OK, so cats don’t really have 9 lives. That rumour was probably due in part to their incredible powers of survival, including the ability to always land on their feet.
But the question of how they do that still puzzled physicists for a very long time. Turning in mid-air seems to violate the conservation of angular momentum, in which an object can neither start nor stop rotating without a force being applied.
The puzzle could only be solved with the invention of high-speed photography, in the late 19th century.
Etienne Jules Marey, 1894
