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.
source https://www.lifetechnology.com/blogs/life-technology-science-news/study-reveals-a-broken-symmetry-in-the-roughness-of-elastic-interfaces