Kohn in her laboratory, 1912.
|Died||26 November 1964 (aged 77)|
|Citizenship||German, American|
|Alma mater||Breslau University|
University of North Carolina
|Doctoral advisors||Otto Lummer, Rudolf Ladenburg|
Hedwig Kohn (5 April 1887 – 26 November 1964) was a German-American physicist who was one of only three women to obtain habilitation (the qualification for university teaching) in physics in Germany before World War II. She was forced to leave Germany during the Nazi regime because she was Jewish. She continued her academic career in the United States, where she settled for the rest of her life.
Born in Breslau (now Wrocław, Poland), Kohn was the daughter of Georg Kohn, a wholesale merchant of fine cloth, and Helene Hancke, a member of a well-to-do family. Her parents were both German Jews.
In 1907, Kohn became the second woman to enter the physics department of Breslau University (Universität Breslau, now University of Wrocław). She obtained her doctorate in physics under Otto Lummer in 1913 and was soon appointed as Lummer's assistant. She stayed at the university's Physics Institute during World War I and obtained her habilitation in 1930.
Kohn was trained by Lummer in the quantitative determination of the intensity of light, both from broad-band sources, such as a "black body", and from the discrete emission lines of atoms and molecules.
Escape from Germany
Kohn was dismissed from her position in 1933 due to Nazi regulations which barred Jews from government service (the Law for the Restoration of the Professional Civil Service). She survived by fulfilling contracts for applied research in the illumination industry until 1938, when she found herself without work or financial resources.
Offered temporary positions at three women's colleges in the United States through the aid of Rudolf Ladenburg, Lise Meitner, Hertha Sponer, the American Association of University Women (AAUW), and many others, Kohn left Germany. She had been given a visa to the United Kingdom in 1939, but it was cancelled because of World War II; she eventually secured a visa to travel to Sweden and immediately went there in July 1940.
On receiving a visa from the United States, she then moved there. The journey to her first position at the Women's College of the University of North Carolina in Greensboro took Kohn through Berlin, Stockholm, Leningrad, Moscow, Vladivostok, Yokohama, San Francisco, and Chicago.
Life in United States
When Kohn arrived in the United States in January 1941, she was seriously ill. After recovering, Kohn taught at the Women's College of the University of North Carolina at Greensboro for a year and a half.
Upon Kohn's retirement as professor in 1952, Hertha Sponer, then professor of physics at Duke University in Durham, North Carolina, offered her a position as a research associate. Kohn set up a laboratory at Duke University and resumed research, where she guided two graduate students to their doctorates and recruited two post-doctoral fellows to assist in her study of flame spectroscopy. She worked there until very shortly before her death in 1964.
Kohn was trained by Otto Lummer in the quantitative determination of the intensity of light, both from broad-band sources, such as a "black body", and from the discrete emission lines of atoms and molecules. She further developed such methods and devised ways of extracting information from intensity measurements and from emission line shapes. She wrote 270 pages in the leading physics text of the 1930s and 1940s in Germany, received one patent, and wrote numerous articles in scientific journals, some of which were still being cited into the 2000s. Two of her students became professors in Germany.
- Müller-Pouillets Lehrbuch der Physik. (II. Auflage), unter Mitwirkung zahlreicher Gelehrter herausgegeben von A. Eucken, O. Lummer (+), E. Wätzmann. In five volumes: I. Mechanik und Akustik; II. Lehre von der strahlenden Energie (Optik); III. Wärmelehre; IV. Elektizität und Magnetismus; V. Physik der Erde und des Kosmos (einschl. Relativitätstheorie). Braunschweig: 1925–1929. Band II, Zweite Hälfte, Erster Teil (Volume II, 2nd half, 1st part), volume editor Karl W. Meissner: 1929.
- Kohn, Hedwig (1929). "Photometrie". Band II (in German) (22): 1104–1320.
- Kohn, Hedwig (1929). "Temperaturbestimmung auf Grund von Strahlungsmessungen". Band II (in German) (25): 1428–1469.
- Kohn, Hedwig (1929). "Ziele und Grenzen der Lichttechnik". Band II (in German) (26): 1470–1482.
- Kohn, Hedwig (1932). Umkehrmessungen an Spektrallinien zur Bestimmung der Gesamtabsorption und der Besetzungszahlen angeregter Atomzustände (in German). 33. Phys. Zeitschrift. pp. 957–963.
- Winnewisser, Brenda P (November 2003). "Hedwig Kohn – eine Physikerin des zwanzigsten Jahrhunderts" [Hedwig Kohn – a physicist of the twentieth century]. Physik Journal (in German): 51–57.
- Winnewisser, Brenda P. (1998). "The Emigration of Hedwig Kohn, Physicist, 1940". Mitteilungen der Österreichischen Gesellschaft für Wissenschaftsgeschichte. (in German): 41–58.
Communications of the Austrian Society for the History of Science
- Winnewisser, Brenda P (2007). "Hedwig Kohn". In Hyman, Paula E.; Ofer, Dalia (eds.). Jewish Women. A Comprehensive Historical Encyclopedia (CD). Jerusalem: Shalvi Publishing. ISBN 978-0827608672.
- Winnewisser, Brenda P. "Hedwig Kohn". Jewish Women's Archive. Retrieved 5 April 2019.
- Kuhn, Thomas S. (7 June 1962). "Oral History Interviews: Hedwig Kohn". American Institute of Physics. Retrieved 5 April 2019.
- "Broadening of Resonance Lines by Various Perturbing Gases Under Flame Conditions". Journal of Quantitative Spectroscopy and Radiative Transfer. 4 (1): 163–176. 1964. doi:10.1016/0022-4073(64)90060-3. Retrieved 5 April 2019.
- "Hedwig Kohn's 132nd Birthday". Google. 5 April 2019. Retrieved 5 April 2019.
- Ryan, Jackson. "Google Doodle celebrates pioneering physicist Hedwig Kohn". CNET. Retrieved 5 April 2019.
- "Google celebrates Hedwig Kohn's 132nd Birthday with colorful doodle". Retrieved 5 April 2019.