{
  "annotation_id": "b98c247d-826f-46c4-ad5d-ebdadacec808",
  "date_created": "2026-03-02T18:02:47.449000Z",
  "date_modified": "2026-03-02T18:02:47.449000Z",
  "file_hash": "5f0f34a8897c46bd88ccd513bfd57bd6814cc0c316a3278805925200b8be1c24",
  "private": false,
  "record": {
    "abstract": "Measurements are ordinarily described with respect to absolute \"Newtonian\"\ntime. In reality however, the switching-on of the measuring device at the\ninstance of the measurement requires a timing device. Hence the classical time\n$t$ must be replaced by a suitable quantum time variable $\\tau$ of a physical\nclock. The main issue raised in this article is that while doing so, we can no\nlonger neglect the {\\em back-reaction} due to the measurement on the clock.\nThis back-reaction yields a bound on the accuracy of the measurement. When this\nbound is violated the result of a measurement is generally not an eigenvalue of\nthe observable, and furthermore, the state of the system after the measurement\nis generally not a pure state. We argue that as a consequence, a sub-class of\nobservables in a closed system cannot be realized by a measurement.",
    "arxiv_id": "quant-ph/9909010",
    "authors": [
      "Aharon Casher",
      "Benni Reznik"
    ],
    "categories": [
      "quant-ph",
      "gr-qc"
    ],
    "doi": "10.1103/PhysRevA.62.042104",
    "journal_ref": "Phys.Rev. A62 (2000) 042104",
    "title": "Back-Reaction of Clocks and Limitations on Observability in Closed   Systems",
    "url": "https://arxiv.org/abs/quant-ph/9909010"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "bf1bd2a4-b012-417b-af21-3e18864eb4eb",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}