  We show that nonrelativsitic scaling of the collisionless Vlasov-Maxwell
system implies the existence of a formal invariant slow manifold in the
infinite-dimensional Vlasov-Maxwell phase space. Vlasov-Maxwell dynamics
restricted to the slow manifold recovers the Vlasov-Poisson and Vlasov-Darwin
models as low-order approximations, and provides higher-order corrections to
the Vlasov-Darwin model more generally. The slow manifold may be interpreted to
all orders in perturbation theory as a collection of formal Vlasov-Maxwell
solutions that do not excite light waves, and are therefore "dark". We provide
a heuristic lower bound for the time interval over which Vlasov-Maxwell
solutions initialized optimally-near the slow manifold remain dark. We also
show how dynamics on the slow manifold naturally inherit a Hamiltonian
structure from the underlying system. After expressing this structure in a
simple form, we use it to identify a manifestly Hamiltonian correction to the
Vlasov-Darwin model. The derivation of higher-order terms is reduced to
computing the corrections of the system Hamiltonian restricted to the slow
manifold.
