Henri Poincaré died 100 years ago today.

Henri Poincaré died 100 years ago today. He is most famous for the conjecture (now theorem) which carries his name and which remained open for almost 100 years, until
Grigori Perelman announced a proof in 2003. But the conjecture isn't all there was to Poincaré. One of his teachers reportedly described him as a "monster of maths" who, perhaps because of his poor eyesight, developed immense powers of visualisation, which must
have helped him particularly in his work on geometry and topology. He has been hailed
one of the last people whose understanding of maths was truly universal. And he also thought about the philosophy of mathematics. He believed that intuition has an important
role to play in maths, and anticipated the work of Kurt Gödel, who proved
that maths cannot ever be completely formalised. Finally, and extremely pleasingly for us here at *Plus*, Poincaré was one of
the few scientists of his time to share his knowledge by writing numerous
popular science articles.

You can find out more about the Poincaré conjecture and related maths in these *Plus* articles:

- Code-breakers, doughnuts, and violins
- The Fields medals 2006
- Mathematical millionaire?
- Exotic spheres, or why 4-dimensional space is a crazy place

And there is more on Poincaré's life and work on the MacTutor history of maths archive.