{
  "id": 8777184,
  "title": "Cooling liquids reveal self-limiting particle clusters behind glass transition",
  "url": "https://urgent.news/2026/09/20/cooling-liquids-reveal-self-limiting-particle-clusters-behind-glass",
  "topic": "science",
  "section": "Science",
  "published": "2026-09-20T21:30:01.000Z",
  "source": {
    "name": "Phys.org",
    "slug": "phys-org",
    "url": "https://phys.org/news/2026-09-cooling-liquids-reveal-limiting-particle.html"
  },
  "original_language": "en",
  "account": "Before delving into the mystery of glass, theoretical physicist Corentin Laudicina revisits high school physics to explain why matter can exist in three states: gas, liquid, and solid. These states differ in the way their molecules move. In a solid, molecules are arranged in a fixed crystal lattice; in a liquid, they can move without a fixed position relative to each other; and in the gas phase, their movements are even more free. However, there is a fourth phase that a material can enter when cooled quickly enough—the glass phase. This phase is unusual because it behaves like a solid structurally, but its internal structure resembles that of a liquid.\n\nTo better understand the glass phase, Laudicina and his colleagues study how a liquid's viscosity changes during cooling. As temperature decreases, molecules' ability to move becomes progressively limited. However, at the glass transition, viscosity increases extremely rapidly, much faster than expected, while the material's structure only slightly changes. This discrepancy lies at the heart of the glass transition mystery.\n\nTo explain the glass transition, Laudicina and his team run computer simulations of a model liquid—a system of perfectly spherical particles that interact simply. The simulations reveal that changes in viscosity are caused by particles moving heterogeneously. Some particles barely move, while others form groups that move together, like people at a crowded festival trying to reach the back of the field.\n\nLaudicina investigates how these clusters change as the liquid cools and how they relate to the gradual slowing of the liquid during the glass transition. Surprisingly, as the liquid cools, clusters initially grow larger, but below a certain temperature, they start to shrink again. Older theories predicted that these clusters would keep growing indefinitely, causing the liquid to abruptly freeze. Laudicina's findings suggest that the clusters effectively put a natural brake on their own growth, preventing an abrupt transition. This discovery highlights a feedback mechanism that the previous theory lacked, causing the sudden transition previously predicted to disappear.",
  "summary": "Before diving into the mystery of glass, theoretical physicist Corentin Laudicina takes us back to high school physics for a moment. Although he has spent years studying exactly what happens in a material during the glass transition, he also understands that his research is not the easiest thing to explain off the cuff at the cafeteria table.",
  "key_points": [],
  "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."
}