{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"b738788079490592feb33da71a50aaef306e4ba3801594f037a8d13ce7c26c6d","created":"2026-10-03T07:17:58Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"8b1cbb2305b3e0122fdb48b1c71d8f8a8250946923645092e17f8009f7d4a29b","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"bio.supercooled-water.water-glass-transition","kind":"well-posed","literature_status":"contested","n":"1","parents":[],"plain":"Glassy water made by very fast cooling shows a small heat-capacity step near 136 K, long taken as its glass transition, and a second step near 116 K was reported in high-density amorphous ice. Whether these steps mark glasses turning into ultraviscous liquids or something else is disputed.","posed_since":"","precise":"Hyperquenched glassy water and low-density amorphous ice show a weak calorimetric step near $136\\,\\mathrm{K}$ at ambient pressure, and pressure-annealed high-density amorphous ice a step near $116\\,\\mathrm{K}$ (2013). Determine whether each step is a glass transition to a diffusive ultraviscous liquid (LDL or HDL) with translational relaxation time about $1\\mathrm{e}2\\,\\mathrm{s}$, or an orientational or sub-$T_{g}$ relaxation with $T_{g}$ of water higher (near $165\\,\\mathrm{K}$, as argued from comparison with hyperquenched inorganic glasses in 2004). An answer is a measurement of translational diffusion or viscous flow just above each step.","problem_ref":null,"references":"","settled_by":"Direct measurement of translational diffusion (isotope intermixing, viscous flow, or dielectric response tied to translation) just above 136 K and 116 K, showing liquid-like or glass-like mobility.","status_note":"Two glass transitions were reported in 2013 (Amann-Winkel et al., PNAS, https://doi.org/10.1073/pnas.1311718110) against the 2004 reassignment of $T_g$ near 165 K (Yue and Angell, Nature, https://doi.org/10.1038/nature02295).","title":"Is the 136 K calorimetric step the glass transition of water","topic_ref":"b1cabd44310015cc3941b7af0461d416e3c8ad464f6c3ad6f6fdbf54214bd97e"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"86f4a3116707296a98ff29fb44e01a5b13d9924a41be397e6b994041ea25745c","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"f2fd0473970aa609daf8fce41226934cae7b8838ca94fa26bbf7f532bf78edb1","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"w2fvrXx7XzWMeIuWPhHA7i5dQkgiKy6BltreCDd1g9LtIihtC9brq_es3mH542W199kJLzMCHe49YaDfP0H4BQ"},"schema":"pubphys.envelope/1"},"record_hash":"86f4a3116707296a98ff29fb44e01a5b13d9924a41be397e6b994041ea25745c","leaf_index":840}