Emil Warburg

Emil Gabriel Warburg ( born March 9, 1846 in Altona, † July 28, 1931 in Grunau ( today Bayreuth) ) was a German physicist. The biochemist and Nobel Prize winner Otto Warburg was his son.

Life

Origin

The Warburg ancestors were originally from Bologna. About the Westphalian Warburg they had finally settled in Altona, since there prevailed freedom of belief and Jews were allowed to engage in trade and shipbuilding. Emil Warburg later converted to the Protestant faith.

Study

1863 took Warburg first to study chemistry at the University of Heidelberg and attended lectures by Robert Wilhelm Bunsen, Gustav Robert Hermann von Helmholtz and Kirchhoff. Not much in the wake of the clear and thoughtful lectures Kirchhoff joined Warburg to physics, because this tray up to his mathematical interests more. In 1865 he continued his studies in Berlin. The resident laboratory of Heinrich Gustav Magnus was at that time one of the few in Germany, which offered students the opportunity for self- experimentation. Under the guidance of laboratory assistants August Kundt he was first engaged in acoustic problems. 1867 doctorate Warburg with the then abzufassenden still in Latin dissertation De systematis corporum vibrantium. This deals with a special vibration system with a differential equation of the fourth order.

In May 1870 Emil Warburg habilitation. Because of the general mobilization he was called up in July and participated as an officer in the German - Prussian War.

France was forced to cede the loser Alsace-Lorraine to the newly founded German Empire. As a result, the University of Strasbourg in 1872 re-established. It should serve to promote the German culture on formerly French territory and was therefore equipped with the necessary financial resources. August Kundt had taken over the building of the Faculty of Physics. To his relief in establishing the Institute, he was able to assert an additional point for the theoretical aspects of physics, according to which, his desire to Warburg in the winter semester 1872/73 received. A separation between experimental physics and theoretical physics did not exist at this time. Emil Warburg is one of the last physicist who mastered both aspects and taught.

Cooperation in the next four years has been hugely rewarding. They published two important works for the kinetic theory of gases. After this, then still controversial theory of internal friction (viscosity) and thermal conductivity of gases up to a limit pressure are constant, that is independent of pressure. This could be verified experimentally up to a pressure of 10-2 Torr. The calculated deviation of Warburg at even lower pressure he was able to confirm 24 years later by the advances in vacuum technology and experimentally.

Further confirmation of the kinetic theory of gases delivered Kundt and Warburg by measuring the adiabatic exponent κ = cp / cv of dilute mercury gas with the help of the developed by Kundt dust figure method. (cp and cv is the specific heat capacity at constant pressure constant volume, respectively ). The experimentally determined value of 5/3 corresponds exactly to the theoretical value, which starts from point-like gas particles. Measurements inter alia of oxygen and nitrogen have been found to deviate from the theoretical value of 1.4. The difference is, as we know today, due to the molecular structure. Was held in spite of these contradictions in the concept of the kinetic theory of gases, not least by Kundts and Warburg measurements and developed them.

Freiburg

1876 ​​Warburg took over with only 29 years in Freiburg, a university of that time subordinate importance, the chair of physics. Here he devoted himself to electromagnetic phenomena. The discovery and theoretical interpretation of the magnetic hysteresis ( 1880) is one of the most important scientific achievements Warburg.

The image comes from the publication of the results in the annals of physics and chemistry 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 in the magnetic reversal, and converted into heat. The term hysteresis curve was coined later. In today's conventional representations of the hysteresis curve, the magnetic moment M is shown as a function of magnetic field strength H.

Berlin

After the early death of August Kundt the 48 -year-old Warburg was awarded in 1894 a call to Berlin. Previously, the favorite for the post Friedrich Wilhelm Kohlrausch had rejected the call because of the anticipated workload. Warburg was able to prevail against its competitors Walther Nernst and Otto Wiener. Also, there was to overcome anti-Semitic resentment. German - national forces were of the view that not only the religion, but also the racial origin are an important recruitment criterion. This principle, the chemist Hans Heinrich Landolt in exploring whether Warburg " certain Jewish characteristics " not too much came to bear. That same year, Warburg was a member of the Prussian Academy of Sciences. In 1897 he became chairman of the Physical Society of Berlin, which merged in the newly formed German Physical Society 1899. Until 1905 he remained its chairman. In the same year he was elected a corresponding member of the Mathematics and Physics Class of the Bavarian Academy of Sciences. Since 1900, he also belonged to the Kungliga Vetenskaps -och Vitterhetssamhället i Göteborg.

After he had in 1905 resigned from his position as full professor at the University of Berlin, he took over the management of the Physikalisch -Technische - Imperial Institute, a position he held until 1922. Under his leadership, the separation of technical and scientific department was abolished. Instead, individual institutions were founded for optics, electricity and magnetism, as well as heat and pressure. Important scientific works from this period are measurements for the black-body radiation and to photochemistry. So, he took part in 1911 of the first Solvay Conference, on the discussed the then leading physicist on radiation theory and quantum. In 1912 he was instrumental in the founding of the German Lighting Technology Society.

With 76 years Warburg retired on April 1, 1922. By the end of his life he exercised his right of nomination for the Nobel Prize for Physics in use. Among the candidates proposed by him were Friedrich Kohlrausch ( 1905-1907, 1909), Otto Lummer, Wilhelm Wien and Max Planck (1910 /11) and Albert Einstein ( 1917-1923 ).

At the age of 85 years Warburg died on 28 July 1931. He was buried in the town cemetery in Bayreuth.

After Emil Warburg named Awards

To commemorate the physicist Emil Warburg Foundation was founded. It promotes research projects at the University of Bayreuth in the field of physics and recognizes special achievements in physics (eg outstanding doctoral theses) and the awarding of prizes from.

The Marian Smoluchowski Emil Warburg Physics Prize is endowed with a silver medal, a certificate and a cash prize of € 3,000 and is in memory of Emil Warburg and the Polish physicist Marian Smoluchowski since 1997 every two years alternately German to one or Polish physicist jointly awarded by the German Physical Society and the Polish Physical Society.

Trivia

For Friends of the Warburg family was Albert Einstein, with the Warburg's daughter Lotte, who in 1933 visited him in Oxford, England, a correspondence entertained. On the occasion of the Nobel Prize to her brother Otto commented Einstein, who had died shortly before Emil Warburg him " always the dearest of all physicists " was.

The campus of the University of Bayreuth leader has existed since 1979, the pedestrian zone Emil Warburg way.