Measuring Dynamical Facilitation in Supercooled Liquids and Related Materials

We provide a physical interpretation for excitation dynamics in kinetically constrained lattice models in the context of supercooled liquids and granular materials. Several physical quantities such as instanton times, onset temperatures, and particle displacement fields are derived. These quantities are used to interpret measurements of dynamical facilitation previously performed for atomistic and molecular supercooled liquids and granular materials. We show that these previous measurements provide strong evidence that dynamical facilitation plays a key role in glassy materials.