Cats Give the Laws of Physics a Biiiiig Stretch

In October of 1894, at a meeting of the French Academy of Sciences, the renowned physiologist Étienne-Jules Marey showed a series of photographs that sent his colleagues into collective uproar. In the flurry of accounts that followed, one conference attendee proclaimed that Marey had presented a scientific paradox that violated the fundamental laws of how objects moved.

At the center of the controversy was a cat. Specifically, a dropped cat that had, in midair, twisted to land on its feet. The fall wasn’t the problem, nor was the touchdown. The scandal was sparked by what happened in between.

For years, scientists had assumed that cats could land on their feet only if they first launched themselves off a surface. The idea hewed to a physical concept known as conservation of angular momentum, which states that bodies that aren’t rotating won’t start unless some, pivoting, it seemed, off of nothing at all.