J. Hans D. Jensen

 

Famous for his work on the German nuclear energy project, which is more popularly known as the Uranium Club, J. Hans D. Jensen was responsible for making contributions to the separation of uranium isotopes. He was a German nuclear physicist who was one of the notable names during World War II. Of note, he is also a Nobel Prize for Physics winner in 1963 where he shared the award with Maria Goeppert-Mayer, when they proposed the model for the nuclear shell which he devised in 1949. Together with the American scientist Goeppert-Mayer, they wrote the book called Elementary Theory of Nuclear Shell Structure, which explained their findings.

Early Life and Educational Background

J. Hans D. Jensen was born Johannes Hans Daniel Jensen on the 25th of June in 1907, and he was the son of Karl Jensen who was a gardener, and Helene Ohm Jensen. His earliest academic interests lay in philosophy, physical chemistry, and mathematics. He studied these courses starting in 1926 at the Universities of Hamburg and Freiburg. There, he was able to obtain his Ph.D. in physics in 1932. He was coached by Wilhem Lenz, a German physicist who was known for his invention of the Ising model. Jensen was able to complete his Habilitation at the University of Hamburg in 1936.

Career and Academic Involvements

He had the chance to work as one of the scientific assistants at the Institute of Theoretical Physics in the University of Hamburg. In 1936, he was able to obtain his D. Sc. from Hamburg and he became one of the Privatdozents at the same university. During his time as a Privatdozent at the University of Hamburg, he began working with the director of the physical chemistry department, Paul Harteck. Paul Harteck had also been the advisor of the Heereswaffenamt or HWA, Army Ordinance Office for explosives.

Paul Harteck, with his assistant Wilhelm Groth, got in touch with the Reich Ministry of War or Reichskriegsministerium (RKM) on the 24th of April in 1939 and they told the authorities of how nuclear chain reactions may be of use for military applications. It was Paul Harteck who brought Jensen into the Uranverein or Uranium Club which started on the first of September in 1939—the same day the Nazis invaded Poland and initiated The Second World War. Together with Harteck, Jensen was able to develop the double centrifuge which was based on a rocking process that facilitated the necessary separation effect.

In 1941, Jensen became the Professor of Theoretical Physics in Hannover’s Technische Hochschule. He became an extraordinarius professor in 1946 at the same university which is now known as the University of Hanover. He had a notable academic career, and in 1949 he was one of the appointed professors at University of Heidelberg. Two years earlier, he had been honored with a professorship at the University of Hamburg, and a year before that, he had a doctorate h.c. from the Technische Universitat Hannover.

Jensen had also been one of the members of the Heidelberg Academy of Sciences which he joined in 1947. He was one of the corresponding members of the Max Planck Gesellschaft which he became a part of in 1960, and he was also one of the members of the Sacri Romani Imperii Academia Naturae Coriosorum, which he joined in 1964.

His other academic involvements included being one of the visiting professors at the University of Wisconsin in 1951, in Princeton’s Institute of Advanced Study and the University of California at Berkeley both in 1952, the California Institute of Technology and the Indiana University in 1953, the University of Minnesota in 1956, and he also visited the University of California in La Jolla in 1961. Because of his contributions to science, especially in the field of physics, he was able to make a name for himself and had the opportunity to educate students outside of Europe as well.

Political Involvement

Jensen’s time had been when Hitler was rising in power, and choosing sides was necessary for people, especially for those who were able to make contributions for the movement. Membership for the Nationalsozialistischer Deutscher Dozentenbund, which was also known as the National Socialist German University Lecturers League or NSDDB, was advantageous for those looking to further their career in academics. Although all of the German universities were under the influence of politics, some were not as strict when it came to enforcing the needed membership to the NSDDB, and this was the case in the University of Hamburg. He was still, however, one of the members of the NSDDB and this went on for three years.

The NSLB or the National Socialist Teachers League expressed their sentiments to Jensen—that he be active in their cause, and this was what they got from him. When the Second World War ended, the denazification process began and when it was time for Jensen to face the proceedings, he went to Werner Heisenberg for help. Heisenberg was one of the most prominent members of the Uranium Club, and it was Heisenberg who testified for Jensen’s character. This testimony was necessary for the acquisition of his whitewash certificate or Persilschein. Heisenberg had been a powerful man to approach when there is a need for this document, since he was never a member of the National Socialist German Workers Party or the NSDAP. For Jensen, Heisenberg wrote the needed documentation and stated that Jensen did indeed join the party organizations so that he would be able to avoid the difficulties posed by political affiliations or lack thereof for someone in the academia.

Jensen had been the recipient of several other honors apart from the Nobel Prize in Physics. These include those which he received from the universities he taught at, and he also became one of the honorary citizens of Fort Lauderdale in Florida. His many achievements gained him a respected name in the United States despite having been previously affiliated with Nazi movements. He was never able to get married, and he died in 1973 at Heidelberg, Germany.