Pierre Curie was Laboratory Chief in charge of all practical work at The City of Paris Industrial Physics and Chemistry Higher Education Institution (ESPCI). Marya Skłodowska[1] was searching for lab space to do a study for which she was retained by the Society for the Encouragement of National Industry[2] relating the magnetic properties of various steels to their chemical composition. She had secured space for her work in the laboratory of Gabriel Lippmann[3]; however, his lab was crowded making her work difficult.
Marie (by now, Marya was going by the French version of her name) mentioned her need for a lab to an acquaintance, Józef Wierusz-Kowalski, a Polish physicist and professor—and a great admirer of Pierre, who at age 35 had already made groundbreaking scientific discoveries related to magnetism and crystals. Unaware of how inadequate Pierre’s own lab facilities were, it occurred to the professor, his friend and colleague might be able to assist the brilliant foreign student. Although Pierre had an impressive title, his lab facilities were poor. Not knowing this, the professor suggested perhaps Pierre could find room there for Marie to work. Józef was honeymooning in Paris, so he invited Pierre and Marie to have tea with him and his wife. Despite an eight-year age difference, the two scientists hit it off immediately. This initial meeting would change not only their lives, but also the course of science.
An extraordinary partnership begins
Pierre welcomed Marie to join him in his laboratory as his student. She ultimately became his research partner, and they divided their work—Pierre focusing primarily on physics and Marie on chemistry. She worked on the properties of steel while he continued his studies on crystals. His respect for her grew when he realized she, too, was a dedicated scientist who wouldn’t inhibit his research, and he began to regard her as his muse. Their mutual passion for science brought them increasingly closer. As Pierre’s feelings deepened, he pursued her romantically; however, she rebuffed him at first because she was still committed to returning to her beloved Poland.
Having been raised by parents whose spirit of patriotism was stoked by living under Tsarist oppression for many years, Marie dreamed of a day when Poland would be an independent sovereign nation. She was driven to succeed as a woman in the sciences, not only because of her innate curiosity and passion for science and discovery, but also because she wanted to contribute her efforts toward preserving their national spirit. She never intended to live as an expatriate in France.
In the summer of 1894, after completing her mathematics exam and being awarded her second Master of Science degree, Marie returned to Poland to visit her family during the school break, uncertain she would return to France. Despite everything she experienced growing up in a country under Tsarist rule, she still believed she would be able to work in her chosen field in Poland. Her hopes were dashed when she was denied a place at Kraków University because she was a woman. Pierre’s heartfelt letters—and his offer to move to Poland himself—helped convince her, she should pursue science and her doctorate in Paris, and not return to Poland.
Marie, in turn, convinced Pierre to write up his magnetism research and get his doctoral degree. Although Pierre was an internationally known physicist, he was an outsider in the French scientific community who was uninterested in fame. He had done important research in multiple scientific fields over the past 15 years, but had never bothered to complete a doctorate. At Marie’s urging, he wrote up his research on the various types of magnetism, and included a presentation on the connection between temperature and magnetism – now known as Curie’s Law[iv]. In March 1895, he was awarded his doctorate of science. At the Municipal School (ESPCI), Pierre was promoted to a professorship[v], and his teaching duties increased; however, his lab got no better.
A colleague called Marie “Pierre’s biggest discovery”; though, it was a perfect match for them both. In Pierre, Marie had found a new love, a partner, and a scientific collaborator on whom she could depend. They married on 26 July 1895 in a simple civil service in the town hall at Sceaux[vi], where Pierre’s parents lived. Instead of a bridal gown, Marie wore a practical dark blue ensemble which would serve her for many years as a laboratory outfit. They used money received as a wedding gift to buy a pair of bicycles, and for their honeymoon, they took a bicycle excursion along the coast of Brittany and into the French countryside. These long, adventurous cycle rides would become a favorite pastime and a way to relax after spending long hours in the lab.
Over the next two years, while Pierre continued his work, Marie completed her research on the magnetic properties of steels. She submitted her final results shortly before giving birth to their first daughter, Irène, in September 1897.[vii] Marie began looking for a research topic which would earn her a doctorate in science. No woman in the world had yet completed this degree.
The discovery of X-rays and “invisible light”
Two recent discoveries by other scientists inspired Marie in her search for a thesis topic.
- In November 1895, German mechanical engineer and physicist, Wilhelm Röntgen[viii], discovered a ray could travel through solid wood or flesh and yield photographs of living people’s bones. He called this wavelength of electromagnetic radiation ‘X-rays’ (X for ‘unknown’). This discovery earned him the first Nobel Prize in Physics in 1901.
- A few months later, in early 1896, French engineer and physicist, Henri Becquerel[ix], reported a serendipitous discovery[x] to the French Academy of Sciences: uranium compounds, even when kept in the dark, emitted rays would expose a photographic plate. Despite this intriguing discovery and his important observations[xi], the scientific community continued to focus its attention on Röntgen’s X-rays, neglecting the much weaker Becquerel rays (uranium rays), and Becquerel did not pursue his observations further after publishing.
Largely ignored by the scientific community, Becquerel’s work, however, did catch the attention of the Curies, and Marie had found a topic for her doctoral thesis.
A new name for a new science: Radioactivity
To begin a systematic investigation of the mysterious uranium rays, Marie had a secret weapon: a highly sensitive electrometer, based on the piezoelectric effect, built by Pierre and his brother Jacques during their earlier studies on magnetism. With its ability to measure weak electrical currents, Marie was able to measure the strength of radiation emitted from uranium compounds. As she checked her results, she unexpectedly discovered uranium pitchblende[xii] emitted about four times as much radiation as one would expect from its uranium content. She announced a revolutionary hypothesis: the emission of these rays was an atomic property of uranium (the rays were not dependent on the uranium’s form, but on its atomic structure). If true, this would mean the accepted view of the atom as the smallest possible fragment of matter was false. In 1898, she hypothesized pitchblende contains a small amount of an unknown radiating element, a revolutionary conclusion which would change the periodic table of the elements and open the door to new scientific study.
Recognizing the importance of this hypothesis—and increasingly intrigued by her work, Pierre gave up his research into crystals and symmetry in nature and joined Marie in her work. At the end of June 1898, they had isolated a substance which was approximately 300 times more strongly active than uranium. When they published their findings in July 1898, they suggested calling this new element polonium, after Poland, Marie’s beloved homeland. In this publication, for the first time, they used the term coined by Marie herself: Radioactivity. In December 1898, the Curies informed the Academy of Sciences they had discovered another new element, for which they suggested the name, radium, derived from the Polish word for happiness, radość. They were able to produce about 0.1 gram which had been derived laboriously from tons of uranium ore[1].
This part of their life together has become the stuff of legend. To separate and analyze these elements (and to handle the tons of slag and pitchblende), they needed more space. The director of ESPCI allowed them to set up shop in a crowded, damp shed where Marie carried out the laborious chemical separations[2] while Pierre took the measurements after each successive step. After thousands of crystallizations, Marie presented the findings of her work in her doctoral thesis on 25 June 1903. The examination committee[3] stated Marie’s findings represented the greatest scientific contribution ever made in a doctoral thesis. Her theory created a new field of study, atomic physics, and she became the first woman in France to earn a doctorate in science.
The 1903 Nobel Prize in Physics
In November 1903, Pierre was named, along with Becquerel, the winner of the Nobel Prize in Physics. Although the nominating committee objected to include a woman as a Nobel Laureate, Pierre insisted the original research was Marie’s—and she had conceived experiments and generated theories about the nature of radioactivity. The committee agreed to include her, making her the first woman to win a Nobel Prize.[4]
Because of their teaching obligations and both being too ill to travel—most likely because of excessive exposure to radioactive materials[5]—the Curies were unable to go to Stockholm until June 1905 to receive the prize.
The price of fame for the celebrity scientists
Winning the Nobel Prize had assuaged the Curie’s financial worries, but they now found themselves the focus of unwanted attention by the press and the public who were enchanted by the story of the brilliant scientists. They found themselves thrust suddenly into the spotlight.
Still, it was Pierre, not Marie, who was promoted to a full professorship. However, because Pierre was able to hire more assistants, he made Marie the official head of the laboratory—enabling her to conduct experiments and be paid for it for the first time. When Paul Appell[6], dean of the faculty of sciences, asked Pierre for permission to submit his name as a possible recipient for the Legion of Honor in July 1903, Pierre replied, “I do not feel the slightest need of being decorated, but I am in the greatest need of a laboratory.” Although he was given a chair at the Sorbonne in 1904 with the promise of a laboratory, two years later, construction still had not yet begun. Pierre Curie would never obtain a real laboratory …
[1] To be able to show with certainty they had discovered two new elements, the Curies would have to produce them in demonstrable amounts, determine their atomic weight, and isolate them. To accomplish this, they would need tons of costly pitchblende (uraninite). They were able to obtain several tons of slag from the slag heaps in the forests surrounding the Joachimsthal mine in Bohemia. They later obtained several tons of pitchblende from the Austrian Academy of Sciences. The Austrians hoped she would find a use for a mineral their mines yielded as a waste byproduct.
[2] Marie would process 20 kilos of raw material at a time. This work was tedious and backbreaking. She would first have to clear away all the forest debris and then spend days at a time stirring the boiling mass with a heavy iron rod which was almost as big as she was.
[3] Of the three members of the examination committee, two would receive the Nobel Prize: Gabriel Lippmann, her former teacher, in 1908 for physics, and Henri Moissan, in 1906 for chemistry (investigation and isolation of the element fluorine). Lippmann was also both Pierre’s and Marie’s doctoral advisor.
[4] For his discovery of spontaneous radioactivity, Henri Becquerel was awarded half of the Nobel Prize for Physics in 1903, the other half being given to Pierre and Marie Curie for their study of the radiation phenomena discovered by Becquerel.
[5] Marie had also recently suffered a miscarriage.
[6] Paul Émile Appel was a French mathematician and Rector of the University of Paris.
[1] Affectionately called Manya, Marie Curie was born Marya Salomea Skłodowska on 7 November 1867 in Warsaw, Congress Poland, Russian Empire.
[2] This society was a group of industrialists who paid Marie to investigate the magnetic properties of different steels.
[3] Jonas Ferdinand Gabriel Lippmann (16 August 1845 – 13 July 1921) was a Franco-Luxembourgish physicist and inventor, and Nobel laureate in physics for his method of reproducing colors photographically based on the phenomenon of interference. He was awarded the Nobel Prize in Physics in 1908 for being the inventor of a method for reproducing colors by photography.
[iv] The Curie law / Curie-Weiss law is a law of magnetism.
[v] Pierre was promoted to Professor of General Physics and Electrical Theory at ESPCI upon earning his doctorate of science.
[vi] Sceaux (pronounced: so), Hauts-de-Seine, is a commune in the southern suburbs of Paris, France, located 9.7 km (6.0 mi) from the city’s center.
[vii] Pierre’s father, a retired doctor, moved in with them and helped raise Irène.
[viii] Wilhelm Röntgen is considered the father of diagnostic radiology.
[ix] Born into a renowned family of scientists, Henri Becquerel had inherited their interest in science as well as the minerals and compounds studied by his father and grandfather. Henri’s grandfather, César, had studied phosphorescent minerals; his father, Edmond, ultraviolent light.
[x] Inspired by Röntgen’s work, Becquerel was exploring the possibility X-rays were related to the fluorescence of the uranium salts he’d been working with. Late one evening, he left a chunk of uranium atop a photographic plate in his desk drawer. Upon returning to the lab days later, he opened the drawer; it appeared as if the plate had been exposed to intense light.
[xi] Becquerel had made several important observations (e.g., gases through which uranium rays passed gained the ability to conduct electricity). After his important work was largely ignored in favor of Röntgen’s work on X-rays, Becquerel left the field.
[xii] About 70 percent uranium, uraninite (formerly, pitchblende)—the crystallized form of uranium oxide is a radioactive, uranium-rich mineral and ore.