James Franck

Born into a Jewish banking family in Hamburg, Franck shared the 1925 Nobel Prize in Physics with Gustav Hertz for experiments (the Franck–Hertz experiment) confirming the quantized energy levels of atoms. After the Nazis took power he resigned his Göttingen professorship in 1933 in protest and emigrated to the United States, where at Chicago he turned to the physical chemistry of photosynthesis, clarifying how plants convert light into chemical energy. His refusal to stay under the regime made him an early symbol of principled scientific opposition.