Blaise Pascal
1623–1662, Clermont-Ferrand, France, Paris, France
French mathematician, physicist and religious philosopher who at sixteen discovered a key theorem of projective geometry, built one of the first mechanical calculators, co-founded probability theory through his 1654 correspondence with Fermat, and gave a systematic treatment of the arithmetic triangle that bears his name.
Blaise Pascal was born on 19 June 1623 in Clermont-Ferrand, France, the only son of Étienne Pascal, a local judge and tax official, and Antoinette Begon, who died when Blaise was three. In 1632 his father moved the family to Paris and took charge of the children's education himself; believing mathematics would overexcite young minds, Étienne initially withheld mathematical books from his son, but on discovering that twelve-year-old Blaise had independently worked out that the angles of a triangle sum to two right angles, he relented and gave him a copy of Euclid's Elements. By fourteen Pascal was attending the weekly scientific gatherings hosted by Marin Mersenne, meeting figures such as Girard Desargues and Gilles Personne de Roberval, and at sixteen, in 1639, he presented a single-page essay on projective geometry containing what became known as Pascal's theorem, on the 'mystic hexagram' inscribed in a conic.
After the family moved to Rouen in 1639, the teenage Pascal designed and built the Pascaline, one of the earliest mechanical calculators, to help his father with tedious tax computations. Returning to the Paris region around 1647, he carried out influential experiments on atmospheric pressure and vacuums, building on Torricelli's work and demonstrating that air pressure decreases with altitude by having his brother-in-law carry a barometer up the Puy de Dôme. Around 1654, a gambling question posed to him led to a celebrated exchange of letters with Pierre de Fermat that laid the mathematical foundations of probability theory; in the same period he gave, in the Traité du triangle arithmétique, the first systematic treatment of the array of binomial coefficients now generally called Pascal's triangle, though earlier versions of it had appeared in Chinese, Persian and Indian mathematics.
On the night of 23 November 1654, Pascal underwent an intense religious experience that he recorded on a parchment sewn into his coat, after which he largely turned away from mathematics and science toward theology and philosophy, aligning himself with the Jansenists of Port-Royal. His final years produced the polemical Lettres provinciales (1656–1657) and the posthumously published Pensées, a collection of philosophical and theological fragments that includes the argument known as Pascal's Wager. He died in Paris on 19 August 1662 at the age of 39.
Workplaces: Paris, under the circle of Marin Mersenne
France