Marie CurieShe Literally Glowed Up

The sticker says She Literally Glowed Up. What Marie Curie actually did was measure a faint electric current more carefully than anyone had.

In 1896 Henri Becquerel found that uranium salts give off rays that fog photographic plates. Curie, choosing a doctoral topic, decided to measure the rays instead of photographing them. They make air conduct a tiny current, and with an electrometer built by Pierre Curie and his brother Jacques she could measure it precisely. Her key finding was a ratio. The activity depended only on how much uranium was present, not on its chemical form, which pointed to something happening inside the atoms themselves. And the ore pitchblende was more active than its uranium content could explain. Something else was in it.

Separating pitchblende, the Curies announced two new elements in 1898: polonium, named for her partitioned homeland, Poland, and radium. Isolating radium took tonnes of residue and until 1902. The 1903 Nobel Prize in Physics went to Becquerel and both Curies. The 1911 prize in Chemistry, for the discovery of radium and polonium and the isolation of radium, went to her alone. She remains the only person awarded Nobel Prizes in two different sciences.

The formulas on this page are what those measurements became. Each radioactive nucleus has a fixed chance per second of decaying, λ, so a sample shrinks exponentially, and its activity is λ times the number of nuclei left. Radium-226 has a half-life of about 1,600 years. The old unit of activity, the curie, is 3.7 × 10¹⁰ decays per second, close to the activity of one gram of radium. The SI unit, the becquerel, is one decay per second.

She handled these materials for decades without the protection later shown to be necessary.

The glow belonged to the radium. The measurements were hers.