{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"8f74e47fe06ead36cbdb2ca463d80a5e9cefbf7583741eda84ed252a8bf67cc0","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b","ed264645728bed1ec687ad4bd3875390250b8f5cab07bf83f47c6553d9b6de0f"],"salt":"d4c77ef7036f860d5a2cd572e04c6054c6cc03dbc12299d3b1ae773a6ecf9eb3","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"identification","assisted_by":[],"external_id":"cosmo.hubble-tension.origin","kind":"phenomenon","literature_status":"contested","n":"2","parents":[],"plain":"Two careful ways of measuring how fast the universe expands today give different answers. The cause could be a measurement error or new physics.","posed_since":"","precise":"Write $H0 = h x 3.24 \\times 10^{-18}\\ \\mathrm{s}^{-1}$. The SH0ES Cepheid plus type Ia supernova ladder gives $h = 0.730 \\pm 0.010$, while Planck CMB in LCDM gives $h = 0.674 \\pm 0.005$. Identify whether the discrepancy comes from distance-ladder systematics, from physics before recombination that shrinks the sound horizon, or from late-time physics, with a model that fits all data at least as well as LCDM.","problem_ref":"ed264645728bed1ec687ad4bd3875390250b8f5cab07bf83f47c6553d9b6de0f","references":"","settled_by":"Independent one-percent $H0$ measurements that agree with one side, plus a model or systematic that removes the discrepancy without spoiling other fits.","status_note":"2025 to 2026 JWST cross-checks by SH0ES find Cepheid, TRGB and JAGB distances agree within about 0.03 mag, while CCHP finds $h$ near 0.70.","title":"What causes the Hubble tension?","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"c441dc812a33e3b440403445398f838d7041e597769497cefe86fa0117e4edbc","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"186fc496b66cfa100bcc584f7632e9d207c2cf88a5013778fcb150d6ddac7eba","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"lREgnHa_IH70wf-vUnbmbWQGJAbDTHi6rBfhexKNYGzUjzrYsWK6dvpGXpsywhETGS_2a1DZ92qCfBq1jTq8Cw"},"schema":"pubphys.envelope/1"},"record_hash":"c441dc812a33e3b440403445398f838d7041e597769497cefe86fa0117e4edbc","leaf_index":3144}