Henri Poincaré

Born 29 April 1854, Jules Henri Poincaré trained as a mathematician, physicist, and engineer, then proceeded to leave his mark on pure math, applied math, celestial mechanics, and the philosophy of science in equal measure. His research on the three-body problem led him to discover chaotic deterministic systems, laying the groundwork for chaos theory; he created the field of algebraic topology, introduced automorphic forms, and in the early 20th century posed the Poincaré conjecture - unsolved for a century until Grigori Perelman cracked it in 2002-2003. He was first to present the Lorentz transformations in modern symmetrical form, discovered the remaining relativistic velocity transformations in a 1905 letter to Hendrik Lorentz, and wrote foundational papers that year on what became special relativity; he proposed gravitational waves in 1905 and in 1912 published an influential mathematical argument for quantum mechanics. Contemporaries called him "the living brain of the rational sciences." He died 17 July 1912.