# Spacetime drag and galaxies' radial velocity mismatch

We know - or theorize - that a spinning black hole drags spacetime in its surroundings, producing measurable effects on the accretion disk (the minimum stable orbit radius). What I cannot grasp is why this isn't the case for a rotating galaxy. Why the mismatch in classical rotational velocity predictions isn't explained from the spacetime dragging of the total mass of the galaxy at a given radius value? Why do we need dark matter to adjust for the "strange" measurements?

• OP seems to be mixing relativistic and non-relativistic effects. – Qmechanic Jan 15 at 6:10
• – safesphere Jan 15 at 7:24