Study reveals a broken symmetry in the roughness of elastic interfaces

A large class of problems in non-equilibrium statistical physics deal with driven dynamics of elastic interfaces in random media. Examples include stress-driven propagation of crack fronts in disordered solids, motion of domain walls driven by applied magnetic fields in disordered ferromagnets, and dynamics of fluid fronts invading a porous medium--for example, when coffee spilled on the table is absorbed by the tablecloth.