Henri Poincaré found chaos while working as a mining engineer
Poincaré was called the last universalist, a mathematician at home in every branch of his subject. Studying how three bodies move under gravity, he became the first to find a deterministic system that behaves chaotically. All the while he kept a day job in France's mining corps, rising to inspector general.
Born in Nancy on 29 April 1854 to a prominent family, Poincaré was the son of a medical professor and cousin of Raymond Poincaré, later President of France. A childhood bout of diphtheria meant lessons from his mother. At the Lycée in Nancy, now named after him, a teacher called him a monster of mathematics and he won national prizes, though music and sport were average at best. During the Franco-Prussian War of 1870 he served with his father in the ambulance corps.
He entered the École Polytechnique at the top of his cohort in 1873, studying under Charles Hermite, then trained at the École des Mines. As a mines inspector he investigated a disaster at Magny in August 1879 that killed 18 miners. His doctoral thesis on differential equations took a new approach, examining the geometric behaviour of solutions and seeing how they might model bodies moving through the Solar System. In 1881 and 1882 he founded the qualitative theory of differential equations, extracting the key behaviour of solutions without solving the equations at all.
The range is astonishing. He is regarded as the creator of algebraic topology, introduced automorphic forms and contributed to number theory, algebraic geometry and complex analysis. In physics he stressed how laws must stay invariant under transformations, put the Lorentz transformations in their modern symmetric form and, in a 1905 letter to Hendrik Lorentz, completed the velocity transformations that make Maxwell's equations fully invariant, a step towards special relativity. He also first proposed gravitational waves.
Contemporaries treated him as the leading mind in mathematics and theoretical physics; Paul Painlevé called him the living brain of the rational sciences, and Karl Popper rated him the greatest philosopher of science. Poincaré originated the conventionalist view of scientific theory and supported political equality. He married Louise Poulain d'Andecy in 1881, had four children, and died on 17 July 1912.
Source: Henri Poincaré
