Even falling and skulking cats obey the laws of physics, research shows
Even if a cat is dropped, it must obey the laws of physics.
Cats may skulk, and cats may fall – but no matter what they do, cats must obey the laws of physics. Scientists have tried repeatedly to figure out how they manage to do it.
At the extreme, physicists analysed what happens to a dropped cat. That’s a cat in free-fall, a cat hurtling earthwards with nothing but kitty cunning to keep it from crashing.
In 1969, TR Kane and MP Scher of Stanford University, in California, published a monograph called A Dynamical Explanation of the Falling Cat Phenomenon. It remains one of the few studies about cats ever published in the International Journal of Solids and Structures. Kane and Scher explain:
“It is well known that falling cats usually land on their feet and, moreover, that they can manage to do so even if released from complete rest while upside-down … numerous attempts have been made to discover a relatively simple mechanical system whose motion, when proceeding in accordance with the laws of dynamics, possesses the salient features of the motion of the falling cat. The present paper constitutes such an attempt.”
And what an attempt it is!
Kane and Scher neither lifted nor dropped a single cat. Instead, they created a mathematical abstraction of a cat: two imaginary cylinder-like chunks, joined at a single point so the parts could (as with a feline spine) bend, but not twist. When they used a computer to plot the theoretical bendings of this theoretical falling chunky-cat, the motions resembled what they saw in old photographs of an actual falling cat. They conclude that their theory “explains the phenomenon under consideration”.
In 1993, a professor at the University of California, Santa Cruz, applied some heavier-duty mathematics and physics tools to the same question. Richard Montgomery’s study, called Gauge Theory of the Falling Cat, leaps and bends across 26 pages of a mathematics journal. Then it mutters that “the original solutions of Kane and Scher [are] both the optimal and the simplest solutions”.
But cats rarely fall from the sky. More commonly, they skulk. And skulking cats are just as provocative, to a physics-minded scientist, as plummeting cats.
In 2008, Kristin Bishop of the University of California, Davis, together with Anita Pai and Daniel Schmitt of Duke University in North Carolina, published a report called Whole Body Mechanics of Stealthy Walking in Cats, in the journal PLoS One.
They studied six cats, three of which “were partially shaved and marked with contrasting, non-toxic paint to aid in kinematic analysis”. They discovered “a previously unrecognised mechanical relationship” between “crouched postures”, “changes in footfall pattern”, and the amount of energy needed to produce those crouched-posture footfall patterns.
Cats that intend to skulk, in Bishop, Pai and Schmitt’s view, are hemmed in by the laws of the physical universe. They must make “a tradeoff between stealthy walking”, which uses a lot of energy, and plain old, energy-efficient cat-walking.
Video: Two of the above six cats…
• Marc Abrahams is editor of the bimonthly Annals of ImprobableResearch and organiser of the Ig Nobel prize