Margolus-Levitin Rate Ceiling for a System at the Limit Energy Density

This paper examines how fast a physical system can pass through mutually distinguishable states when its total energy is capped by the Limit density. The calculation is performed in a frame with a finite maximum density, the neutron-branch value rho_A = 9.718e+57 kg per cubic metre, with the electron branch at 2.874e+51 kg per cubic metre for comparison. Headline results include a bounce temperature of 3.278e+22 K, a Landauer cost at that temperature of 3.137e-01 J per bit against 2.871e-21 J per bit at 300 K, a Bekenstein allowance of 1.049e+94 bits for the stated centimetre reference region, and a Margolus-Levitin rate of 2.209e+103 per second for the same region. The reference region admits a formal rate near 1.05e107 state changes per second, a figure whose size exposes how far the energy ceiling sits above any realisable clock. All numbers are computed from the stated assumptions in the accompanying script; the study is simulated and computed, not measured.