{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"37559d235c23a0b40ee26c0ca1f266ed9745ec63c347dff2f364dcce101031ac","created":"2026-10-03T07:17:56Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"9e10b4386ed1cdfd47b78eb4a97f542268e6f6179ab75809202de0fdc07e60c1","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"bio.accuracy-timekeeping.kaiabc-cost","kind":"well-posed","literature_status":"open","n":"1","parents":[],"plain":"Three proteins called KaiA, KaiB and KaiC keep a 24-hour rhythm in a test tube by burning ATP. The question is whether they spend close to the least energy that physics allows for their precision.","posed_since":"","precise":"For the reconstituted KaiABC oscillator (period $\\sim 24\\,\\mathrm{h}$; ATP use of approximately 15 ATP per KaiC monomer per day), measure the phase-diffusion constant and the total entropy production per period, and compare with the thermodynamic uncertainty relation $\\operatorname{Var}(N_T)/\\langle N_T\\rangle^2 \\ge 2 k_B/\\Sigma_T$ for the cycle count $N_T$ over time T with entropy production $\\Sigma_T$. Answer: the ratio of measured cost to the bound.","problem_ref":null,"references":"","settled_by":"Simultaneous measurement of phase diffusion and ATP hydrolysis rate in the reconstituted oscillator at fixed protein concentrations.","status_note":"A 2015 model (Cao, Wang, Ouyang, Tu) linked KaiABC precision to its free-energy consumption; a direct test against a rigorous bound is not established.","title":"Does the cyanobacterial KaiABC clock run near minimal cost?","topic_ref":"fa5a2b5a5ef38544b68e067ac335f685369c4bef3348616fa71997a19f8444ca"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"4d4d98442ba86ec2451653cb2c2e88d246bad1c8231a88c8f9c60c510e7f0b65","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"781986220a6978c1a1eb0a92ba5ff41d6391e777b088381e82d7f415c7feb643","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"fRGn6sLDRpxptSBT3MYwDMQg0ezV0uV3oVoWxq9En8aY6HHFTsqUWyvDpp3MzehgRl_3s746Krp7CJ24SoB-Bg"},"schema":"pubphys.envelope/1"},"record_hash":"4d4d98442ba86ec2451653cb2c2e88d246bad1c8231a88c8f9c60c510e7f0b65","leaf_index":714}