Greg Gbur among experts interviewed on the BBC’s CrowdScience podcast
Greg Gbur, Ph.D., professor in the Department of Physics and Optical Science, was among the experts interviewed for the BBC’s CrowdScience podcast episode, “Answers to even more questions.”
In this episode of CrowdScience, presenter Caroline Steel called upon experts to help answer bonus questions submitted by listeners. After listening to the episode “Why can’t my dog live as long as me?” a listener asked, “When cats fall, why do they always land on their feet?”
Gbur is the author of the book, “Falling Felines and Fundamental Physics” (Yale University Press, 2019), which explores this exact question. He traces the history of physicists perplexed by cats always landing on their feet, beginning with the first scientific paper in 1700.
“Scientists got this view of angular momentum that if you’re in free fall, and there’s nothing to twist against, then there’s no way you could turn over because that would be a change of angular momentum,” Gbur explained. “So they assumed that cats must be pushing off of something just at the moment they start to fall in order to get themselves starting to rotate.”
This could sometimes explain how cats are landing on their feet, but it’s not the main explanation. Cats can use different parts of their bodies to twist to complete the motion to land on their feet. This increases their ability to land safely, even when falling from large heights such as windows.
Studies have shown that cat injuries increase the higher the height of windows they fall from, up until about the 8th floor. From there, injuries actually begin to decrease dramatically.
“The best hypothesis is they realize they’re in trouble, they tense up and are a little bit freaked out. But then they reach terminal velocity at about the 7th or 8th floor,” said Gbur. “Then they feel their normal weight, they have a good sense of what way is up and down, and they’re able to have a few critical seconds to relax and absorb it.”