From The New York Times:
Dr. Taimina, a math researcher at Cornell University, started crocheting the objects so her students could visualize something called hyperbolic space, which is an advanced geometric shape with constant negative curvature. Say what? Well, balls and oranges, for example, have constant positive curvature. A flat table has zero curvature. And some things, like ruffled lettuce leaves, sea slugs and cancer cells, have negative curvatures. This is not some abstract – or frightening – math lesson. Hyperbolic space is useful to many professionals – engineers, architects and landscapers, among others. So Dr. Taimina expected some attention for her yarn work, especially from math students destined for those professions. But her work has recently drawn interest from crocheting enthusiasts.