{
  "annotation_id": "72bd897e-0d1a-4016-910a-7905640d5b64",
  "date_created": "2026-03-02T18:00:49.908000Z",
  "date_modified": "2026-03-02T18:00:49.908000Z",
  "file_hash": "3cb871a69deec6741c449069b013b00f91d996aa17fb07a59725458448f60ee9",
  "private": false,
  "record": {
    "abstract": "In accordance with an old suggestion of Asher Peres (1962), we consider the\nelectromagnetic field as fundamental and the metric as a subsidiary field. In\nfollowing up this thought, we formulate Maxwell\u0027s theory in a diffeomorphism\ninvariant and metric-independent way. The electromagnetic field is then given\nin terms of the excitation $H=(H,D)$ and the field strength $F=(E,B)$.\nAdditionally, a local and linear ``spacetime relation\u0027\u0027 is assumed between $H$\nand $F$, namely $H \\sim \\kappa F$, with the constitutive tensor $\\kappa$. The\npropagation is studied of electromagnetic wave fronts (surfaces of\ndiscontinuity) with a method of Hadamard. We find a generalized Fresnel\nequation that is quartic in the wave covector of the wave front. We discuss\nunder which conditions the waves propagate along the light cone. Thereby we\nderive the metric of spacetime, up to a conformal factor, by purely\nelectromagnetic methods.",
    "arxiv_id": "physics/0404101",
    "authors": [
      "Friedrich W. Hehl",
      "Yuri N. Obukhov"
    ],
    "categories": [
      "physics.class-ph",
      "gr-qc",
      "hep-th"
    ],
    "doi": "10.1007/s10701-005-8659-y",
    "journal_ref": "Found.Phys. 35 (2005) 2007-2025",
    "title": "To consider the electromagnetic field as fundamental, and the metric   only as a subsidiary field",
    "url": "https://arxiv.org/abs/physics/0404101"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "a219d69e-b230-49ed-8166-7acd695ef152",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}