Scientifically Speaking, Cats Are a Form of Liquid
The mystery behind "liquid cats" is solved
Hiya!
If you follow me on Twitter, you’ve already seen images of my newest fur-nephew, a bright-eyed and mischievous creamsicle-colored kitten named Felix. My brother and sister-in-law decided to get their other cat, Pilot, a little brother once they returned from their honeymoon a couple of weeks ago, and just as they thought, Pilot loves his new little brother.
Like all cats, Pilot and Felix turn into liquid sometimes. Or at least, that’s what it seems like — the phenomenon is even known as “liquid cats.” If you haven’t witnessed it, check out this Buzzfeed article with over 40 hilarious examples. It’s as if their bones dissolve and practically melt through our arms when holding them.
This same ability allows them to fit into tiny spaces or contort themselves into seemingly impossible positions that don’t look at all comfortable. I often stare at them in awe and wonder, how do they do this?
Anatomy of a Cat
While researching this article, I found the answer to the liquid cat mystery is more involved than I expected. Part of it has to do with a cat’s anatomy, but it also involves its psychology and a fair amount of physics. I’ll try to summarize as best I can.
Physically speaking, a few aspects of a cat’s anatomy allow them to contort themselves more than Circus Sole performers. The first has to do with their clavicles, and the other is their spine.
Unlike us, cats’ collar bones are free floating. Ours connect to a bone in our shoulder blade called the acromion via the acromioclavicular joint (AC joint). But a cat’s clavicles attach to muscle only, so they aren’t as constricted in movement — This also means they aren’t limited to the broadness of their shoulders. In fact, the only part of their body that determines which spaces they can fit in is their skull size.
Their spines are also uniquely designed to function similarly to a spring. As predators, their spring-like spines allow them to contract before pouncing on their prey. Their spines are also super flexible and twist easily, which explains how cats always seem to reorient themselves to land on their feet after falling.
So this explains how cats are physically able to achieve a liquid state, but could we take things a step further? Could the term “liquid cat” be more than an analogy? Can cats actually be classified as a liquid?
Surprisingly, science says yes.
A Scientist Successfully Proves Cats Are Liquid
Before researching this topic, I figured the term “liquid cat” was just a convenient analogy. But it turns out, it may be a more accurate term than we realize. At least one study published in 2014 by French physicist Marc-Antoine Fardin aimed to determine whether cats could be classified as a liquid scientifically.
Fardin claims that according to physics, they can. Understandably, his claims have made a few waves, and since publication, Fardin has appeared for a TED Talk and wrote about his findings in The Conversation. And in 2017, he won the Ignoble Nobel Prize (IG Nobel) in physics for it.
(Side note: If you haven’t heard of the IG Nobel prize, I was right there with you. But I gotta say, it’s kinda awesome. Marc Abrahams started it in 1991 to celebrate new scientific discoveries and inventions that “make people laugh…and then make them think.” Harvard hosts the ceremony every year, and while there are plenty of chuckles and good times, the research presented is always serious.)
The Research
As you know, liquid has a fixed volume but no defined shape. It’s a substance that conforms to the container it’s in. Fardin uses rheology and our knowledge of non-newtonian liquids to create an equation proving that cats can be classified as a liquid under certain circumstances.
Rheology is the science of the deformation and flow of matter. It looks at the relationship between strains and stresses on materials such as fluids to predict how the substance will behave in various conditions.
In rheology, the time it takes for a substance to settle, or “relax,” into its position is called its Relaxation Time, and the length of time it stays in that position is called the Experimental Time. For example, the relaxation time would be how long it takes for a cat to climb and fully settle into a container. While the experimental time is how long it stays there.
As Fardin explains in the Conversation article if you divide the relaxation time by the experimental time and get a result that’s more than one, then the material is relatively solid — but if the result is less than one, the substance is relatively liquid. This number is called the Deborah number, a dimensionless number since it calculates time, not space. Honestly, it deserves its own article, perhaps I’ll write that soon.
Anyway, the equation looks like this:
A STEM Fellowship article about Fardin’s findings provides a nice breakdown of how the equation applies to cats:
“The time that a cat spends to fill a sink is about 5 seconds, and we observe this phenomenon for about 60 seconds. In this case, the relaxation time (5s) is smaller than the experimental time (60s), so the Deborah number is less than 1. Thus, under this circumstance, this cat is a liquid.”
The results show that cats are a type of non-newtonian liquid every time. Non-Newtonian Liquids are liquids that don’t follow Newton’s law of Viscosity. Basically, it’s liquids like ketchup that aren’t consistent — ketchup might not come out of the bottle at first, but shaking it makes it runnier and easier to pour.
So, it appears the term “liquid cat” is far more than an endearing and silly attribute of cats. It’s a scientifically and mathematically proven fact.
Perspective Shift
The entire idea seems too strange to be true — A mammal that can be solid and liquid? It’s the stuff of science fiction. Yet, not only is it real life, but the very animals capable of the ability are our furry, friendly felines!
It’s almost as if Pilot and Felix have a superpower! No wonder little Felix is fearless in his explorations.
Also, do you realize that we just discussed biology, psychology, and physics within a single conversation? It never ceases to astound me how connected everything is.
To understand how anything works individually, it makes sense to learn about multiple components/subjects separately, but Nature shows that nothing is solitary. Everything is connected. So perhaps, as we progress, we should look for more connections and experiment with combining various specialties. I wonder what that could teach us.
Just as a reminder, you’re currently reading my free newsletter Curious Adventure. If you’re itching for more, you’ll probably enjoy my other newsletter, Curious Life, which you’ve already received sneak peeks of on Monday mornings.
Any payments go toward helping me pay my bills so I can continue doing what I love — ethically following my curiosities and sharing what I learn with you.
You can find more of my writing on Medium. If you’re not a member but want to be, click here to sign up! Doing so allows you to read mine and thousands of other indie writers to your heart’s content.
Lastly, if you enjoy my work and want to show me support, you can donate to my Ko-fi page, where you can also commission me to investigate a curiosity of your own! Thank you for reading. I appreciate you.
