To close out this difficult year, this month’s blog series is going to look back at a few of the titans of scientific discovery from years past. This week, we return to the topic of nuclear fission with the story of Lise Meitner—an Austrian physicist who discovered the fundamental mechanism behind nuclear fission. Meitner’s story is pocked with the sexism and anti-Semitism that characterized Europe in the early 1900s. But despite the adversity she faced, Meitner made one of the most pivotal scientific discoveries of her time—one that would make nuclear power (and nuclear bombs) possible.
Lise Meitner was born in Vienna, Austria to Jewish parents in 1878. At the time, girls in the public education system in Austria would only educate girls up to fourteen years old after which they were expected to help out at home while “day-dreaming of marriage.” Girls who wished to pursue further schooling could seek private schooling, but the only career available to these women was non-university teaching. But the opportunities for women were quickly changing. In fact, Meitner and all four of her sisters pursued higher education. With private tutoring, Meitner was able to take the Matura—the university entrance exam in Austria—and enroll in the University of Vienna in 1901. She studied physics and was the second woman in Austria to earn her doctorate in 1906.
Even after Meitner earned her doctorate, there were still really no careers available for women in Austria beyond teaching. For a while, she taught at a girls’ school in Vienna during the day while performing radiation experiments at night. Eventually, dissatisfied with teaching and the lack of opportunities for women in science, Meitner moved to Berlin in 1907. Berlin, at the time, was home to many influential physicists, like Albert Einstein and Max Planck. Meitner attended several lectures by Planck while collaborating on radiation research with chemist Otto Hahn. They worked on research in Emil Fischer’s Chemistry Institute where, in the beginning, Meitner had to work exclusively in the basement carpentry shop. Women were not allowed in the building’s main labs because Fischer believed that they would “set fire to their hair” (clearly a man who has never heard of hair ties). So Hahn would prepare radioactive samples in the labs above and bring them down to Meitner for her to run experiments on. Meitner would have to walk down the street to a nearby restaurant to use the ladies’ room.
Even when women were allowed into the main building a year later, Lise Meitner still found herself purposefully excluded by many of her male colleagues. But, despite all these obstacles, she remained relentlessly dedicated to scientific research. In 1912, Max Planck offered her a position as his assistant at the Kaiser Wilhelm Institute (KWI) where he taught. She was the first woman appointed to an assistant professor position in all of Prussia. By 1919, she was promoted to the position of full professor at KWI. In the meantime, Meitner continued working on radiochemistry research with Hahn making many promising discoveries.
In 1919, Hahn won the Emil Fischer award for their work. Meitner was left out of the award—even though, as the physicist in their collaboration, she was the one who made many of the actual discoveries with the materials Hahn prepared. Hahn was offended by this snub, but Meitner was unsurprised. She was aware that, in their collaborations, she would always be perceived as Hahn’s subordinate, regardless of the actual value of her contribution. But their collaboration was fruitful, and he was one of the few scientists in Berlin she could count as a friend. So Meitner didn’t object to Hahn being listed as the first author on many of their papers. Together, they discovered the new isotope protactinium-231, investigated the processes of beta decay—where radioactive substances emit electrons—and began studying the products formed by neutron bombardment of uranium (spoiler alert: it’s nuclear fission).
In 1933, when Hitler rose to power, Meitner was protected, for a time, by her Austrian citizenship. But in 1938, when Hitler annexed Austria, her career—and life—were put in jeopardy (Meitner actually converted to Lutheranism as an adult, but it turns out the Nazis didn’t really care). Hahn and many of her colleagues begged her to leave Germany immediately. Multiple physicists living abroad invited her to give lectures to provide her with an excuse to travel. But she remained in Germany far longer than advised and just barely managed to escape in the summer of 1938. She was smuggled out of Germany to Holland by Dutch physicists with little more than ten marks and a diamond ring, which Hahn gifted her in case of an emergency.
Meitner eventually settled in Stockholm, Sweden working with her nephew, Otto Frisch and—over correspondence—with Hahn. Together, they sought to resolve the mechanism through which uranium falls apart into two smaller atoms when bombarded by a neutron. Meitner was the first to come up with a feasible mechanism based on the “liquid drop model” of atomic structure. A water droplet is held together in a gravity-defying dome shape because of surface tension, created by the polar attraction of water molecules to each other. Similarly, there is a force keeping the subatomic particles of the nucleus together despite the electromagnetic repulsion between them (this is now called the strong nuclear force). With the drop of water, the perfect dome shape breaks, and the water disperses, when enough water is added for the strength of gravity to exceed the surface tension. Meitner’s suggestion was that, when a neutron is added to the nucleus of uranium, the nuclear “surface tension” is too weak to keep the nucleus together against the strength of the electrostatic repulsion. This repulsion causes the nucleus to fly apart and release massive amounts of energy in the process.
Through experimental work, Hahn was able to show that uranium broke apart and produced barium as one of the main products, and he was able to publish that work. But, unable to claim a Jewish woman as coauthor, Hahn was forced to publish the fission result without Meitner. His paper couldn’t provide a full explanation of how the fission occurred though, so a few weeks later, Meitner published the full mechanism behind “Hahn’s discovery” in a letter to the editor. In 1944, Hahn alone was awarded the Nobel Prize in Chemistry for his discovery of nuclear fission, snubbing Meitner.
The discovery of nuclear fission suddenly made nuclear weaponry possible, leading to the Manhattan project (and competing Nazi efforts). Meitner was invited to work on the Manhattan project but she declined: “I will have nothing to do with a bomb.” Despite losing out on the Nobel prize, Meitner was awarded the Max Planck medal in 1949 and the Enrico Fermi Award in 1966. In 1997, the International Union of Pure and Applied Chemistry (IUPAC) renamed element 109 Meitnerium in honor of her contribution to science. Lise Meitner died on October 27, 1968. Her long-time friend Otto Robert wrote the inscription on her headstone: “Lise Meitner: A physicist who never lost her humanity.”
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