Polarisation Rotation Through a Bounce Phase: A Negative Result from the Density Bound Alone

This paper examines whether the density bound that defines the bounce framework - a maximum density of 9.72e54 grams per cubic centimetre on the neutron branch - by itself predicts any polarisation rotation for photons passing through or emerging from the bounce phase. The calculation is performed from stated assumptions and published polarisation measurements, using the deposited script so that every quoted number can be reproduced. The headline outputs are: rho A g cm3 = 9.72e+54; t A s = 1.24e-24; unconditional rotation = not supplied - no parity-odd coefficient in the density bound; conditional deg at xi0p01 = 0.573. The treatment separates what the published measurements supply from what a theoretical framework must additionally provide; where a required quantity is not supplied, that absence is reported plainly as a negative result rather than replaced by an assumed value. The study is computed from stated assumptions and published inputs; it is not a new measurement. SIMULATED, NOT MEASURED in the sense that all derived quantities are calculated, not observed.