Lise Meitner was part of the team that discovered nuclear fission, an achievement for which her colleague Otto Hahn was awarded the Nobel Prize. Meitner is often mentioned as one of the most glaring examples of scientific achievement overlooked by the Nobel committee. A 1997 Physics Today study concluded that Meitner's omission was "a rare instance in which personal negative opinions apparently led to the exclusion of a deserving scientist" from the Nobel.
In 1930, Meitner taught a seminar on nuclear physics and chemistry with Leó Szilárd. With the discovery of the neutron in the early 1930s, speculation arose in the scientific community that it might be possible to create elements heavier than uranium (atomic number 92) in the laboratory. A scientific race began between Ernest Rutherford in Britain, Irene Joliot-Curie in France, Enrico Fermi in Italy, and the Meitner-Hahn team in Berlin. At the time, all concerned believed that this was abstract research for the probable honor of a Nobel prize. None suspected that this research would culminate in nuclear weapons.
When Adolf Hitler came to power in 1933, Meitner was acting director of the Institute for Chemistry. Although she was protected by her Austrian citizenship, all other Jewish scientists, including her nephew Otto Frisch, Fritz Haber, Leó Szilárd and many other eminent figures, were dismissed or forced to resign from their posts – most of them emigrating. Her response was to say nothing and bury herself in her work. In 1946 she acknowledged that "It was not only stupid but also very wrong that I did not leave at once.
After the Anschluss, her situation became desperate. In July 1938, Meitner, with help from the Dutch physicists Coster and Fokker, escaped to Holland. She was forced to travel under cover to the Dutch border, where Coster persuaded German immigration officers that she had permission to travel to the Netherlands. She reached safety, though without her possessions. Meitner later said that she left Germany forever with 10 marks in her purse. Before she left, Otto Hahn had given her a diamond ring he had inherited from his mother: this was to be used to bribe the frontier guards if required. It was not required, and Meitner's nephew's wife later wore it. Meitner was lucky to escape, as Kurt Hess, a chemist who was an avid Nazi, had informed the authorities that she was about to flee. However, unknown friends only checked after they knew she was safe. An appointment at Groningen University did not come through, and she went instead to Stockholm, where she took up a post at Manne Siegbahn's laboratory, despite the difficulty caused by Siegbahn's prejudice against women in science. Here she established a working relationship with Niels Bohr, who travelled regularly between Copenhagen and Stockholm. She continued to correspond with Hahn and other German scientists.
Hahn and Meitner met clandestinely in Copenhagen in November to plan a new round of experiments; in this regard they subsequently exchanged a series of letters. Hahn then performed the difficult experiments which isolated the evidence for nuclear fission at his laboratory in Berlin. The surviving correspondence shows that Hahn recognized that fission was the only explanation for the barium, but, baffled by this remarkable conclusion, he wrote to Meitner. The possibility that uranium nuclei might break up under neutron bombardment had been suggested years before, notably by Ida Noddack in 1934. However, by employing the existing "liquid-drop" model of the nucleus, Meitner and Frisch were the first to articulate a theory of how the nucleus of an atom could be split into smaller parts: uranium nuclei had split to form barium and krypton, accompanied by the ejection of several neutrons and a large amount of energy (the latter two products accounting for the loss in mass). She and Frisch had discovered the reason that no stable elements beyond uranium (in atomic number) existed naturally; the electrical repulsion of so many protons overcame the "strong" nuclear force. Meitner also first realized that Einstein's famous equation, E = mc2, explained the source of the tremendous releases of energy seen in atomic decay, by the conversion of the mass-defect into energy.
A letter from Bohr, commenting on the fact that the amount of energy released when he bombarded uranium atoms was far larger than had been predicted by calculations based on a non-fissile core, had sparked the above inspiration in December 1938. Hahn claimed that his chemistry had been solely responsible for the discovery, although he had been unable to explain the results.
It was politically impossible for the exiled Meitner to publish jointly with Hahn in 1939. Otto Hahn and Fritz Strassmann had sent the manuscript of their paper to Naturwissenschaften in December 1938, reporting they had detected the element barium after bombarding uranium with neutrons; simultaneously, they had communicated their results to Meitner in a letter. Meitner, and her nephew Otto Robert Frisch, correctly interpreted their results as being nuclear fission. Frisch confirmed this experimentally on 13 January 1939.
Meitner recognized the possibility for a chain reaction of enormous explosive potential. This report had an electrifying effect on the scientific community. Because this could be used as a weapon, and since the knowledge was in German hands, Leó Szilárd, Edward Teller, and Eugene Wigner together jumped into action, persuading Albert Einstein, who had the celebrity, to write President Franklin D. Roosevelt a warning letter; this led directly to the establishment of the Manhattan Project. Meitner refused an offer to work on the project at Los Alamos, declaring "I will have nothing to do with a bomb!
Einstein himself respected Meitner and called her "our Marie Curie."
In 1944, Hahn received the Nobel Prize for Chemistry for the discovery of nuclear fission. Some historians who have documented the history of the discovery of nuclear fission believe Meitner should have been awarded the Nobel Prize with Hahn. In 1966 Hahn, Fritz Strassmann and Meitner together were awarded the Enrico Fermi Award. On a visit to the USA in 1946 she received American press celebrity treatment as someone who had "left Germany with the bomb in my purse." She was honoured as "Woman of the Year" by the National Women's Press Club (USA) in 1946, and received the Max Planck Medal of the German Physics Society in 1949. Meitner was suggested to receive the prize three times. An even rarer honour was given to her in 1997 with naming element 109 meitnerium in her honour.
Meitner became a Swedish citizen in 1949, but moved to Britain in 1960 and died in Cambridge in 1968, shortly before her 90th birthday. As was her wish, she was buried in the village of Bramley in Hampshire, at St. James parish church, close to her younger brother Walter, who had died in 1964. Her nephew Otto Robert Frisch composed the inscription on her headstone. It reads "Lise Meitner: a physicist who never lost her humanity."