Bekologic Libor Šmejkal has a fondness for the artwork of M. C. Escher, whose work was often inspired by mathematics. One of Šmejkal’s favourite pieces is Horseman, a striking picture that features an elaborate, tessellating series of mounted figures. Strangely enough, it was this piece that inspired him to predict the existence of an entirely new kind of magnetism. We have known of magnets for millennia. Today, they are at the heart of a raft of modern technologies, from electric generators and...