{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"98bbfe778daef8a56d59be36e444718f6a1f01cf046f63789e946a53df534ad2","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b","dbe290ee5aa920742bb9b74e3a968d6a0517b7d833e470bd65bbd6c2e2fe7dbd"],"salt":"13ef1252dbb7b2d7d53fbcaaf0e78f1a36669cab977e53f06e35b3cda7593b46","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"identification","assisted_by":[],"external_id":"amo.newtonian-g.nist-bipm-gap","kind":"well-posed","literature_status":"open","n":"2","parents":[],"plain":"NIST rebuilt the instrument used by the international measurement bureau (BIPM) and got a value about 2 parts in 10000 lower. Since the design is the same, the difference should be traceable to a specific cause.","posed_since":"2024","precise":"The NIST measurement (2026, Metrologia), using a torsion-strip balance of the BIPM design in both servo and Cavendish modes, gives $G = 6.67387 \\times 10^{-8}\\,\\mathrm{cm}^3\\,\\mathrm{g}^{-1}\\,\\mathrm{s}^{-2}$, about 235 ppm below the BIPM 2013 value. Identify the effect (mass metrology, torsion-strip anelasticity, source-mass density inhomogeneity, alignment, environment) that accounts for the difference.","problem_ref":"dbe290ee5aa920742bb9b74e3a968d6a0517b7d833e470bd65bbd6c2e2fe7dbd","references":"","settled_by":"A cross-check with exchanged source masses or fibers, or a third realization of the same apparatus, that isolates the component responsible for the 235 ppm offset.","status_note":"NIST's blinded result was unblinded in July 2024 and published in April 2026.","title":"Same apparatus design, different G: the NIST versus BIPM discrepancy","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"22489e2f4eee11dbd32eb9540e18f4393fd0cdd9f9c301f837c98b125cacbaa9","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"4308b4ddfa706207081048e54991e6cbcff024399c9ab69e3d2b2368ee22954d","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"1r6hy9P1gW1lvs1VBPvylSsm9pf0dxx8zsDIXBH4fEHp4GWc-f2Zld6QiwOtzyRqTo1qW1zhKGBgYXWkpOO7Dg"},"schema":"pubphys.envelope/1"},"record_hash":"22489e2f4eee11dbd32eb9540e18f4393fd0cdd9f9c301f837c98b125cacbaa9","leaf_index":2262}