  Numerical simulations are used to test the kinetic theory constitutive
relations of inertial granular shear flow. These predictions are shown to be
accurate in the dilute regime, where only binary collisions are relevant, but
underestimate the measured value in the dense regime, where force networks of
size $\xi$ are present. The discrepancy in the dense regime is due to
non-collisional forces that we measure directly in our simulations and arise
from elastic deformations of the force networks. We model the non-collisional
stress by summing over all paths that elastic waves travel through force
networks. This results in an analytical theory that successfully predicts the
stress tensor over the entire inertial regime without any adjustable
parameters.

Soft Condensed Matter