{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"77dc3ad21647cd7efae0a41d4f3120046d8a1b16d5b8e1e4779511e5867d805f","created":"2026-10-03T07:17:57Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"62f90aaeb0a66a1740bb3927fb383443e70736205576a470d18389c7a52b038b","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"bio.glass-transition.johari-goldstein-relaxation","kind":"phenomenon","literature_status":"contested","n":"1","parents":[],"plain":"Below the glass point most molecules are frozen, yet glasses of even rigid molecules still show a faster, smaller relaxation, the Johari-Goldstein $\\beta$ process. Which molecular motions produce it, and whether it is the precursor of the main relaxation, is disputed.","posed_since":"1970","precise":"In molecular glass formers, including glasses of rigid molecules, dielectric and mechanical spectra show a secondary $\\beta$ relaxation that persists below $T_g$ with Arrhenius $\\tau_\\beta(T)$ and an empirical activation energy of roughly $24\\ k_B T_g$ per molecule (approximate). Determine whether it is carried by localized islands of mobility or by small-angle motion of all molecules, and whether it is the precursor of the alpha relaxation as assumed in coupling-type models. An answer identifies the motions in a model glass equilibrated near or below T_g and reproduces the measured $\\beta$ peak and its link to $\\tau_\\alpha$.","problem_ref":null,"references":"","settled_by":"Simulation of a swap-equilibrated model glass that resolves which particles and motions produce the $\\beta$ peak and reproduces its activation energy and its relation to $\\tau_{\\alpha}$, consistent with NMR and dielectric data.","status_note":"","title":"Microscopic nature of the Johari-Goldstein secondary relaxation","topic_ref":"b6cec0edf29a3e5b5b7b70395d6ca2460f15dfb7644125d881ab5595366caa14"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"6ad6e95dc92ac148ea63b1a5df01cb03d42a7320e0198fc0ee6b27230801ae6b","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"4412790f437555223818dc544bb5c9582029174d20f772f910f74d27e551aa2d","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"5ZXf2Hf5Yya_IRKh-02x3TneKrkOAR_rlMKbqOCXpMlWf1cqM77cpYp8-4MUx7uDy33f0D5Bf2Z_7XJpnPZADQ"},"schema":"pubphys.envelope/1"},"record_hash":"6ad6e95dc92ac148ea63b1a5df01cb03d42a7320e0198fc0ee6b27230801ae6b","leaf_index":777}