Marie Curie
Can a stone glow on its own?
That time, that place
In Poland women could not attend university. Maria Skłodowska worked for years as a governess, paying for her sister's studies, before she could get to Paris.
Around then Becquerel reported something odd: a photographic plate stored in a drawer with a uranium compound had fogged. Most scholars took it for a minor curiosity and moved on.
Why this question
She chose exactly that for her doctoral subject — the thing others had passed over.
Her method differed too. Instead of judging by eye how much a plate had fogged, she used an electrometer built by her husband Pierre to measure, as a number, how much the radiation made air conduct. Measurement rather than impression.
What was found
Measuring revealed two things.
First, the intensity depended only on how much uranium was present. It did not change with the compound, the temperature, or exposure to light. So this was not a chemical reaction but something coming from the atom itself — squarely against the belief that atoms do not change.
Second, uranium ore emitted far more than its uranium content could account for. Something much stronger had to be in there.
She found it: polonium and radium. Getting a tenth of a gram of radium in hand took four years of boiling and filtering tons of ore in a leaking shed.
Atoms do not change
Intensity proportional only to quantity, indifferent to compound, temperature, or light
She received Nobel Prizes in both physics and chemistry. No one knew the danger; her notebooks remain radioactive and are kept in lead-lined boxes