Edwards statistical mechanics for jammed granular matter

Granular materials are systems of macroscopic grains such as sugar, sand, or rice. These systems exhibit a transition to a jammed state similar to an amorphous solid. Although the jammed state concept is simple as it is determined by excluded volume interactions, describing this state of matter is highly challenging. The approach of Edwards is reviewed here which describes jammed granular materials using the volume ensemble of equally probable jammed states. The Edwards volume ensemble is reviewed for various packings providing insight into an unifying phase diagram for jammed matter.