Ernst Back (21.10.1881 - 20.07.1959) was a German experimental physicist. He was born in Freiburg. He studied law at the universities of Strasbourg, Berlin and Munich, graduating from the last of these in 1906. In 1908 he gave up his career as a lawyer and took up experimental physics under F. Paschen at the University of Tübingen. In 1908-14, 1920-26 and 1936—48 he worked at that university (from 1936 as professor).
His research concerned atomic physics and spectroscopy. In 1912, together with F. Paschen, he discovered the simplification of the pattern of the Zeeman splitting of spectral lines in strong magnetic fields (the Paschen-Back effect).