Explaining the science contained in a simple assembly of grains—the most abundant form of matter present on Earth.Granular media—composed of vast amounts of grains, consolidated or not—constitute the most abundant form of solid matter on Earth. Granular materials assemble in disordered configurations scientists often liken to a bag of marbles. Made of macroscopic particles rather than molecules, they defy the standard scheme of classification in terms of solid, liq...