Researchers work out the shape of a paper strip.

The article explains how to create a möbius band, a two-dimensional surface with the puzzling property of having only one side. Despite its mind-bending characteristic, möbius band is an easy object to make. Just take a long strip of paper, give one end a half-twist, and tape the two ends together. Because of the half-twist, the front side of one end of the strip joins with the reverse side of the other end, so that the taped-together band has only one side.