Marie Curie

In December 1911, in the midst of a widely publicized adultery scandal, Marie Curie was urged to wait until her name had been cleared before claiming the Nobel Prize in Chemistry. In defending her right to claim the announced award, Curie wrote back insisting that “there is no connection between my scientific work and ... private life.” In fact, however, there was a connection: Both professionally and personally, Curie’s life was governed by fierce determination coupled with a sense of personal dignity.

The International Year of Chemistry, 2011, marks the 100th anniversary of Marie Curie’s Nobel Prize “in recognition of her services to the advancement of chemistry by the discovery of the elements radium and polonium, by the isolation of radium and the study of the nature and compounds of this remarkable element.” Curie’s discoveries not only helped revolutionize fundamental concepts of matter and energy but also inaugurated the use of radiation for medical research and treatment. This year’s celebration provides a welcome opportunity to reflect on this great scientist’s career and legacy.

Maria Skłodowska was born in 1867 in Warsaw. The Polish city was under control of czarist Russia, determined to eradicate Polish national identity. After her mother’s premature death from tuberculosis, Maria and her siblings were raised by their father, who had taught high school math and physics until his dismissal for pro-Polish beliefs. Maria, who graduated at the top of her high school class, hoped to get an advanced degree; her sister Bronislawa (Bronya) wanted medical training. Women, however, were barred from the University of Warsaw. Maria agreed to help subsidize Bronya’s medical education in Paris by working as a governess; when Bronya was professionally established, she would contribute to Maria’s education.

In spare moments as a governess, Maria studied physics and chemistry on her own and, by correspondence with her father, took an advanced math course. Here and there, she also gained some laboratory experience. After her father secured a decently paid position as director of a reform school, he was able to contribute to his daughters’ studies. In the fall of 1891, Maria began studies at the Sorbonne in Paris, where she changed her name to its French equivalent, Marie.

Despite a lack of fluency in technical French and inadequate formal training in math and science, within three years Marie completed, with distinction, the equivalent of master’s degrees in both physics and math. A commission from the Society for the Encouragement of National Industry led her to search for lab space so she could relate the magnetic properties of several steels to their chemical compositions. That hunt culminated in an introduction in 1894 to French physicist Pierre Cu rie, then-laboratory chief of the Municipal School of Industrial Physics & Chemistry, in Paris. The school’s director permitted Marie to work on the premises, where, in fact, Pierre had no satisfactory lab.

As their relationship deepened, Pierre convinced Marie to pursue doctoral studies in Paris. Finances had forced him to postpone his own doctoral work, despite the fact that he had already codiscovered the piezoelectric effect and invented a sensitive scientific balance named in his honor. Just months before their marriage in 1895 and at Marie’s insistence, Pierre completed a doctorate by writing up the discoveries he had already made about a basic relationship between magnetic properties and temperature. (He had completed the work some time before, but had never written it up until Marie insisted he do so to obtain a doctorate.) The degree led to Pierre’s promotion to a professorship but not to an upgrade of his lab at the Municipal School.

The Curies’ first child, future Nobel Laureate Irène, was delivered by Pierre’s physician father in 1897. After the sudden death of Pierre’s mother, his father moved in with the young family and helped raise Irène. Having completed her commissioned research, Marie sought a thesis topic at a time when no woman anywhere had completed a scientific doctorate. She decided to study rays emitted by uranium compounds, whose ability to fog a photographic plate, even when the rays were emitted in darkness, was accidentally discovered in 1896 by French physicist Henri Becquerel. Pierre adapted the Curie electrometer to enable Marie to measure the faint currents given off by the rays.

In her 1923 memoir, Marie explained that her measurements suggested a revolutionary hypothesis: “My experiments proved that the radiation of uranium compounds ... is an atomic property of the element uranium ... and depends neither on conditions of chemical combination, nor on external circumstances, such as light and temperature.” By April 1898, her subsequent tests of the other known elements revealed that thorium compounds also emitted Becquerel rays. She coined the term “radioactivity,” from the Latin word for ray, to describe the behavior of uranium and thorium.

When Marie’s research revealed that pitchblende and chalcolite, two uranium ores, were much more radioactive than pure uranium, Pierre joined her in the search for more undiscovered radioactive elements. Their hunt turned up polonium and radium in 1898. After these discoveries, Pierre concentrated on investigating radium’s physical properties, and Marie did chemical experiments to facilitate the preparation of pure compounds containing newly found elements.

It would take more than three years for her to isolate a tenth of a gram of pure radium chloride. She never succeeded in isolating polonium, which has a half-life of only 138 days. The reasons for her failure were not understood until Ernest Rutherford and Frederick Soddy published their theory of radioactive decay in 1903. Pierre, meanwhile, discovered that radium emits heat spontaneously and that its emissions can damage living tissue, a discovery that inaugurated the use of radioactive treatments for cancer and other ailments.

To augment their income, Pierre accepted an appointment as the physics chair to a Sorbonne program for medical students. The appointment came without provision for laboratory facilities, so the Curies continued their radioactivity research at the Municipal School, where Pierre also continued to teach. Marie, whose research was unfunded, took a paid position as the first woman lecturer at France’s elite teacher-training institute for women; she was also the first to include lab work in the institute’s physics curriculum.

In June 1903, Marie defended her thesis, “Research on Radioactive Substances,” which, her examiners claimed, contributed more to scientific knowledge than any previous thesis ever published. Six months later, Becquerel and both Curies were awarded the Nobel Prize in Physics for “their joint researches on the radiation phenomena discovered by Professor Henri Becquerel.”

The Curies’ ill health, which they refused to attribute to the radiation, kept them from traveling to Stockholm until June 1905 for the obligatory lecture describing their work’s importance. Speaking on behalf of both, Pierre revealed that, despite the perhaps “more fertile” explanation offered by Rutherford and Soddy, he and Marie maintained that “it is not absurd to suppose that space is constantly traversed by very penetrating radiations which certain substances would be capable of capturing in flight.” But by the time she delivered her own Nobel lecture, “Radium and the New Concepts in Chemistry,” in 1911, Marie acknowledged that Rutherford’s work “has provided a backbone for the new science, in the form of a very precise theory admirably suited to the study of the phenomena.”

The physics prize led to Pierre’s professorship at the Sorbonne and to Marie’s appointment as salaried laboratory chief. Shortly after their move to the Sorbonne, their second daughter, Eve, was born. Marie soon returned to research and to teaching at the teacher-training institute.

By spring 1906, the couple believed that they were making progress in their attempt to measure the radioactive gas emitted by radium. Then, tragedy struck. On a rainy April afternoon, Pierre was killed in a traffic accident. The following month, the Sorbonne offered Marie Pierre’s academic position, which she accepted with the hope of establishing a research institute in his honor. Curie, the Sorbonne’s first woman professor, eventually succeeded in creating that institution, the Radium Institute. Over the next four years, she isolated radium metal, published a comprehensive textbook on radioactivity, and secured the right to define the curie—the international standard for radium emissions—for use in industrial and medical applications.

For nearly all of 1912, however, Curie was a stranger to her lab. The cause was the aforementioned scandal, which erupted after the publication of rumors of her romantic entanglement with Paul Langevin, a brilliant former pupil of Pierre’s. Langevin, who had taken over Curie’s position at the teacher-training school, was unhappily married to a woman who resented what she perceived as his commitment to science over family. While Curie was attending an international conference of physicists in Brussels, where she was the only woman, the right-wing press published intimate letters she and Langevin had exchanged, falsely hinting, among other things, that Pierre’s death was no accident but a suicide caused by his wife’s infidelity.

While the scandal grew, Curie received a telegram from the Nobel committee announcing the award of her chemistry prize. But an influential Swedish scientist on the committee urged her to decline it until the scandal abated. If Curie had been less insistent that she had every intention of accepting the accolade, which celebrated her scientific achievement and not her personal relationships, she might not have become the first of a still small group of individuals ever to have won a second Nobel Prize. After mustering the spirit to deliver an impressive Nobel lecture, Curie suffered a lengthy period of ill health and depression, returning to the lab in December 1912. With the scandal behind her, she never had another romantic attachment. She and Langevin remained friends; her granddaughter Hélène and his grandson Michel would later marry and pursue scientific careers of their own.

Curie dedicated most of the rest of her life to the Radium Institute. Although the institute was ready to open in August 1914, World War I intervened. Determined to put X-ray technology to use in military hospitals, Curie, assisted by Irène, ran a radiology service to help physicians locate bullets, shrapnel, and broken bones. Not completely aware of the dangers of overexposure to X-rays, the mother-daughter team took inadequate precautions, wearing cloth gloves, occasionally separating themselves from the equipment with small metal screens, and avoiding direct beams whenever possible.

Curie subsequently trained about 150 female radiological assistants at the Radium Institute; Irène, then a Sorbonne student, assisted. Curie also established a military radiotherapy service, using radon—a radioactive gas emitted as radium decays—sealed in thin glass tubes, which, when placed inside needles strategically positioned within patients’ bodies, could destroy diseased tissue. After the war’s end in November 1918, Curie also offered radiology courses to U.S. soldiers through the Radium Institute.

Despite her distrust of journalists, Curie granted an interview in 1920 to U.S. women’s magazine editor Marie Mattingly (Missy) Meloney. Shocked to learn that Curie, discoverer of radium, had only 1 g in her laboratory, while U.S. research and medical institutions had about 50 times as much, Meloney organized a six-week tour of the U.S. in 1921 for Curie to raise money for the Radium Institute.

Educated U.S. women hoped the tour would prove that women could play an important role in science. Curie, however, found little time in her schedule to meet with U.S. women scientists. She was nonplussed by the coeds she encountered, who seemed lacking in the commitment to science that had driven her. Curie’s visit may have worsened scientific opportunities for aspiring U.S. women scientists by providing a new rationale for discrimination. U.S. universities now justified their failure to hire women scientists on the grounds that they failed to live up to the high standard set by the double Nobel Laureate.

The Marie Curie Radium Campaign succeeded on its own terms, however, yielding for Curie’s institute a second gram of radium, costly equipment and ores, as well as money.

Directing the institute replaced research as the defining purpose of Curie’s life. Under her directorship, it became one of four major world centers for radioactivity research. Although she always included some women on her research staff, Curie was no feminist. Despite her personal devotion to research, she told her daughter Eve, “What I want for women and young girls is a simple family life and some work that will interest them.”

Still, several women did significant research at the Radium Institute, including Marguerite Perey, who discovered the element francium, and Irène, who in collaboration with her husband, Frédéric Joliot, discovered artificial radioactivity some months before Curie’s death. Curie, however, was not necessarily a better employer of women than male institute heads of her day, including Edward Pickering at the Harvard College Observatory, who paid low wages to female assistants hired to do the tedious classification of photographic plates. Many of the women in Curie’s lab were assigned similarly detail-oriented but ultimately boring, repetitive, and uncreative tasks. Pickering, however, paid women for their labor, while Curie exploited the gratis efforts of many women volunteers.

As Curie’s health declined over the final 14 years of her life, she refused to acknowledge a possible link between her health and radiation exposure. On July 4, 1934, Curie died in a sanatorium in Switzerland from what the sanatorium director called “an aplastic pernicious anemia,” probably caused by “a long accumulation of radiations.” For more than 60 years she lay in a cemetery alongside Pierre’s remains. In 1995, however, their remains were transferred to the Panthéon, France’s national mausoleum. Curie thus became the first woman whose own achievements merited her burial alongside France’s most important men.

At the time of the transfer, researchers analyzed the radium levels in her original coffin. They concluded that the levels were too low to account for her death. The current theory, therefore, is that Curie died not from the radium she handled with bare hands—and often sucked up with pipettes to transfer from container to container—but rather from exposure to X-rays during the war.

Among the 159 individuals to have been awarded the Nobel Prize in Chemistry, Curie is the first of only four females. The women prize winners to follow her are her daughter Irène (1935), Dorothy Crowfoot Hodgkin (1964), and Ada E. Yonath (2009). One wonders how many women chemists will be so honored over the coming century, and what role personal and professional determination may play in their achieving this most prestigious of all awards. ◾