{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"b9103e2a8df04b557305cf824cc1228a80d9139eb7e67c193944d4cdaab1cd7e","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["76ffc5ac426ef9ddc70ca9a2f6ee7096703c16cee697d42bac3ecc38d658871b","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"cf2035c299a4985303f5f9c672f134445a08be3dbfcf7a5bc492f193fc262060","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"qft.string-nonperturbative.ikkt-four-dims","kind":"well-posed","literature_status":"contested","n":"2","parents":[],"plain":"A model built from ten large matrices is proposed as a complete definition of one string theory. Whether it produces a universe with three large expanding space directions is unknown.","posed_since":"1996","precise":"The type IIB (IKKT) matrix model of ten $N$ x N Hermitian bosonic matrices and fermions is proposed as a nonperturbative definition of type IIB string theory. Determine whether its Lorentzian version at large N dynamically generates a smooth expanding $(3+1)$-dimensional spacetime with $\\mathrm{SO}(9) \\to \\mathrm{SO}(3)$ breaking, rather than singular configurations.","problem_ref":"76ffc5ac426ef9ddc70ca9a2f6ee7096703c16cee697d42bac3ecc38d658871b","references":"","settled_by":"Large-N simulations of the Lorentzian model with controlled sign-problem treatment showing (or excluding) smooth emergent 3+1 expansion.","status_note":"Early Lorentzian simulations (2012) reported three expanding directions; later work found singular Pauli-matrix-like structures tied to approximations, and complex Langevin studies continued through 2025.","title":"Do four expanding spacetime dimensions emerge in the IKKT model?","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"fc75f23a38f9aeea5d59d74081d8c3332b2049823b6419aedbb33c92cb8de6ad","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"7a32d8ab207a8b01559c8c841add2b5d64f62becc40d9b931fab70a4a9f4234c","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"_QhjhYxE9FGx6JiYvOPfgy2UK_anNBkz5NVmLwD2wtNHjs0oK3_iBRc5VEINrJPxqhkqbMGoe3cf2YwyIS6WDA"},"schema":"pubphys.envelope/1"},"record_hash":"fc75f23a38f9aeea5d59d74081d8c3332b2049823b6419aedbb33c92cb8de6ad","leaf_index":3680}