{
  "abstract": "The cosmic microwave background temperature at $z=0.886$ is known to $2\\%$ from molecular absorption towards PKS~1830$-$211; CO absorbers and Sunyaev-Zel'dovich clusters extend the measurement to $z\\simeq3$. We use them on a question that cosmologies with torsion leave open. When the geometry exchanges energy with several matter components, which of them receives it? In Einstein-Cartan theory the Noether identities of each sector fix the answer. A sector's energy-momentum fails to be conserved only in proportion to its own spin, so minimally coupled light, which has none, is conserved whatever the torsion does. A metric-affine cosmology fitted to DESI DR2 distributes the exchange ``universally'' among all fluids, radiation included; the photons then gain almost a third of their energy. If the photons stay a blackbody, as FIRAS requires of any source set by local conditions, the model predicts a background colder than $T_{0}(1+z)$ by $7\\%$ at $z\\simeq0.9$ and by $8.5\\%$ at $z\\gtrsim3$, with no free parameter. PKS~1830$-$211 gives $5.08\\pm0.10\\,\\mathrm{K}$ against a predicted $4.78\\,\\mathrm{K}$; with the CO absorbers it favours the standard scaling by $Δχ^{2}=13$, and 18 Planck cluster bins give $χ^{2}=50.8$ versus $15.5$. Under the same reading the primary anisotropies would change their spectral shape by amounts Planck excludes. If dark matter carries the spin instead, $H(z)$ moves by less than $10^{-4}$ below $z=3$ at the fitted parameters and $T(z)$ is standard again.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2611.08422",
  "author_total": 3,
  "authors": [
    {
      "name": "Fernando Izaurieta"
    },
    {
      "name": "Samuel Lepe"
    },
    {
      "name": "Cristian Quinzacara"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/dfe16wkbcd1xf.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2611.08422",
  "fulltext_url": null,
  "id": "dfe16wkbcd1xf",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2611.08422",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.CO"
    ],
    [
      "arxiv",
      "gr-qc"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2611.08422",
  "pmcid": null,
  "pmid": null,
  "published": "2026-11-05",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/dfe16wkbcd1xf.ris",
  "sources": [
    {
      "first_seen": "2026-11-06T18:21:30Z",
      "native_id": "2611.08422",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2611.08422"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    },
    {
      "field": "physics",
      "origin": "arxiv:gr-qc",
      "subfield": "gravitation"
    }
  ],
  "title": "Torsion talks only to spin: the CMB temperature as a test of energy exchange in Einstein-Cartan cosmology",
  "title_text": "Torsion talks only to spin: the CMB temperature as a test of energy exchange in Einstein-Cartan cosmology",
  "type": "preprint",
  "updated_at": "2026-11-09T00:20:41Z",
  "url": "https://research.draconitic.com/paper/dfe16wkbcd1xf",
  "venue": "arXiv",
  "versions": []
}