  We have recently shown that both passive and active gravitational masses of a
composite body are not equivalent to its energy due to some quantum effects. We
have also suggested an idealized and more realistic experiments to detect the
above mentioned inequivalence for a passive gravitational mass. The suggested
idealized effect is as follows. A spacecraft moves protons of a macroscopic
ensemble of hydrogen atoms with constant velocity in the Earth's gravitational
field. Due to non-homogeneous squeezing of space by the field, electron ground
state wave function experiences time-dependent perturbation in each hydrogen
atom. This perturbation results in the appearance of a finite probability for
an electron to be excited at higher energy levels and to emit a photon. The
experimental task is to detect such photons from the ensemble of the atoms.
More realistic variants of such experiment can be realized in solid crystals
and nuclei, as first mentioned by us. In his recent Comment on our paper,
Crowell has argued that the effect, suggested by us, contradicts the existing
experiments and, in particular, astronomic data. We show here that this
conclusion is incorrect and based on the so-called "free fall" experiments,
where our effect does not have to be observed.
