The central issue in my view is the origin of the outgoing modes [18]. In a con-
densed matter model with a UV cutoff these must arise from somewhere other than
the near horizon region, either from “superluminal” modes behind the horizon, from
“subluminal” modes that are dragged towards the horizon and then released, or from
no modes at all. The last scenario refers to the possibility that modes “assemble”
from microscopic degrees of freedom in the near horizon region. This seems most
likely the closest to what happens near a spacetime black hole, and for that reason
deserves to be better understood. Other than a linear model that has been studied
in the cosmological context [19], and a linear model of quantum field theory on a
1+1 dimensional growing lattice [20], I don’t know of any work focusing on how to
characterize or study such a process.