{
  "abstract": "We discuss Einstein equations with a non-conserved energy-momentum $T^{μν}$. The energy-momentum tensor $\\tilde{T}^{μν}$ on the right hand side of Einstein equations is expressed in the form $8πGT^{μν}-g^{μν}Λ+Σ^{μν}$ where $G$ is the Newton constant, $Λ$ is the cosmological term and $T^{μν}$ is the energy-momentum of an ideal fluid. The remaining part $Σ^{μν}$ describes the viscosity and a heat flow. We discuss space-time-dependent Newton ``constant\" $G$ and the cosmological term $Λ$. The covariant conservation law for $\\tilde{T}^{μν}$ imposes a relation between the energy-momentum (non)conservation and the variation of $G$ and $Λ$. The covariant derivative $\\nabla_μT^{μν}$ can be related to the first law of thermodynamics and expressed by the temperature $T$ and the entropy $S$. The energy-momentum non-conservation in our models is a consequence of a diffusion of its constituting particles. We describe a gas of diffusing massive particles in a homogeneous isotropic space-time as a system with a time-dependent linear barotropic equation of state $P_{t}=w_{t}ρ_{t}$ with $0<w_{t}\\leq \\frac{1}{3}$. The gas of massive diffusing particles in an expanding universe tends in a limit of infinite time to the gas of diffusing massless particles. We obtain results on the energy density, entropy and phase space dstribution in a soluble model of massless relativistic particles in a spatially flat expanding universe.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": "Journal reference: Entropy 2026,28(10),1152",
  "arxiv": "2610.34341",
  "author_total": 1,
  "authors": [
    {
      "name": "Z. Haba"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/07fyr6404jj5t.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.34341",
  "fulltext_url": null,
  "id": "07fyr6404jj5t",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.34341",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "gr-qc"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2610.34341",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-25",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/07fyr6404jj5t.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:35:35Z",
      "native_id": "2610.34341",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.34341"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:gr-qc",
      "subfield": "gravitation"
    }
  ],
  "title": "Relativistic diffusing particles, entropy and varying cosmological constants",
  "title_text": "Relativistic diffusing particles, entropy and varying cosmological constants",
  "type": "preprint",
  "updated_at": "2026-10-30T12:35:35Z",
  "url": "https://research.draconitic.com/paper/07fyr6404jj5t",
  "venue": "arXiv",
  "versions": [
    {
      "doi": "10.3390/e28101152",
      "pid": null,
      "relation": "published-as",
      "title": null,
      "venue": null
    }
  ]
}