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This work aims to present major updates and consolidations in the Relaxation-Driven Cyclic Cosmology framework, focusing on observable predictions.

May 30, 2026Open Access

Relaxation-Driven Cyclic Cosmology (RDCC) v47.0

Key Points

This work aims to present major updates and consolidations in the Relaxation-Driven Cyclic Cosmology framework, focusing on observable predictions.
Integrated updated Core and observational components, leading to a coherent framework for various cosmic phenomena.
Introduced modern derivations and interfaces for associating relaxation dynamics with measurable cosmological signatures.
Revised companions related to neutrino physics and gravitational lensing capabilities.
Predicted α ≈ 0.016 through observational convergence across channels.
Identified slight variations from ΛCDM, including specific values for spectral tilt and dark radiation excess.
Resolved cosmological puzzles like the singularity issue and baryon asymmetry with CPT symmetric frameworks.

Abstract

RDCC v47. 0 - Relaxation-Driven Cyclic CosmologyComplete Release of the Core Framework, Numerical Fits, Euclid Interface, and Modernized Companion Papers (I–CI v2. 0) Relaxation-Driven Cyclic Cosmology (RDCC) v47. 0 presents a major consolidation and the most observationally complete formulation of the framework to date. This release integrates the fully updated RDCC Core (Companions XIII–XXI), the revised observational block (Companions XXIV–XXVII), and the modernized structural foundations of the theory. RDCC v47. 0 provides a unified, one-parameter description of early- and late-time cosmology, gravitational waves, structure formation, and lensing observables. The central feature of RDCC remains its one-parameter prediction structure: all deviations from ΛCDM are governed by the infrared relaxation parameter α. The correlated predictions for the scalar spectral tilt, the dark-radiation excess, the growth-rate deviation, and the tensor amplitude and modulation frequency form a tightly constrained observational vector. RDCC v47. 0 incorporates the modernized derivations of these relations and updates the observational interfaces accordingly. This release introduces several major improvements. The RDCC Core Companions XIII–XXI have been fully modernized, providing a consistent 2026-level formulation of neutrino physics, dark matter, baryons, reionisation, small-scale structure, and nonlinear evolution. The observational block has been completely updated: Companion XXIV (Reionisation), Companion XXV (21-cm Lensing), Companion XXVI (Gravitational Lensing), and Companion XXVII (Redshift-Space Distortions) have been rewritten in the new RDCC style, including analytical structures, numerical settings, and CLASS-level implementation details. These Companions now form a coherent and internally consistent observational module that connects the relaxation dynamics to measurable cosmological signatures. RDCC v47. 0 also includes the updated Companion CI v2. 0 on black holes and CPT-conjugate inter-sector horizons, which extends the RDCC framework into the strong-gravity regime. The Flagship Paper and Companion V (Global Fit) remain fully compatible with this release. Companion V continues to provide the unified likelihood architecture and the prototype global fit, demonstrating that all observational channels converge to α ≈ 0. 016, consistent with the analytic estimate α ≈ (1 − ns) /2. The GitHub repository associated with this release contains all modernized PDF and TEX sources of the RDCC Companions, ensuring full transparency and reproducibility. ----------------------------------------------------------------------Key Theoretical Outcomes of RDCC---------------------------------------------------------------------- RDCC addresses several long-standing cosmological puzzles within a single structural framework based on global CPT symmetry and a bipartite quantum state. The approach provides natural mechanisms for: • the thermodynamic arrow of time• the replacement of the cosmological singularity by a nonsingular CPT-symmetric bounce• the resolution of the Tolman low-entropy problem• the emergence of dark matter as the gravitational shadow of the CPT-conjugate sector• the apparent weakness of gravity through sectoral energy distribution• the emergence of the invariant speed of light as an inter-sector coherence boundary• the late-time acceleration and the coincidence problem via freeze-out of the relaxation rate• the horizon and flatness problems through global CPT coherence• baryon asymmetry from asymmetric relaxation or projection effects (proposed mechanism) • the strong CP problem through global CPT symmetry (potential resolution) • global information conservation in the bipartite Hilbert space RDCC predicts correlated small deviations from ΛCDM, including: • a specific scalar spectral tilt• a dark-radiation excess• percent-level shifts in growth rates• characteristic oscillations in the stochastic gravitational-wave background• a turnover in the 21-cm power spectrum at the relaxation scale kᵣel• modified halo profiles and baryon fractions• delayed and smoother cosmic reionization A further structural extension arises from the RDCC interpretation of black holes and white holes (detailed in Companion CI v2. 0). In a bipartite, CPT-symmetric Hilbert space, a black hole in the visible (+) sector and its CPT-conjugate white hole in the (−) sector form a single global configuration. The horizon acts as an inter-sector information interface: what appears as irreversible infall in the (+) sector corresponds to time-reversed outflow in the (−) sector. This structure provides a globally unitary perspective on the black-hole information paradox and links strong-gravity phenomena to the same CPT-symmetric and relaxation-driven mechanisms that govern the cosmological bounce and the thermodynamic arrow of time. RDCC v47. 0 establishes Relaxation-Driven Cyclic Cosmology as a coherent, testable, and fully documented framework, offering new insights into cosmic acceleration, structure formation, baryonic physics, reionization, and the earliest luminous epochs of the Universe. Michael Lehmannmi. lehmann@gmx. de

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