A Bound on Bounce-Frame Propagation Corrections From the Bright Siren Distance

This paper asks a single question and computes its answer. If propagation through a universe whose density is capped at the Aldred ceiling slightly altered the effective luminosity distance, how large could that alteration be at the GW170817 distance, given the density history along the line of sight? Working in a flat LambdaCDM background and carrying the bounce-frame density ceiling explicitly — the Aldred Limit, rho_A = rho_Pl (m/m_Pl)^2/(8 pi C), with the neutron branch at 9.72e+54 g per cubic centimetre — the calculation gives the headline values ratio = 9.5e-85, ratio10 = 1.3e-81, corr = 9.5e-87, rhoA = 9.72e+54. The bound is extraordinarily small at every redshift: the ambient density today is more than eighty orders of magnitude below the ceiling, and even at redshift ten the ratio remains negligible by any observational standard. Bounce-frame propagation corrections to siren distances are therefore zero for all practical purposes. Every number reported here comes from the deposited computation script, which states its assumptions in full. This study is simulated and computed from stated assumptions and published catalogue values; it is not a measurement.