Based on particle physics, the fundamental CPT invariance suggests a Big Jets model for the beginning of the universe, in which two oppositely directed jets evolved into a gigantic 'matter half-universe' and a gigantic 'antimatter half-universe' after annihilation and decay processes. In the geometric-optics limit, quantum Yang-Mills gravity with T 4 translational gauge symmetry in flat spacetime leads to an effective metric tensor in the Hamilton-Jacobi equation for macroscopic objects. This effective metric tensor does not exist in the wave equations of quantum particles. For cosmological expansion, we assume that an "effective metric tensor" for spacetime geometry based on Yang-Mills gravity corresponds to the usual FLRW form. Dynamical equations of expansion for the matter half-universe are obtained and solved. The time-dependent scale factors and the estimated age of the universes, t Y M o ≈ 15.3 × 10 9 yr, based on Yang-Mills gravity are consistent with experiments. CPT invariance implies that the same evolution process and dynamics of cosmic expansion also hold for the distant 'antimatter half-universe.'