The 21-cm Power-Spectrum Amplitude at Cosmic Dawn in the Bounce Frame

The sky-averaged signal measures the mean; the power spectrum measures the fluctuations, and the two together constrain far more than either alone. Using the stated cosmology and the brightness-temperature relations described in the Methods, the calculation gives the following headline values: power mK2 = 210; k hMpc = 0.10; z = 17.0; hera upper mK2 = 730; fraction of limit = 0.29. The comparison values taken from the published record — including the EDGES and SARAS reports, HERA limits and the Planck optical depth where relevant — are used exactly as published, and the bounce contribution enters only through the named timing, heating or shear inputs. The result is a computed prediction for the delayed-onset history, with its sensitivity to each input stated in the Discussion. This study is simulated and computed from stated assumptions; it is not a measurement.