LAUSR

Models of inflationary cosmology admit a choice of the metric for which geometry becomes flat Minkowski space in the infinite past. In this primordial flat frame all mass scales vanish in the infinite past and quantum scale symmetry is realized. The cosmological evolution is dominantly described by the slow increase of a scalar field which sets the scale of all masses. We construct the primordial flat frame for standard models of inflation as Starobinsky inflation or chaotic inflation. In particular, we discuss the evolution of inhomogeneous solutions in the neighborhood of the homogeneous isotropic background solution and their relation to the observable primordial fluctuation spectrum. Our observed inhomogeneous Universe can be extrapolated back to the infinite past in physical time. If the propagator for the graviton and all other fields remain regular, there is no physical big-bang singularity -- the latter reflects only a singular choice of "field coordinates".