  This article investigates the physics that is responsible for creating the
outgoing Poynting flux emanating from the ergosphere of a rotating black hole
in the limit that the magnetic energy density greatly exceeds the plasma rest
mass density (magnetically dominated limit). The underlying physics is derived
from published 3-D simulations that obey the general relativistic equations of
perfect magnetohydrodynamics (MHD). It is found that the majority of the
outgoing radial Poynting flux emitted from the magnetically dominated regions
of the ergosphere is injected into the magnetosphere by a source outside of the
event horizon. It is concluded that the primary source of the Poynting flux is
associated with inertial forces in the magnetically dominated region proper or
in the lateral boundaries of the region. However, the existing numerical data
does not rule out the possibility that large computational errors are actually
the primary source of the Poynting flux.
