Liouville quantum gravity (LQG) is in some sense the canonical model of a two-dimensional Riemannian manifold and is defined using the (formal) metric tensor \[ e^{\gamma h(z)} (dx^2 + dy^2)\] where $h$ is an instance of some form of the Gaussian free field and $\gamma \in (0,2)$ is a parameter. This expression does not make literal sense since $h$ is a distribution and not a function, so...