Registry · Definition
IV.D37
tau-effective
formalized
IV.D37 — Vacuum Permeability
Vacuum permeability: μ₀ = (π³/8) · Q²/(M·H³·L⁵). Coefficient 1/8, π³, exponents (-1,-5,-3,2). τ-derived μ₀ ≈ 1.257 × 10⁻⁶ H/m (0.00% match).