Biography

 

This famous mathematician started life in the humanities… then turned to the sciences to prepare for Polytechnique and then entry to the Ponts et Chaussées, where he came top of his class in 1807. In 1808, he was assigned to work on the Canal de l’Ourcq.On leaving the School, Cauchy was sent to Cherbourg, in Navy service, where he worked on the construction of the Port Napoléon.However, his first interest was his mathematical research:he wrote very well received papers on polygons and polyhedra, substitution in calculus and group theory.In 1813, he returned to Paris to work on the Canal de l’Ourcq with the help of Prony.Hoping to be elected to the Academy of Sciences, he published prolifically (on defined integrals and wave theory), and in 1815 demonstrated one of Fermat’s two theorems on polygonal numbers.In the same year, he entered the Ecole Polytechnique as Poinsot’s substitute in analysis, then became a full professor in mechanical analysis in 1816.He was also appointed a member of the Institute in 1816 (by a royal order which, for political reasons, excluded Lazare Carnot and Gaspard Monge).His monarchist loyalty paid off…Also in 1817, he entered the Collège de France as Professor of mathematical physics, replacing Biot.With the publication of his course in algebraic analysis in 1821, Cauchy moved increasingly towards the mechanics of continuous media and elasticity theory, as well as the theory of light.

With the revolution of 1830, however, Cauchy refused to swear allegiance to Louis-Philippe and went into exile in Switzerland, then Italy, and finally Prague:he lost his professorial titles at the Polytechnique and the the faculty of sciences, and as an engineer at Ponts et Chaussées.Initially under the protection of King Charles-Albert, in Turin, he became a member of the Turin Academy of Sciences and worked on the development of complex variable functions and boundary calculations(the so-called “Turin Theorem”).Then in Prague from 1833 to 1838, he became tutor to the Duke of Bordeaux, who bestowed on him the title of Baron.Returning to Paris, he rejoined the ranks of the Academy of Sciences and published an almost weekly memo or paper in the proceedings of the Academy.Appointed to the Bureau des Longitudes in 1839, after the death of Prony, he did not take up his seat, having still not sworn allegiance to Louis-Philippe.In 1843, for similar political reasons, he was denied the mathematics chair at the Collège de France.It was only in 1849 that he returned to higher education through the chair in celestial mechanics at the Paris Faculty of Sciences.It was here that Cauchy was able to present his function theory, together with his algebraic equivalences theory and his theory of imaginary numbers.Whilst continuing to focus on algebraic analysis, Cauchy did not forget his political convictions and was behind the creation of the Catholic Institute in 1839 and the Ecoles d’Orient in 1856.

His scientific opus is substantial:more than 800 articles on a wide range of topics in mathematics and physics.He was a pioneer, revolutionising certain aspects of mathematical physics.He is one of the founders of modern analysis,responsible in particular for differential equation theory and the mechanical theory of elasticity.

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