{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"cf7e7f0058d908861f7f50acf2b22672e8308a2633ccabe00fa0cb698325e95c","created":"2026-10-03T07:17:54Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["3358a8ece5f1ed5008265559fc402766171bd67d30216f1a1e2aa8234b7bc6a9","5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"0473d1cd3a57bb949708ae1ff96e93c2722574815383a0274dd91a6f503ca228","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":"1","parents":[{"note":"","parent_revision":"3358a8ece5f1ed5008265559fc402766171bd67d30216f1a1e2aa8234b7bc6a9","relation":"special_case"}],"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 $G = 6.67387e-8\\,\\mathrm{cm}^3\\,\\mathrm{g}^{-1}\\,\\mathrm{s}^{-2}$, 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":null,"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":"e5522d18821c2173b9833ad46620a1ae7d5f42c3c43509b22e231c630bb90895"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"dbe290ee5aa920742bb9b74e3a968d6a0517b7d833e470bd65bbd6c2e2fe7dbd","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"b8c91966bf47735553eba1245ffb3b64af60c73e523c8fdd854ffad90b38f03e","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"R9lOS_i2BQ0QefJ8WPIiv5f9JFd-fAFUpRpdpwvzeL90JP3UAvQ1h94b7Fv978QC6-nmifUg0Zhk1uK3WplZCA"},"schema":"pubphys.envelope/1"},"record_hash":"dbe290ee5aa920742bb9b74e3a968d6a0517b7d833e470bd65bbd6c2e2fe7dbd","leaf_index":432}