German physicist who won a Nobel Prize in 1925 for his experiments on inelastic electron collisions in gasses. He did important work on atomic physics and ultrasound.
He received a doctorate in 1911 while working as an assistant under Heinrich Leopold Rubens from 1911 to 1914.
He worked as a professor at the University of Leipzig after returning to Germany from the Soviet Union in 1955.
He married Ellen, née Dihlmann, in 1919 and together they had two sons, Carl and Johannes.
Another German scientist like him was Albert Einstein.