Henri Poincaré

Henri Poincaré, in full Jules Henri Poincaré, (born April 29, 1854, Nancy, France—died July 17, 1912, Paris), French mathematician, one of the greatest mathematicians and mathematical physicists at the end of 19th century. He made a series of profound innovations in geometry, the theory of differential equations, electromagnetism, topology, and the philosophy of mathematics.

Poincaré grew up in Nancy and studied mathematics from 1873 to 1875 at the École Polytechnique in Paris. He continued his studies at the Mining School in Caen before receiving his doctorate from the University of Paris in 1879. While a student, he discovered new types of complex functions that solved a wide variety of differential equations. This major work involved one of the first “mainstream” applications of non-Euclidean geometry, a subject discovered by the Hungarian János Bolyai and the Russian Nikolay Lobachevsky about 1830 but not generally accepted by mathematicians until the 1860s and ’70s. Poincaré published a long series of papers on this work in 1880–84 that effectively made his name internationally. The prominent German mathematician Felix Klein, only five years his senior, was already working in the area, and it was widely agreed that Poincaré came out the better from the comparison.