Marie Curie is most known for her pioneering research on radioactivity, a term she coined herself. She discovered two chemical elements, polonium and radium, and became the first person to win two Nobel Prizes, one in Physics (1903) and one in Chemistry (1911). Her work fundamentally changed our understanding of atomic physics and laid the groundwork for modern cancer treatment.
Coining the Term “Radioactivity”
In the late 1890s, physicist Henri Becquerel noticed that uranium emitted mysterious rays. Marie Curie took this observation and turned it into a new field of science. She gave the phenomenon its name, “radioactivity,” and set out to understand it systematically. Working with her husband Pierre, she tested uranium ore and noticed something unexpected: the leftover ore, after uranium had been extracted, was actually more radioactive than pure uranium itself. That could only mean one thing. The ore contained other, unknown radioactive elements far more powerful than uranium.
Discovering Polonium and Radium
Curie’s hunt for those hidden elements led to years of painstaking work processing pitchblende, a heavy uranium-bearing mineral. In July 1898, the Curies announced they had found a new element related to bismuth in its chemical properties. They named it polonium, after Marie’s home country of Poland. Five months later, on December 26, 1898, they announced a second discovery alongside their assistant Gustave Bémont: radium. The sample they extracted contained barium mixed with enough radium to produce radioactivity 900 times greater than uranium.
Isolating pure radium was a brutal physical process. It required what Marie described as “most minute and delicate fractional crystallization,” a technique of repeatedly dissolving and recrystallizing material to gradually separate radium from barium. She spent years processing tons of pitchblende ore in a poorly ventilated shed, working with vats of chemicals and heavy equipment. The result was tiny quantities of purified radium, but the proof was definitive.
Two Nobel Prizes
In 1903, Marie and Pierre Curie shared the Nobel Prize in Physics with Henri Becquerel for their combined work on radioactivity. This made Marie the first woman to receive a Nobel Prize. Eight years later, in 1911, she won a second Nobel, this time in Chemistry, specifically for the discovery of radium and polonium and her investigation of their properties. No one before her had won the prize twice, and she remains the only person to win Nobel Prizes in two different sciences.
Mobile X-Rays in World War I
When World War I broke out, Curie turned her expertise toward saving lives on the battlefield. Wounded soldiers desperately needed X-rays to locate bullets and shrapnel before surgery, but X-ray machines were stuck in city hospitals far from the front lines. Curie’s solution was to bring the machines to the soldiers.
Frustrated by slow military funding, she approached the Union of Women of France for money to build her first mobile X-ray vehicle. It saw action at the Battle of the Marne in 1914, a pivotal Allied victory that kept German forces out of Paris. She then leveraged her scientific reputation to persuade wealthy Parisian women to donate vehicles, eventually assembling a fleet of 20 mobile units. Soldiers nicknamed them “petites Curies.” Beyond the mobile fleet, she oversaw the construction of 200 radiological rooms at fixed field hospitals behind the battle lines. Over the course of the war, an estimated one million wounded soldiers received X-ray examinations through her efforts.
Foundations of Cancer Treatment
Curie’s discovery of radium had immediate medical consequences. As early as 1899, just months after radium’s announcement, a Swedish physician reported the first case of a skin tumor cured by applying a radioactive source directly to the cancer. By 1907, medical manuals in the United States were listing tumors treatable by radiotherapy, many of which are still treated with radiation today.
Radium became the first element used in brachytherapy, a technique where a radioactive source is placed in direct contact with tumor tissue. Initially, doctors placed radium on the surface of tumors or inside body cavities to treat cancers of the cervix and vagina. By the 1910s, they were inserting radioactive sources deep into tumors. This was crude by modern standards, and the absence of proper dosing methods led to serious complications and deaths, including Curie’s own. But the painful process of learning from those early mistakes produced the safety principles and precision dosing that modern radiotherapy relies on.
The Radium Institute
Under Curie’s direction, the Radium Institute in Paris became the world’s leading center for the study of radioactivity. Between 1919 and her death in 1934, scientists working there published 483 papers and books, 31 of them by Curie herself. The institute served multiple roles: a pure research lab, an international measurement center for verifying the radium content of commercial products, and a hub connecting radioactivity research to applications in medicine, industry, and science. Curie continued working to isolate and purify polonium and actinium until the very end of her life. The institute eventually became what is now the Institut Curie, still one of the leading cancer research centers in Europe.
Breaking Barriers for Women in Science
Curie’s career was a series of firsts. She was the first woman to win a Nobel Prize, the first person to win two, and the first woman to hold a professorship at the Sorbonne in Paris, which she received in 1906 after Pierre was killed in a traffic accident. She was also the first woman whose remains were placed in France’s Panthéon, the monument reserved for the nation’s most honored citizens, on her own merits.
Her Death From Radiation Exposure
The dangers of radiation were poorly understood during the decades Curie spent handling radioactive materials. She worked without protective equipment, carried test tubes of radioactive isotopes in her pockets, and stored them in her desk drawers. Her personal belongings remain so contaminated that they are kept in lead-lined boxes at France’s national library, and anyone who wants to view them must wear protective clothing. In 1934, Curie died of aplastic anemia, a form of leukemia caused by her prolonged radiation exposure. She was 66 years old. Her death itself became part of the scientific record, a stark demonstration of the very forces she had spent her life studying.