{"state_type":"pith_open_graph_state","state_version":"1.0","pith_number":"pith:2020:V4SV2NDOOHA2PPMDM554WL7Q4P","merge_version":"pith-open-graph-merge-v1","event_count":2,"valid_event_count":2,"invalid_event_count":0,"equivocation_count":0,"current":{"canonical_record":{"metadata":{"abstract_canon_sha256":"797b2c8ee469f2c6470ed74098bdb057f57c5e176efdee31cf6fae805c052718","cross_cats_sorted":[],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"gr-qc","submitted_at":"2020-08-26T21:47:13Z","title_canon_sha256":"899b4e23bea9a99360a03e040261f373a8c60d2c9ee338ddffc5211ed3407d27"},"schema_version":"1.0","source":{"id":"2008.11836","kind":"arxiv","version":1}},"source_aliases":[{"alias_kind":"arxiv","alias_value":"2008.11836","created_at":"2026-07-05T01:30:54Z"},{"alias_kind":"arxiv_version","alias_value":"2008.11836v1","created_at":"2026-07-05T01:30:54Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.2008.11836","created_at":"2026-07-05T01:30:54Z"},{"alias_kind":"pith_short_12","alias_value":"V4SV2NDOOHA2","created_at":"2026-07-05T01:30:54Z"},{"alias_kind":"pith_short_16","alias_value":"V4SV2NDOOHA2PPMD","created_at":"2026-07-05T01:30:54Z"},{"alias_kind":"pith_short_8","alias_value":"V4SV2NDO","created_at":"2026-07-05T01:30:54Z"}],"graph_snapshots":[{"event_id":"sha256:ced2fb5f3e8b5d553cf32c99da3da77aa2b75469d828fd0eb4ab9127cbf2ba4b","target":"graph","created_at":"2026-07-05T01:30:54Z","signer":{"key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signer_id":"pith.science","signer_type":"pith_registry"},"payload":{"graph_snapshot":{"author_claims":{"count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","strong_count":0},"builder_version":"pith-number-builder-2026-05-17-v1","claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"integrity":{"available":true,"clean":true,"detectors_run":[],"endpoint":"/pith/2008.11836/integrity.json","findings":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938","summary":{"advisory":0,"by_detector":{},"critical":0,"informational":0}},"paper":{"abstract_excerpt":"We analyze the necessary conditions for a body to remain rigid in an expanding cosmological Universe. First, we establish the main theorems and definitions for having a rigid body in a general spacetime as well as the new concept of quasilocal rigidity. We apply the obtained results to a homogeneous universe exploring the differences with flat spacetime. We discuss how the concept of rigid body helps to understand the expansion of space in cosmology. Finally, using a rigid system as a reference frame, we calculate the gravitational energy, and we compare it with previous results in the literat","authors_text":"Gustavo E. Romero, Luciano Combi","cross_cats":[],"headline":"","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"gr-qc","submitted_at":"2020-08-26T21:47:13Z","title":"Relativistic rigid systems and the cosmic expansion"},"references":{"count":0,"internal_anchors":0,"resolved_work":0,"sample":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2008.11836","kind":"arxiv","version":1},"verdict":{"created_at":null,"id":null,"model_set":{},"one_line_summary":"","pipeline_version":null,"pith_extraction_headline":"","strongest_claim":"","weakest_assumption":""}},"verdict_id":null}}],"author_attestations":[],"timestamp_anchors":[],"storage_attestations":[],"citation_signatures":[],"replication_records":[],"corrections":[],"mirror_hints":[],"record_created":{"event_id":"sha256:f187fceab256d8cd4474fe086ecbf28f313343b281ed95e6bc100b8edf67cadb","target":"record","created_at":"2026-07-05T01:30:54Z","signer":{"key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signer_id":"pith.science","signer_type":"pith_registry"},"payload":{"attestation_state":"computed","canonical_record":{"metadata":{"abstract_canon_sha256":"797b2c8ee469f2c6470ed74098bdb057f57c5e176efdee31cf6fae805c052718","cross_cats_sorted":[],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"gr-qc","submitted_at":"2020-08-26T21:47:13Z","title_canon_sha256":"899b4e23bea9a99360a03e040261f373a8c60d2c9ee338ddffc5211ed3407d27"},"schema_version":"1.0","source":{"id":"2008.11836","kind":"arxiv","version":1}},"canonical_sha256":"af255d346e71c1a7bd83677bcb2ff0e3d208e5354e96c80bca3386112cde474a","receipt":{"algorithm":"ed25519","builder_version":"pith-number-builder-2026-05-17-v1","canonical_sha256":"af255d346e71c1a7bd83677bcb2ff0e3d208e5354e96c80bca3386112cde474a","first_computed_at":"2026-07-05T01:30:54.534120Z","key_id":"pith-v1-2026-05","kind":"pith_receipt","last_reissued_at":"2026-07-05T01:30:54.534120Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","receipt_version":"0.3","signature_b64":"hM9x+WIk4VovO7J7djFwbTMrISC4mIp9UY3ZFUYqGw5XF9uj9gG7PcfYfbcvdjzdF/CaM1mTiyc/37J0dr0+AA==","signature_status":"signed_v1","signed_at":"2026-07-05T01:30:54.534569Z","signed_message":"canonical_sha256_bytes"},"source_id":"2008.11836","source_kind":"arxiv","source_version":1}}},"equivocations":[],"invalid_events":[],"applied_event_ids":["sha256:f187fceab256d8cd4474fe086ecbf28f313343b281ed95e6bc100b8edf67cadb","sha256:ced2fb5f3e8b5d553cf32c99da3da77aa2b75469d828fd0eb4ab9127cbf2ba4b"],"state_sha256":"c2fa6d569665737d82a1a7d8a53428352bb25c0291f2f39877828a5d5a75ee83"}