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 α_IR,• the freeze‑out Hubble rate H_IR,• the coherence length ℓ_coh ≈ c / (α_IR H_IR),• the maximal cosmic scale R_max,• and the cycle duration T_cycle ≈ 1 / (α_IR H_IR). 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