{"schema":"pubphys.bundle/1","record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"ca9ec33955c23f625b7c9b5a43a18c5813171e89ff42605f7fe1b818deb0ffbb","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["4fc1111f295375647f80e05235178e90b3a607128874c44e674a982642eedfbd","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"7837228c76853e5ce54b570a4aba455dbe55666733e4cc535fae636a8d9faf95","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"nuc.quark-gluon-plasma.early-hydrodynamization","kind":"phenomenon","literature_status":"partially-resolved","n":"2","parents":[],"plain":"Fluid models describe heavy-ion collisions starting about $3 \\times 10^{-24}$ seconds after impact, which seems too early for the matter to have settled down. How the system starts behaving as a fluid so soon is not fully understood.","posed_since":"","precise":"Determine how and when the energy-momentum tensor of matter formed in $A+A$ collisions reaches viscous-hydrodynamic form (hydrodynamization) while the pressure anisotropy $P_L/P_T$ is still far from 1, at proper times $\\tau$ about $0.5\\ \\text{to}\\ 1\\ \\mathrm{fm}/c$. Answer: a QCD-based mechanism (attractor solutions, weak-coupling kinetic theory, or strong-coupling holography) with a predicted hydrodynamization time as a function of $\\eta/s$ and energy density, tested against data.","problem_ref":"4fc1111f295375647f80e05235178e90b3a607128874c44e674a982642eedfbd","references":"","settled_by":"QCD effective kinetic theory simulations with realistic transverse geometry, compared with photon and dilepton data sensitive to the early pressure anisotropy.","status_note":"Hydrodynamic attractor solutions found since 2015 (Heller and Spalinski) explain early hydrodynamic behavior in simplified expansions; the full three-dimensional QCD case remained open as of 2026.","title":"How the quark-gluon plasma becomes a fluid so quickly","topic_ref":null},"content_withheld":"false","files":[],"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"639ee0a66e799dbc59423f515971ee234f484bff1e1c6aeae063e82e892cbb91","schema":"pubphys.attested/1"},"id_token":null,"id_token_withheld":"false","envelope":{"attested_hash":"66e3d378f1ca428f574c64bb14f534a97fc6aae94f25a3440fab7031942cafc0","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"81A3hCIR70UHTTuYe3530dXEI5ga_HqdPCHkbDD_Xdp7-aKwi6d1HLiumMjOeGRcLYKi-pRM6lh0PqUsH2r_DA"},"schema":"pubphys.envelope/1"},"ots":{"attested":["AE9wZW5UaW1lc3RhbXBzAABQcm9vZgC_ieLohOiSlAEIZuPTePHKQo9XTGS7FPU0qX_GqulPJaNED6twMZQsr8DxIGbXm3ki72kH77aGoisFvMmDP-XOT5JR_NYoLnBFcBQpCPEg7L-iafVH2AFmvf2AWGxMvJpm_oex5fQKx7tpM5fy0pcI8SDrbXL-1PDtlMSk9qPmtb94AkPJGVSZDHPQht7_CoDMFAjxIMFaZYJpfwoAsPU-lpAFiyLXKL9XNTOfpOXhGRo-uWS0CPAgxQchpAVwcmTSOROZWbuHz7Y3INBv1wNbxBxCkoDp0R0I8CBTjr7VtxmM2Ok7TsTdkxCS55j9aiB0iyautrjnqhQBSAjxIJ6xxSFbP5yKvGDsivHs5WdfqkpRl9d-xpUzY-9mzCvLCPAgNWsj73C-FdBKnM-YIq56Rzi4rZw0zXjVnprUdC52gz4I8SBcP9hQb3hxUiLf8dFx-DuqZHA2xkmG-c_qCFt8QfQHCAjwIOv_x0B6HyZ6WMHKeIf_d_EUIvwPGdZeVY-hXN3RLDM5CPEgHd9u6OIGCvUV12A1B1xdiOprSJ-4w0cqwfe7CzVX5HsI8CDQo_sIWZiWXaTGRSQBLmU-lHJKskYKqsjO1r02DhB8LAj_8Ajn9YmozHwo9QjwEJ46aM9ZDv3TdtqV3ZbRsNgI8SBOF8pILGf1kodr5MKmQs6Cd93joraGn3g6UPt_-kewPwjwIOG-gmM7bd_eR4AiDMNfluS3xvr7vicLR-sCBr5qtG2cCPAgrVNFrCoeQcCxhlmnE0BzHgR8HQpZAlfqzDDFzfWb8GUI8QRq0WWT8AjZJ2cF_c7k8ACD3-MNLvkMjiwraHR0cHM6Ly9ib2IuYnRjLmNhbGVuZGFyLm9wZW50aW1lc3RhbXBzLm9yZ_AI9ZMS1zxd7IEI8BDd00WgJZ0RncsC1Fyai_4aCPEgvxMFrnu7F05IW5INiraQ3OVEYMjNx6JfBxw1Q4jPLi4I8QRq0WWS8Ag2zxPAtI5JsP8Ag9_jDS75DI4uLWh0dHBzOi8vYWxpY2UuYnRjLmNhbGVuZGFyLm9wZW50aW1lc3RhbXBzLm9yZwjxIHAnv4KFFf4uiYEFJvLxiMxSyz8VowJP4roTfDD9h7bICPAgj5tgvbNF7mxSP4jGGE66ezUFRLnI4g1VTkvuV4VtCPAI8CCxlc1HuKORuHgn7DYIYcDhc4oo99OkTWBEvddBypoa7AjwIFcjjaF8kDNDYCZGaNISlRjvX-I7in-QNwsr4JYQbFJvCPAgnl0k4gs7LuY5i1umiHO-J7My3uBThLJUWQoY9LdVSrQI8SA6-Ft11_K_GqMNWYhkVsVqCFvXSYbp4S8JoLsLBnUzvgjxIBC8_mAE7JBP35SNxDBcG7joLJwURpMxdV2vSO64_jEOCPEge04Coj1xSi7CE8UwqiBGNhPyZ5QdD_YZwn-heSdObU4I8SBgdDSgr3VUx1j8m_pK7-OzMwwFgXeLy43ujffCv-hf5AjwIMl-PnAt4xjoBEVU4-nkyN0NKRa9AvX4kEMfllFyIJS9CPFZAQAAAAHz4rV-uwQFg02bVnEMUFgpIdGKjM4tWuID1kTVnrjisAAAAAAA_v___wJURAIAAAAAABYAFBFys2oc0-U-bYrC3VulGLzND5fbAAAAAAAAAAAiaiDwBHLTDgAICPEgMJIBYi46xOIuFDwzJ9nOx14ngW5HbglUf65ORpkoIYcICPAgHgGWEGCDHWgscwT92NOoJ7s-ezbPkyiWr2RnYZDC_dwICPAgtffMyyLu-MscJsDc0dzwGspwSrrmvVAnMNgsgWhHClgICPAgMUl1OfBDUwhp5VZjHwVA0nuz1F5HZTUJCHAnM1L1F3MICPAgStK7UWpnrUueV5EaE7uE0y6BLMp6EANmrbhrTqEBZu8ICPAg5LVW7IHtUL5mNOvPx1hOTfLMmqlQ7t9EFW-KDtrISIQICPAgABgXZ6upFU8qiDQKFtQFpqkjKwl0PsxM4JUjVLlDKbkICPAgEwb96FiOhjlbwI8GFZQ4a5GXwxs4bUdqVOMKrtBWV30ICPEgqBg-wp0c8CAPV9k6J7wIa9_GtQfpWmhpE1zqFZyi2pQICPAg2pZLTVPGJbriiz0UhMytYDVYAXOgQnWDcrMOewK9O8cICPEgxm3QwzbvT4siJzubQGnST67bWv-exYwSPP1KDi7CaUwICPEgm6udUudfjUaM0gUFTylKGDMypj7ptMTG0zmxd_T5yTcICPAgMpOInkjFCVp1pOZhfZnyPAl8hdWGmHzQcrGLgLwSKLgICAAFiJYNc9cZAQPzpjs"],"envelope":["AE9wZW5UaW1lc3RhbXBzAABQcm9vZgC_ieLohOiSlAEIUHCMMtnDpM2lTNAtptLfdVkD6QNTYkvn2vOSlX6f9d_wIFB1CQN7I_A0u9HjwE6sY-S4lXa80Gbz34ve3mBb6s7UCPEg6uj1LJEVevXexs8R6ksJ6mu3dnKo0FdsYX5TJjeD41cI8SDgXidn26GqJQtkLGk4foptIm7AuR2_MsQnTjWtS2ni4AjwIIDdbmX1p_z07KHIno1o0Hisi19bAJULUm-LiMpl8RPgCPEgafys2gGxmxFJPpDfav8V3lAzM8y3-n6jOrcE_KH_2lEI8CDOazlbUPzET1EgpVe_36yfWu27Tg2DY59k28Sda2phUAjwILRHKIw6kWwderhYJaG85inV3mmnLkU_qFqH8lkj_LlZCPAgPjYOETLLdPZ3KisQfRmeRF8geFLOzyylnb3d7Q66gUQI8CCFjG9pSMiq3eVzHAmZsjRKj0iAZic3nIa3eyIChZggbAjwIOv_x0B6HyZ6WMHKeIf_d_EUIvwPGdZeVY-hXN3RLDM5CPEgHd9u6OIGCvUV12A1B1xdiOprSJ-4w0cqwfe7CzVX5HsI8CDQo_sIWZiWXaTGRSQBLmU-lHJKskYKqsjO1r02DhB8LAj_8Ajn9YmozHwo9QjwEJ46aM9ZDv3TdtqV3ZbRsNgI8SBOF8pILGf1kodr5MKmQs6Cd93joraGn3g6UPt_-kewPwjwIOG-gmM7bd_eR4AiDMNfluS3xvr7vicLR-sCBr5qtG2cCPAgrVNFrCoeQcCxhlmnE0BzHgR8HQpZAlfqzDDFzfWb8GUI8QRq0WWT8AjZJ2cF_c7k8ACD3-MNLvkMjiwraHR0cHM6Ly9ib2IuYnRjLmNhbGVuZGFyLm9wZW50aW1lc3RhbXBzLm9yZ_AI9ZMS1zxd7IEI8BDd00WgJZ0RncsC1Fyai_4aCPEgvxMFrnu7F05IW5INiraQ3OVEYMjNx6JfBxw1Q4jPLi4I8QRq0WWS8Ag2zxPAtI5JsP8Ag9_jDS75DI4uLWh0dHBzOi8vYWxpY2UuYnRjLmNhbGVuZGFyLm9wZW50aW1lc3RhbXBzLm9yZwjxIHAnv4KFFf4uiYEFJvLxiMxSyz8VowJP4roTfDD9h7bICPAgj5tgvbNF7mxSP4jGGE66ezUFRLnI4g1VTkvuV4VtCPAI8CCxlc1HuKORuHgn7DYIYcDhc4oo99OkTWBEvddBypoa7AjwIFcjjaF8kDNDYCZGaNISlRjvX-I7in-QNwsr4JYQbFJvCPAgnl0k4gs7LuY5i1umiHO-J7My3uBThLJUWQoY9LdVSrQI8SA6-Ft11_K_GqMNWYhkVsVqCFvXSYbp4S8JoLsLBnUzvgjxIBC8_mAE7JBP35SNxDBcG7joLJwURpMxdV2vSO64_jEOCPEge04Coj1xSi7CE8UwqiBGNhPyZ5QdD_YZwn-heSdObU4I8SBgdDSgr3VUx1j8m_pK7-OzMwwFgXeLy43ujffCv-hf5AjwIMl-PnAt4xjoBEVU4-nkyN0NKRa9AvX4kEMfllFyIJS9CPFZAQAAAAHz4rV-uwQFg02bVnEMUFgpIdGKjM4tWuID1kTVnrjisAAAAAAA_v___wJURAIAAAAAABYAFBFys2oc0-U-bYrC3VulGLzND5fbAAAAAAAAAAAiaiDwBHLTDgAICPEgMJIBYi46xOIuFDwzJ9nOx14ngW5HbglUf65ORpkoIYcICPAgHgGWEGCDHWgscwT92NOoJ7s-ezbPkyiWr2RnYZDC_dwICPAgtffMyyLu-MscJsDc0dzwGspwSrrmvVAnMNgsgWhHClgICPAgMUl1OfBDUwhp5VZjHwVA0nuz1F5HZTUJCHAnM1L1F3MICPAgStK7UWpnrUueV5EaE7uE0y6BLMp6EANmrbhrTqEBZu8ICPAg5LVW7IHtUL5mNOvPx1hOTfLMmqlQ7t9EFW-KDtrISIQICPAgABgXZ6upFU8qiDQKFtQFpqkjKwl0PsxM4JUjVLlDKbkICPAgEwb96FiOhjlbwI8GFZQ4a5GXwxs4bUdqVOMKrtBWV30ICPEgqBg-wp0c8CAPV9k6J7wIa9_GtQfpWmhpE1zqFZyi2pQICPAg2pZLTVPGJbriiz0UhMytYDVYAXOgQnWDcrMOewK9O8cICPEgxm3QwzbvT4siJzubQGnST67bWv-exYwSPP1KDi7CaUwICPEgm6udUudfjUaM0gUFTylKGDMypj7ptMTG0zmxd_T5yTcICPAgMpOInkjFCVp1pOZhfZnyPAl8hdWGmHzQcrGLgLwSKLgICAAFiJYNc9cZAQPzpjs"]},"log":{"leaf_index":"3530","tree_size":"3804","proof":["df18ff7bbcaf35e8434590b10c55647c25aaeb6e4f3e76b6ca0f68f62a3e547d","8855ce2e5a3cc53e412cefb26c78369761ffdc26e5a3c16425fc78e2498cf29f","364360f81547b72054d25843cd6aeff2ebb0385e9dcc04d6574ae2b95e85e1d8","82aef77b87cebba239a12cf87d5aa0bbf0ec770ff73a7dcd7db34dcd36bac256","9a17c88baad4ff4bceccbd097f1dbfd897ee59d9c7a403c5d9738e367fa19c70","68b9b21c71345d7a61159cb26c0f41da5833a037b1a75d1dcab7903dd3db95cc","266c6a520f7af5a577207d98d84af6d8d9ce15ca8b2ab64aa8d6617192db65df","32c308752f9217b1c4a86dd18bd7c428e4bf0819f03bcecd3c244aeb14e5c028","5bc8f1bbb7a36ffa2afc301ec767424419006f77d79dfc7ac3adb0dab9eb36e8","98b5a14b42b3a202b6ef825f66833fa505601404c4c0f14575f3ec922607a858","af34d80d0065c0ab502282775e865492e2cb49c9493f4594d63ba5577922854a","3c578dccc15502c5f3efe228cadc99fee76ab536ed01f66b14d316fdcc157429"],"checkpoint":"pubphys.com/log/v1\n3804\nAK6t4qgu96+M9wScTrIlsJ10d/zhKVEtYguyM3aeJvo=\n\n— pubphys.com/log/v1 JFPwIPP8EtoxgcsQg7V7CwIdL4UKPqJtpv+eB8sFNJjyQHIdyA1VabmBsPyLqq2bLxJPn57rA6fQi8y0QDDjRXHvlQg=\n","promise":"pubphys.com/log/v1 promise\n1a151c028c60ff8e8edf5b767d5b8c19b078e2a6f8062f54bc0fd5e0ddfadcdd\n3530\n2026-10-15T23:43:57Z\n2026-10-16T01:43:57Z\n\n— pubphys.com/log/v1 JFPwIKThRu30HLmv1s7byF+0ICr/qidAmIAp+SMC/yETaE7r1x0v0VttkXI0PtxRru2nbat7KaSH7Jk3sXOyMwQ5iAw=\n"},"orcid_key_evidence":[],"attesting":null}