17 November 24

For my annual celebration of the birthday (on 17 November) of August Ferdinand Möbius (1790-1868), I'm wearing my self-crafted ribbon Möbius loop. It's a circle of ribbon including a single twist. This object has a single side and a single edge, which you can prove by working to paint the loop or to trace along the edge; as you progress in your work, continuing down the path, you eventually reach the point where you started, having traveled twice the circumference of the loop. Put somewhat differently, what seem to be two sides of the ribbon are just one. Mr. Möbius explored the topology of this kind of object and other continuous surfaces.