{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"57a5cf230764fbadd892de2009f97920c11077a9cd1cf421071e8d1dc201a3a2","created":"2026-10-03T07:18:02Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"68f486b36c54428f812cab6632b899e5c8fc34c1772f5c62a56175d15a27d30e","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"identification","assisted_by":[],"external_id":"cosmo.lithium-problem.lithium7-deficit","kind":"phenomenon","literature_status":"open","n":"1","parents":[],"plain":"Old metal-poor stars in the Milky Way halo show a constant lithium level, but it is about three times below the Big Bang prediction. Either the stars destroyed lithium, or the early universe made less of it.","posed_since":"","precise":"Standard BBN with the Planck baryon density $\\eta \\sim 6.1e-10$ predicts $\\mathrm{Li}/\\mathrm{H} \\sim 5e-10$, while the Spite plateau of metal-poor dwarfs ($[\\mathrm{Fe}/\\mathrm{H}] < -1.5$) gives $\\mathrm{Li}/\\mathrm{H} \\sim 1.6e-10$, a factor 3 to 4 at more than $5\\,\\sigma$. Identify the cause: stellar depletion by atomic diffusion and mixing, nuclear-rate errors, or non-standard physics (decaying particles, varying constants).","problem_ref":null,"references":"","settled_by":"A measurement of unprocessed lithium, or a validated stellar model reproducing the plateau from the BBN value.","status_note":"2024 to 2025 work favors stellar depletion and finds nuclear-rate solutions negligible, but no quantitative stellar model is established.","title":"What explains the threefold lithium-7 deficit in old halo stars?","topic_ref":"3b29f7c24689f116d4e24a9b9965296a8a7d4d58f92b9ab5ac13f314c66ba629"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"ed5e485b3467dc65495dddf71ecabf6c985963ff241c7c94e99b47c98c1ea091","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"7d6f2ce5f5783d6583fad680e274b33936c1bb65cfb5b99542eebb891cf29131","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"bCi_Ou_SYHIaT3Q0BX_owvQTYq3veLhxJT1W8Xulmt8lhIk4YoFzApDapZcF3cSLV1UFOdVEv-7jKFZLNEhLBg"},"schema":"pubphys.envelope/1"},"record_hash":"ed5e485b3467dc65495dddf71ecabf6c985963ff241c7c94e99b47c98c1ea091","leaf_index":1265}