Nuclear fission is one of the most important discoveries of the 20th century. Yet not many know that it was Lise Meitner who was behind the discovery, just after her escape from Nazi Germany to Sweden in 1938. In 1944 Otto Hahn, Lise Meitner’s laboratory partner of thirty years, who remained in Berlin throughout the Third Reich, was awarded the Nobel Prize for Chemistry. The separation of the former collaborators and Meitner’s exile in Sweden led to the Nobel committee’s failure to understand her part in the work. The Nobel committee’s mistake was never acknowledged, but was partly rectified in 1966, when Hahn, Meitner, and Strassmann were awarded the United States Fermi Prize. She was also awarded numerous prizes and honorary doctorates by universities in the United States and Europe.
Who was Lise Meitner?
Lise Meitner was born in 1878 as the third of eight children of a Viennese Jewish family. She showed an early talent for mathematics and was privately tutored. Her father insisted that each of his daughters should receive the same education as his sons. Due to Austrian restrictions on female education, she entered the University of Vienna in 1901, at an age of 23. She was the first woman admitted to the university’s physics lectures and laboratories. With Ludwig Boltzmann as her teacher, she came to the conclusion that physics was her calling and earned a doctoral degree in physics in 1905. Three of her sisters also earned Ph.D. degrees later.
Meitner was invited to Berlin by Max Planck to continue with her post-doctoral studies. From 1907–1912 Meitner worked as an unpaid research scientist at the Berlin Institute for Chemistry but was not permitted access to the laboratories since women were prohibited entry to the institute. During this time she met the radio-chemist Otto Hahn, who became a thirty-year research partner in experimental work discovering new radioactive elements and unraveling their complex physical properties.
After World War I Otto Hahn was named the administrative director of the Kaiser Wilhelm Institute for Chemistry, while Meitner supervised the Physics Section, which she led successfully for over twenty years until forced to flee Berlin under the Third Reich. Meitner became an official University Lecturer in 1922, but even in liberalizing Berlin the press jokingly reported the topic of her inaugural speech as “Cosmetic Physics” instead of cosmic physics. In 1926 she was given the title of Professor.
From 1924 to 1934, the Meitner-Hahn team gained international prestige and were competing with the Paris team of the Irene Joliot-Curies and Rome’s Enrico Fermi to unravel the complexities of the mysterious “transuranic” elements. They were nominated for the Nobel Prize in Chemistry for ten consecutive years. They were also nominated for the Nobel Prize in Physics by Max Planck, Werner Heisenberg, Bohr and von Laue in 1936. Meitner was nominated for the Physics Prize three times by Niels Bohr after the World War II.
In 1938 when the National Socialists issued an order forbidding famous scientists to travel abroad, the international physics community under lead of Danish physicist Niels Bohr orchestrated Meitner’s escape route from Berlin. Her final destination was Stockholm, Sweden. Niels Bohr arranged work for Meitner at the new Nobel Research Institute of Physics under the leadership of Professor Manne Siegbahn, who won the Nobel Prize in Physics in 1924 for his discoveries in the field of X-ray spectroscopy. In Stockholm, Meitner lived on a meagre research assistant’s salary. She was neither asked to join Siegbahn’s group nor given the resources to form her own, she had laboratory space but no collaborators, equipment, or technical support, not even her own set of keys to the laboratory.1 According to some authors Siegbahn blocked Meitner’s research career in Sweden since he distrusted female scientists and he feared that Meitner, who was a brilliant physicist would outshine him with her ground-breaking research. Some physicist also later accused Sigebahn of having hindered her from receiving the Nobel price due to his extraordinary strong position in Swedish scientific community and membership of the Nobel committee.2
Meitner continued to exchange letters almost daily with Hahn. They met in Copenhagen in 1938 and planned new experiments. She urged him and their assistant Fritz Strassman in Berlin to continue research she had instigated on uranium. On December 24, she received a letter from Hahn recounting a strange “bursting” he described as occurring to uranium, forming barium. Hahn asked his trusted colleague to interpret this process: “What would physics say about such bursting?” He had written up their findings and submitted them to Die Naturwissenschaften on December 21 without crediting her contributions, and this act would literally eclipse Lise Meitner’s contributions to the discovery of nuclear fission in 1938.
Meitner and her nephew Otto Frisch, while hiking in the snowy Swedish woods, realized Bohr’s “liquid-drop” model of the atomic nucleus could explain the result mathematically. They scribbled formulas on a scrap of paper in the woods: A uranium atom could elongate when bombarded by neutrons, and occasionally some of the uranium atoms could split apart into two “smaller drops.” Frisch later dubbed this process “fission”, a term used by biologists to describe the elongated splitting of a cell. In fact, the uranium atoms in Hahn’s experiments had split to form the much lighter atoms barium and krypton, and ejected neutrons and a very large amount of energy, with a loss of some mass. Meitner was the first to realize Einstein’s famous equation E=mc2 was at play here, converting mass into energy. In January–March 1939, she wrote a series of articles to be published in Nature with Frisch on the nuclear fission of uranium.
In Sweden Meitner encountered concentration camp victims, which convinced her to never return to Germany, although in 1947 Hahn and Strassmann invited her to re-join them at the rebuilt Institute for Chemistry. She declined their invitation to form a new Max Planck Institute for Chemistry named after their mentor, and instead retired in Sweden on a small pension. Meitner spent most of her 70s and 80s traveling, encouraging female students to “remember that science can bring both joy and satisfaction to your life.” During her final years she lived close to her nephew Otto Frisch, in Cambridge, England, where she died on October 27, 1968.
- Lise Meitner: A Life in Physics, Ruth Lewin Sime, California Studies in the History of Science (11), 1997
- The Key to Nuclear Restraint: The Swedish Plans to Acquire Nuclear Weapons During the Cold War, Thomas Jonter, Palgrave Macmillan, 2016