%0 Online Multimedia %A Goulko, Olga %A Kent, Adrian %D 2017 %T animation027 from The grasshopper problem %U https://rs.figshare.com/articles/media/animation027_from_The_grasshopper_problem/5576809 %R 10.6084/m9.figshare.5576809.v1 %2 https://rs.figshare.com/ndownloader/files/9696991 %K geometric combinatorics %K spin models %K Bell inequalities %K statistical physics %X We introduce and physically motivate the following problem in geometric combinatorics, originally inspired by analysing Bell inequalities. A grasshopper lands at a random point on a planar lawn of area 1. It then jumps once, a fixed distance d, in a random direction. What shape should the lawn be to maximize the chance that the grasshopper remains on the lawn after jumping? We show that, perhaps surprisingly, a disc-shaped lawn is not optimal for any d > 0. We investigate further by introducing a spin model whose ground state corresponds to the solution of a discrete version of the grasshopper problem. Simulated annealing and parallel tempering searches are consistent with the hypothesis that, for d < π−1/2, the optimal lawn resembles a cogwheel with n cogs, where the integer n is close to π(arcsin (√πd/2))−1. We find transitions to other shapes for dπ−1/2. %I The Royal Society