{
  "annotation_id": "43d79dd4-a5a1-48b8-a424-dacdb7995d65",
  "date_created": "2026-03-02T18:02:47.998000Z",
  "date_modified": "2026-03-02T18:02:47.998000Z",
  "file_hash": "96255ff2a9ece0ff0e5937dc32299a538728a5f8d9ece94312f0a30f5051253b",
  "private": false,
  "record": {
    "abstract": "The most general description of the classical world is in terms of local\ndensities (such as number, momentum, energy), and these typically evolve\naccording to evolution equations of hydrodynamic form. To explain the emergent\nclassicality of these variables from an underlying quantum theory, it is\ntherefore necessary to show, firstly, that these variables exhibit negligible\ninterference, and secondly, that the probabilities for histories of them are\npeaked around hydrodynamic evolution. The implementation of this programme in\nthe context of the decoherent histories approach to quantum theory is\ndescribed. It is argued that, for a system of weakly interacting particles, the\neigenstates of local densities (averaged over a sufficiently large volume)\nremain approximate eigenstates under time evolution. This is a consequence of\ntheir close connection with the corresponding exactly conserved (and so exactly\ndecoherent) quantities. The subsequent derivation of hydrodynamic equations\nfrom decoherent histories is discussed.",
    "arxiv_id": "quant-ph/9912037",
    "authors": [
      "J. J. Halliwell"
    ],
    "categories": [
      "quant-ph"
    ],
    "title": "The Emergence of Hydrodynamic Equations from Quantum Theory: A   Decoherent Histories Analysis",
    "url": "https://arxiv.org/abs/quant-ph/9912037"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "e5c91136-39fa-44a8-bfba-b9c23a93674a",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}