Relaxation-Driven Cyclic Cosmology v1.1: A Minimal Model with Emergent Tilt, Mirror Dark Matter, and Testable ISW Excess

Relaxation-Driven Cyclic Cosmology from a Tilted Double-Well Scalar Field (RDCC) Relaxation-Driven Cyclic Cosmology from a Tilted Double-Well Scalar Field presents a nonsingular, eternal cosmological model based on a single complex scalar field evolving in a tilted double-well potential. The universe is described as a globally CPT-symmetric system without a beginning or end, in which cosmic expansion and contraction arise dynamically from vacuum relaxation rather than from an initial singularity or a constant cosmological constant. The scalar field constitutes the fundamental physical entity, from which vacuum structure, effective dark energy, and matter-sector phenomena emerge. Relaxation of the field within the asymmetric potential generates a time-dependent effective vacuum energy that drives large-scale expansion during one phase of the cosmic cycle and contraction during the complementary phase. Expansion is therefore not fundamental but a macroscopic manifestation of underlying field dynamics. RDCC incorporates a CPT-conjugate mirror sector with an opposite thermodynamic arrow of time. This mirror sector gravitationally mirrors ordinary matter and provides an effective dark matter contribution through its gravitational influence, without requiring the introduction of new particle species. The model predicts a globally symmetric, cyclic cosmology with recurrent but near-identical cosmic epochs, avoiding singularities, entropy divergence, and the need for finely tuned initial conditions. RDCC is fully deterministic at the fundamental level; stochasticity and apparent randomness arise only as emergent, effective descriptions. Distinct observational consequences include a dynamical equation of state for dark energy, deviations from standard late-time expansion histories, and testable signatures such as a predicted excess in the integrated Sachs–Wolfe effect and characteristic modulations in the 21-cm hydrogen signal.