Is it possible to deduce the shape of the universe without stepping outside of it? Henri Poincaré thought so. Similar to how the Greeks were able to discern the spherical nature of the earth (and even its rough diameter) using mathematics, he proposed that we should be able to make conclusions about our universe. Stanford University mathematician Keith Devlin explains the Poincaré Conjecture, which became a legendary problem in mathematics, with the help of a short animation.
More from this series: Mathematical Universe

This program is part of The Big Idea Series, made possible with support from the John Templeton Foundation.

Recorded June 2011; Posted November 2011