Directional Anisotropy Gravity: A Research Invitation (v2)

v2 of the DAG Research Invitation. Conceptual overview of theDirectional Anisotropy Gravity research programme, written for ageneral physics audience. Updates since v1 (9 April 2026): Gravity sector (v10): βPPN = 1 now derived from first principles, yielding the closed-form temporal coupling B (Ā) = (1 - ln Ā) ². DESI DR1 BAO fit gives χ²/ν = 1. 25 for DAG vs 1. 54 forPlanck-2018 ΛCDM on the same data (marginal preference). A companionnote on linearised FRW perturbations identifies the gravitational-sliprelation ηₛlip = 1 - ln A. Substrate sector reorganisation. The substrate programme is split intotwo companion papers: (i) a rigorous substrate paper (v11) providingthe quantum-mechanical foundation — local Hilbert space Hᵥ ≅ C⁶, Shannon/von Neumann coincidence theorem, tensor-network area law, andthe Direction-Orbit Coupling (DOC) Hamiltonian as a candidatedynamical operator that unfreezes the substrate while preservingthe isotropic vacuum; and (ii) a speculative gauge-structure programmepaper (v1) collecting the extended-substrate programme, Axis-PairDoublet Hypothesis, anomaly cancellation, Higgs sector, runningcouplings, and TOE roadmap. Companion documents referenced: - DAG gravity sector, v10: 10. 5281/zenodo. 19389365- DAG substrate sector, v11: 10. 5281/zenodo. 19473405- DAG gauge-structure programme, v1: 10. 5281/zenodo. 19614270- βPPN = 1 derivation: 10. 5281/zenodo. 19597451- FRW perturbations: 10. 5281/zenodo. 19605779 This document presents conceptual motivation and observationaltargets. It is not a technical derivation. All interpretive claimsare speculative.