Marie Curie ca. 1920. Inset: Pierre Curie (Marie's favorite picture of her husband).

Pierre Curie (1859-1906)
Marie Curie (1867-1934)

By the time he met Marie Sklodowska, Pierre Curie had already established an impressive reputation. In 1880, he and his brother Jacques had discovered piezoelectricity whereby physical pressure applied to a crystal resulted in the creation of an electric potential. He also had made important investigations into the phenomenon of magnetism including the identification of a temperature, the curie point, above which a material's magnetic properties disappear. However, shortly after his marriage to Marie in 1895, Pierre subjugated his research to her interests.

Together, they began investigating the phenomenon of radioactivity recently discovered in uranium ore. Although the phenomenon was discovered by Henri Becquerel, the term radioactivity was coined by Marie. After chemical extraction of uranium from the ore, Marie noted the residual material to be more "active" than the pure uranium. She concluded that the ore contained, in addition to uranium, new elements that were also radioactive. This led to their discoveries of the elements of polonium and radium, but it took four more years of processing tons of ore under oppressive conditions to isolate enough of each element to determine its chemical properties.

For their work on radioactivity, the Curies were awarded the 1903 Nobel Prize in physics. Tragically, Pierre was killed three years later in an accident while crossing a street in a rainstorm. Pierre's teaching position at the Sorbonne was given to Marie. Never before had a woman taught there in its 650 year history! Her first lecture began with the very sentence her husband had used to finish his last. In his honor, the 1910 Radiology Congress chose the curie as the basic unit of radioactivity: the quantity of radon in equilibrium with one gram of radium (current definition: 1 Ci = 3.7x1010 dps). A year later, Marie was awarded the Nobel Prize in chemistry for her discoveries of radium and polonium, thus becoming
the first person to receive two Nobel Prizes. For the remainder of her life she tirelessly investigated and promoted the use if radium as a treatment for cancer. Marie Curie died July 4, 1934, overtaken by pernicious anemia no doubt caused by years of overwork and radiation exposure.