Heinrich Rubens

Heinrich Rubens (30 March 1865, Wiesbaden, Duchy of Nassau – 17 July 1922, Berlin, Germany) was a German physicist. He is known for his measurements of the energy of black-body radiation which led Max Planck to the discovery of his radiation law. This was the genesis of quantum theory.

After having attended realgymnasium Wöhlerschule in Frankfurt am Main, he started in 1884 to study electrical engineering at institutes of technology in Darmstadt and Berlin.^[1] The following year he switched to physics at the University of Berlin which was more to his liking.^[2] After just one semester there he transferred to Strasbourg. There he benefited much from the lectures by August Kundt who in 1888 took over the vacant position of Hermann Helmholtz at the University of Berlin. Rubens followed after and got his doctors degree there the same year. In the period 1890–1896 he was employed as an assistant at the physics institute and made his habilitation in 1892. He was then a privatdozent and was allowed to teach. Already then he was praised for his experimental investigations of infrared radiation.^[3]

Rubens got a permanent position in 1896 as docent at the Technische Hochschule in Charlottenburg (now Technische Universität Berlin). He could continue his experimental research at the nearby Physikalisch-Technische Reichsanstalt. It was there he in 1900 did his important measurements of black-body radiation which made him world-famous. He was promoted to professor the same year.

After Paul Drude retired in 1906 from his professorship at the University in Berlin, the position was given to Rubens. He was at the same time appointed director of the physics institute.^[1] In this way he could influence and lead a large group of colleagues and students. The year after he was elected to the Prussian Academy of Sciences and became in 1908 a corresponding member Göttingen Academy of Sciences and Humanities.^[1] He participated at the two first Solvay conferences after having received the Rumford Medal in 1910 "on the ground of his researches on radiation, especially of long wave length.".

Heinrich Rubens died in 1922 after a longer illness. At a memorial meeting in the science academy the following year Max Planck said about him:^[4]

Without the intervention of Rubens the formulation of the radiation law and thereby the foundation of quantum theory would perhaps have arisen in quite a different manner, or perhaps not have developed in Germany at all.

He is buried at the Alter St.-Matthäus-Kirchhof in Berlin-Schöneberg with his wife Marie. She took her life in 1941 for fear of being deported and killed by the Nazis.^[5] The burial place is near that of Gustav Kirchhoff, who founded spectroscopy and formulated the first laws of black-body radiation.