The internet is awash with ‘if it fits, I sits’ memes. Cats seem able to take any form, fitting into boxes, jars, sinks and any other place they can make themselves comfortable. The ability for cats to adapt their shape to fit any container is exactly how we describe a liquid. So are cats liquid?

Researcher Marc-Antoine Fardin decided to apply rheo­logy to the question. Rheology is a branch of physics that deals with the deformation and flow of materials. In his research, Fardin calculated the ‘Deborah’ number of cats. The number is a measure to describe how fluid something is, so if an object’s Deborah number is greater than one it is solid, but if it is less than one it is a liquid. The results were confusing.

Fardin concluded that cats can be both liquid and solid. A cat in a small space will act as a liquid, filling up all of the space and deforming to fit it. But they can also behave like solids, as anyone who has seen a cat come into contact with water will know.

This creative research also found that if you wait long enough, anything can be a liquid. Flows are based on the time it takes for an object to relax into the shape of its container. So, given enough time, even a mountain can flow.

Fardin’s research questions the very nature of solids and liquids. It won him the 2017 Ig Nobel Prize.

For more science that makes you laugh and then think, head to

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