Hedwig Kohn

Hedwig Kohn
Kohn in her laboratory, 1912.
Born	(1887-04-05)5 April 1887 Breslau, German Empire (now Wrocław, Poland)
Died	Durham, North Carolina, U.S.
Citizenship	German, American
Alma mater	Breslau University
Scientific career
Fields	Physics
Institutions	Breslau University University of North Carolina Wellesley College Duke University
Thesis	(1913)
Doctoral advisors	Otto Lummer, Rudolf Ladenburg

Hedwig Kohn (5 April 1887 – March 26, 1964) was a German physicist who was one of only three women to obtain habilitation, the qualification for university teaching of physics in Germany before World War II. She was forced to leave Germany during the Nazi regime due to her Jewish heritage and continued teaching after ultimately settling in the United States.

Biography

Early 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.^[a] 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.^[a] She stayed at the university's Physics Institute during World War I and obtained her habilitation in 1930.^[a]

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. 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,^[a] 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.^[a] 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 significantly unwell.^[a] After recovering, Kohn taught at the Women's College of the University of North Carolina at Greensboro for a year and a half.^[a]

In 1942, she began teaching at Wellesley College in Massachusetts.^[a] Kohn established a research laboratory for flame spectroscopy while at the college.^[a]

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.^[a] 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.^[a] She worked there until very shortly before her death in 1964.^[a]

Legacy

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. 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 1980s. Two of her students became professors in Germany.

Google Doodle

To commemorate her 132nd birth anniversary on 5 April 2019, the Google Doodle of the day paid Dr. Kohn homage.

Published works

• 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. In Band II, Chapter 22, Photometrie. 1104–1320; Chapter 25, Temperaturbestimmung auf Grund von Strahlungsmessungen. 1428–1469; Chapter 26, Ziele und Grenzen der Lichttechnik. 1470–1482.
• Kohn, Hedwig (1932). Umkehrmessungen an Spektrallinien zur Bestimmung der Gesamtabsorption und der Besetzungszahlen angeregter Atomzustände. Vol. 33. Phys. Zeitschrift. pp. 957–963.

Further reading

• 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. {{cite book}}: Cite has empty unknown parameter: |1= (help)
• "Hedwig Kohn Photo Collection". American Institute of Physics, Emilio Segrè Visual Archives. Retrieved April 5, 2019.

External links

• doodle "Google celebrates Hedwig Kohn's 132nd Birthday with colorful goldenwaffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles waffles doodle". Retrieved 5 April 2019. {{cite web}}: Check |url= value (help)