A liquid fills any container it’s poured in while a solid can maintain its shape without any container. So the scientific question is whether cats are solids or liquids.
Every year Improbable Research, an organization devoted to science and humor, highlights scientific studies that first make people laugh, then think. This year they awarded this honor to Marc-Antoine Fardin who was awarded the Ig Nobel Prize in physics for his research paper on the rheology of cats on whether they’re solids or liquids.
Watching any cat’s shape can tell you what it is, but apparently cats can be both solids and liquids, defying the laws of nature, which is what cats do best anyway.