Taijitu Relaxation Cosmology (TRC) v3.0: A CPT-Symmetric Cosmology with Opposite Time Arrows

**Taijitu Relaxation Cosmology (TRC) v3.0** A CPT-Symmetric Cosmology with Opposite Time Arrows Michael Lehmann (Independent Researcher, December 2025) Taijitu Relaxation Cosmology (TRC) describes an eternal, singularity-free universe that oscillates between two nearly degenerate vacua of a single complex scalar field $ϕ = ρ e^{iθ}$ with the tilted double-well potential $$V(ϕ) = λ(|ϕ|^2 − v^2)^2 + ϵ Re(ϕ) + δ,$$ where $ϵ, δ ∼ 10^{-120} M_{Pl}^4$ are tiny symmetry-breaking parameters. The slow relaxation dynamics of the field generate: - dynamical dark energy with $w(z=0.3) ≈ −1.003 ± 0.005$, - spontaneous baryogenesis via the phase-induced chemical potential $μ_θ ∝ \dot{θ}$, - opposite thermodynamic arrows of time ($\dot{θ} > 0$ in our vacuum, $\dot{θ} < 0$ in the mirror vacuum), - exact global CPT symmetry across the full breathing cycle. The model has effectively only one new physical parameter and predicts: - ≈12 % excess Integrated Sachs–Wolfe effect measurable by Euclid weak lensing, - ≈0.28 % periodic modulation of the 21-cm power spectrum detectable by SKA Phase II, - small, characteristic low-redshift deviations from ΛCDM. TRC v3.0 provides a minimal, testable, CPT-symmetric alternative to ΛCDM that simultaneously explains dynamical dark energy, the baryon asymmetry, and the arrow of time without fine-tuning or additional fields. This record is version 3.0 (December 2025). Major changes relative to v2.0: full CPT-symmetric formulation with opposite time arrows, explicit Euclid and SKA predictions, and refined vacuum relaxation dynamics. DOI of previous versions: 10.5281/zenodo.17680370 (v1.0) 10.5281/zenodo.17842042 (v2.0)