We investigate the quantum dynamics of a self-gravitating spherical du
st shell. The wave functions of the discrete spectrum are not localize
d inside the Schwarzschild radius. We argue that such shells can trans
form into white holes (in another space). It is plausible that shells
with bare masses larger than the Planck mass loose their mass emitting
lighter shells. (C) 1997 Published by Elsevier Science B.V.