  To Milne's Lorentz-group-based spacetime and Gelfand-Naimark unitary
representations of this group we associate a Fock space of 'cosmological
preons'-quantum-theoretic universe constituents. Milne's 'cosmological
principle' relies on Lorentz invariance of 'age'--global time. We divide
Milne's spacetime into 'slices' of fixed macroscopic width in age, with
'cosmological rays' defined on (hyperbolic) slice boundaries-Fock space
attaching only to these exceptional universe ages. Each (fixed-age) preon
locates within a 6-dimensional manifold, one of whose 3 'extra' dimensions
associates in Dirac sense to a self-adjoint operator that represents preon
(continuous) local time, the operator canonically-conjugate thereto
representing preon (total) energy. Self-adjoint-operator expectations at any
spacetime-slice boundary prescribe throughout the following slice a
non-fluctuating 'mundane reality'- electromagnetic and gravitational potentials
'tethered' to current densities of locally-conserved electric charge and
energy-momentum. The ray at the upper boundary of a slice is determined from
the lower-boundary ray by branched slice-traversing Feynman paths that carry
(divergence-free) potential-depending action. A macroscopically-stable
positive-energy single-preon wave function identifies either with a
Standard-Model elementary particle or with a graviton. Within
intermediate-density universe regions such as the solar system, where
reproducible measurement is meaningful, special relativity--Poincar\'e
invariance-is accurate for spacetime scales far below that of Hubble and far
above that of Planck.
