Editing Werner Heisenberg (section)

==Post-Second World War==
===1945: Alsos Mission===
{{Main|Alsos Mission}}
[[File:Haigerloch-nuclear-reactor ArM.JPG|thumb|upright=1.15|right|Replica of the German experimental nuclear reactor captured and dismantled at Haigerloch]]
The Alsos Mission was an Allied effort to determine whether the Germans had an atomic bomb program and to exploit German atomic-related facilities, research, material resources, and scientific personnel for the benefit of the US. Personnel on this operation generally swept into areas that had just come under control of the Allied military forces, but sometimes they operated in areas still under control by German forces.<ref>{{harvnb|Goudsmit|1986|p= x}}</ref><ref name=pash>[[Boris Pash|Pash, Boris T.]] (1969) ''The Alsos Mission''. Award. pp. 219–241.</ref><ref name=Cassidy1992_491_5000>{{harvnb|Cassidy|1992|pp=491–500}}</ref> Berlin had been a location of many German scientific research facilities. To limit casualties and loss of equipment, many of these facilities were dispersed to other locations in the latter years of the war. The ''Kaiser-Wilhelm-Institut für Physik'' (KWIP, Kaiser Wilhelm Institute for Physics) had been bombed so it had mostly been moved in 1943 and 1944 to [[Hechingen]] and its neighbouring town of [[Haigerloch]], on the edge of the [[Black Forest]], which eventually became included in the French occupation zone. This allowed the American task force of the Alsos Mission to take into custody a large number of German scientists associated with nuclear research.<ref>[[Norman Naimark|Naimark, Norman M.]] (1995) ''The Russians in Germany: A History of the Soviet Zone of Occupation, 1945–1949''. Belkanp. pp. 208–209. {{ISBN|978-0-674-78406-2}}</ref><ref>{{harvnb|Bernstein|2001|pp=49–52}}</ref>

On 30 March, the Alsos Mission reached [[Heidelberg]],<ref>{{cite thesis |last=Mahoney |first=Leo J. |title=A History of the War Department Scientific Intelligence Mission (ALSOS), 1943–1945 |degree=PhD |publisher=Kent State University |year=1981 |oclc=223804966 |page=298}}</ref> where important scientists were captured including [[Walther Bothe]], [[Richard Kuhn]], [[Philipp Lenard]], and [[Wolfgang Gentner]].<ref>{{harvnb|Goudsmit|1986|pp= 77–84}}</ref> Their interrogation revealed that Otto Hahn was at his laboratory in Tailfingen, while Heisenberg and [[Max von Laue]] were at Heisenberg's laboratory in [[Hechingen]], and that the experimental natural uranium reactor that Heisenberg's team had built in Berlin had been moved to Haigerloch. Thereafter, the main focus of the Alsos Mission was on these nuclear facilities in the [[Württemberg]] area.<ref name="Groves-1962">{{cite book |last=Groves|first=Leslie |author-link=Leslie Groves |title=Now it Can be Told: The Story of the Manhattan Project |url=https://archive.org/details/nowitcanbetolds00grov|url-access=registration|location=New York |publisher=Harper & Row |year=1962 |isbn=978-0-306-70738-4 |oclc=537684 |pages=[https://archive.org/details/nowitcanbetolds00grov/page/231 231]}}</ref> Heisenberg was smuggled out from Urfeld, on 3 May 1945, in an alpine operation in territory still under control by elite German forces. He was taken to Heidelberg, where, on 5 May, he met Goudsmit for the first time since the Ann Arbor visit in 1939. Germany surrendered just two days later. Heisenberg would not see his family again for eight months, as he was moved across France and Belgium and flown to England on 3 July 1945.<ref>{{harvnb|Cassidy|1992|pp=491–510}}</ref><ref>{{harvnb|Bernstein|2001|p=60}}</ref><ref name=pash/>

===1945: Reaction to Hiroshima===
Nine of the prominent German scientists who published reports in ''[[Kernphysikalische Forschungsberichte|Nuclear Physics Research Reports]]'' as members of the ''Uranverein''<ref>{{harvnb|Walker|1989|pp=268–274, Reference #40 on p. 262}}</ref> were captured by Operation Alsos and incarcerated in England under [[Operation Epsilon]].<ref>{{harvnb|Bernstein|2001|pp=50, 363–365}}</ref> Ten German scientists, including Heisenberg, were held at Farm Hall in England. The facility had been a [[safe house]] of the British foreign intelligence [[Secret Intelligence Service|MI6]]. During their detention, their conversations were recorded. Conversations thought to be of intelligence value were transcribed and translated into English. The transcripts were released in 1992.<ref>[[Frederick Charles Frank|Frank, Charles]] (1993) ''Operation Epsilon: The Farm Hall Transcripts''. University of California Press.</ref><ref>{{harvnb|Bernstein|2001|pp=xvii–xix}}</ref> On 6 August 1945, the scientists at Farm Hall learned from media reports that the US had dropped an atomic bomb in [[Hiroshima]], [[Japan]]. At first, there was disbelief that a bomb had been built and dropped. In the weeks that followed, the German scientists discussed how the United States might have built the bomb.<ref>{{harvnb|Macrakis|1993|p = 143}}</ref>

The [[Farm Hall transcripts]] reveal that Heisenberg, along with other physicists interned at Farm Hall including Otto Hahn and [[Carl Friedrich von Weizsäcker]], were glad the Allies had won World War II.<ref>{{cite book|last1=Bernstein|first1=Jeremy|title=Hitler's Uranium Club|date=1996|publisher=AIP Press|location=Woodbury NY|page=139}}</ref> Heisenberg told other scientists that he had never contemplated a bomb, only an atomic pile to produce energy. The morality of creating a bomb for the [[Nazi Party|Nazis]] was also discussed. Only a few of the scientists expressed genuine horror at the prospect of nuclear weapons, and Heisenberg himself was cautious in discussing the matter.<ref>{{cite web|title=Transcript of Surreptitiously Taped Conversations among German Nuclear Physicists at Farm Hall (August 6–7, 1945)|url=http://germanhistorydocs.ghi-dc.org/pdf/eng/English101.pdf|publisher=German History in Documents and Images|access-date=26 April 2017|archive-url=https://web.archive.org/web/20170519001219/http://germanhistorydocs.ghi-dc.org/pdf/eng/English101.pdf|archive-date=19 May 2017|url-status=live}}</ref><ref>{{cite web|last1=Sartori|first1=Leo|title=Reviews|url=https://www.aps.org/units/fps/newsletters/2000/october/roct00.html|publisher=American Physical Society|access-date=26 April 2017|archive-url=https://web.archive.org/web/20150915232546/http://www.aps.org/units/fps/newsletters/2000/october/roct00.html|archive-date=15 September 2015|url-status=live}}</ref> On the failure of the German nuclear weapons program to build an atomic bomb, Heisenberg remarked, "We wouldn't have had the moral courage to recommend to the government in the spring of 1942 that they should employ 120,000 men just for building the thing up."<ref>{{harvnb|Macrakis|1993|p = 144}}</ref>

When in 1992 the transcripts were declassified, German physicist [[:de:Manfred Popp|Manfred Popp]] analyzed the transcripts, as well as the documentation of Uranverein. When the German scientists heard about the Hiroshima bomb, Heisenberg admitted that he had never calculated the critical mass of an atomic bomb before. When he subsequently attempted to calculate the mass, he made serious calculation errors. [[Edward Teller]] and [[Hans Bethe]] saw the transcript, and drew the conclusion that Heisenberg had done it for the first time as he made similar errors as they had. Only a week later Heisenberg gave a lecture about the physics of the bomb. He correctly recognized many essential aspects, including the efficiency of the bomb, although he still underestimated it. For Popp, this is proof that Heisenberg did not spend time on a nuclear weapon during the war; on the contrary, he avoided even thinking about it.<ref>{{Cite news |last=POPP |first=Manfred |date=2017-01-04 |title=Darum hatte Hitler keine Atombombe |url=https://www.zeit.de/wissen/geschichte/2016-12/ns-zeit-adolf-hitler-atombombe-entwicklung-werner-heisenberg-kernphysik/komplettansicht |website=Die Zeit.}}</ref><ref>{{Citation |last=Teller |first=Edward |title=Heisenberg, Bohr and the atomic bomb |url=https://www.webofstories.com/people/edward.teller/34?o=SH |access-date=2023-08-02 |language=en}}</ref>