Signed Coordinate Invariance, invariant lagrangians and manifolds, the time problem in quantum cosmology, quantum space time, spacetimes and antispacetimes

Standard general coordinate invariance for the volume element is extended to general coordinate transformations that have a negative jacobian. This is possible by introducing a non Riemannian Measure of integration, which transforms according to the jacobian of the coordinate transformation, not the absolute value of the jacobian of the coordinate transformation as it is the case with $\sqrt{-g}$. For some signed general transformations a change of boundary conditions is involved in GR and restoring the original limits of integrations can restore symmetry of the action. The discussion totally changes when a non Riemannian Measure of integration is introduced, in the case of signed general coordinate transformations, and even when we have, boundaries, since the modified measure is constructed out of scalar fields becomes also the integration manifold, Since the measure fields that define the non metric measure are scalars. if a signed general coordinate transformations is considered, there is no change in the measure fields, indicating strict invariance of both lagrangian density and integration manifold, implying boundary terms for manifolds with boundaries in coordinate space to be irrelevant . This analysis can be applied to give a framework where to certain interesting scenarios . We consistently formulate the non Riemannian measure theory extension of General Relativity, that could be related to Linde Universe Multiplication model, although there are some fundamental differences. The assumption of a coordinate independent measure of integration appears also useful in the study of Baby Universe Creation. The formulation provides also a new natural way to address the problem of time in Quantum Cosmology, a proposal for a quantum space time and identification of space times and anti space times states in the gravitational theory.