# mobius strip

A Klein bottle can't hold any liquid because it doesn't have an inside. How do you construct this strange thing and why would you want to? |
Saul Schleimer and Henry Segerman show off some of their beautiful 3D printed mathematical structures. |

Is the Universe finite, with an edge, or infinite, with no edges? Or is it even stranger: finite but with no edges? It sounds far-fetched but the mathematical theory of topology makes it possible, and nobody yet knows the truth.
Janna Levin tells us more. |