Are Cats Liquid?

An in-depth study.

Panda the Red
Published in
11 min readJul 5, 2019


Photo: Imgur

Most contemporary physicists are concerned with technical, big-picture questions: Why do neutrinos have mass when the Standard Model says that they shouldn’t? Why are quantum field theory and general relativity irreconcilable even though both are empirically valid? Can nuclear fusion be used as an efficient power source? And so on. These questions are important but they aren’t really in line with the sort of everyday, practical problems that occupy the minds of the general public. For example, are cats liquids or solids?

The earliest (c. 2014) researcher to have seriously investigated this question seems to be a person named Tom who submitted his findings to the Funny Animals section of the journal Bored Panda in an article entitled “15 Proofs That Cats are Liquids.” Drawing from the results of 15 experiments using a variety of cat breeds and container geometries, Tom concluded that cats have a tendency to assume the shape of their container, which is a fundamental property of both liquids and gases. Furthermore, cats in the experiment tended to show negligible change in volume, which is a characteristic property of liquids.

Perhaps unsatisfied by the strictly qualitative nature of Tom’s study and the peer review standards of Bored Panda, further research was conducted by Marc-Antoin Fardin at the École normale supérieure (Paris) later in that same year using a more rigorous definition of “liquid,” discussed in a letter entitled “On the Rheology of Cats.” Fardin found that cats exhibit a much richer and more complex range of rheological behaviors than was found in the initial Bored Panda study and it is not strictly appropriate to say that cats are strictly liquids. For his work in advancing progress in cat physics and demonstrating the implications of that emerging field with regards to the broader study of continuum mechanics, and also for being really, really funny, Fardin was awarded the 2017 Ig Nobel Prize in Physics.

Liquids, solids, and gases

Enough joking around.

While Fardin’s paper was obviously intended to be humorous, it does at least play at taking the question seriously and discusses the question using the language of modern rheology, the branch of mechanics that studies the motion of materials that have…



Panda the Red

“Now it is our turn to study statistical mechanics.”