Lise Meitner. Photo: Fotograf im Auftrag der United States Information Agency via Wikimedia Commons, Public Domain
The element meitnerium (Mt), atomic number 109, is a group nine transuranium element in the periodic table. This is a synthetic element discovered in the year 1982 by scientists at the Darmstadt Laboratory, Germany. This is the only element named for a woman scientist, Lise Meitner. Hers is an extraordinary story.
Many people today know about nuclear fission, and are familiar with the accompanying fear of nuclear weapons. Even today, nearly eight decades after these weapons were first used to end the Second World War, we spontaneously equate great wars with nuclear bombs. Meitner was the physicist who discovered fission, launching the world’s nuclear era in 1939.
As it happens, Otto Hahn won the Nobel Prize for chemistry in 1944, “for his discovery of the fission of heavy nuclei”. Meitner’s name was thus forgotten, even by those who knew of her contributions, and erased from the history of nuclear fission.
Meitner was born in Vienna in 1887 to a Jewish family. Her father was a progressive man and, contrary to the convention of his community, had his daughters sent to school. Lise Meitner, however, couldn’t continue her higher studies. Even though she was fascinated by mathematics and science, the only option she had was to become a French teacher.
When higher education institutes did open up for girls and women, she completed her higher secondary schooling and joined the University of Vienna. Encouraged by the lectures of the physicist Ludwig Boltzmann at the University, she became the second woman there to secure a doctoral degree, in 1905. She started her research career in optics and later delved into the scattering of alpha particles[footnote]Each alpha particle is two protons and two neutrons bound together.[/footnote].
Meitner later moved to Berlin, where she attended lectures by Max Planck at Friedrich Wilhelm University. Planck, considered the founder of quantum theory, was opposed to women’s participation in research, and only admitted Meitner because he believed she was exceptionally brilliant. Later, Meitner managed to get a position with the experimental physics group of the university as an unpaid guest. There, she worked with Otto Hahn, a well-known chemist, and subsequently became a professor at the Kaiser-Wilhelm Institute.
Hahn and Meitner jointly had a productive time in the interdisciplinary field of artificial radioactivity, which led to the discovery of the element protactinium in 1918. They subsequently worked independently for many years: while Hahn concentrated on pure radio-chemistry, Meitner worked on beta-decay and other nuclear processes. By the 1920s she had become an international figure in the field of nuclear physics.
After James Chadwick discovered neutrons in 1932, many researchers became interested in transmutation experiments[footnote]The conversion of one element into another by the addition or subtraction of nuclear particles.[/footnote], in which uranium or thorium were bombarded with neutrons. Meitner was one of them, and started working on it with the help of Hahn and Fritz Strassmann. They worked together for more than four years and produced many publications out of their research.
Once Adolf Hitler ascended to power in Germany, many people were dismissed from the country, but Meitner could continue with the Institute because of its non-government status and her Austrian visa. However, the situation changed once Germany annexed Austria.
By July 1938, Meitner had to leave her institute, where she had worked for more than 30 years. She could fly from Germany because of her influential friends. At the age of 59, she was forced to go to Sweden to work at Manne Siegbahn’s Nobel Institute for Experimental Physics. She went from being a professor, the head of a department, with many students and technicians working under her supervision, to suddenly a penniless refugee in a foreign land.
Meitner survived on borrowed money, away from her friends, family and colleagues, even as Siegbahn was unhelpful to her because he considered her to be an outsider.
A few months after Meitner left Berlin, nuclear fission was discovered. Hahn had been in touch with Meitner, and she had disputed his claim that he had detected radium after bombarding uranium with neutrons. Later, through rigorous chemical analysis, Hahn and Strassmann were able to confirm the presence of barium in one of their experiments. When Hahn shared this finding with Meitner, she realised that something unexpected had happened.
She explained to Hahn that the heavy uranium nucleus had broken down into two elements in the barium mass region. But when Hahn communicated this finding to the journal Naturwissenschaften, he did not include Meitner’s name as a co-author, probably because of the political conditions in Germany. Meitner also shared the news of the new findings with her nephew Otto Robert Frisch during their Christmas holidays in Sweden.
Imagining the uranium nucleus to be an unstable liquid drop, Meitner and Frisch found that they could explain why it would split as its surface energy diminished. Together, they worked out the equations and found that a huge amount of energy would be released in this process. They named the process ‘fission’, borrowing the title of the analogous process in cell biology, in a paper published in February 1939 in Nature.
Meitner’s condition in Sweden was pathetic. She often regretted her decision to come to Siegbahn’s lab without an offer. She did not have a proper position; her salary was very low; and she didn’t have any technical assistance for her work. She couldn’t conduct any follow-up experiments on fission in Sweden, even though the institute had a particle accelerator.
Despite her miserable situation, she was strong enough to refuse an offer to join a team working on nuclear weapons. Even her nephew, Otto Frisch, went to Los Alamos in 1943 to join the US’s Manhattan Project on atomic weapons. She was so distraught after hearing about the Hiroshima and Nagasaki bombings that she wandered the streets to calm herself down.
She also became very popular at this time for her work on nuclear physics itself and received invitations from many countries to deliver lectures. She joined the Royal Institute of Technology in Sweden and continued her research in fundamental nuclear physics and worked on the design and construction of a nuclear reactor. In 1960, she moved to Cambridge to stay near Frisch and his family, and died in 1968.
Meitner had made significant contributions even before nuclear fission. She was nominated about a dozen times for the Nobel Prize before she left Germany. Overall, she received 49 nominations (30 for physics and 19 for chemistry), attesting to the importance of her contributions. However, she didn’t get as much recognition as she deserved until after she died.
Today, she has had an asteroid, a satellite and several prizes named after her. When element 109 was discovered, Darmstadt Laboratory scientists recommended the name ‘meitnerium’ for it, and the International Union of Pure and Applied Chemistry made it official in 1997. It was a thoughtful tribute to one of the great scientists of the 20th century. Whatever the reasons the Nobel committee had for overlooking her, her work and her character have today rendered them regrettable.
Golda Komalan Satheedas is a scientist in the Nuclear Physics Group, Inter-University Accelerator Centre, New Delhi.