Appendix Γ to PNS: A Birth–Death Hypothesis of Gravity — A Speculative PNS Note with a First SPARC Consistency Test

This is a speculative working note, not a verified theory or a claim of new physics. It records a hypothesis and a first quantitative constraint from real data.This note does not claim evidence for the birth or death of gravity. It records a speculative hypothesis and a first quantitative constraint: any viable version must reproduce the observed radial-acceleration relation while producing additional history-, boundary-, or time-dependent signatures beyond MOND-like reformulations.We quantitatively test the hypothesis that gravity is not a fundamental force but emerges from a lower-level event structure and is temporally born and dies. Confronting 175 SPARC galaxies (3,197 points) without any dark-matter term, we confirm a single deviation curve from Newtonian gravity below a critical acceleration a0 ≈ 1.0×10⁻¹⁰ m/s² (scatter 0.19 dex). An 8-fold random split-sample test shows this rule is a transferable universal law, not a tuning (85.6% improvement over Newton). A naive monotonic switch-off model is falsified (the deviation runs the opposite way), and this deviation is shown to be a gate that cannot by itself distinguish emergence, modification, or dark matter.Extrapolation to the Hubble tension requires a 17% enhancement of G at recombination, which violates the Big Bang Nucleosynthesis helium constraint at 6.3σ, excluding monotonic forms. A sign-table analysis forbids a single scalar coupling and forces a multi-component form. A physical rule — "at recombination, matter gains self-motion and gravity decouples from temperature" — then generates the required enhancement without hand-tuning, locking BBN automatically and compressing the remaining freedom into a single strength parameter, for which the baryon inertia fraction R/(1+R) ≈ 0.38 is a candidate near the needed 0.34.Reverse-engineering the event weight from four anchors points to "one bit inscribed on the horizon" — information and entropy being the same quantity up to a constant factor — rooted in a directionless restoring tendency inherited from before the Big Bang.All results beyond the Hubble-tension section are candidates, not confirmations. This is a research note appended to the Presentization Number System (PNS). The relation between presentization and restoration remains a fundamental open question. Both an English version and the Korean original are included.