The Physics Behind Why Cats Always Land on Their Feet

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Cats have a reputation for having nine lives. Although this is a myth, it does seem that they survive the impossible, and one thing that gives this impression is the fact that they always land on all four paws when they fall. Many people have wondered why this is, including scientists who have taken the time to research the subject and have come up with several theories. In the past, there have been four distinct hypotheses relating to the way that cats fall, says Ars Technica. One of the original hypotheses was called the ‘tuck and turn’ model, which describes the way that cats tuck in one set of paws to allow them to turn the rest of their body to land on their feet.

Another theory was offered by physicist James Clerk Maxwell in the 19th century. His theory is called the ‘falling figure skater’ explanation. This involves the cat extending its paws or pulling them in to adjust the angular momentum. This is similar but different to the ‘bend and snap’ maneuver that involves the cat bending at the waist and then counter-rotating the two halves of its body. The final hypothesis that has been offered relating to how cats land on all four paws when they fall is the ‘propeller tail’. This theory describes how a cat can use the rotation of its tail to reverse the rotation of its body.

Greg Gbur is a professor at the University of North Carolina, and he is also a cat lover. He has been interested in the various theories regarding how cats fall and land for many years. He is so interested in this topic that he has written the book ‘Falling Felines and Fundamental Physics.’ In the book, he examines each of the hypotheses offered thus far in great detail, but in a humorous manner.

Although there are four main hypotheses, Gbur found multiple research papers relating to this topic during the research for his book. He was extremely surprised by the level of interest people have had in solving this mystery over the years. Every paper seemed to offer a different angle, none of which were entirely satisfactory to Gbur. One problem with many of the papers was that they were written before advancements in photographic technology allowed high-speed photography that showed the different stages of motion a cat goes through during a fall. The first time high-speed photographs were taken was during Etienne-Jules Marey’s research into living creatures in motion.

When Marey presented his high-speed photographs of a cat falling to the scientific community, many of them were genuinely shocked by what the photographs revealed. One scientist even commented that the photographs presented a new problem that seemed to defy the laws of physics. On further studies of the cat’s movements in the photograph, it became clear that they did not quite defy the laws of physics. However, complicated motions made by cats were difficult to explain. While each of the main hypotheses seemed to play a part in some parts of the motion, none fully explained the full range of movements that were demonstrated in the photographs.

This led to Gbur conducting some of his own research while he was writing his book. He notes that each of the hypotheses does explain a section of the movement, so it is unfair to say that any of the hypotheses are wrong. He concludes that they all, in part, play some role in how a cat lands on his feet. Gbur also notes that it is important to consider individual differences between cats, as not all cats have the same motion during their fall. He uses the specific example of the role that a cat’s tail plays in turning them during a fall. Studies of cats with tails show that they do rotate their tail during the fall, and this will impact on the movement of the rest of the cat’s body. However, there are some breeds of cats that do not have a tail. These cats are equally likely to land on their feet after a fall as cats with a tail. Therefore, the movement of the tail is not the only factor at play.

Similarly, the physical traits of cats can differ significantly. Some are long, some are short, some are heavy, and some are light. Regardless of their shape, size, or weight, all cats are able to land on their feet after a fall. However, each cat will bend or twist in a slightly different manner. It is these individual differences that have previously been overlooked in the research. According to Gbur, one of the problems with the previous and current research is that physicists are trying to find a single, simple solution to the age-old question of how cats always land on all four paws. In Gbur’s opinion, this is over-simplifying the problem as he does not think there is one clear and simple answer, and he believes a greater emphasis should be put on the individual features of cats and the different features of their falls.

Now, the emphasis of research into this problem has switched to the field of robotics. There are scientists attempting to create robotic cats that rotate and flip in the same way that cats do during their fall. This is another topic that Gbur has covered in his book. While the robotics element of the research into the problem takes a modern approach to how cats fall and land the way they do, Gbur has stressed the importance of using science history as this gives you the background into what research has been done, what has been disproved, and which papers have correlating results. The use of science history is something that he covers in his own blog, Skulls in the Stars. For now, the exact physics of how cats fall and then land on all four paws remains a mystery, although scientists are getting ever closer to discovering how these animals achieve this amazing feat.