  The action reaction principle is violated in the standard formulation of
Quantum Mechanics, so that its phase space is incomplete. Moreover, projection
of state of a quantum system under indirect measurement, when there are
alternative virtual paths and one of them is discarded by negative detection
implies, according to the action reaction principle, a reaction on the
detector, although its macroscopic state does not change. If all interactions
are local, mediated by fields with relativistically causal evolution, some
system, different from the particle which follows another path, must locally
interact with the detector. Relativistic locality and the action reaction
principle predict the existence of de Broglie fields. A formulation of Quantum
Mechanics in extended Hilbert spaces is presented, in which kinematic and
dynamical representations of physical magnitudes are distinguished.
