  A celebrated feature of SYK-like models is that at low energies, their
dynamics reduces to that of a single variable. In many setups, this
"Schwarzian" variable can be interpreted as the extremal volume of the dual
black hole, and the resulting dynamics is simply that of a 1D Newtonian
particle in an exponential potential. On the complexity side, geodesics on a
simplified version of Nielsen's complexity geometry also behave like a 1D
particle in a potential given by the angular momentum barrier. The agreement
between the effective actions of volume and complexity succinctly summarizes
various strands of evidence that complexity is closely related to the dynamics
of black holes.
