Her notebooks sit in a French library inside lead-lined boxes, and anyone who wants to read them puts on protective gear first. They will stay dangerously radioactive for centuries. Maria Skłodowska was born in Warsaw in 1867 under Russian imperial rule, into a family ruined financially for its part in Polish uprisings. Her eldest sister died of typhus caught from a lodger the family had taken in for rent money. Her mother died of tuberculosis when Maria was ten, and watching both waste away ended her Catholic faith and pushed her toward what could be measured. Barred from university as a woman, she studied at the Flying University, a clandestine network that admitted women and kept changing locations to stay ahead of Russian authorities.

She and her sister Bronisława made a pact: Maria would work as a governess and send her wages to Paris to fund Bronisława’s medical degree, and Bronisława would then pay for hers. Years of waiting produced a frightening discipline. In Paris she lived in an unheated garret wearing every piece of clothing she owned, ate bread and tea, and fainted from forgetting to eat, taking a physics degree in 1893 and a mathematics degree in 1894. She went home to Poland intending to stay, and Kraków University rejected her for being a woman, which is how modern physics stayed in France. Then she picked an unglamorous thesis topic nobody cared about: the faint rays Henri Becquerel had noticed coming off uranium.

• Measuring uranium with Pierre’s electrometer, she found the radiation depended only on the quantity of uranium, not its chemical state, which meant it had to come from inside the atom itself. Until that moment the atom was believed to be indivisible.
• Pitchblende registered four times more active than its uranium content allowed, so something unknown was hiding in the ore. She named the first element she found polonium, forcing every scientist alive to say the name of a country that had been erased from the map.
• Isolating it meant four years of boiling tons of donated mine waste in a leaky dissecting shed, stirring vats with iron rods nearly her own height, to get one tenth of a gram. The glowing tubes they found beautiful were killing them.
• She refused to patent radium, believing an element belonged to humanity, and spent the rest of her life fundraising to afford her own discovery. In the war she taught herself anatomy and auto mechanics and built mobile X-ray units that treated over a million wounded men.