Siméon Denis Poisson

French mathematician and physicist

• Born: June 21, 1781; Pithiviers, France
• Died: April 25, 1840; Sceaux, France

Nineteenth-century French mathematician Siméon Denis Poisson made important contributions in the areas of statistics and physics. A student of French astronomer Pierre Laplace, Poisson is one of seventy-two French scientists, engineers and notables who have their names engraved on the Eiffel Tower in recognition of their work.

Primary fields: Mathematics; physics

Specialties: Electromagnetism; probability theory

Early Life

Siméon Denis Poisson was born in Pithiviers, France on June 21, 1781. His father, Siméon Poisson, was a soldier and neither he nor Poisson’s mother was from a noble family. However, changes in French society that came about as a result of the French Revolution in 1789 would result in unprecedented educational opportunities for Poisson as a young man.

Poisson was the first of the children in his family to survive beyond infancy. Because he was not of good health, his family put him in the care of a nurse to ensure his survival. His father taught him to read and write and wished for him to study medicine.

As a young man, Poisson was sent to Fontainebleau in Paris to apprentice with an uncle who was a surgeon. However, he found that he lacked the necessary hand coordination required for conducting surgery, and had little interest in being a physician.

In 1796, Poisson returned to Fontainebleau, this time to the École Centrale, where he quickly distinguished himself as a student of mathematics. At the urging of his teachers, he sat for the exam for École Polytechnique in Paris. Despite his lack of a formal education in mathematics, Poisson was named first in his class in 1798. His work in mathematics drew the attention of two men whose work was deeply respected: astronomer Pierre-Simon Laplace and mathematician Joseph-Louis Lagrange. Poisson’s lack of fine motor skills was again an impediment, as it made drawing mathematical diagrams tedious and difficult. This was especially problematic for geometry. Nonetheless, Poisson had an interest in pure mathematics and was able to work around this limitation.

Life’s Work

Poisson’s greatest achievements lay in his work as a theoretical mathematician and educator. By 1802, Poisson was a deputy director at École Polytechnique. Upon his graduation in 1800, he was appointed to the position of teaching assistant. He was also published twice in the École Polytechnique’s Recueil des savants étrangers (Reports of foreign scientists), a great honor for an eighteen-year-old student.

In 1802, Poisson became an assistant professor. He attained a professorship in 1806, when Jean Baptiste Joseph Fourier vacated the position. In 1808, Poisson was appointed as an astronomer at the Bureau des Longitudes. He also had a treatise on celestial mechanics published. This work, Sur les inégalités séculaires des moyens mouvements des planets (On the motions of planets), examined the stability of planetary orbits. By 1811, Poisson had begun his work on the application of mathematics to electricity and magnetism, mechanics, and other areas of physics. He published Traité de mécanique (Treatise of mechanics) in 1811. This work served as a standard reference on the subject for many years.

In 1812, Poisson became a member of the Institut de France, an academic society. He also published a memoir on his two-fluid theory of electricity. In this theory, Poisson posited that electricity was made up of two fluids that contained particles, which repelled like particles and attracted unlike particles. He calculated the reactive force as inversely proportional to the square of the distance between them.

Poisson developed his probability theory, which became known as the Poisson equation, in 1813. He was named examiner for the military school at Saint-Cyr in 1815. In 1816, he was named graduation examiner at the École Polytechnique. He married Nancy de Bardi in 1817 and was elected a fellow of the Royal Society of London in 1818.

Poisson became a fellow of the Royal Society of Edinburgh in 1820. That same year, he accepted a nomination to the Conseil Royal de L’Université. During this time, professional science and science education were falling into disregard in France because of political instability, and Poisson used his position to defend the role of science in everyday life and in the academy.

He published Sur la libération de la lune, another work on celestial mechanics, in 1821. In 1822, he was elected a foreign member of the Royal Swedish Academy of Sciences. In 1924, he published a paper on his two-fluid theory of magnetic potential, and in 1825 he published his views on the wave theory of light.

When his longtime mentor Lagrange died in 1827, Poisson replaced him as geometer of the Bureau des Longitudes, a scientific association dedicated to navigational standards. In the interest of advancing Lagrange’s work as well as his own, Poisson undertook the task of writing a comprehensive mathematical text made up of various volumes. He would not live to complete this task, but his work did produce another publication on celestial mechanics, Sur le mouvement de la terre autour de son centre de gravité (On the movement of the Earth around its center of gravity), released in 1827.

In 1829, Poisson published Sur l’attraction des spheroids (On the attraction of spheroids). In 1832, he received the prestigious Copley Medal for his contributions to science form the Royal Society of London. He published a memoir on the movement of the moon in 1833.

Impact

Poisson’s passion for mathematics is summed up in a statement attributed to him by French mathematician and politician Dominique François Jean Arago: “Life is good for only two things, discovering mathematics and teaching mathematics.” In all, Poisson published over three hundred works in pure mathematics, applied mathematics, mathematical physics, and rational mechanics. His contributions to the field of electricity and magnetism were fundamental to the creation of a new branch of mathematical physics. Poisson’s work on attractive forces influenced British mathematical physicist George Green’s work on electricity and magnetism. He is equally well remembered for his work in celestial mechanics. The Poisson distribution, dealing with the law of large numbers, is still used to predict the occurrence of such unlikely events as airplane crashes.

Bibliography

Falk, Michael, Jürg Hüsler, and Rolf-Dieter Reiss. Laws of Small Numbers: Extremes and Rare Events. Basel: Birkhäuser, 1994. Print. Explores the theory and applications of probability theory, including information about Poisson approximations.

Gekhtman, Michael, Michael Shapiro, and Alek Vainshtein. Cluster Algebras and Poisson Geometry. Providence: American Mathematical Society, 2010. Print. Examines cluster algebra, as introduced by Fomin and Zelevinsky, and as it applies to Poisson geometry and the theory of integrable systems.

Karasev, M. V., Maria Shishkova, Elena Novikova, and Yu M. Vorobjev. Quantum Algebras and Poisson Geometry in Mathematical Physics. Providence: American Mathematical Society, 2005. Print. Explores new applications of Poisson geometry, noncommutative algebra theory, and representation theory to well-known problems in mathematical physics.