Jean le Rond d'Alembert

File:Jean le Rond d'Alembert 250px.jpg

Jean le Rond d'Alembert, pastel by Maurice Quentin de la Tour

Jean le Rond d'Alembert (November 16, 1717 – October 29, 1783) was a French mathematician, mechanician, physicist and philosopher. He was also co-editor with Diderot of the Encyclopédie, the original French encyclopedia. D'Alembert's method for the wave equation is named after him.

Childhood

Born in Paris, d'Alembert was the illegitimate child of the writer Claudine Guérin de Tencin and the chevalier Louis-Camus Destouches (an artillery officer). Destouches was abroad at the time of d'Alembert's birth, and a couple of days after birth his mother left him on the steps of the Saint-Jean-le-Rond de Paris church. According to custom, he is named after the protecting saint of the church. D'Alembert was placed in an orphanage but was soon adopted by the wife of a glazier. Destouches secretly paid for the education of Jean le Rond, but did not want his parentage officially recognised.

Studies

D'Alembert first attended a private school. The chevalier Destouches left d'Alembert an annuity of 1200 livres on his death in 1726. Under the influence of the Destouches family, at the age of twelve D'Alembert entered the jansenist Collège des Quatre-Nations (the institution was also known under the name "Collège Mazarin"). Here he studied philosophy, law, and art, graduating as bachelier in 1735. In his later life, D'Alembert scorned the Cartesian principles he had been taught by the Jansenists: "physical premotion, innate ideas and the vortices".

The Jansenists steered D'Alembert toward an ecclesiastical career, attempting to deter him from pursuits such as poetry and mathematics. Theology was, however, "rather unsubstantial fodder" for d'Alembert. He entered law school for two years, and was nominated avocat in 1738.

He was also interested in medicine and mathematics. Jean was first registered under the name Daremberg, but later changed it to d'Alembert. In July of 1739 he made his first contribution to the field of mathematics, pointing out the errors he had detected in L'analyse démontrée (published 1708 by Charles René Reynaud) in a communication addressed to the Académie des Sciences. At the time L'analyse démontrée was a standard work, which D'Alembert himself had used to study the foundations of mathematics. D'Alembert was also a Latin scholar of some note and worked in the latter part of his life on a superb translation of Tacitus, from which he received wide praise including that of Denis Diderot.

In 1740, he submitted his second scientific work from the field of fluid mechanics Memoire sur le refraction des corps solides, which was recognized by Clairaut. In this work d'Alembert theoretically explained refraction. He also wrote about what is now called D'Alembert's paradox: that the drag on a body immersed in an inviscid, incompressible fluid is zero.

When the Encyclopédie was organized in the late 1740s, d'Alembert was engaged as co-editor (for mathematics and science) with Diderot, and served until a series of crises temporarily interrupted the publication in 1757. For it he authored over a thousand articles.

While he made great strides in mathematics and physics, d'Alembert is also famously known for incorrectly arguing in Croix ou Pile that the probability of a coin landing heads increased for every time that it came up tails. In gambling, the strategy of decreasing one's bet the more one wins and increasing one's bet the more one loses is therefore called the D'Alembert system, a type of martingale.

He suffered bad health for many years and his death was as the result of a bladder illness. As a known unbeliever, D'Alembert was buried in a common unmarked grave.

In France, the fundamental theorem of algebra is known as the d'Alembert/Gauss theorem.

He also created his ratio test, a test to see if a series converges.

Bibliography

• Jean d'Alembert by Ronald Grimsley. (1963)

See also

• Liberalism
• Contributions to liberal theory
• Gambler's fallacy
• Wave equation
• D'Alembert's principle

External links

Wikisource has original text related to this article:

Jean le Rond d'Alembert

• English translation of part of the Encyclopédie of Diderot and d'Alembert

• John J. O'Connor and Edmund F. Robertson. Jean le Rond d'Alembert at the MacTutor archive

Preceded by: Jean-Baptiste Surian

Seat 25 Académie française 1754–1783

Succeeded by: Marie-Gabriel-Florent-Auguste de Choiseul-Gouffier Credits New World Encyclopedia writers and editors rewrote and completed the Wikipedia article in accordance with New World Encyclopedia standards. This article abides by terms of the Creative Commons CC-by-sa 3.0 License (CC-by-sa), which may be used and disseminated with proper attribution. Credit is due under the terms of this license that can reference both the New World Encyclopedia contributors and the selfless volunteer contributors of the Wikimedia Foundation. To cite this article click here for a list of acceptable citing formats.The history of earlier contributions by wikipedians is accessible to researchers here: Jean le Rond d'Alembert  history The history of this article since it was imported to New World Encyclopedia: History of "Jean le Rond d'Alembert" Note: Some restrictions may apply to use of individual images which are separately licensed.