivals Walther Nernst and Otto Wiener and also overcome anti-Semitic resentments. German national forces were of the opinion that not only religious affiliation, but also “racial” origin are important recruitment criteria. The chemist Hans Heinrich Landolt, for example, made inquiries as to whether Warburg did not emphasize “certain Jewish characteristics” too much.

In 1895 Warburg became a full member of the Prussian Academy of Sciences . In 1897 he became chairman of the Physical Society in Berlin, which in 1899 became part of the newly founded German Physical Society . Warburg remained its chairman until 1905 and became an honorary member in 1917. In the same year he was elected a corresponding member of the mathematical-physical class of the Bavarian Academy of Sciences . Since 1900 he was also a member of the Royal Science and Literature Society in Gothenburg .

In 1899 Warburg published a mathematical model describing the capacity of an electrode under an alternating current ; the experimental data for this were obtained from the doctoral student Elsa Neumann . The model is known today as Warburg impedance , also known as the Warburg element.

Solvay Conference, 1911 (Emil Warburg, bottom row, 5th from left)

In 1905 he resigned from his position as full professor at Berlin University to take over the management of the Physikalisch-Technische-Reichsanstalt , which he held until 1922. Under his leadership, the institute was reorganized: the separation of technical and scientific departments was abolished, and instead individual institutes for optics, electricity and magnetism as well as for heat and pressure were founded. Important scientific works from this time are measurements of black body radiation and photochemistry. In 1911, for example, he took part in the first Solvay conference , at which the leading physicists of the time discussed radiation theory and quanta. In 1913 he recognized the importance of Bohr's atomic model early on . In 1912 he was instrumental in founding the German Lighting Technology Society .

At the age of 76, Warburg retired on April 1, 1922. Until the end of his life, he made use of his right to propose the Nobel Prize in Physics. The candidates he proposed included Friedrich Kohlrausch (1905 to 1907, 1909), Otto Lummer , Wilhelm Wien and Max Planck (1910/11) and Albert Einstein (1917 to 1923).

Bayreuth

Emil Warburg's grave in the Bayreuth city cemetery

Warburg spent his last years with his daughter Lotte Meyer-Viol in Bayreuth, where he lived from 1922. He died at the age of 85 on July 28, 1931. He was buried in the Bayreuth city cemetery.

Awards named after Emil Warburg

The Emil Warburg Foundation was established in memory of the physicist. It promotes research projects at the University of Bayreuth in the field of physics and recognizes special achievements in physics (e.g. outstanding doctoral theses) by awarding prizes.

In memory of Emil Warburg and the Polish physicist Marian Smoluchowski, the Marian Smoluchowski Emil Warburg Physics Prize has been awarded every two years by the German Physical Society and the Polish Physical Society, alternating between a German and a Polish physicist.

Others

Albert Einstein was one of the friends of the Warburg family, with whom Warburg's daughter Lotte, who visited him in Oxford, England , exchanged letters in 1933 . On the occasion of the award of the Nobel Prize to her brother Otto, Einstein said that Emil Warburg, who had recently died, was "always the dearest of all physicists" to him.

Leading to the campus of the University of Bayreuth , the pedestrian zone Emil-Warburg-Weg has existed since 1979 .

Individual evidence

  1. ^ Directory of the old men of the German fraternity. Überlingen am Bodensee 1920, p. 124.
  2. ^ Members of the previous academies. Emil Warburg. Berlin-Brandenburg Academy of Sciences and Humanities , accessed on June 26, 2015 .
  3. ^ Emil Gabriel Warburg: About the behavior of so-called non-polarizable electrodes against alternating current . In: Gustav Heinrich Wiedemann and Eilhard Wiedemann (Hrsg.): Annals of Physics and Chemistry . New episode 67 ( Annalen der Physik. Volume 303 ), no. 3 . Publisher by Johann Ambrosius Barth, Leipzig 1899, chap. 1 , p. 493–499 , doi : 10.1002 / andp.18993030302 ( Internet Archive [accessed on August 15, 2015] from the Thuringian University and State Library Jena (ThULB) ).
  4. ↑ Thomas Klett, LiTG, History of Lighting Technology, and Henning v. Weltzien et al., LiTG, Festschrift for the 100th anniversary in 2012
  5. ↑ Who was Emil Warburg? in: Nordbayerischer Kurier from January 28, 2019, p. 8.
  6. ↑ uni-bayreuth.de: Emil Warburg Foundation
  7. ↑ dpg-physik.de: Statute of the Polish-German Marian Smoluchowski - Emil Warburg Physics Prize ( Memento of the original from November 18, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. ; dpg-physik.de: Smoluchowski-Warburg laureate after years . @1@ 2Template: Webachiv / IABot / www.dpg-physik.de
  8. ↑ Bernd Mayer: “The genius with the always laughing mouth” in the Heimatkurier of the North Bavarian Courier, 1/2005, p. 5

literature

  • Albert Einstein : Emil Warburg as a researcher. In: The natural sciences. Volume 10, 1922, pp. 823-828.
  • James Franck : Emil Warburg in memory. In: The natural sciences. Volume 19, 1931, pp. 993-997.
  • Georg Gehlhoff : Emil Warburg as a teacher. In: Journal for Technical Physics. Volume 3, 1922, pp. 193-194.
  • E. Gerke: Warburg as a physicist. In: Journal for Technical Physics. Volume 3, 1922, pp. 186–192 (The work contains a list of Warburg's scientific publications).
  • Eduard Grüneisen : Emil Warburg on his eightieth birthday. In: The natural sciences. Volume 14, 1926, pp. 203-207.
  • Friedrich Paschen : Memorial speech on Emil Warburg, given at the Academy of Sciences on June 30, 1932. In: Christa Kirsten u. a. (Ed.): Inaugural speeches, responses to the admission of physicists to the Berlin Academy, commemorative speeches 1870–1929 (= physicists on physicists, volume 2), Akademischer Verlag, Berlin 1979, pp. 185–191.
  • Harald Schering : Emil Warburg and technology. In: The natural sciences. Volume 14, 1926, pp. 208-211.
  • Stefan L. Wolff: Emil Warburg - more than half a century of physics. In: Physical sheets. Volume 48, 1992, No. 4, pp. 275-279.
  • Stefan L. Wolff: Emil Warburg and Marian von Smoluchowski . In Physikalische Blätter Volume 54, 1998, No. 1, p. 65.
  • Stefan L. Wolff: Warburg, Emil Gabriel In: Neue Deutsche Biographie (NDB) , Volume 27, Duncker & Humblot, Berlin 2020, pp. 419–421.

Web links

Commons : Emil Warburg  - Collection of pictures, videos and audio files
Wikisource: Emil Warburg  - Sources and full texts
personal data
SURNAME Warburg, Emil
ALTERNATIVE NAMES Warburg, Emil Gabriel (full name)
BRIEF DESCRIPTION German physicist
DATE OF BIRTH March 9, 1846
PLACE OF BIRTH Altona
DATE OF DEATH July 28, 1931
Place of death Bayreuth