  In this thesis the Bohm-de Broglie interpretation of quantum mechanics is
applied to canonical quantum gravity. It is shown that, irrespective of any
regularization or choice of factor ordering of the Wheeler-DeWitt equation, the
unique relevant quantum effect which does not break spacetime is the change of
its signature from lorentzian to euclidean. The other quantum effects are
either trivial or break the four-geometry of spacetime. A Bohm-de Broglie
picture of quantum geometrodynamics is constructed, which allows the
investigation of these latter structures. For instance, it is shown that any
real solution of the Wheeler-De Witt equation yields a generate four-geometry
compatible with the strong gravity limit of General Relativity and the Carroll
group. We prove that quantum geometrodynamics in the Bohm-de Broglie
interpretation is consistent for any quantum potential. As a previous step to
introduce our metodology, we study the quantum theory of fields in Minkowski
spacetime in the Bohm-de Broglie interpretation and exhibit a concrete example
where Lorentz invariance of individual events is broken.
