{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"08fe4c3f190eded7841eb467bdf99be6302891638bbd68b52d6342bfe417e475","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["ab24ab5039676ea09cea6242356dc65d0fdd628b5014271d9b0d8b6f1be12037","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"d07885234b9081d339ae83a052209ace794228dd7a6fc35e7b216ae6741dd3ec","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"bio.supercooled-water.llcp-location","kind":"well-posed","literature_status":"open","n":"2","parents":[],"plain":"If water's second critical point exists, its temperature and pressure must be pinned down. Model estimates disagree by tens of kelvin and by thousands of atmospheres.","posed_since":"","precise":"Assuming the LLCP exists, determine $(T_{c}, P_{c})$ for $\\mathrm{H_2O}$. Published model results and extrapolations from experiment span roughly $T_{c} = 170 \\text{ to } 230\\,\\mathrm{K}$ and $P_{c}$ from about $0 \\text{ to } 2 \\times 10^{9}\\,\\mathrm{dyn}/\\mathrm{cm}^{2}$ ($0 \\text{ to } 2\\,\\mathrm{kbar}$), all approximate. An answer is a measured or reliably computed $(T_{c}, P_{c})$ with error bars, consistent with thermodynamic data at accessible conditions.","problem_ref":"ab24ab5039676ea09cea6242356dc65d0fdd628b5014271d9b0d8b6f1be12037","references":"","settled_by":"Experimental location of the LLCP, or first-principles simulations including nuclear quantum effects whose predictions match measured response functions of supercooled water.","status_note":"A 2026 ultrafast X-ray experiment placed the critical temperature near $210 \\pm 8\\,\\mathrm{K}$ (You et al., Science 2026); the critical pressure and an independent confirmation remain open.","title":"Location of water's liquid-liquid critical point","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"5cfd2ffb67155491c0eb3964ccf34ddedd4c37dd2156dea7fe07e740f0ea61b4","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"36c963f46f90b2ca2995c13b3e765927a3b166f3c3fcedad2c093a3b93d70264","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"xcAo9PJmHGKT4Q12ORICnOzI6DeYKbaUux6VEy-3uG8yzILgixHKYn-UhgSBrWxl8RykE-8WjXd5DK39_wCrBQ"},"schema":"pubphys.envelope/1"},"record_hash":"5cfd2ffb67155491c0eb3964ccf34ddedd4c37dd2156dea7fe07e740f0ea61b4","leaf_index":2634}