Editing Niels Bohr (section)

=== Meeting with Heisenberg ===
[[File:Heisenbergbohr.jpg|thumb|right|Werner Heisenberg (left) with Bohr at the Copenhagen Conference in 1934|alt=A young man in a white shirt and tie and an older man in suit and tie sit at a table, on which there is a tea pot, plates, cups and saucers and beer bottles.]]
Bohr was aware of the possibility of using uranium-235 to construct an [[atomic bomb]], referring to it in lectures in Britain and Denmark shortly before and after the war started, but he did not believe that it was technically feasible to extract a sufficient quantity of uranium-235.{{sfn|Gowing|1985|pp=267–268}} In September 1941, Heisenberg, who had become head of the [[German nuclear energy project]], visited Bohr in Copenhagen. During this meeting the two men took a private moment outside, the content of which has caused much speculation, as both gave differing accounts.
According to Heisenberg, he began to address nuclear energy, morality and the war, to which Bohr seems to have reacted by terminating the conversation abruptly while not giving Heisenberg hints about his own opinions.{{sfn|Heisenberg|1984|p=77}} [[Ivan Supek]], one of Heisenberg's students and friends, claimed that the main subject of the meeting was [[Carl Friedrich von Weizsäcker]], who had proposed trying to persuade Bohr to mediate peace between Britain and Germany.<ref>{{cite web |author=Portal Jutarnji.hr |date=19 March 2006 |url=http://jutarnji.hr/clanak/art-2006,3,19,supek_intervju,17440.jl?artpg=1 |title=Moj život s nobelovcima 20. stoljeća |trans-title=My Life with the 20th century Nobel Prizewinners |work=[[Jutarnji list]] |language=hr |access-date=13 August 2007 |quote={{lang|hr |Istinu sam saznao od Margrethe, Bohrove supruge.&nbsp;... Ni Heisenberg ni Bohr nisu bili glavni junaci toga susreta nego Carl Friedrich von Weizsaecker.&nbsp;... Von Weizsaeckerova ideja, za koju mislim da je bila zamisao njegova oca koji je bio Ribbentropov zamjenik, bila je nagovoriti Nielsa Bohra da posreduje za mir između Velike Britanije i Njemačke.}} [I learned the truth from Margrethe, Bohr's wife.&nbsp;... Neither Bohr nor Heisenberg were the main characters of this encounter, but Carl Friedrich von Weizsaecker. Von Weizsaecker's idea, which I think was the brainchild of [[Ernst von Weizsäcker|his father]] who was [[Ribbentrop]]'s deputy, was to persuade Niels Bohr to mediate for peace between Great Britain and Germany.] |archive-date=28 June 2009 |archive-url=https://web.archive.org/web/20090628102407/http://jutarnji.hr/clanak/art-2006,3,19,supek_intervju,17440.jl?artpg=1  }} An interview with Ivan Supek relating to the 1941 Bohr&nbsp;– Heisenberg meeting.</ref>

In 1957, Heisenberg wrote to [[Robert Jungk]], who was then working on the book ''[[Brighter than a Thousand Suns: A Personal History of the Atomic Scientists]]''. Heisenberg explained that he had visited Copenhagen to communicate to Bohr the views of several German scientists, that production of a nuclear weapon was possible with great efforts, and this raised enormous responsibilities on the world's scientists on both sides.<ref>{{cite web |url=http://www.childrenofthemanhattanproject.org/MP_Misc/Bohr_Heisenberg/bohr_2.htm |title=Letter From Werner Heisenberg to Author Robert Jungk |access-date=21 December 2006 |last=Heisenberg |first=Werner |author-link=Werner Heisenberg |publisher=The Manhattan Project Heritage Preservation Association, Inc. |url-status=usurped |archive-url = https://web.archive.org/web/20061017232033/http://childrenofthemanhattanproject.org/MP_Misc/Bohr_Heisenberg/bohr_2.htm <!-- Bot retrieved archive --> |archive-date = 17 October 2006}}</ref> When Bohr saw Jungk's depiction in the Danish translation of the book, he drafted (but never sent) a letter to Heisenberg, stating that he deeply disagreed with Heisenberg's account of the meeting,<ref>"I am greatly amazed to see how much your memory has deceived you in your letter to the author of the book"</ref> that he recalled Heisenberg's visit as being to encourage cooperation with the inevitably victorious Nazis<ref>"...you and Weizsäcker expressed your definite conviction that Germany would win and that it was therefore quite foolish for us to maintain the hope of a different outcome of the war and to be reticent as regards all German offers of cooperation'</ref> and that he was shocked that Germany was pursuing nuclear weapons under Heisenberg's leadership.<ref>"...you spoke in a manner that could only give me the firm impression that, under your leadership, everything was being done in Germany to develop atomic weapons... [...] If anything in my behaviour could be interpreted as shock, it did not derive from such reports but rather from the news, as I had to understand it, that Germany was participating vigorously in a race to be the first with atomic weapons."</ref><ref>{{cite web |url=http://www.nbarchive.dk/collections/bohr-heisenberg/ |title=Release of documents relating to 1941 Bohr-Heisenberg meeting |access-date=4 June 2007 |archive-url = https://web.archive.org/web/20170217070953/http://www.nbarchive.dk/collections/bohr-heisenberg/ |archive-date =17 February 2017|last=Aaserud |first=Finn |date=6 February 2002 |publisher=Niels Bohr Archive}}</ref>

[[Michael Frayn]]'s 1998 play ''[[Copenhagen (play)|Copenhagen]]'' explores what might have happened at the 1941 meeting between Heisenberg and Bohr.<ref>{{cite web |url=http://www.complete-review.com/reviews/fraynm/cophagen.htm |title=Copenhagen – Michael Frayn |publisher=The Complete Review |access-date=27 February 2013 |archive-date=29 April 2013 |archive-url=https://web.archive.org/web/20130429014906/http://www.complete-review.com/reviews/fraynm/cophagen.htm |url-status=live }}</ref> [[Copenhagen (2002 film)|A television film version]] of the play by the [[BBC]] was first screened on 26 September 2002, with [[Stephen Rea]] as Bohr. With the subsequent release of Bohr's letters, the play has been criticised by historians as being a "grotesque oversimplification and perversion of the actual moral balance" due to adopting a pro-Heisenberg perspective.<ref>{{cite journal|title='Copenhagen': An Exchange|first1=Gerald |last1=Holton |author-link1=Gerald Holton |first2=Jonothan |last2=Logan |first3=Thomas |last3=Powers |author-link3=Thomas Powers |first4=Michael |last4=Frayn |journal=The New York Review of Books |author-link4=Michael Frayn |publisher=The New York Review|date=11 April 2002|volume=49 |issue=6 |url=https://www.nybooks.com/articles/2002/04/11/copenhagen-an-exchange/ |access-date=18 May 2024}}</ref>

The same meeting had previously been dramatised by the BBC's ''[[Horizon (BBC TV series)|Horizon]]'' science documentary series in 1992, with [[Anthony Bate]] as Bohr, and Philip Anthony as Heisenberg.<ref>''Horizon: Hitler's Bomb'', [[BBC Two]], 24 February 1992</ref> The meeting is also dramatised in the Norwegian/Danish/British miniseries ''[[The Heavy Water War]]''.<ref>{{cite web |url=http://www.channel4.com/programmes/the-saboteurs/episode-guide/ |title=The Saboteurs – Episode Guide |publisher=Channel 4 |access-date=3 March 2017 |archive-date=3 March 2017 |archive-url=https://web.archive.org/web/20170303123755/http://www.channel4.com/programmes/the-saboteurs/episode-guide/ |url-status=live }}</ref>