She translated Newton's Principia, discovered kinetic energy, and debated the finest minds of Europe — at a time when women weren't allowed to enter scientific academies.
Émilie du Châtelet (1706–1749) was a French mathematician and physicist who worked in an era when women were formally excluded from France's scientific institutions. She gained access to scientific debate by disguising herself as a man to enter a café frequented by mathematicians, where she regularly outargued the men inside.
Du Châtelet had a long intellectual and romantic partnership with Voltaire. The two set up a private laboratory together at her château in Cirey, where they conducted experiments and wrote prolifically. Voltaire freely credited her as his intellectual superior in mathematics and physics.
Her most lasting scientific contribution was developing the concept of kinetic energy — specifically demonstrating that the energy of a moving object is proportional to the square of its speed (what we now write as ½mv²). This extended and corrected the work of Leibniz and helped lay groundwork for the modern understanding of energy conservation.
She also submitted an anonymous paper on the nature of fire to the French Royal Academy of Sciences in 1738 — the same competition Voltaire entered. Both lost, but hers was published alongside the winning entries after the judges discovered it was written by a woman. The Academy found it so impressive they felt it had to be preserved.
Du Châtelet spent the final years of her life translating Newton's Principia Mathematica into French — a massive undertaking she knew she was racing against time to finish. She was pregnant late in life and feared she would not survive the birth. She completed the manuscript just days before delivering the child; she died six days after giving birth, at age 42. Her translation remains the standard French edition to this day.