GAIM 2021 Featured Woman: Hedwig Kohn, Physicist

“Hedwig, they’re burning the temple!” One of Hedwig’s students had burst through the door of her small office in the back of the Physics Institute in Breslau, Germany. Hedwig had already lost her teaching position to anti-semitic laws just five years prior, but this was the first sign of outright violence. The date was November 9th, 1938, and supporters of the Nazi-lead government were burning the city. She decided she needed to escape.

Hedwig Kohn, a German Jew and one of the only female physics scholars of the early 1900s, was no stranger to hurdles. She began attending Breslau University in 1907 when women were not permitted to enroll, insisting on auditing class until the next year when women were finally given the go ahead. She earned her doctorate only six years later and was recruited by her advisor, Otto Lummer, to work with him on flame spectroscopy and radiometry, the measure of electromagnetic radiation. When World War I erupted, Hedwig poured herself into teaching and research to the admiration of students and colleagues alike. This eventually earned her a medal for her service. 

Breslau (Wroclaw) University

In 1930, Hedwig became one of only three women in Germany to receive Habilitation, the equivalent of a postdoctoral position. This allowed her to serve as a professor until 1933, when the Nazi government barred her and other Jews from holding any kind of position of authority. In spite of this law, Hedwig continued to informally advise her students, eight of whom received their doctorates under her guidance the same year that she finally found a route to escape the hostility of Nazi Germany. A lecturer at Breslau, Rudolf Ladenburg, had helped to direct Kohn’s research while she was a doctoral student. Now an esteemed physicist at Princeton, he became a fierce advocate for her, recruiting numerous organizations and individuals who went to bat on her behalf to secure both a Swedish and an American visa. 

19th Century Spectroscope

Upon hearing of the visas granted to her, Hedwig immediately departed to Sweden and then to America in a long and arduous journey to report to her position at The Women's College of the University of North Carolina. After a year and a half there she moved on to Wellesley College in Massachusetts, where she became a preeminent physicist and professor. There, she continued to work in the fields of flame spectroscopy and radiometry, making great strides and winning awards for her research. Even after her retirement from teaching, she moved back to North Carolina to continue her research at Duke University. In total, she published 20 journal articles, a textbook, and 1 patent over the course of her career. As a result of her work, Kohn is considered one of the founding physicists of radiometry. She remained in the US for the rest of her career in spite of honors and awards granted to her by post-war Germany, accepting research contracts and continuing to advise doctoral and postdoctoral students until her death in 1964.