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.

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.

[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.".

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.

Already as a student was Rubens fascinated by electromagnetic radiation as theoretically described by Maxwell and experimentally demonstrated by Hertz.

As a related result he could present an experimental verification of Maxwell's theory for electromagnetic waves in different media.

This lead him to a new, powerful method by selective reflexion from several crystals to isolate a narrow range of infrared wavelengths from a broader spectrum of radiation.

[4] Together with Ferdinand Kurlbaum he started the same year to measure the energy content of black-body radiation in the far infrared region using this technique.

[9] On 14 December Planck could present to Deutsche Physikalische Gesellschaft a derivation of his new radiation law based on the idea of quantization of energy.

This enabled him also to make more and more accurate tests of Plancks new radiation theory and related studies of matter which soon could be described by quantum mechanics.