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Sunday, October 30, 2016

Lise Meitner: The Joy Of Scientific Objectivity And Her Discovery Of Atomic Fission

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How Pioneering Physicist Lise Meitner Discovered Nuclear Fission, Paved The Way For Women In Science, And Was Denied The Nobel Prize

In the fall of 1946, a South African little girl aspiring to be a scientist wrote to Einstein and ended her letter with a self-conscious entreatment: “I hope you will not think any the less of me for being a girl!” Einstein responded with words of assuring wisdom that resonate to this day: “I do not mind that you are a girl, but the main thing is that you yourself do not mind. There is no reason for it.”

And yet reasons don’t always come from reason. The history of science, like the history of the world itself, is the history of unreasonable asymmetries of power, the suppressive consequences of which have meant that the comparatively few women who rose to the top of their respective field did so due to inordinate brilliance and tenacity.

Among the most outstanding yet under-celebrated of these pioneering women is the Austrian physicist Lise Meitner (November 7, 1878–October 27, 1968), who led the team that discovered nuclear fission but was excluded from the Nobel Prize for the discovery, and whose story I first encountered in Alan Lightman’s illuminating 1990 book The Discoveries. This diminutive Jewish woman, who had barely saved her own life from the Nazis, was heralded by Einstein as the Marie Curie of the German-speaking world. She is the subject of the excellent biography Lise Meitner: A Life in Physics (public library) by chemist, science historian, and Guggenheim fellow Ruth Lewin Sime.
Lise Meitner, 1906
Meitner was born in Vienna a little more than a year after pioneering astronomer Maria Mitchell, who paved the way for women in science across the Atlantic, admonished the first class of female astronomers: “No woman should say, ‘I am but a woman!’ But a woman! What more can you ask to be?” Although Meitner showed a gift for mathematics from an early age, there was little correlation between aptitude and opportunity for women in 19th-century Europe. At the end of her long life, she would recount, not bitterly but wistfully:
Thinking back to … the time of my youth, one realizes with some astonishment how many problems then existed in the lives of ordinary young girls, which now seem almost unimaginable. Among the most difficult of these problems was the possibility of normal intellectual training.
Sime herself, who spent decades as the only woman at her university department, captures the broader cultural necessity of telling Meitner’s story: “I was known as the woman the all-male chemistry department did not want to hire; under such circumstances one becomes, and remains, a feminist.” She writes of Meitner’s Sisyphean rise to stature:
Her schooling in Vienna ended when she was fourteen, but a few years later, the university admitted women, and she studied physics under the charismatic Ludwig Boltzmann. As a young woman she went to Berlin without the slightest prospects for a future in physics, but again she was fortunate, finding a mentor and friend in Max Planck and a collaborator in Otto Hahn, a chemist just her age. Together Meitner and Hahn made names for themselves in radioactivity, and then in the 1920s Meitner went on, independent of Hahn, into nuclear physics, an emerging field in which she was a pioneer. In the Berlin physics community she was, as Einstein liked to say, “our Marie Curie”; among physicists everywhere, she was regarded as one of the great experimentalists of her day… The painfully shy young woman had become an assertive professor — “short, dark, and bossy,” her nephew would tease — and although at times she was haunted by the insecurity of her youth, she never doubted that physics was worth it.
Illustration of Lise Meitner from Women in Science: 50 Fearless Pioneers Who Changed the World by Rachel Ignotofsky
Meitner never married nor had children and, as far as her personal papers indicate, never had a serious romance. But her life was a full one, warmed by deep human connection — she was an exceptionally devoted friend and surrounded herself with people she cherished, in Meitner’s own words, as “great and lovable personalities” who provided a “magic musical accompaniment” to her life. Above all, she was besotted with science — so much so that she patiently chipped away at and eventually broke through every imaginable obstruction to pursuing her passion.

Since her formal schooling had ended at the age of fourteen, Meitner spent a few years repressing her scientific ambitions. But they burned in her with irrepressible ardor. Finally, when Austrian universities began admitting women in 1901, she obtained her high school certification at the age of twenty-three after compressing eight years’ worth of logic, literature, mathematics, Greek, Latin, botany, zoology, and physics into twenty months of study in order to take the examination that would qualify her for university. She received her Ph.D. in 1905, one of a handful of women in the world to have achieved a doctorate in physics by that point.

But when 29-year-old Meitner traveled to Berlin, hoping to study with the great Max Planck, she seemed to have entered a time machine — German universities still had their doors firmly shut to women. She had to ask for a special permission to attend Planck’s lectures.

In the fall of 1907, she met Otto Hahn — a German chemist four months her junior, as interested in radioactivity as she was, and unopposed to working with women. But women were forbidden from entering, much less working at, Berlin’s Chemical Institute, so in order to collaborate, Meitner and Hahn had to work in a former carpentry shop converted into a lab in the basement of the building. Hahn was allowed to climb up the floors, but Meitner was not — a hard fact that fringes on metaphor.
Meitner and Hahn in their basement laboratory, 1913
The two scientists filled each other’s gaps with their respective aptitudes — Meitner, trained in physics, was a brilliant mathematician who thought conceptually and could design highly original experiments to test her ideas; Hahn, trained in chemistry, excelled at punctilious lab work. Over the thirty years they collaborated, Meitner and Hahn emerged as pioneers in the study of radioactivity. Eventually, Meitner gained independence from Hahn — she published fifty-six papers on her own between 1921 and 1934.

But as her career was taking off, the Nazis began usurping Europe. Meitner and Hahn’s third collaborator, a junior scientist named Fritz Strassmann, had already gotten in trouble for refusing to join Nazi organizations. In 1938, just as the three scientists were performing their most visionary experiments, Nazi troops marched into Austria. Meitner refused to hide her Jewish heritage. Her only remaining option was to leave, but the Nazis had already put anti-Semitic laws in place prohibiting university professors from exiting the country. On July 13, with the help of Hahn and a few other scientist friends, Meitner made a narrow escape across the Dutch border. From Holland, she migrated to Denmark, where she stayed with her friend Niels Bohr. She finally found a permanent home at the Nobel Institute for Physics in Sweden. (Three centuries earlier, Descartes, supreme champion of reason, had also fled to Sweden to avoid the Inquisition after witnessing the trial of Galileo.)
Lise Meitner shortly before her exile
That November, Hahn and Meitner met secretly in Copenhagen to discuss some perplexing results Hahn and Strassmann had obtained: After bombarding the nucleus of a uranium atom (atomic number 92) with a single neutron, they had ended up with the nucleus of radium (atomic number 88) — a seemingly magical transmutation that didn’t make physical sense. That a tiny neutron moving at low speed would destabilize and downright shatter something as robust as an atom, knocking down its atomic number into a wholly different element, seemed as mythic as David taking out Goliath with a slingshot.

At that point, Hahn was one of the world’s best radiochemists and Meitner one of the world’s best physicists. She told him unequivocally that his chemical reaction made no sense on physical grounds and urged him to repeat the experiment.

Meitner herself continued to ponder the perplexity. The epiphany arrived on Christmas day, during a walk with her nephew and collaborator, Otto Robert Frisch. In recounting the occasion in his memoir, Frisch would inadvertently provide the most perfect metaphor for how women make progress in science relative to their male peers:
We walked up and down in the snow, I on skis and she on foot (she said and proved that she could get along just as fast that way).
In making sense of the nonsensical results, Meitner and Frisch came up with what they would call nuclear fission — a word used for the very first time in the seventh paragraph of the paper they published the following month. The notion that a nucleus can split and be transformed into another element was radical — no one had fathomed it before. Meitner had provided the first understanding of how and why this happened.
Illustration from Our Friend the Atom, a 1956 Disney primer on nuclear energy
Nuclear fission would prove to be one of the most powerful — and dangerous — discoveries in the history humanity, a power that succumbed to our dual capacities for good and evil: It was central to the invention of the deadliest weapon in human history, the atomic bomb. In fact, later in life Meitner was cruelly referred to as “the Jewish mother of the atomic bomb,” even though her discovery was purely scientific, it predated this malevolent application by many years, and once she saw it put into practice to destructive ends, she adamantly refused to work on the bomb. She, like the rest of the world, saw the bomb as a grave turning point for humanity. Years later, she would issue a bittersweet lamentation for the era that ended with its invention:
One could love one’s work and not always be tormented by the fear of the ghastly and malevolent thins that people might do with beautiful scientific findings.
The discovery of fission itself was a supreme example of these beautiful scientific findings — a triumph of the human intellect over the mysteries of nature, as well as a testament to interpretation as a creative act. The nonsensical empirical results were Hahn’s, but what extracted meaning from them was Meitner’s interpretation — she had dis-covered, in the proper sense of uncovering something obscured from view, the underlying principle that made sense of the grand perplexity.

Hahn took her groundbreaking insight and ran with it, publishing the discovery without mentioning her name. It is beside the point whether his reasons were personal jealousies or the political cowardice of incensing the Nazi authorities — the point is that Meitner felt deeply betrayed by the injustice. She wrote to her brother Walter:
I have no self confidence… Hahn has just published absolutely wonderful things based on our work together … much as these results make me happy for Hahn, both personally and scientifically, many people here must think I contributed absolutely nothing to it — and now I am so discouraged.
Lise Meitner at age 50
In 1944, the discovery of nuclear fission was awarded the Nobel Prize in Chemistry — to Hahn alone. Sime writes:
The distortion of reality and the suppression of memory are recurrent themes in any study of Nazi Germany and its aftermath. By any normal standard of scientific attribution, there would have been no doubt about Meitner’s role in the discovery of fission. For it is clear from the published record and from private correspondence that this was a discovery to which Meitner contributed from beginning to end — an inherently interdisciplinary discovery that would, without question, have been recognized as such, were it not for the artifact of Meitner’s forced emigration. But nothing about this discovery was untouched by the politics of Germany in 1938. The same racial policies that drove Meitner out of Germany made it impossible for her to be part of Hahn and Strassmann’s publication, and dangerous for Hahn to acknowledge their continuing ties. A few weeks after the discovery was made, Hahn claimed it for chemistry alone; before long, he suppressed and denied not only his hidden collaboration with a “non-Aryan” in exile but the value of nearly everything she had done before as well. It was self-deception, brought on by fear. Hahn’s dishonesty distorted the record of this discovery and almost cost Lise Meitner her place in its history.
Meitner received countless accolades in her lifetime and even had a chemical element, meitnerium, posthumously named after her, but the slight was never righted. Although every imaginable roadblock had been placed before her in pursuing a scientific education, she had survived Nazi persecution, and had endured the anguish of exile, she considered the Nobel omission that most irredeemable sorrow of her life.
Sime writes:
Except for a few brief statements, she did not campaign on her own behalf; she did not write an autobiography, nor did she authorize a biography during her lifetime. Only seldom did she speak of her struggle for education and acceptance, although the insecurity and isolation of her formative years affected her deeply later on. And she almost never spoke of her forced emigration, shattered career, or broken friendships. She would have preferred that the essentials of her life be gleaned from her scientific publications, but she knew that in her case that would not suffice.
[…]
Scientist that she was, she preserved her data. Her rich collection of personal papers, in addition to archival material from other sources, provides the basis for a detailed understanding of her work, her life, and the exceptionally difficult period in which she lived.
Sime considers the more systemic implications of Meitner’s case:
To insist that Meitner contributed nothing to the fission discovery, to imply that Meitner and Frisch had been given an unfair advantage — these were ways of denying that she had been treated unjustly and, in a larger sense, of refusing to confront the injustice and crimes of the Nazi period. Rather than acknowledging that Meitner’s exclusion from fission was political, Hahn and his hangers-on invented spurious scientific reasons for it. Arrogantly, and with misplaced national pride, they denied the injustice, created new injustice — and implicated themselves.
Given the echo chamber of interpretive opinion we call history, Hahn’s view was readily echoed by his followers and, in turn, by generations of journalists and uncritical commentators on the history of science. The Nobel exclusion was the most obvious, but the egregious erasure of Meitner’s legacy didn’t end there. The fission apparatus — the very instrument she had used in her Berlin laboratory to make her discoveries — was on display at Germany’s premiere science museum for thirty-five years without so much as mentioning her name.

This, of course, was far from the last time that a woman was excluded from a Nobel Prize for a discovery she either made or made possible with her significant contribution: There is, perhaps most famously, Jocelyn Bell Burnell’s discovery of pulsars, to say nothing of Vera Rubin, whose confirmation of the existence of dark matter furnished a major leap in our understanding of the universe and yet remains, decades later, bereft of a Nobel. But as physicist and novelist Janna Levin wrote in her excellent NPR op-edabout the foibles of scientific acclaim, “scientists do not devote their lives to the sometimes lonely, agonizing, toilsome investigation of an austere universe because they want a prize.”

Meitner herself articulated the same sentiment in a speech she gave in Vienna at the age of 75:
Science makes people reach selflessly for truth and objectivity; it teaches people to accept reality, with wonder and admiration, not to mention the deep joy and awe that the natural order of things brings to the true scientist.
Lise Meitner late in life (Photograph: Sara Darling)
Meitner died peacefully in her sleep on October 27, 1968, days before her ninetieth birthday. Otto Robert, one of her dearest friends, chose the inscription for her headstone:
Lise Meitner: a physicist who never lost her humanity.
Complement the intensely interesting and important Lise Meitner: A Life in Physics with pioneering astrophysicist Vera Rubin on what it’s like to be a woman in science, Margot Lee Shetterly on the untold story of the black women mathematicians who powered space exploration, and this illustrated homage to trailblazing women in science.


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