How Physics Found Out Why Cats Always Land On Their Feet

A few of my favorite things – history, science, and cats – come together in this lively and entertaining adventure into a question that has plagued physicists for hundreds of years.

Apparently physicists’ fascination with felines didn’t begin with Erwin Schrödinger’s dilemma with a cat. Long before Schrödinger designed his thought problem about a cat both alive and dead to illustrate a problematic paradox with quantum mechanics, cats were already frustrating physicists with a different question: why do they always seem to land on their feet? This is the question explored in Falling Felines and Fundamental Physics (Yale Press 2019).

In this brief, yet brilliant romp through history, physics professor and blogger Gregory J. Gbuir (@drskyskull), guides readers through the long journey to answer that question. At first, I was somewhat skeptical an entire book could be devoted to a single question, much less maintain my interest until the end. But little did I know just how complicated, exciting, and surprising the history of this particular question would prove to be. 

Before photography was invented, paintings were the only way the movement of animals could be frozen in time. It wasn’t until the mid-1800’s that technology would first begin to allow curious individuals to attempt to capture how, exactly, animals move. Gbuir, who is clearly quite apt at both historical research as well as writing, does a marvelous job guiding the reader through the origin and development of photography and how it was eventually applied to the problem of cats.

If you’ve ever been curious how cameras came about, you’ll get to learn all about it in the first two chapters – and it turns out to be quite engaging. Gbuir includes the earliest surviving heliograph from around 1826. Made of “Bitumen of Judea, or Syrian asphalt,” it “was chemically modified by light exposure into a form that was resistant to being dissolved in petroleum. A film of this bitumen could be put on glass and exposed to light, becoming hard in spots where the light was brightest and remaining soft in the dark regions.”

When photography, as it came to be called, developed further and became faster, a scientist finally applied it to capturing animal movement. Eadweard Muybridge, who produced the famous “Horse in Motion” gallery in 1878, inspired the work of Étienne-Jules Marey, who would produce a short film called “Falling Cat” in 1894. When Marey presented his findings to the French Academy of Sciences that year, outrage ensued. What he presented, according to a report from the time, was “a scientific paradox in direct contradiction with the most elementary mechanical principles.”

Falling cat, Wikimedia Commons

Now things were really heating up. Physicists turned their attention toward answering the question of exactly how cats managed to turn themselves right-side-up seemingly without momentum. How did the cats even ensure they were turning the right way? It puzzled physicists, and Gbuir carefully keeps his readers puzzled as well, leading us through each clue chronologically.

Along with the history, Gbuir also introduces readers to general concepts in physics to ensure we understand why the cat falling question was so confounding. Even though I have not taken physics yet, I was able to understand his discussions reasonably well. I didn’t feel overwhelmed at any point.

The history was slightly more engaging for me because I’m currently taking a course on the history of science in the twentieth century and we just discussed physics at the turn of the century. Many of the figures in my class were also discussed in Gbuir’s book, helping me contextualize the book further. But even without a history class, readers will be able to follow along quite well. Gbuir’s writing is excellent and the storytelling is easy to absorb.

Gbuir takes readers from the past into the modern day by the end of the book. In 2016, a researcher named Alexis Noel presented her surprising findings about the cat tongue to the American Physical Society Division of Fluid Dynamics Meeting. She showed how hooks on the cat’s tongue, which help untangle the fur as they groom, are also “hollow and pull liquid into them via capillary action” to help the cleaning process.

Insights like this are helping inspire new ways to engineer robots. Biorobotics eventually led to the creation of a robot that twists like a cat when it falls to right itself. This is a fascinating application of the physics of how cats always land on their feet. And Gbuir includes plenty of interesting anecdotes and stories about cats and physics, my favorite being that of F.D.C. Willard. This is the pen name of a Siamese cat of physicist Jack Hetherington, who was told he could not publish as a single author in the Physics Review Letters journal in 1975 and so included his cat as a co-author.

Hetherington could not hide the identity of his colleague for long, and some people were “delighted” with the revelation, according to Gbuir. F.D.C. Willard even signed a copy of the paper with his paw. Gbuir includes a photo of both the famous cat and the autograph in his book, which I loved. There are lots of other great images included throughout the book, helping illustrate the stories Gbuir discusses and bring his subjects to life.

This is the perfect book for readers who enjoy a little history with their science and can appreciate a tender fascination with felines. And as for the answer to how cats always land on their feet, you’ll just have you to read it and find out.

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