OK, so first of all, how can a fabric possibly get thicker when stretched? Doesn’t that go against the laws of physics? Not, it turns out, when that material is auxetic. Cat skin and shin bones also apparently possess this quality. The University of Exteter, in collaboration with their spin-off company Auxetix Ltd, have developed an auxetic blast-proof curtain. If a bomb were to go off near such a curtain, the pressure wave would stretch the fabric outwards, thus thickening it and making it better able to hold back flying glass and other debris. The curtain is intended to be fitted over windows of buildings that are terrorist targets, or that are subject to events such as hurricanes.