Karl Eugen Julius Wirtz (24 April 1910 – 12 February 1994) was aGermannuclear physicist, born inCologne. He was arrested by the allied British and American Armed Forces and incarcerated atFarm Hall for six months in 1945 underOperation Epsilon.

From 1929 to 1934, Wirtz studiedphysics,chemistry, andmathematics at theUniversity of Bonn, theAlbert Ludwigs University of Freiburg, and theUniversity of Breslau. He received his doctorate in 1934 under C. Schäfer. From 1935 to 1937, he was a teaching assistant toCarl-Friedrich Bonhoeffer at theUniversity of Leipzig. During this period, he became a member of theNationalsozialistischer Lehrerbund (NSLB,National Socialist Teachers League), but not theNationalsozialistische Deutsche Arbeiterpartei (NSDAP, National Socialist German Workers Party).

Some of the more established scientists, such asMax von Laue, could demonstrate more autonomy than the younger and less established scientists.^[1] This was, in part, due to political organizations, such as theNationalsozialistischer Deutscher Dozentenbund (NSDDB, National Socialist German University Lecturers League), whose district leaders had a decisive role in the acceptance of anHabilitationsschrift, which was a prerequisite to attaining the rank ofPrivatdozent necessary to becoming a university lecturer.^[2] Hence joining such organizations became a tactical career consideration. In 1938, he completed hisHabilitation at theHumboldt University of Berlin with a Habilitationsschrift on the electrochemical foundations of electrolyticheavy water production.^[3]

In 1937, Wirtz became a staff scientist at theKaiser Wilhelm Institute for Physics, an institute under theKaiser-Wilhelm-Gesellschaft ) and located inDahlem-Berlin. In 1940, he worked on the horizontal layer reactor design withFritz Bopp andErich Fischer. In 1941, he also became aPrivatdozent at theHumboldt University of Berlin.

In 1944, Wirtz was appointed head of the experimental department at the KWIP, which had been moved toHechingen in 1943 to avoid bombing casualties to the personnel. In late spring 1945, Wirtz was arrested by the alliedBritish andAmerican Armed Forces and incarcerated atFarm Hall for six months underOperation Epsilon.^[3]

From 1946, Wirtz worked at theMax-Planck Institut für Physik, which was the renamedKaiser Wilhelm Institute for Physics and had been opened in theBritish Occupation Zone inGöttingen.

From 1948 to 1957, he was also an extraordinarius professor at theUniversity of Göttingen. From 1950, he also became a scientific member of theKaiser-Wilhelm-Gesellschaft.^[3]From 1957 to 1979, Wirtz was an ordinarius professor of physical foundations of reactor technology at theTechnische Hochschule Karlsruhe and director of the Institute of Neutron Physics and Reactor Technology at the Center for Nuclear Research, which was established in 1957 in Karlsruhe. From 1965 to 1967, he was chairman of the scientific council of the Karlsruhe Center for Nuclear Research. From 1974 to 1976, he was dean of the faculty of mechanical engineering at Technische Hochschule Karlsruhe.^[3]

• 1966 – 1968: Executive Vice President of the European Atomic Energy Society and consultant to the West German Government in affairs related to theNuclear Non-Proliferation Treaty.^[3]
• 1972 – 1977: Member of the presiding committee of the Deutsches Atomforum (Atomic Forum).^[3]

The following reports were published inKernphysikalische Forschungsberichte (Research Reports in Nuclear Physics), an internal publication of the GermanUranverein. The reports were classified Top Secret, they had very limited distribution, and the authors were not allowed to keep copies. The reports were confiscated under the AlliedOperation Alsos and sent to theUnited States Atomic Energy Commission for evaluation. In 1971, the reports were declassified and returned to Germany. The reports are available at theKarlsruhe Nuclear Research Center and theAmerican Institute of Physics.^[4][5]

• Erica Cremer and Karl WirtzUntersuchungen des Schwerwassergehaltes einiger technischer Elektrolyseure in Deutschland G-21 (21 June 1940)
• Karl WirtzBericht II. Eine 10-stufige Elektrolyseuranlage zur Gewinnung von schwerem Wasser G-61 (19 January 1940)
• Fritz Bopp,Erich Fischer,Werner Heisenberg,Carl-Friedrich von Weizsäcker, and Karl WirtzUntersuchungen mit neuen Schichtenanordnungen aus U-metall und Paraffin G-127 (March 1942)
• Werner Heisenberg, Fritz Bopp, Erich Fischer, Carl-Friedrich von Weizsäcker, and Karl WirtzMessungen an Schichtenanordnungen aus 38-Metall und Paraffin G-162 (30 October 1942)
• Karl WirtzDie elektrolytische Schwerwassergewinnung in Norwegen G-198 (26–28 February 1942)
• Karl WirtzEinrichtung der Elektrolyse zur Aufbearbeitung von schwerem Wasser G-296 (8 August 1944)
• Fritz Bopp,Walther Bothe, Erich Fischer, Erwin Fünfer, Werner Heisenberg,O. Ritter, and Karl WirtzBericht über einen Versuch mit 1.5 to D₂O und U und 40 cm Kohlerückstreumantel (B7) G-300 (3 January 1945)

• Horst Korsching and Karl WirtzTrennung von Flüssigkeitsgemischen mittels kombinierter Thermodiffusion und Thermosiphonwirkung: Methode vonClusius und Dickel,Naturwissenschaften Volume 27, Number 7, Page 110 (February, 1939)

• Horst Korsching and Karl WirtzTrennung der Zinkisotope durch Thermodiffusion in flussiger Phase (Verlag der Akademie der Wissenschaften, 1939)
• Karl Heinrich Beckurts and Karl WirtzNeutron Physics (Springer-Verlag, New York, NY, 1964)
• Karl Winnacker and Karl WirtzDas unverstandene Wunder: Kernenergie in Deutschland (Econ, 1975)ISBN 3-430-19792-9
• Karl Winnacker and Karl WirtzAtome Illusion ou Miracle? (P.U.F., 1977)
• Karl WirtzLectures on Fast Reactors (Universität Karlsruhe, 1978, 1982)
• Karl Winnacker and Karl WirtzNuclear Energy in Germany (American Nuclear Society, 1993)ISBN 0-89448-018-9

• Bernstein, JeremyHitler’s Uranium Club: The Secret Recording’s at Farm Hall (Copernicus, 2001)ISBN 0-387-95089-3
• Hentschel, Klaus, editor and Ann M. Hentschel, editorial assistant and TranslatorPhysics and National Socialism: An Anthology of Primary Sources (Birkhäuser, 1996)ISBN 0-8176-5312-0
• Hoffmann, DieterBetween Autonomy and Accommodation: The German Physical Society during the Third Reich,Physics in Perspective 7(3) 293-329 (2005)
• Mark WalkerGerman National Socialism and the Quest for Nuclear Power 1939-1949 (Cambridge, 1993)ISBN 0-521-36413-2

• Powers, Thomas, "The Private Heisenberg and the Absent Bomb" (review of Werner and Elisabeth Heisenberg,My Dear Li: Correspondence, 1937–1946, edited by Anna Maria Hirsch-Heisenberg and translated from the German by Irene Heisenberg, Yale University Press, 312 pp., $40.00),The New York Review of Books, vol. LXIII, no. 20 (22 December 2016, pp. 65–67. "[Werner] Heisenberg,Carl Friedrich von Weizsäcker, and... Karl Wirtz [during World War II led] an effort [to prevent] a complete shutdown [of work toward a German atom bomb], which would condemn young physicists to military service... or takeover by Nazi extremists who might think an atomic bomb could still give Hitler a complete victory." (p. 66.) Desiring on ethical grounds to prevent the introduction of nuclear weapons into the world, the key German nuclear physicists "'agreed... not to deny [the feasibility of] an atomic bomb, but... to [argue] that it could not be implemented within a realistic time frame...'" (p. 67.)

• Annotated Bibliography for Karl Wirtz from the Alsos Digital Library for Nuclear Issues

• 1910 births
• 1994 deaths
• German nuclear physicists
• University of Bonn alumni
• Nuclear program of Nazi Germany
• Operation Epsilon
• 20th-century German physicists
• Commanders Crosses of the Order of Merit of the Federal Republic of Germany
• Scientists from Cologne
• Max Planck Society people

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