{"paper":{"title":"Friedmann equations from nonequilibrium thermodynamics of the Universe: A unified formulation for modified gravity","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["astro-ph.CO"],"primary_cat":"gr-qc","authors_text":"David Wenjie Tian, Ivan Booth","submitted_at":"2014-09-15T14:44:43Z","abstract_excerpt":"Inspired by the Wald-Kodama entropy $S=A/(4G_{\\text{eff}})$ where $A$ is the horizon area and $G_{\\text{eff}}$ is the effective gravitational coupling strength in modified gravity with field equation $R_{\\mu\\nu}-Rg_{\\mu\\nu}/2=$ $8\\pi G_{\\text{eff}} T_{\\mu\\nu}^{\\text{(eff)}}$, we develop a unified and compact formulation in which the Friedmann equations can be derived from thermodynamics of the Universe. The Hawking and Misner-Sharp masses are generalized by replacing Newton's constant $G$ with $G_{\\text{eff}}$, and the unified first law of equilibrium thermodynamics is supplemented by a nonequ"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1409.4278","kind":"arxiv","version":2},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"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"}