What Is the Geometry of the Universe?

Some of my favourite stories are those that answer questions I didn’t even know one could ask. Fairly heavy stuff here, but with nice, very helpful illustrations. So next time you need a conversation starter that has nothing to do with coronavirus whatsoever, try this: «Just as life in the two-dimensional torus was like living in an infinite two-dimensional array of identical rectangular rooms, life in the three-dimensional torus is like living in an infinite three-dimensional array of identical cubic rooms. You’ll see infinitely many copies of yourself.»