Ning Li and Douglas Torr's 1991 Physical Review D paper models a superconductor's passive response to an external gravitomagnetic field; the field-generating 'antigravity' claim belongs to their later, unread 1992–1994 papers

fringe-sciencephysicsantigravitysuperconductivityning-liprimary-source-verification

Physicist Ning Li (1943–2021), then at the University of Alabama in Huntsville, and Douglas Torr published "Effects of a gravitomagnetic field on pure superconductors" in Physical Review D (43(2): 457–459, 15 January 1991). Read directly at OSTI.GOV's primary catalog record, its own abstract calculates how a superconductor's internal fields respond to gravitomagnetic and magnetic fields imposed from outside it — the reverse causal direction from the "generator" claim (that rotating ions inside a superconductor could actively produce a gravitomagnetic field strong enough for a repulsive antigravity effect) that Tier-4 secondary summaries, including this note's original Wikipedia source, attribute to Li and Torr's work overall. That active-generator claim does not appear in this specific paper's abstract; it most likely belongs to the pair's 1992 Physical Review B paper and a 1994 University of Alabama in Huntsville preprint (Li, Torr & Karwacki), neither read this session — see question-verify-li-torr-1992-1994-active-generator-claim. The proposal, across whichever paper actually states it, borrowed the vocabulary of a real general-relativistic phenomenon — frame-dragging, the twisting of spacetime by a rotating mass — but asserted a laboratory-scale, useful magnitude the real effect does not approach. The work sat inside NASA Marshall's speculative-propulsion orbit before migrating into a privately funded venture, AC Gravity LLC.

The claim belongs to the vault's cluster on how scientific error is — or is not — formally closed. Unlike the fabricated data that Jorge Hirsch helped expose in Ranga Dias's superconductivity work, the Li–Torr claim-family was not entirely without a formal reply: a named physicist did publish a peer-reviewed rebuttal, per claim-harris-1999-rebutted-torr-li-gravitoelectric-coupling-claim — but it targets the pair's 1993 sequel paper specifically, not this 1991 one, which otherwise failed to replicate and drifted out of active research the softer way, much like the yellow-rain case where a decisive refutation never reached the official record.

Correction history.

• 2026-08-23 — This note originally described the 1991 paper itself as proposing that rotating ions could generate a gravitomagnetic antigravity field, sourced from Tier-4 Wikipedia paraphrase. A direct read of the 1991 paper's own abstract (OSTI.GOV, Tier 1) shows it calculates the reverse: a superconductor's internal response to fields imposed from outside. The active "generator" claim was not found in this paper and most likely belongs to the pair's unread 1992–1994 papers. Found and corrected during promotion of 10-inbox/raw/2026-08-23-what-do-the-primary-sources-say-about-ning.md (resuming question-verify-ning-li-antigravity-primaries), which also located Harris's 1999 formal rebuttal of the related, stronger 1993 paper.