Mathematician & Astronomer
Christiaan Huygens
The physicist who wrote probability's first textbook almost as a side project — then spent his last years insisting Newton had gotten gravity wrong
In 1655, on a visit to Paris, Christiaan Huygens heard secondhand about Pascal and Fermat's private letters on gambling problems -- and went home to write De Ratiociniis in Ludo Aleae, the first printed book on probability theory and the only one in circulation for the next fifty years. This bio also covers the rest of a genuinely wide-ranging career: discovering Saturn's moon Titan and the true shape of its rings, inventing the pendulum clock, proposing the wave theory of light, and, in his final years, publicly rejecting Isaac Newton's theory of gravity as 'absurd.'