Niels Bohr’s Flight From the Nazis Was a Science Drama
He escaped in the belly of a British fighter
Danish physicist Niels Bohr was a scientific genius who also displayed a coincidental penchant for espionage and intrigue. He employed these skills, along with a bit of science, to foil the Nazi at several turns.
His small crusade began in 1933 after the Nazis came to power in Germany. Over the next few years several scientists fled Germany with Bohr’s help. Many escapees went on to work on the Manhattan Project, including Edward Teller, James Franck and Otto Frisch. Some of them stayed with Bohr in Denmark, working at the Bohr Institute until moving elsewhere.
In April 1940 the Nazis crossed the border into Denmark. Bohr stayed despite the danger. As the Germans marched into Copenhagen, he even deprived them of a bit of the loot they intended to claim.
Max Von Laue and James Franck, both Germans, won the Nobel Prize in physics in 1914 and 1925, respectively. Von Laue openly opposed the Nazis and Franck was Jewish. The Nobel Prize included a large gold medal with the winner’s name plainly inscribed. Both men previously left their medals at Bohr’s Institute for safekeeping, but with the Nazi occupation, the medals seemed as good as gone.
Bohr considered burying them but feared the Germans would find them. A Hungarian chemist, Georgy de Hevesy, worked at the Institute and realized he could dissolve them. Gold is difficult to dissolve but one substance known as “aqua regia” can do it. A few hours later the two medals were rendered into a liquid state, placed into a beaker and stored on a high shelf.
The Nazis arrived and searched the entire building, but ignored the orange-tinted beaker, literally full of liquid gold. Later, after Bohr fled the country, Hevesy left for Sweden. He returned to Denmark after the war and found the beaker intact and undisturbed. The chemist reversed the process, extracted the gold and in 1950 shipped it back to the Nobel Foundation. They recast new medals using the original gold and reissued them to Von Laue and Franck.
Bohr’s wartime adventures didn’t end with a pair of gold medals. His knowledge of physics and atomic theory brought the attention of the Nazi’s head nuclear scientist, Werner Heisenberg. In September 1941 Heisenberg and Bohr met for a stroll in a park in occupied Copenhagen.
What they discussed is still unclear. Heisenberg later wrote he suggested that nuclear scientists in Europe suppress knowledge of atomic weapons to prevent their creation during the war. Bohr claimed Heisenberg boasted of Germany’s eventual victory and talked about the creation of the bomb. At the time, Bohr didn’t consider an atomic weapon feasible in the near future.
Whatever the case, Bohr’s opposition to the Nazis and his mother’s Jewish heritage made him a marked man in the eyes of the Third Reich. He also came under the scrutiny of the Allies, who knew Germany had an atomic bomb project. Bohr’s presence in occupied Europe meant he could be forced to help the German development effort. Bohr was contacted and agreed to be extracted from Denmark in late September 1943.
Above — Werner Heisenberg, left, with Bohr at the Copenhagen Conference in 1934. At top — Bohr with James Franck, Albert Einstein and Isidor Isaac Rabi. Photos via Wikipedia
The operation was carried out with great secrecy but at the last minute the Nazis learned of the plan and went after Bohr at his home. As they entered the house through the front door, the 58-year-old Bohr ran out the back, pausing at his icebox to grab a beer bottle filled with heavy water. A few Danish resistance fighters laid down covering fire, allowing Bohr to escape.
Soon he boarded a fishing boat that took him to Sweden. Safely ashore, he traveled to Stockholm.
The British arranged to secretly fly him out of Sweden, but Bohr had an appointment first. He reportedly met with Swedish leaders and implored them to help Danish Jews. While there is controversy over how much Bohr’s efforts effected the decision, Sweden did offer asylum and thousands of Jewish Danes took refuge there.
The British sent a De Havilland Mosquito fighter bomber to retrieve the scientist. A modified version of the Mosquito served as a fast transport for special cargoes during the war. Bohr met the definition. On Oct. 7, 1943 the plane took off from a clandestine airstrip with Bohr laying on his back in the converted bomb bay.
The aircraft flew high and fast to avoid Nazi fighters. This required pilot and passenger to wear oxygen masks due to the altitude. Bohr didn’t put his on and soon passed out from oxygen deprivation. When the pilot couldn’t talk to the unconscious Dane, he realized what must have happened and descended, saving the man’s life.
Bohr didn’t regain consciousness until after the plane landed. He went to the hospital still clutching his precious bottle of heavy water.
After recovering, Bohr went to the United States to join the Manhattan Project. His contribution, even by his own admission, was minimal. By the time he arrived the scientists already at work on the bomb had surpassed his knowledge. Still, the rescue mission likely saved Bohr from a concentration camp or outright execution.
He returned to Denmark after the war and died there in 1962.
Bohr’s time adventures read like a spy novel even though he provided little help to the development of the atomic bomb. There was one final, amusing indignity. The bottle of heavy water Bohr grabbed during his escape and so carefully smuggled to England turned out to be the wrong one. It contained only beer.