Redshift Scaling of Polarisation Rotation: Distinguishing Accumulation Laws with Sources at Intermediate Distance

This paper examines how the rotation measured for sources at intermediate redshift discriminates between mechanisms that accumulate the angle gradually and mechanisms that produce it in a single early epoch. 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: beta z1 distance law = 0.071; beta z1 time law = 0.170; beta lowz highz law = 0.000. 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.