Causal Edge Study: Entropic Gravity Trajectories Constrained by O3 Standard Sirens

Causal Edge Study (Reviewer Build) This repository is a review-focused, run-once reproduction seed for locally checking reproducible parts of the entropic-gravity framework discussed in: G. Bianconi, Gravity from entropy, Phys. Rev. D 111, 066001 (2025), DOI 10.1103/PhysRevD.111.066001, arXiv:2408.14391. (Context article) Popular Mechanics: “Gravity Might Emerge From Entropy” (secondary summary; not the source of truth). The Popular Mechanics piece is a secondary summary. The reproducible source is the PRD/arXiv manuscript above. What This Repo Checks (Scope) The PRD paper is primarily theoretical. There is not a large numerical data product to re-fit. So the local reproduction targets are: Warm-up scalar-field derivation checks: closed-form matrix identities and the resulting entropic Lagrangian. Emergent cosmological-constant check for the G-field sector: positivity and small-perturbation (quadratic) scaling of Tr(G − I − ln G). A minimal FRW probe-limit toy simulation: a reduced scalar ansatz phi(a) that produces derived proxies for a running effective coupling and a “Planck-resolution of the causal boundary”. Optional manuscript build: compile the cached arXiv sources locally if LaTeX is installed. Important: the “Planck constant getting finer” language is treated here as a proxy for an effective Planck length derived from a running effective Newton coupling (not a claim that ℏ varies). One-Command Seed Reproduction (Recommended) This produces a timestamped folder under outputs/ containing report.md, summary.json, logs, and FRW figures/tables: make seed Then open the generated report: ls -lt outputs/seed_repro_* | head cat outputs/seed_repro_*/report.md If you also want to build the cached arXiv TeX PDF as part of the seed run (requires pdflatex): ./.venv/bin/python scripts/run_seed_repro.py --build-paper Other Useful Commands Run only the analytic reproduction checks: make repro Run only the FRW toy simulation (probe-limit; writes to outputs/frw_gfield_probe_*): make sim-frw Run an accelerated-expansion scenario (adds an event-horizon proxy; useful for “causal edge” diagnostics): make sim-whitehole Derive a GW-propagation target curve (R(z)=d_L^{GW}/d_L^{EM}) from the latest FRW output: make gw-prop Generate a toy “amplitude-only vs phase” waveform demonstration: make toy-waveform Explore how strongly the toy model can evolve the effective coupling and the implied propagation curve (R(z)): make sweep-edge Run a kinematic “alpha_M(a)” scenario (hypothesis-side; useful for testing the internal logic of the causal-edge story): make kinematic-edge Run a compact diagnostic comparing the BD-like toy dynamics to kinematic (\alpha_M) scenarios: make whitehole-diag Generate a phase diagram over (turn-on redshift, running strength) for logistic (\alpha_M(a)): make phase-diagram Fit/score the phase-diagram grid against external constraints on (R(z)) placed in inputs/Rz_measurements.csv: make reality-check Build the CQG-style manuscript in CQG_PAPER/ (requires pdflatex): make build-cqg-paper Build the cached arXiv TeX PDF locally: make build-paper Local Sources (Cached) ArXiv sources are cached under: third_party/arxiv/2408.14391/ The LaTeX build uses a small yfonts.sty shim because minimal TeX installs often omit the yfonts package. The shim only provides the two macros actually used by the source (\\textswab, \\textfrak) and otherwise stays out of the way. Notes notes/reproduction_scope.md: what is reproduced, what is not. notes/white_hole_hypothesis.md: speculative bridge to the “white hole” framing (clearly separated from the reproduced paper). notes/target_observables.md: how the toy (\phi(a)) trajectory maps to testable observables (e.g. GW propagation ratio (R(z))).