---
title: "Gravity Probe B measured Earth's frame-dragging at 37.2 ± 7.2 mas/yr, matching general relativity's 39.2 mas/yr prediction"
type: "claim"
status: "budding"
audit_status: "capture-verified (the batch worker read the Tier-1 Physical Review Letters PDF hosted at einstein.stanford.edu at capture time; an independent headless re-fetch of the exact figures was not performed, so the note is held to capture-verified rather than verified-verbatim) — APPEND 2026-07-12, cross-model audit (writer claude-opus-4-8, auditor claude-fable-5): independent re-fetch performed — extract_pdf on the einstein.stanford.edu PDF (sha256 509b1993…) plus the arXiv:1105.3456 abstract. Figures confirmed against Table II and the abstract: joint frame-dragging −37.2 ± 7.2 mas/yr vs GR prediction −39.2 mas/yr; geodetic −6601.8 ± 18.3 vs −6606.1. Raised to verified-verbatim. One correction: the prior source_quote was the capture worker's paraphrase ('37.2 ± 7.2 milliarcseconds/year of spacetime drag against a GR prediction of 39.2 mas/yr'), not the paper's wording; replaced with the verbatim abstract sentence (published values carry negative signs — the note's prose use of magnitudes is unchanged and fine)."
source_url: "https://einstein.stanford.edu/content/sci_papers/papers/PhysRevLett.106.221101.pdf"
source_author: "C. W. F. Everitt et al. (Gravity Probe B collaboration)"
source_date: "2011-05-31T00:00:00.000Z"
source_quote: "Analysis of the data from all four gyroscopes results in a geodetic drift rate of −6601.8 ± 18.3 mas/yr and a frame-dragging drift rate of −37.2 ± 7.2 mas/yr, to be compared with the GR predictions of −6606.1 mas/yr and −39.2 mas/yr, respectively"
source_tier: 1
provenance: "Promotion from 10-inbox/raw/2026-07-09-hop-ning-li-antigravity-conspiracy.md, 2026-07-11"
origin: "batch"
derived_from: "10-inbox/raw/2026-07-09-hop-ning-li-antigravity-conspiracy.md"
date_created: "2026-07-11T00:00:00.000Z"
writer_model: "claude-opus-4-8"
tags: ["physics","general-relativity","frame-dragging","gravity-probe-b","metrology"]
audits: ["2026-07-12 claude-fable-5"]
drafted_in: ["status-exists"]
---


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
[[claim-ning-li-1991-gravitomagnetic-superconductor-antigravity-proposal|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
[[claim-superconductor-antigravity-effects-never-independently-replicated|replication record for such claims]]
is empty.

> [!note] Seek's commentary:
> This note exists as a scale bar. When an unreplicated claim borrows the
> vocabulary of a real effect ("gravitomagnetic," "frame-dragging"), the honest
> check is not "is the mechanism plausible?" but "how big is the real thing it
> names?" Here the real thing is 37 mas/yr — and that answers the question before
> any mechanism argument begins. — Seek