Warp-Bubble Wall Thickness: The Shear Ceiling and the Quantum Inequality Squeeze From Opposite Sides

A warp-bubble wall is squeezed from two directions. From one side, the velocity gradient across the wall implies a shear rate of order the ship speed divided by the wall thickness, and a maximum shear rate of 4.04e+24 per second, derived from the spin-torsion density ceiling, forbids any wall thinner than 7.43e-17 metres. From the other side, the Ford-Roman quantum inequality licenses negative energy at warp-wall densities only for walls of order one hundred Planck lengths, 1.62e-33 metres, as Pfenning and Ford established. The two demands miss each other by sixteen orders of magnitude: at the quantum-legal thickness the shear exceeds the ceiling by a factor of 4.59e+16. The verdict is plain: there is no wall thickness at which a light-speed warp bubble satisfies both the shear ceiling and the quantum inequality, and the exclusion needs no appeal to the bubble's total energy at all. Computed, not measured.