Heisenberg's speech notes from the 1942 Harnack Haus conference were recovered from KGB archives by Rainer Karlsch and published in 2005. These reveal that Heisenberg actively promoted development of an atomic bomb to fellow scientists, military chiefs and political leaders at that conference.
Luftwaffe General Field Marshall Erhard Milch recalled in his memoirs that when he asked Heisenberg at the conference how big such a bomb would need to be, Heisenberg replied no bigger than a pineapple. Heisenberg called for establishment of three different research projects
- Uranium 235 Enrichment
- Nuclear reactors to obtain Plutonium ("eka-Osmium")
- Harvesting Protactinium 233
Heisenberg was personally involved with research to develop nuclear reactors but because of his expertise in Matrix theory of transmutation he was also employed as a consultant to Forschungsstelle-D at Bisingen. This was the connection between Heisenberg and Bohr. Before the war Bohr had been published for his experiments with transmutation of Protactinium from Thorium. Heisenberg was trying to acquire Bohr's knowledge for the German war effort.
Various OSS reports corroborated this based on intelligence smuggled to Switzerland from Reichstag official Dr Erwin Respondek during 1943.
On 22 April 1945 the US 1269th Engineers Battalion attached to ALSOS captured and dismantled an advanced 23 MeV syncrotron device at Bisingen. The ALSOS mission also captured a 1.8MeV Van der Graff generator at Tubingen not far away. These were involved with efforts by Otto Hahn to transmute Thorium which also involved use of the Paris cyclotron from 1941.
The informant of this was Dr Ing. Ernst Nagelstein [informant H-98] who was interrogated 1st November 1944 in Switzerland by Goudsmitt and Wardenberg.
Thus to suggest Heisenberg was trying to prevent Nazi development of the Bomb is either misleading or at best ignorant of the truth.
Heisenberg was not a central figure in the Nazi atomic bomb project. That accolade belongs to prof Kurt Deibner who headed a rival and far more secret project for Army Ordnance (Heereswaffenamt) to develop an atomic bomb.
Postwar focus on Heisenberg misses the point entirely that Heisenberg himself was not key to the Geramn Atomic bomb project and in fact was quite peripheral and largely unaware of Diebner's achievements. Hesienberg was a vain, arrogant man who thought himself superior to other scientists and thus he perhaps saw himself at the centre of Germany's nuclear efforts, but this was light years from the truth.