This year bears witness to the two hundredth birthday of the man who coined the word "group." Of course, Évariste Galois only lived a tenth of two hundred, having died at the age of twenty in a duel. This talk will be a modest mix of history, algebra, and geometry. We'll talk about one of the most romantic lives in mathematical history, about the mathematics to which he gave birth (and which makes possible most of number theory today), and applications to geometric questions--some of which were thousands of years old, and some which are only a decade old. The prerequisites are minimal: I will assume you know what a polynomial is, what a sphere is, what a ruler is, what a circle is, and what a duel is. (Duel is not a mathematical term.)

• imf.au.dk/events/ffs