Microwave Background Spectral Distortions from Bounce-Era Dissipation: A Limit on Small-Scale Power

Energy released into the early photon bath leaves a characteristic distortion in the microwave background spectrum, of the kind parameterised by a chemical potential when the release is early. For a cutoff at one thousand per megaparsec the predicted distortion falls to 1.02e-08, with a surviving power fraction of 0.511; at two hundred per megaparsec it falls further, to 4.34e-09; the standard value is 2.00e-08, and the firm observational limit from past measurement is 9 in a hundred thousand. A future instrument reaching the standard prediction could therefore detect the absence of power the cutoff implies, turning a null result at the expected level into positive evidence about the initial spectrum at scales no other probe reaches. Computed from stated assumptions, not measured.