{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"09dc1cf6feaa0ddc6b675d68427416d8f782fe7b814e09814ad878e4d1b208e3","created":"2026-10-03T07:18:09Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"dfcbc4df1147c802198724605f1675cff428280eb857347f079f65c507448507","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"proof","assisted_by":[],"external_id":"qft.double-copy.exact-classical","kind":"well-posed","literature_status":"partially-resolved","n":"1","parents":[],"plain":"Some exact black-hole solutions of Einstein's equations are squares of simple electromagnetic solutions. Whether every solution of Einstein's equations has such a gauge-theory partner is unknown.","posed_since":"","precise":"The Kerr-Schild double copy (2014), the Weyl double copy (2018) and the self-dual double copy (Monteiro and O'Connell, 2011) map Kerr-Schild, algebraically special (Petrov types D and N) and self-dual vacuum metrics to exact Maxwell or Yang-Mills solutions. Determine whether an exact, nonperturbative map exists from every Ricci-flat 4D metric, including Petrov type I, to solutions of gauge-theory field equations that reduces to the amplitude double copy order by order, or prove that none exists.","problem_ref":null,"references":"","settled_by":"A constructive map valid for Petrov type I spacetimes with a proof of its perturbative agreement, or a no-go theorem.","status_note":"Exact maps exist for Kerr-Schild metrics, for Petrov type D and N vacuum solutions (Weyl double copy) and for self-dual solutions; no exact map for Petrov type I is known as of 2026.","title":"Exact classical double copy for generic vacuum spacetimes","topic_ref":"1423f8d1d6c45d6696107efe735144c4230462c57b3f02acac8489226faee33e"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"77c413dd5f838a071f93b8c502f3b339d088cee4b0bcdf5b7f223986901bcbc8","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"a406407901248bfa925e78861eba6fccd252c11dba5f4ba4c4f2646358c47660","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"PlVLHv4NQuaZzOfzCo3ax1mHht0m6TH9OhW5RAChggSPbPrmAJNo88FsaZHpert_SB7Rv_BHklHnNILOZYUvDw"},"schema":"pubphys.envelope/1"},"record_hash":"77c413dd5f838a071f93b8c502f3b339d088cee4b0bcdf5b7f223986901bcbc8","leaf_index":1905}