  It has been shown [1,2] that the electromagnetic quantum vacuum makes a
contribution to the inertial mass, $m_i$, in the sense that at least part of
the inertial force of opposition to acceleration, or inertia reaction force,
springs from the electromagnetic quantum vacuum. As experienced in a Rindler
constant acceleration frame the electromagnetic quantum vacuum mainfests an
energy-momentum flux which we call the Rindler flux (RF). The RF, and its
relative, Unruh-Davies radiation, both stem from event-horizon effects in
accelerating reference frames. The force of radiation pressure produced by the
RF proves to be proportional to the acceleration of the reference frame, which
leads to the hypothesis that at least part of the inertia of an object should
be due to the interaction of its quarks and electrons with the RF. We
demonstrate that this quantum vacuum inertia hypothesis is consistent with
general relativity (GR) and that it answers a fundamental question left open
within GR, viz. is there a physical mechanism that generates the reaction force
known as weight when a specific non-geodesic motion is imposed on an object?
The quantum vacuum inertia hypothesis provides such a mechanism, since by
assuming the Einstein principle of local Lorentz-invariance (LLI), we can
immediately show that the same RF arises due to curved spacetime geometry as
for acceleration in flat spactime. Thus the previously derived expression for
the inertial mass contribution from the electromagnetic quantum vacuum field is
exactly equal to the corresponding contribution to the gravitational mass,
$m_g$. Therefore, within the electromagnetic quantum vacuum viewpoint proposed
in [1,2], the Newtonian weak equivalence principle, $m_i=m_g$, ensues in a
straightforward manner.
