Torsion Bounds from Casimir Pressure Measurements Between Metallic Plates

This paper examines whether precision Casimir pressure measurements already limit a uniform axial torsion background through its vacuum pressure contribution. The system considered is parallel metallic plates separated by 100 nm to 5 micrometres, and the observable is Casimir pressure and its fractional measurement uncertainty. Evaluating the ordinary behaviour of the system and the spin-torsion contribution under explicit assumptions about polarisation and uniformity, and inverting the comparison at the stated laboratory precision, gives a quantitative bound rather than a qualitative assertion of smallness. The computed record is: pressures contains 5 evaluated points; point 1 d_nm = 100; point 1 P_Pa = 13; point 1 one_percent_Pa = 0.13; point 2 d_nm = 200; point 2 P_Pa = 0.8126; point 2 one_percent_Pa = 0.008126; point 3 d_nm = 500; point 3 P_Pa = 0.0208; point 3 one_percent_Pa = 2.080e-04; headline_P_Pa_at_200nm = 0.8126; torsion_bound_per_m = 1.594e+06; precision_assumed = 0.01. The torsion-related contribution is far below the level that would alter the ordinary behaviour of the system at current precision, and the value that would have produced a visible residual is stated so that future improvements can be assessed against it directly. No new measurement is reported. This study is simulated and computed from stated assumptions, not measured.