Grain already studied from 1886 mathematics and physics in Freiburg and later Leipzig, where he received his doctorate in 1890 at Eilhard Wiedemann and Carl Gottfried Neumann (On the applicability of combinatorial methods for the reduction of problems of hydrodynamics, electrodynamics and the magnetic induction). He then studied further in Berlin, Paris, London and Würzburg. In 1895 he completed his habilitation at the University of Munich (On the motion of continuous mass systems ), where he was a lecturer and associate professor in 1903. 1914 finally took over at the TU Berlin the chair of physics.
He was a visiting professor in 1928 at the University of Madrid.
As a scientist, he worked on the theory of elasticity, potential theory, theoretical mechanics, integral equations, with the telegraph equation and other problems of electrical engineering and quantum mechanics.
Grain was known for his attempts to telegraphy. A first " reasonably acceptable " (grain ) transfer of an image over a telephone line (Munich -Nuremberg- Munich) he succeeded already in 1904. He used while the selenium cell as a sampling instrument and the Nernst lamp as a light source. On October 17, 1906, he was a portrait by telegraphic transmission over 1800 km ship. At the naturalist Congress in Vienna showed grain 1913, the first successful picture telegraphic transmission of a cinematographic recording.
Media attention in 1923, he succeeded in transmitting an image of Pope Pius XI. across the Atlantic. From 1928 his system at the German police has been introduced.
Since grain was of Jewish ancestry, he was dismissed in 1933 from his position by the Nazis, but emigrated in 1939 with his family over to the U.S. from Mexico.
There he got a chair of physics and mathematics at Stevens Institute of Technology in Hoboken, New Jersey.
In 1930 he became an honorary doctorate from the Technical University of Wroclaw.
- Electrical remote photography and the like. 2nd edition, S. Hirzel, Leipzig, 1907.