The Torsion Bound in Inverse Metres: A Length Scale for the Aldred Limit and Its Reach

The Aldred Limit can be stated as a bound on torsion itself: through the Cartan equation, T_A = square root of (8 pi G rho_A / c squared). On the neutron branch T_A is 1.347e+16 per metre, a characteristic length of 7.425e-17 m. That length is 4.594e+18 times the Planck length and a factor 2.8 below the neutron Compton wavelength. On the electron branch the torsion bound is 7.325e+12 per metre, a length of 1.365e-13 m. Stating the bound in inverse metres does more than change units. It identifies the scale at which torsion, if it approached its bound, would vary appreciably, and it gives experimentalists a length to compare with the reach of spin-sensitive instruments instead of an abstract density. No existing instrument operates within many orders of magnitude of these scales in the relevant sense, which is the quantitative form of the statement that the bound is a high-energy frontier, not a laboratory one. Computed from stated assumptions, not measured.