Lise Meitner (1878-1968) helped to develop the theory behind nuclear fission, and became the first woman professor in Germany.
The prototypical female scientist of the early twentieth century was a woman devoted to her work, sacrificing family and personal relationships in favor of science; modestly brilliant; generous; and underrecognized. In many ways Austrian-born physicist Lise Meitner embodies that image. In 1938, along with her nephew Otto Robert Frisch, Meitner developed the theory behind nuclear fission that would eventually make possible the creation of the atomic bomb. She and lifelong collaborator Otto Hahn made several other key contributions to the field of nuclear physics. Although Hahn received the Nobel Prize in 1944, Meitner did not share the honor—one of the more frequently cited examples of the sexism rife in the scientific community in the first half of this century.
Elise Meitner was born November 7, 1878 to an affluent Vienna family. Her father Philipp was a lawyer and her mother Hedwig travelled in the same Vienna intellectual circles as Sigmund Freud. From the early years of her life, Meitner gained experience that would later be invaluable in combatting—or overlooking—the slights she received as a woman in a field dominated by men. The third of eight children, she expressed interest in pursuing a scientific career, but her practical father made her attend the Elevated High School for Girls in Vienna to earn a diploma that would enable her to teach French—a much more sensible career for a woman. After completing this program, Meitner's desire to become a scientist was greater than ever. In 1899, she began studying with a local tutor who prepped students for the difficult university entrance exam. She worked so hard that she successfully prepared for the test in two years rather than the average four. Shortly before she turned twenty three, Meitner became one of the few women students at the University of Vienna.
At the beginning of her university career in 1901, Meitner could not decide between physics or mathematics; later, inspired by her physics teacher Ludwig Boltzmann, she opted for the latter. In 1906, after becoming the second woman ever to earn a Ph.D. in physics from the University of Vienna, she decided to stay on in Boltzmann's laboratory as an assistant to his assistant. This was hardly a typical career path for a recent doctorate, but Meitner had no other offers, as universities at the time did not hire women faculty. Less than a year after Meitner entered the professor's lab, Boltzmann committed suicide, leaving the future of the research team uncertain. In an effort to recruit the noted physicist Max Planck to take Boltzmann's place, the university invited him to come visit the lab. Although Planck refused the offer, he met Meitner during the visit and talked with her about quantum physics and radiation research. Inspired by this conversation, Meitner left Vienna in the winter of 1907 to go to the Institute for Experimental Physics in Berlin to study with Planck.
Soon after her arrival in Berlin, Meitner met a young chemist named Otto Hahn at one of the weekly symposia. Hahn worked at Berlin's Chemical Institute under the supervision of Emil Fischer, surrounded by organic chemists—none of whom shared his research interests in radiochemistry. Four months older than Hahn, Meitner was not only intrigued by the same research problems but had the training in physics that Hahn lacked. Unfortunately, Hahn's supervisor balked at the idea of allowing a woman researcher to enter the all-male Chemical Institute. Finally, Fischer allowed Meitner and Hahn to set up a laboratory in a converted woodworking shop in the Institute's basement, as long as Meitner agreed never to enter the higher floors of the building.
This incident was neither the first nor the last experience of sexism that Meitner encountered in her career. According to one famous anecdote, she was solicited to write an article by an encyclopedia editor who had read an article she wrote on the physical aspects of radioactivity. When she answered the letter addressed to Herr Meitner and explained she was a woman, the editor wrote back to retract his request, saying he would never publish the work of a woman. Even in her collaboration with Hahn, Meitner at times conformed to gender roles. When British physicist Sir Ernest Rutherford visited their Berlin laboratory on his way back from the Nobel ceremonies in 1908, Meitner spent the day shopping with his wife Mary while the two men talked about their work.
Within her first year at the Institute, the school opened its classes to women, and Meitner was allowed to roam the building. For the most part, however, the early days of the collaboration between Hahn and Meitner were filled with their investigations into the behavior of beta rays as they passed through aluminum. By today's standards, the laboratory in which they worked would be appalling. Hahn and Meitner frequently suffered from headaches brought on by their adverse working conditions. In 1912 when the Kaiser-Wilhelm Institute was built in the nearby suburb of Dahlem, Hahn received an appointment in the small radioactivity department there and invited Meitner to join him in his laboratory. Soon thereafter, Planck asked Meitner to lecture as an assistant professor at the Institute for Theoretical Physics. The first woman in Germany to hold such a position, Meitner drew several members of the news media to her opening lecture.
When World War I started in 1914, Meitner interrupted her laboratory work to volunteer as an X-ray technician in the Austrian army. Hahn entered the German military. The two scientists arranged their leaves to coincide and throughout the war returned periodically to Dahlem where they continued trying to discover the precursor of the element actinium. By the end of the war, they announced that they had found this elusive element and named it protactinium, the missing link on the periodic table between thorium (previously number 90) and uranium (number 91). A few years later Meitner received the Leibniz Medal from the Berlin Academic of Science and the Leibniz Prize from the Austrian Academy of Science for this work. Shortly after she helped discover protactinium in 1917, Meitner accepted the job of establishing a radioactive physics department at the Kaiser Wilhelm Institute. Hahn remained in the chemistry department, and the two ceased working together to concentrate on research more suited to their individual training. For Meitner, this constituted a return to beta radiation studies.
Throughout the 1920s, Meitner continued her work in beta radiation, winning several prizes. In 1928, the Association to Aid Women in Science upgraded its Ellen Richards Prize—billing it as a Nobel Prize for women—and named Meitner and chemist Pauline Ramart-Lucas of the University of Paris its first recipients. In addition to the awards she received, Meitner acquired a reputation in physics circles for some of her personal quirks as well. Years later, her nephew Otto Frisch, also a physicist, would recall that she drank large quantities of strong coffee, embarked on ten mile walks whenever she had free time, and would sometimes indulge in piano duets with him. By middle age, Meitner had also adopted some of the mannerisms stereotypically associated with her male colleagues. Not the least of these, Hahn later recalled, was absent-mindedness. On one occasion, a student approached her at a lecture, saying they had met earlier. Knowing she had never met the student, Meitner responded earnestly, "You probably mistake me for Professor Hahn."
Meitner and Hahn resumed their collaboration in 1934, after Enrico Fermi published his seminal article on "transuranic" uranium. The Italian physicist announced that when he bombarded uranium with neutrons, he produced two new elements—number 93 and 94, in a mixture of lighter elements. Meitner and Hahn joined with a young German chemist named Fritz Strassmann to draw up a list of all the substances the heaviest natural elements produced when bombarded with neutrons. In three years, the three confirmed Fermi's result and expanded the list to include about ten additional substances that resulted from bombarding these elements with neutrons. Meanwhile, physicists Irène Joliot-Curie and Pavle Savitch announced that they had created a new radioactive substance by bombarding uranium by neutrons. The French team speculated that this new mysterious substance might be thorium, but Meitner, Hahn, and Strassmann could not confirm this finding. No matter how many times they bombarded uranium with neutrons, no thorium resulted. Hahn and Meitner sent a private letter to the French physicists suggesting that perhaps they had erred. Although Joliot-Curie did not reply directly, a few months later she published a paper retracting her earlier assertions and said the substance she had noted was not thorium.
Current events soon took Meitner's mind off these professional squabbles. Although her father, a proponent of cultural assimilation, had all his children baptized, Meitner was Jewish by birth. Because she continued to maintain her Austrian citizenship, she was at first relatively impervious to the political turmoil in Weimar Germany. In the mid-1930s she had been asked to stop lecturing at the university but she continued her research. When Germany annexed Austria in 1938, Meitner became a German citizen and began to look for a research position in an environment hospitable to Jews. Her tentative plans grew urgent in the spring of 1938, when Germany announced that academics could no longer leave the country. Colleagues devised an elaborate scheme to smuggle her out of Germany to Stockholm where she had made temporary arrangements to work at the Institute of the Academy of Sciences under the sponsorship of a Nobel grant. By late fall, however, Meitner's position in Sweden looked dubious: her grant provided no money for equipment and assistance, and the administration at the Stockholm Institute would offer her no help. Christmas found her depressed and vacationing in a town in the west of Sweden.
Back in Germany, Hahn and Strassmann had not let their colleague's departure slow their research efforts. The two read and reread the paper Joliot-Curie had published detailing her research techniques. Looking it over, they thought they had found an explanation for Joliot-Curie's confusion: perhaps instead of finding one new substance after bombarding uranium, as she had thought, she had actually found two new substances! They repeated her experiments and indeed found two substances in the final mixture, one of which was barium. This result seemed to suggest that bombarding uranium with neutrons led it to split up into a number of smaller elements. Hahn immediately wrote to Meitner to share this perplexing development with her. Meitner received his letter on her vacation in the village of Kungalv, as she awaited the arrival of her nephew, Frisch, who was currently working in Copenhagen under the direction of physicist Niels Bohr. Frisch hoped to discuss a problem in his own work with Meitner, but it was clear soon after they met that the only thing on her mind was Hahn and Strassmann's observation. Meitner and Frisch set off for a walk in the snowy woods—Frisch on skis, with his aunt trotting along—continuing to puzzle out how uranium could possibly yield barium. When they paused for a rest on a log, Meitner began to posit a theory, sketching diagrams in the snow.
If, as Bohr had previously suggested, the nucleus behaved like a liquid drop, Meitner reasoned that when this drop of a nucleus was bombarded by neutrons, it might elongate and divide itself into two smaller droplets. The forces of electrical repulsion would act to prevent it from maintaining its circular shape by forming the nucleus into a dumbbell shape that would—as the bombarding forces grew stronger—sever at the middle to yield two droplets—two completely different nuclei. But one problem still remained. When Meitner added together the weights of the resultant products, she found that the sum did not equal the weight of the original uranium. The only place the missing mass could be lost was in energy expended during the reaction.
Frisch rushed back to Copenhagen, eager to test the revelations from their walk in the woods on his mentor and boss, Bohr. He caught Bohr just as the scientist was leaving for an American tour, but as Bohr listened to what Frisch was urgently telling him, he responded: "Oh, what idiots we have been. We could have foreseen it all! This is just as it must be!" Buoyed by Bohr's obvious admiration, Frisch and Meitner spent hours on a long-distance telephone writing the paper that would publicize their theory. At the suggestion of a biologist friend, Frisch coined the word "fission" to describe the splitting of the nucleus in a process that seemed to him analogous to cell division.
The paper "On the Products of the Fission of Uranium and Thorium" appeared in Nature on February 11, 1939. Although it would be another five and a half years before the American military would successfully explode an atom bomb over Hiroshima, many physicists consider Meitner and Frisch's paper akin to opening a Pandora's box of atomic weapons. Physicists were not the only ones to view Meitner as an important participant in the harnessing of nuclear energy. After the bomb was dropped in 1944, a radio station asked First Lady Eleanor Roosevelt to conduct a transatlantic interview with Meitner. In this interview, the two women talked extensively about the implications and future of nuclear energy. After the war, Hahn found himself in one of the more enviable positions for a scientist—the winner of the 1944 Nobel prize in chemistry—although, because of the war, Hahn did not accept his prize until two years later. Although she attended the ceremony, Meitner did not share in the honor.
But Meitner's life after the war was not without its plaudits and pleasures. In the early part of 1946, she travelled to America to visit her sister—working in the U.S. as a chemist—for the first time in decades. While there, Meitner delivered a lecture series at Catholic University in Washington, D.C. In the following years, she won the Max Planck Medal and was awarded numerous honorary degrees from both American and European universities. In 1966 she, Hahn, and Strassmann split the $50,000 Enrico Fermi Award given by the Atomic Energy Commission. Unfortunately, by this time Meitner had become too ill to travel, so the chairman of the A. E. C. delivered it to her in Cambridge, England, where she had retired a few years earlier. Meitner died just a few weeks before her 90th birthday on October 27, 1968.
Further Reading on Lise Meitner
Crawford, Deborah, Lise Meitner, Atomic Pioneer, Crown, 1969.
Irving, David, The German Atomic Bomb: The History of Nuclear Research in Nazi Germany, Simon & Schuster, 1967.
Rhodes, Richard, The Making of the Atom Bomb, Simon & Schuster, 1988.
Watkins, Sallie, "Lise Meitner and the Beta-ray Energy Controversy: An Historical Perspective," in American Journal of Physics, Volume 51, 1983, pp. 551-553.
Watkins, Sallie, "Lise Meitner: The Making of a Physicist," in Physics Teacher, January, 1984, pp. 12-15.