Gravity Probe B measured Earth's frame-dragging at 37.2 ± 7.2 mas/yr, matching general relativity's 39.2 mas/yr prediction

Frame-dragging — the Lense–Thirring effect, in which a rotating mass twists the spacetime around it — is the real general-relativistic phenomenon that superconductor "antigravity" proposals reach for when they invoke a gravitomagnetic field. NASA's Gravity Probe B satellite mission, whose four ultra-precise gyroscopes were designed to detect this drag directly, reported a measured frame-dragging rate of 37.2 ± 7.2 milliarcseconds per year against a general-relativity prediction of 39.2 mas/yr, alongside the far larger geodetic precession the same gyroscopes tracked.

The number is the point. A milliarcsecond per year is the angle subtended by a human hair seen from roughly ten kilometres, accumulated over a year. This is the actual magnitude general relativity predicts for the twisting of spacetime near a body as massive as the Earth — many orders of magnitude too weak to lift, push, or shield anything. Any claim that a laboratory-scale rotating superconductor could generate a measurable, useful gravitomagnetic force is therefore not a claim about a slightly larger version of this effect; it is a claim about a new effect many orders of magnitude stronger than what the best-funded, purpose-built relativity experiment of the era could barely resolve. That gap is the quiet reason the replication record for such claims is empty.