We consider the quantum mechanics of a system consisting of two identical,
Planck-sized Schwarzschild black holes revolving around their common centre
of mass. We find that even in a very highly excited state such a system ha
s very sharp, discrete energy eigenstates, and the system performs very rap
id transitions from one stationary state to another. For instance, when the
system is in the 100th excited state, the lifetimes of the energy eigensta
tes are of the order of 10(-30) s, and the energies of gravitons released i
n transitions between nearby states are of the order of 10(22) eV.