The Maximum Range of Gravity: From 7-Series Bridge Pool to Cosmic Limit

Standard physics asserts gravity has infinite range. Bootstrap cosmology derives a finite range from prime number structure. The 7-series primes (p ≡ 1 mod 6) provide bridges for gravitational propagation; their cumulative products exhibit a digit gap at 10⁶³, establishing a closure limit. Resonance points are natural numbers addressable as 7-series products — beyond this scale, no address exists without factor 3, which is excluded from the prime lattice. Each proton, the smallest unit of gravity respecting icosahedral geometry, claims 20-62 resonance points from this pool. The resulting gravity range is ~10⁴⁶ m — approximately 10²⁰ times larger than the observable universe (10²⁶ m). We verify that the 1/r² law holds at proton scale (100% match) and show the calculation is robust: all reasonable estimates of proton "integer cost" yield the same order of magnitude. This paper is part of a series establishing that the universe is closed. A companion paper shows the observable universe equals the Schwarzschild radius of its own mass.