Things have to start from the situation at that time. 1943 It was the climax of World War II, and both Germany and the United States were stepping up research and development of atomic bombs. Due to the tension in Europe and Hitler's persecution, many European scientists went to America. Bohr, the leader of Copenhagen School, insisted on staying in Copenhagen. Although the Germans occupied Denmark in 1940, Bohr and his colleagues were able to continue their research. Like Einstein, Bohr opposed all violence, but he naively believed that war and persecution could stop as long as the parties pleaded with Hitler.
Fearing that the Nazis would build an atomic bomb first, the allies were very anxious. In terms of atomic nuclear fission, Bohr completed the nuclear fission experiment in 1943, pointing out that only uranium with atomic weight of 235 can be induced by slow neutrons. Both the Allies and the Nazis knew Bohr's weight. Now Bohr is under the supervision of the Germans. If he is brought to Germany by the Nazis to serve them, the Nazis may take the lead in building an atomic bomb.
Although Bohr was unwilling to serve the Germans who occupied the motherland, the allies were still extremely worried. Therefore, the allies secretly urged Bohr to go to England through his close friends, and ensured that he could get a job with "high spirits". Bohr doesn't want to leave his motherland. He won't leave as long as he can stay. However, the situation in Denmark is getting worse. The Germans forced the Danish government to provide a large number of military supplies, madly pursued Danish patriots and shot and killed rebellious civilians and Jews. 1943 In August, the Nazis announced the implementation of the wartime law, and Bohr was in danger of being arrested at any time. After the war, people learned from the Nuremberg trial that the Nazis did intend to arrest Bohr on the day when the wartime decree was announced.
Looks like Bohr's leaving. On September 29th, all the paper documents that could not fall into Nazi hands were destroyed. But what about the Nobel gold medal that Frank and Lowe stored here? Obviously, they can't be taken away. A close call. Bohr put two medals in "aqua regia". Aqua regia is a mixture of concentrated nitric acid and concentrated hydrochloric acid. The gold medal gradually became smaller and soon disappeared. Bohr poured these "aqua regia" with gold medals into humble bottles and put them on the shelves with unimportant items.
Many stories about this period have been misinformed. The most obvious point is that Bohr ruined his Nobel gold medal. In fact, his 1922 gold medal has long been donated to Finland. After the war, people raised gold and recast another one for Bohr. Laue and Frank were the winners of 19 14 and 1925 respectively. They are also Bohr's good friends. They put the medal in Bohr's research institute because they were worried about losing it because of the war. Frank in particular was hated by the Nazis.
Two other stories have been exaggerated. Bohr said that when he left Copenhagen, he planned to take away the heavy water in the institute. According to the most popular saying, Bohr hid heavy water in an ordinary beer bottle. But I took the wrong bottle in a hurry and took a bottle of beer to Sweden. The story also said that Britain later took decisive action to rescue the bottle of heavy water from the refrigerator of the institute. The actual situation is not so romantic. Heavy water is in the cyclotron. However, a lost paper by Bohr has never been found. It is said that this lost manuscript contains all the secrets of the atomic bomb, which is also an exaggeration.
At the end of 1943, Heisenberg, Bohr's favorite pupil, the founder of the uncertainty principle and the core figure in the development of the German atomic bomb, visited the Bohr Institute in Denmark and thought it was of no value to the German war. However, the Danish underground party thought that the Germans would use it to study secret weapons, so they placed a lot of explosives and prepared to blow up the institute at a dangerous moment.
Thanks to Bohr's timely letter from the United States, the institute was preserved. You know, besides expensive instruments and equipment, there are two Nobel gold medals hidden there! 1On August 25th, 945, just after the Second World War, the Boers returned to their hometown. Walking into the intact Bohr Institute of Theoretical Physics, Bohr saw at a glance that among the many bottles on a shelf, there was a bottle full of yellow liquid. Dissolved in it is the Nobel gold medal. Later, it was restored and expelled and returned to their owners.