Higher order graviton scattering in $M\left(\mathrm{atrix}\right)$ theory

In matrix theory the effective action for graviton-graviton scattering is a double expansion in the relative velocity and inverse separation. We discuss the systematics of this expansion and subject matrix theory to a new test. Low-energy supergravity predicts the coefficient of the $v^6{/r}^{14}$ term, a two-loop effect, in agreement with explicit matrix model calculations.