Infinity is bigger than any number. But saying just how much bigger is not so simple. In fact, infinity comes in infinitely many different sizes—a fact discovered by Georg Cantor in the late 1800s.

The mysteries of infinity could lead us to a fantastic structure above and beyond mathematics as we know it WHEN David Hilbert left the podium at the Sorbonne in Paris, France, on 8 August 1900, few ...