Relaxation-Driven Cyclic Cosmology (RDCC) + Companion Papers I, II, III, IV, V v2.0, VI, VII, VIII + Speculative Extensions

Relaxation‑Driven Cyclic Cosmology (RDCC) Framework v39. 0 It includes the Flagship Paper, Companions I–VIII, and the “Speculative Extensions / Conceptual Companions II” document, forming a coherent theoretical architecture that develops RDCC from its foundational principles to its phenomenological and structural consequences. RDCC describes the Universe as a globally CPT‑symmetric quantum state with a bipartite Hilbert‑space structure. Classical spacetime, causality, and the thermodynamic arrow of time emerge only after sectoral projection, while the relaxation parameter α (a) governs decoherence, tensor‑sector interference, and the long‑term cyclic dynamics. Across the Companions, the framework establishes connections to scalar tilt, dark radiation, growth‑rate deviations, tensor modulation, and the freeze‑out of α (a). This release consolidates all components of the RDCC program into a single versioned archive for citation, reproducibility, and long‑term accessibility. What is new in Version 39. 0: The only addition in v39. 0 is the new Companion VIII: Companion VIII - Emergent Speed of Light as an Inter‑Sector Coherence Boundary in RDCCThis Companion introduces a structurally motivated interpretation of the invariant speed c. Rather than treating c as a fundamental constant, Companion VIII shows that: • c can be understood as an inter‑sector coherence boundary, • representing the maximal rate at which global quantum coherence can propagate across the bipartite CPT‑symmetric state, • before relaxation dynamics enforce sectoral decoherence. The Companion derives qualitative scaling relations linking: • the infrared relaxation scale αIR, • the freeze‑out Hubble rate HIR, • the coherence length ℓcoh ≈ c / (αIR HIR), • the maximal cosmic scale Rₘax, • and the cycle duration Tcycle ≈ 1 / (αIR HIR). It further connects this interpretation to: • the dimension‑six inter‑sector operator, • the decay of off‑diagonal density‑matrix components, • the freeze‑out of α (a), • and the log‑periodic tensor modulation established in earlier Companions. Companion VIII thus provides a structural completion of the RDCC framework by clarifying the role of c within the global CPT‑symmetric architecture. Included Documents in v39. 0: • Flagship Paper• Companion I - RDCC Foundations• Companion II - Tensor Modulation• Companion III - Relaxation Dynamics• Companion IV - Growth‑Rate Deviations• Companion V v2. 0 - Dark Radiation and Scalar Tilt• Companion VI - Freeze‑Out of α (a) • Companion VII - RDCC Prediction Vector• Companion VIII - Emergent Speed of Light as an Inter‑Sector Coherence Boundary (new in v39. 0) • RDCC Speculative Extensions / Conceptual Companions II <-- (This document is not part of the predictive RDCC framework but a conceptual interpretation. The analogies do not validate RDCC, but demonstrate that its underlyingstructure is deeply rooted in known physics. ) --- Related documents and the full RDCC ecosystem are available via Zenodo: https: //zenodo. org/records/18204087 Michael Lehmannmi. lehmann@gmx. de