The Elements of Marie Curie: How the Glow of Radium Lit a Path for Women in Science

by Dava Sobel

Mme. Curie disclosed decades later in an autobiographical essay. “My mother had an exceptional personality. With all her intellectuality she had a big heart and a very high sense of duty . . . Her influence over me was extraordinary, for in me the natural love of the little girl for her mother was united with a passionate admiration.”

“So it was in November, 1891, at the age of twenty-four,” she recalled three decades later, “that I was able to realize the dream that had been ever present in my mind for several years.”

“The room I lived in,” she recalled in later years, “was in a garret, very cold in winter, for it was insufficiently heated by a small stove which often lacked coal. During a particularly rigorous winter, it was not unusual for the water to freeze in the basin in the night; to be able to sleep I was obliged to pile all my clothes on the bedcovers. In the same room I prepared my meals with the aid of an alcohol lamp and a few kitchen utensils. These meals were often reduced to bread with a cup of chocolate, eggs or fruit. I had no help in housekeeping and I myself carried the little coal I used up the six flights.” Even so, the life held “a real charm” for her. “All that I saw and learned that was new delighted me. It was like a new world opened to me, the world of science, which I was at last permitted to know in all liberty.”

He had long since sworn off intimacy. As he rationalized in some diary notes set down at age twenty-two, “A woman loves life for the living of it far more than we do. Women of genius are rare. Thus when we . . . give all our thoughts to some work which estranges us from those nearest us, it is with women that we must struggle. The mother wants the love of her child above all things, even if she should make an imbecile of him. The mistress also wishes to possess her lover, and would find it quite natural to sacrifice the rarest genius in the world for an hour of love.”

In French, the word for “magnet,” aimant, also means “loving.” Love makes an apt metaphor for the attraction of magnetic opposites. Two bar magnets will cling together when their opposite poles are put in proximity but repel one another if like ends meet. As in the case of human allure, magnetic attraction may fade with time. In fact, although scientists of the late nineteenth century divided magnetic materials into “permanent” and “temporary” categories, they conceded that “permanent magnetism” was probably as elusive as everlasting love.

That summer of 1894, separated by a thousand miles, she and Pierre corresponded regularly. “It would be a beautiful thing,” he wrote to her in August, “to pass through life together, hypnotized by our dreams: your dream for your country; our dream for humanity; our dream for science. Of all these dreams, I believe the last, alone, is legitimate.” Only in the realm of science, he explained, could they be certain of accomplishing more good than harm. “The territory here is more solid and obvious, and however small it is, it is truly in our possession.”

“I do not know why I have got it into my head to keep you in France, to exile you from your country and family without having anything good to offer you in exchange for such a sacrifice.” At the same time, he honestly believed that professional prospects for her were likely better in Paris than in Poland. If she would not marry him, might she agree to live with him in friendship? There were suitable rooms available “on the rue Mouffetard,” he informed her, “with windows overlooking a garden. This apartment is divided into two independent parts.”

It was the first time either of them had spent more than a few hours away from the other since their marriage. Pierre pined for her in his best beginner’s Polish: “My little girl, so dear, so sweet, whom I love so much, I had your letter today and was very happy.”

“My dear husband!” she replied by postcard, mindful of his limited vocabulary in her language. “Fine weather here, the sun is shining and it’s warm. I’m very sad without you. Come quickly. I wait for you from morning till evening and still don’t see you coming. I’m fine. I work as much as I can, but Poincaré’s book is more difficult than I expected. I need to talk with you about it and look together with you at the parts that are giving me trouble.”

“I think of my dearest who fills up my life, and I long to have new powers. It seems to me that in concentrating my mind exclusively on you, as I am doing, that I should succeed in seeing you, and in following what you are doing; and also to make you feel that I am entirely yours at this moment,—but the image does not come.”

In December she submitted her report to the Société pour l’Encouragement de l’Industrie Nationale. The society announced her findings immediately in its monthly bulletin, praising her work as “important,” and published the full text of her paper soon afterward. The 1,500 francs she received as compensation for her research enabled Marie to repay a kindness. She well remembered how the 1893 Alexandrovitch Scholarship of 600 rubles had allowed her to live another year in Paris, to work toward a second university degree, to accept a challenge from the steel industry, and to enjoy all that had followed from those experiences. Here was an opportunity to give someone else a chance at advancement. Her show of gratitude startled the granting agency and made Marie the anonymous patroness of another deserving student—someone as impoverished as she had been, and whose identity she would never know.

“In our life together,” she wrote in retrospect, “it was given to me to know him as he had hoped I might, and to penetrate each day further into his thought. He was as much and much more than all I had dreamed at the time of our union. My admiration of his unusual qualities grew continually; he lived on a plane so rare and so elevated that he sometimes seemed to me a being unique in his freedom from all vanity and from the littlenesses that one discovers in oneself and in others, and which one judges with indulgence although aspiring to a more perfect ideal.”

Mme. Curie saw in ionization a way to quantify the uranic rays released from various substances—by measuring the electrical conductivity they excited in the air around them.

The uranic-ray activity did not disappear or even dissipate when uranium combined chemically with other elements. Nor did the activity of her samples alter if she heated them to high temperatures, or exposed them to strong light, or bombarded them with X-rays. Nothing sapped uranium’s emissive power. On the basis of these observations, she concluded that the release of uranic rays must be an essential atomic property of uranium, as constant and defining as its atomic weight. Yet uranium’s behavior defied the most fundamental physical principles. Basic “laws” of physics stipulated that energy could be neither created nor destroyed, but only changed from one form to another.

Marie turned for help to her former professor, Gabriel Lippmann, who read aloud her paper, “Rays Emitted by the Compounds of Uranium and Thorium,” at the April 12 meeting. The most stunning remarks in Mme. Curie’s paper concerned the mineral pitchblende. She had examined three samples of the blackish ore, two from mines in eastern Europe and one from Cornwall in England. Each had yielded a different activity reading, with one of them tripling and another quadrupling the value for uranium. “This fact is very remarkable,” she affirmed, “and leads to the belief that these minerals may contain an element which is much more active than uranium.” Now all she had to do was find it.

Marie had taken to calling uranic rays by the more general term “Becquerel rays” after she detected them in thorium. Now she introduced an altogether original term for the ability of select heavy elements such as uranium and thorium to radiate: “radio-active” appeared for the first time in the title of the report she coauthored with Pierre, “On a New Radio-active Substance Contained in Pitchblende,” which Becquerel read to the assembled Académiciens on July 18, 1898.

The Curies admitted they could not yet separate their new radio-active substance from bismuth by any means. Nevertheless, they felt so certain of the element’s existence that they had already christened it: “We propose to call it polonium from the name of the country of origin of one of us.”

The new element practically named itself—not by any color but rather by its extraordinary degree of radio-activity, which multiplied that of uranium a thousandfold. The Curies and their collaborator Bémont thought the difference might be even greater, but they had run out of pitchblende and could go no further till they got more. On the day after Christmas in 1898, Henri Becquerel informed the Académie des Sciences of the discovery of “radium.”

Marie lost the ever-ready companionship of her sister Bronya. The doctors Dluski moved in the autumn of 1898 to Zakopane, part of Austrian Poland in the Tatra Mountains, to create a modern tuberculosis sanitarium. “You can’t imagine what a hole you have made in my life,” Marie wailed to Bronya in early December. “With you two, I have lost everything I clung to in Paris except my husband and child. It seems to me that Paris no longer exists, aside from our lodging and the school where we work.”

“I miss my family enormously, above all you, my dears, and Father. I often think of my isolation with grief. I cannot complain of anything else, for our health is not bad, the child is growing well, and I have the best husband one could dream of; I could never have imagined finding one like him. He is a true gift of heaven, and the more we live together the more we love each other.”

Marie’s early estimate of a 1 percent polonium content in pitchblende had been wildly optimistic. Since sizable lumps of pitchblende had yielded only barely discernible traces of the desired end products, the proportion by weight veered toward one-thousandth or even one-hundred-thousandth of one percent. And so, instead of a mere hundred grams of pitchblende, they now ordered one hundred kilograms (about 220 pounds) from the mine in Bohemia and paid for it with Marie’s prize money. Clearly their operations would no longer fit into the tiny lab space on the ground floor of the industrial school. Once again the accommodating director, Paul Schützenberger, found room for Marie’s activities. Across the courtyard from the school stood an old wooden shed that had once served as an anatomy theater for medical students. A cast-iron stove, a blackboard, and a few worn pine tables were the only furnishings left in the place, which looked more like a hangar than a laboratory. It had an asphalt floor and a glass roof that leaked. A century would pass before the term “glass ceiling” gained currency as a metaphor for invisible barriers to women’s advancement, but Marie Curie toiled under an actual glass ceiling from 1899 to 1902, the years she spent in that “poor, shabby hangar,” spinning pitchblende into radium.

Ernest Rutherford, for example, a young New Zealander studying under J. J. Thomson at the Cavendish Laboratory in Cambridge, discovered through experiments with uranium that uranic rays were of two distinct types. The ones he dubbed “alpha rays” played the primary role in ionizing gases, but they did not travel far and could be blocked altogether by a sheet of paper. The “beta rays,” on the other hand, ionized only weakly but were extremely penetrating. They could pass through metal screens and cover considerable distances. Adherents of the new science had also learned that radioactivity was contagious: an active source such as radium could render other objects radioactive, too, at least temporarily. This “induced radioactivity,” Pierre said, had contaminated just about everything in the Curies’ lab.

On the day of her dissertation defense, June 25, 1903, she appeared at the Sorbonne students’ hall wearing the new black silk-and-wool dress that Bronya, visiting for the occasion, had made her buy. The family—Bronya, Pierre, and old Dr. Curie—sat at the back of the crowded room near a coterie of Sèvres students. Marie had invited these young women to attend, in the hope that their presence would embolden her, and also with the goal of showing them where their own studies might lead. In addition to her mentor Gabriel Lippmann, the three-member faculty jury seated at the oak table included chemist Henri Moisson, who had supplied her with her earliest samples of uranium, and physicist Edmond Bouty. She stood before them, occasionally augmenting her answers to their questions with an equation or diagram sketched on the chalkboard. At length they congratulated Mme. Curie on her historic success as the first woman in France to receive the PhD degree in physics. Automatically she became the first wife—as well as the first mother—to own that achievement. And although most of the audience remained ignorant of the fact, she was also the first person to defend a dissertation while pregnant.

Early in 1903, Pierre received word from one of the nominators that he alone—and not Marie—would likely share the physics prize with Henri Becquerel for the discovery and study of radioactivity. “This would be a great honor for me,” he replied, “however I should very much like to share the honor with Mme. Curie, and for us to be considered jointly, in the same way that we have done our work.” He reiterated the details of that work to clarify Marie’s role, and at length the physics committee agreed to include her.

Alluding to the injury that radium inflicted when held close to the body, Pierre conceded the element might “become very dangerous in criminal hands.” He raised the question as to “whether mankind benefits from knowing the secrets of Nature.” In answer, Pierre invoked Alfred Nobel’s powerful explosives, which had facilitated both “wonderful work” and “also a terrible means of destruction.” “I am one of those who believe with Nobel,” Pierre said in closing, “that mankind will derive more good than harm from the new discoveries.”

The next week, sitting alone at her workplace in the rue Cuvier, she spilled her thoughts on the graph-paper pages of a lab notebook. “Cher Pierre, whom I’ll never see again,” she began, “I want to talk to you in the silence of this laboratory, where I could not have imagined I would ever find myself without you.” She wrote a dozen pages detailing every moment of their final days together. Even as she strained to render those intimate, idyllic hours indelible in her memory, she could see them blurring and slipping away. “Soon I’ll have only your pictures to rely on. Oh! If only I could paint or sculpt a dear vision to keep you ever present in my eyes.” She tried to make a measurement for a graph on which they had each plotted several points, but felt the impossibility of going on. “In the street I walk as if hypnotized, without noticing anything. I will not kill myself. I have no desire for suicide. But among all these vehicles is there not one to make me share the fate of my beloved?”

Marie continued to speak to Pierre in this journal of her grief. She cursed the anguish that consumed her. She fretted for her children, especially Irène, “because I dreamed, Pierre, as I often told you, that this girl with her calm, serious manner would one day work alongside you. Now who will give her what you could have given her?”

The man of science must have been sleepy indeed who did not jump from his chair like a scared dog when, in 1898, Mme. Curie threw on his desk the metaphysical bomb she called radium. —Henry Adams, The Education of Henry Adams

“Yesterday I gave the first class replacing my Pierre,” she wrote in her private journal. “What grief and what despair!” Addressing Pierre directly, she said: “You would have been happy to see me as a professor at the Sorbonne, and I would have done it so willingly for you.—But to do it in your place, oh my Pierre, could one dream of a thing more cruel? And how I suffered through it, and how discouraged I am.”

“Physically,” Harriet noted, “she is extremely frail and her two children naturally absorb some of her attention.” Yet Madame the director proved “ever ready to grapple with the difficulties and problems of those working with her, even when she was a prey to anxieties that would unnerve most women.”

Marie’s altogether different experience of marriage had not only advanced her career instead of ending it, but positioned her to assume her singular role as female head of a laboratory. Wedded to her research partner, she had managed to incorporate love and motherhood into the fullness of a life in science, if only for a while. “A year has passed,” she wrote on the anniversary of Pierre’s death. “I live, for your children, for your aged father. The grief is dull but always there. The burden weighs heavily on my shoulders. How sweet will it be to go to sleep and not wake up? How young my poor dear ones are! How tired I feel!”