Early years From 1909 to 1910, Esau was a volunteer at the radio transmission division of the Berlin telegraph battalion. From 1910 to 1912, he was teaching assistant at the
Martin-Luther-Universität Halle-Wittenberg. From 1914, he was on active duty with the German military in
Togo; he became a prisoner of war of the French and did not return to Germany until 1918. On the initiative of
Erich Schumann, the
Reichsforschungsrat (RFR, Reich Research Council) was inaugurated on 16 March 1937 by Reich Minister
Bernhard Rust of the
Reichserziehungsministerium (REM, Reich Education Ministry). The RFR was set up to centralize planning for all basic and applied research in Germany, with the exception of aeronautical research, which was under the supervision of Reich Marshal
Hermann Göring. Support for research was decided by the heads of 13 special sections of the RFR (Fachspatenleiter). Esau was a member of the RFR from its inception, and he was head of the physics section (Fachspatenleiter für Physik), which included mathematics, astronomy, and meteorology. From this position in the RFR, he would play major roles in the
German nuclear energy project, sometimes also referred to as the
Uranverein (Uranium Club). In 1938, Esau was appointed Professor of Military Telecommunications Technology in the Faculty of Military Engineering, which had recently been founded at the Technische Hochschule Berlin (today, the
Technische Universität Berlin), in
Berlin-Charlottenburg.
World War II and the Uranverein Shortly after the discovery of
nuclear fission in December 1938/January 1939, the
Uranverein, i.e., the
German nuclear energy project, had an initial start in April before being formed a second time under the
Heereswaffenamt (HWA, Army Ordnance Office) in September.
First Uranverein Paul Harteck was director of the physical chemistry department at the
University of Hamburg and an advisor to the
Heereswaffenamt (HWA, Army Ordnance Office). On 24 April 1939, along with his teaching assistant
Wilhelm Groth, Harteck made contact with the
Reichskriegsministerium (RKM, Reich Ministry of War) to alert them to the potential of military applications of nuclear chain reactions. Two days earlier, on 22 April 1939, after hearing a colloquium paper by
Wilhelm Hanle on the use of
uranium fission in a
Uranmaschine (uranium machine, i.e.,
nuclear reactor),
Georg Joos, along with Hanle, notified Wilhelm Dames, at the
Reichserziehungsministerium (REM, Reich Ministry of Education), of potential military applications of nuclear energy. The communication was given to Abraham Esau, head of the physics section of the
Reichsforschungsrat (RFR, Reich Research Council) at the REM. On 29 April, a group, organized by Esau, met at the REM to discuss the potential of a sustained
nuclear chain reaction. The group included the physicists
Walther Bothe,
Robert Döpel,
Hans Geiger,
Wolfgang Gentner (probably sent by
Walther Bothe),
Wilhelm Hanle,
Gerhard Hoffmann, and Georg Joos;
Peter Debye was invited, but he did not attend. After this, informal work began at the
Georg-August University of Göttingen by Joos, Hanle, and their colleague Reinhold Mannfopff; the group of physicists was known informally as the first
Uranverein (Uranium Club) and formally as
Arbeitsgemeinschaft für Kernphysik. The group's work was discontinued in August 1939, when the three were called to military training.
Second Uranverein The second
Uranverein began after the
Heereswaffenamt squeezed out the
Reichsforschungsrat of the
Reichserziehungsministerium and started the formal German nuclear energy project under military auspices. The second
Uranverein was formed on 1 September 1939, the day World War II began, and it had its first meeting on 16 September 1939. The meeting was organized by
Kurt Diebner, advisor to the HWA, and held in Berlin. The invitees included
Walther Bothe,
Siegfried Flügge,
Hans Geiger,
Otto Hahn,
Paul Harteck, Gerhard Hoffmann,
Josef Mattauch, and
Georg Stetter. A second meeting was held soon thereafter and included
Klaus Clusius,
Robert Döpel,
Werner Heisenberg, and
Carl Friedrich von Weizsäcker. Also at this time, the
Kaiser-Wilhelm Institut für Physik (KWIP, Kaiser Wilhelm Institute for Physics, after World War II the
Max Planck Institute for Physics), in
Berlin-Dahlem, was placed under HWA authority, with Diebner as the administrative director, and the military control of the nuclear research commenced. When it was apparent that the nuclear energy project would not make a decisive contribution to ending the war effort in the near term, control of the KWIP was returned in January 1942 to its umbrella organization, the
Kaiser-Wilhelm Gesellschaft (KWG, Kaiser Wilhelm Society, after World War II the
Max-Planck Gesellschaft), and HWA control of the project was relinquished to the RFR in July 1942. The nuclear energy project thereafter maintained its
kriegswichtig (important for the war) designation and funding continued from the military. On 9 June 1942,
Adolf Hitler issued a decree for the reorganization of the RFR as a separate legal entity under the
Reichsministerium für Bewaffnung und Munition (RMBM, Reich Ministry for Armament and Ammunition, after autumn 1943 the Reich Ministry for Armament and War Production); the decree appointed Reich Marshal
Hermann Göring as the president. The reorganization was done under the initiative of Reich Minister for Armament and Ammunition
Albert Speer; it was necessary as the RFR under Minister Bernhard Rust was ineffective and not achieving it purpose. It was the hope that Göring would manage the RFR with the same discipline and efficiency as he had in the aviation sector. On 8 December 1942, Abraham Esau was appointed as
Hermann Göring's Bevollmächtiger (plenipotentiary) for nuclear physics research under the RFR – at this point, Esau was in charge of the German nuclear energy project. At the end of 1943, Esau resigned as plenipotentiary of nuclear physics; in December,
Walther Gerlach replaced him as plenipotentiary for nuclear physics and as head of the physics section of the RFR. As of 1 January 1944, Esau, replacing
Johannes Plendl, became the plenipotentiary of the high-frequency engineering and radar working group (
A. G. Hochfrequenzphysik). In the final analysis, placing the RFR under Göring's administrative control had little effect on the German nuclear energy project. Over time, the HWA and then the RFR controlled the German nuclear energy project. The most influential people were
Erich Schumann, Abraham Esau,
Walther Gerlach, and
Kurt Diebner. During World War II, Esau was one of the most powerful and influential physicists in Germany. Even after Esau left his position as plenipotentiary for nuclear physics and head of the physics section at the RFR at the end of 1942, he continued to have significant authority and influence as president of the
Physikalisch-Technische Reichsanstalt, as is attested to by the fact that he was able to continue research efforts for the
Urainverein under the highest priority level for urgent development projects (
Dringlichkeitsentwicklung, DE).
Post-World War II After the war, the Americans turned Esau over to the Dutch to stand trial for his involvement in the plunder of research facilities of the electronics firm
Philips. He was acquitted and expelled in 1948. Later, he was tried and convicted
in absentia; without a conviction, the Dutch could not make a legal claim for damages from Germany. Thanks to support from Leo Brandt, a science policy-maker of
North Rhine-Westphalia, Esau was able to establish himself back into the German scientific community. From 1949, Esau was a visiting professor of short-wave technology at the
RWTH Aachen University. From 1953, he was also head of the Institute of High-Frequency Engineering of the German Aeronautical Research Institute in
Mülheim an der Ruhr. Esau died in
Düsseldorf. ==Honors==