{"record_type":"pith_number_record","schema_url":"https://pith.science/schemas/pith-number/v1.json","pith_number":"pith:2008:CYZ4RNF55XFYQ6CBZN5RT5KPIB","short_pith_number":"pith:CYZ4RNF5","schema_version":"1.0","canonical_sha256":"1633c8b4bdedcb887841cb7b19f54f4069216e93f00e4a111e451917918d4fb3","source":{"kind":"arxiv","id":"0808.2669","version":1},"attestation_state":"computed","paper":{"title":"Closed Timelike Curves Make Quantum and Classical Computing Equivalent","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["cs.CC"],"primary_cat":"quant-ph","authors_text":"John Watrous, Scott Aaronson","submitted_at":"2008-08-19T23:04:28Z","abstract_excerpt":"While closed timelike curves (CTCs) are not known to exist, studying their consequences has led to nontrivial insights in general relativity, quantum information, and other areas. In this paper we show that if CTCs existed, then quantum computers would be no more powerful than classical computers: both would have the (extremely large) power of the complexity class PSPACE, consisting of all problems solvable by a conventional computer using a polynomial amount of memory. This solves an open problem proposed by one of us in 2005, and gives an essentially complete understanding of computational c"},"verification_status":{"content_addressed":true,"pith_receipt":true,"author_attested":false,"weak_author_claims":0,"strong_author_claims":0,"externally_anchored":false,"storage_verified":false,"citation_signatures":0,"replication_records":0,"graph_snapshot":true,"references_resolved":false,"formal_links_present":false},"canonical_record":{"source":{"id":"0808.2669","kind":"arxiv","version":1},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"quant-ph","submitted_at":"2008-08-19T23:04:28Z","cross_cats_sorted":["cs.CC"],"title_canon_sha256":"c1510a66a5ef25e94636f071a2ea9aca08e47b7967a479630569228088f67958","abstract_canon_sha256":"9ea839a0aec39936dc273af17055daeca0d9ec1abb3b509ee9f20727a4c241d5"},"schema_version":"1.0"},"receipt":{"kind":"pith_receipt","key_id":"pith-v1-2026-05","algorithm":"ed25519","signed_at":"2026-07-04T17:12:24.757841Z","signature_b64":"RKSbJ+KiHm6ykYfzxgDrpE230rdfPWmBAE7/kZy2IW/TCofK6TB7OmE++ocJNkWZpyA88IHW7aZswEhSPjTXAA==","signed_message":"canonical_sha256_bytes","builder_version":"pith-number-builder-2026-05-17-v1","receipt_version":"0.3","canonical_sha256":"1633c8b4bdedcb887841cb7b19f54f4069216e93f00e4a111e451917918d4fb3","last_reissued_at":"2026-07-04T17:12:24.757504Z","signature_status":"signed_v1","first_computed_at":"2026-07-04T17:12:24.757504Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"graph_snapshot":{"paper":{"title":"Closed Timelike Curves Make Quantum and Classical Computing Equivalent","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["cs.CC"],"primary_cat":"quant-ph","authors_text":"John Watrous, Scott Aaronson","submitted_at":"2008-08-19T23:04:28Z","abstract_excerpt":"While closed timelike curves (CTCs) are not known to exist, studying their consequences has led to nontrivial insights in general relativity, quantum information, and other areas. In this paper we show that if CTCs existed, then quantum computers would be no more powerful than classical computers: both would have the (extremely large) power of the complexity class PSPACE, consisting of all problems solvable by a conventional computer using a polynomial amount of memory. This solves an open problem proposed by one of us in 2005, and gives an essentially complete understanding of computational c"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"0808.2669","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/0808.2669/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"},"aliases":[{"alias_kind":"arxiv","alias_value":"0808.2669","created_at":"2026-07-04T17:12:24.757559+00:00"},{"alias_kind":"arxiv_version","alias_value":"0808.2669v1","created_at":"2026-07-04T17:12:24.757559+00:00"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.0808.2669","created_at":"2026-07-04T17:12:24.757559+00:00"},{"alias_kind":"pith_short_12","alias_value":"CYZ4RNF55XFY","created_at":"2026-07-04T17:12:24.757559+00:00"},{"alias_kind":"pith_short_16","alias_value":"CYZ4RNF55XFYQ6CB","created_at":"2026-07-04T17:12:24.757559+00:00"},{"alias_kind":"pith_short_8","alias_value":"CYZ4RNF5","created_at":"2026-07-04T17:12:24.757559+00:00"}],"events":[],"event_summary":{},"paper_claims":[],"inbound_citations":{"count":0,"internal_anchor_count":0,"sample":[]},"formal_canon":{"evidence_count":0,"sample":[],"anchors":[]},"links":{"html":"https://pith.science/pith/CYZ4RNF55XFYQ6CBZN5RT5KPIB","json":"https://pith.science/pith/CYZ4RNF55XFYQ6CBZN5RT5KPIB.json","graph_json":"https://pith.science/api/pith-number/CYZ4RNF55XFYQ6CBZN5RT5KPIB/graph.json","events_json":"https://pith.science/api/pith-number/CYZ4RNF55XFYQ6CBZN5RT5KPIB/events.json","paper":"https://pith.science/paper/CYZ4RNF5"},"agent_actions":{"view_html":"https://pith.science/pith/CYZ4RNF55XFYQ6CBZN5RT5KPIB","download_json":"https://pith.science/pith/CYZ4RNF55XFYQ6CBZN5RT5KPIB.json","view_paper":"https://pith.science/paper/CYZ4RNF5","resolve_alias":"https://pith.science/api/pith-number/resolve?arxiv=0808.2669&json=true","fetch_graph":"https://pith.science/api/pith-number/CYZ4RNF55XFYQ6CBZN5RT5KPIB/graph.json","fetch_events":"https://pith.science/api/pith-number/CYZ4RNF55XFYQ6CBZN5RT5KPIB/events.json","actions":{"anchor_timestamp":"https://pith.science/pith/CYZ4RNF55XFYQ6CBZN5RT5KPIB/action/timestamp_anchor","attest_storage":"https://pith.science/pith/CYZ4RNF55XFYQ6CBZN5RT5KPIB/action/storage_attestation","attest_author":"https://pith.science/pith/CYZ4RNF55XFYQ6CBZN5RT5KPIB/action/author_attestation","sign_citation":"https://pith.science/pith/CYZ4RNF55XFYQ6CBZN5RT5KPIB/action/citation_signature","submit_replication":"https://pith.science/pith/CYZ4RNF55XFYQ6CBZN5RT5KPIB/action/replication_record"}},"created_at":"2026-07-04T17:12:24.757559+00:00","updated_at":"2026-07-04T17:12:24.757559+00:00"}