James Franck

James Franck (26 August 1882 – 21 May 1964) was a German physicist who, along with Gustav Hertz, conducted the Franck–Hertz experiment in 1914, providing the first electrical confirmation of quantized energy states in atoms and supporting Niels Bohr's model of the atom. For this discovery of the laws governing electron impacts on atoms, Franck shared the 1925 Nobel Prize in Physics with Hertz. Born in Hamburg to a Jewish family, he studied at the universities of Heidelberg, Berlin, and Göttingen, becoming a professor and director of the physics institute at Göttingen, where he advanced experimental atomic physics amid the early quantum revolution.

In 1933, despite exemption from Nazi racial laws due to his World War I service, Franck resigned his position at Göttingen in protest against the regime's dismissal of Jewish scientists, publicly declaring his opposition to maintain scientific integrity and emigrating to the United States. There, he joined Johns Hopkins University and later the University of Chicago, shifting toward physical chemistry and photosynthesis research while contributing to the Manhattan Project as director of the chemistry division at the Met Lab. In June 1945, Franck chaired a committee that produced the Franck Report, recommending against surprise atomic bombings on Japan and advocating a public demonstration to foster international nuclear control, reflecting his ethical concerns over indiscriminate use of the weapon. After the war, he returned to Göttingen in 1952, continuing work until his death.

James Franck was born on August 26, 1882, in Hamburg, Germany, into a Sephardic Jewish family whose forebears had immigrated from Portugal in the late 16th century and resided in the city for over two centuries. His father, Jacob Franck, worked as a banker and upheld religious traditions while favoring a commercial path for his son in keeping with family heritage, whereas his mother, Rebecka (née Nachum-Drucker), descended from a line of rabbis. The household reflected the assimilated, middle-class status of Hamburg's Jewish community in the pre-World War I era, prioritizing education alongside pragmatic economic pursuits in a stable urban setting.

Franck began his formal schooling at the Wilhelm Gymnasium in Hamburg in the fall of 1891, where instruction emphasized classical studies including Latin, Greek, English, and French, typical of the rigorous Gymnasium system. Despite this curriculum's focus on humanities, Franck exhibited an early affinity for physics from childhood, pursuing independent interests in the subject contrary to his father's business-oriented expectations and amid the empirical mindset reinforced by familial commerce. This environment in Hamburg's prosperous Jewish milieu nurtured his foundational curiosity in scientific principles through self-motivated reading and observation, prior to advanced studies.