Frame-Dragging from the Azimuthal Flow A spinning mass with angular momentum J entrains the surrounding substrate into azimuthal flow that weakens outward as 1 over r squared and varies as sine theta. Frame-dragging is just the local angular velocity of this flow. A free draining vortex would conserve circulation, giving v_phi proportional to 1 over r and a dragging rate of 1 over r squared, which is not the Lense-Thirring law. The substrate is instead entrained: the force-free azimuthal flow obeys an Euler equation with roots plus one and minus two, so the decaying solution gives v_phi proportional to 1 over r squared and a dragging rate of 2GJ over c squared r cubed, exactly Kerr to linear order. Gravity Probe B confirms both the geodetic and frame-dragging precessions. Frame-Dragging is the Spinning Substrate A spinning mass entrains the substrate into azimuthal flow. Frame-dragging is nothing but the local angular velocity of that flow — an entrained dipole, not a free-draining vortex. spin axis J vφ  ∝  sinθ / r² strongest at the equator frame-dragging rate = local flow rotation: ωdrag = vφ / (r sinθ) = 2GJ / c²r³ Why 1/r³, not the bathtub's 1/r² ✗ free vortex (bathtub): Γ = 2πr vφ const → vφ ∝ 1/r → ω ∝ 1/r² — not the Lense–Thirring law ✓ entrained boundary: f″ + (2/r)f′ − (2/r²)f = 0, roots +1, −2 → vφ ∝ 1/r² → ωdrag ∝ 1/r³ — exactly Kerr / Lense–Thirring to linear order Gravity Probe B Precession Predicted GP-B measured Geodetic radial ebb (mass sector) 6604 6601.8 ± 18.3 Frame-dragging azimuthal vφ (spin sector) 41 37.2 ± 7.2 mas/yr · geodetic matches GR to 0.03%; same G as the mass sector, applied to J