Her notebooks, still radioactive

Marie Curie recorded everything: measurements, sketches of apparatus, chemical steps, and in other notebooks her babies' weights and the household accounts. She handled radium with bare hands for decades and kept samples in her desk and pockets, admiring their glow, so the pages absorbed it.

A century later her laboratory notebooks remain measurably radioactive. Radium-226 loses only half its strength in about 1,600 years, so the contamination will long outlast us. The Curie papers given by the family are held by the Bibliothèque nationale de France, which reportedly keeps the most contaminated items in lead-lined boxes and asks readers to sign a waiver and wear protective clothing. Some notebooks are at the Wellcome Collection in London; one runs from 27 May 1899 to 4 December 1902, the years of the shed.

They are a quiet reminder that the first radiochemists did not know the danger, and that she paid for her discoveries with her health. For years she would say only that perhaps radium had something to do with her troubles, but that it could not be affirmed with certainty.