Today in History – June 25, 1903 – Marie Curie defends her doctoral thesis, then gets Nobel Prize five months later. Did she just procrastinate? Or were thesis standards higher a century ago at the Sorbonne? I haven’t seen a good explanation for the delay, other than she was busy discovering new elements.

Earlier in 1898, Marie and Pierre Curie made repeated separations of the various substances in pitchblende (photo on left) and used a Curie electrometer to identify two unidentified radioactive fractions that remained in pitchblende after uranium was removed. They discovered that the one containing mostly bismuth also contained a new element they named “polonium” in honor of the country of Marie’s birth. The barium fraction contained another new element, which they named “radium” from the Latin word for ray. They were able to add two new elements in the Periodic Table. While the chemical properties of the two new elements were completely dissimilar, they both had strong radioactivity. Radium was later isolated as a pure metal in 1902, but the discovery was not published in the popular press until this day in 1903.

Evidently, Marie Curie was so focused on her research that she had neglected to complete the writing of her thesis, which she finally got around to defending on June 25, 1903 titled: “Research on radioactive substances”.

Marie and Pierre Curie shared the 1903 Nobel Prize in Physics, along with Henri Becquerel, their contributions associated with the discovery of spontaneous radioactivity. Marie Curie was awarded the Nobel Prize in Chemistry in 1911 “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”. Alas Pierre Curie was not able to share the Nobel Prize this time as he was killed earlier in a carriage accident in a rainstorm in Paris on April 11, 1906. The curie is a unit of radioactivity originally named in honor of Pierre Curie by the Radiology Congress in 1910, after his death.

Marie Curie was the first person to win two Nobel prizes. Her daughter, Irene Joliot-Curie (photo below right), also won a Nobel Prize in 1935.

See the Engineering Pathway’s educational resources on Marie and Pierre Curie and radium. Or visit the Nuclear Engineering Education community site for more information. Also our resources on women in science and engineering and gender equity today.