  Using the concept of tunneling two level systems we explain the reduction of
rotational inertia of disordered solid 4He observed in the torsional oscillator
experiments. The key point is a peculiar quantum phenomenon of momentum deficit
for two level systems in moving solids. We show that an unusual state which is
essentially different from both normal and superfluid solid states can be
realized in quantum glasses. This state is characterized by reduced rotational
inertia in oscillator experiments, by absence of a superflow, and by normal
behavior in steady rotation.
