Siméon Denis Poisson

Siméon Denis Poisson (1781–1840) was a French mathematician of astonishing output — he is said to have produced hundreds of works — with a personal motto that life is only good for two things: doing mathematics and teaching it.

The big idea

When a field is shaped by a source spread through space — charge creating an electric field, mass creating gravity — it obeys Poisson's equation, the "with a source" cousin of Laplace's equation. His name is also stamped on the Poisson distribution, which counts rare random events (raindrops on a paving stone, calls to a switchboard), and on ideas running through electricity, heat and mechanics.

As a child Poisson was so clumsy with his hands that his family tried steering him toward almost any trade but the delicate ones — the classic tale is that he could barely be trusted to hold a needle or a paintbrush. Mathematics needed no coordination beyond a pen, and there he was unstoppable. He rose to the very top of French science, yet he supposedly said his real talents were just doing and teaching maths — the two things that never required steady fingers.