ON THE DYNAMICS OF SPHERICALLY SYMMETRICAL SYSTEMS IN QUANTUM-GRAVITY

Within the formalism of quantum gravity, we consider a general metric with spherical symmetry and study under which circumstances it is possible to consistently reduce the number of degrees of freedom of the theory. In case of separation of variables, we show that only the Kantowski-Sachs and Robertson-Walker geometries are consistent minisuperspaces. We analyze some minisuperspaces adequate for the study of the black hole physics, but we find that they are either trivial or inconsistent.