{
  "id": 4605117,
  "title": "No show again for mirror neutrons",
  "url": "https://urgent.news/2026/08/31/no-show-again-for-mirror-neutrons",
  "topic": "science",
  "section": "Science",
  "published": "2026-08-31T08:40:49.000Z",
  "source": {
    "name": "Physics World",
    "slug": "physics-world",
    "url": "https://physicsworld.com/a/no-show-again-for-mirror-neutrons/"
  },
  "original_language": "en",
  "account": "A team of physicists from the Paul Scherrer Institute in Switzerland has ruled out the possibility of mirror neutrons existing in parallel to our world. By conducting experiments with ultracold neutrons, they found no evidence of neutron-to-mirror-neutron transitions, which would be necessary for mirror neutrons to exist. This finding not only contradicts the hypothesis of a mirror world but also eliminates mirror neutrons as potential components of dark matter. Although mirror particles have been proposed since the 1950s to address problems related to parity symmetry conservation, these mirror particles are extremely difficult to detect as they only interact with ordinary matter through gravity and rare oscillations of neutrons. The researchers used ultracold neutrons cooled to a temperature of 5 K in a deuterium crystal cooled down to 5 K. By generating a precisely controlled magnetic field and scanning a wide range of magnetic field strengths, they were able to rule out the existence of mirror neutrons with a very high probability. The study also sets new limits on the n − n ′ oscillation time constant.",
  "summary": "For now, the existence of a mirror universe cannot be confirmed, say physicists at the PSI The post No show again for mirror neutrons appeared first on Physics World .",
  "key_points": [
    "Physicists from Paul Scherrer Institute ruled out mirror neutrons.",
    "No evidence of neutron-to-mirror-neutron transitions found.",
    "Study sets new limits on n − n ′ oscillation time constant."
  ],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}