STEM Files: “This Kiss” by Faith Hill

Welcome to STEM Files, a series of articles dedicated to exploring the manner in which different scientific properties and concepts are discussed in song lyrics. For our debut article, we will be throwing it back to 1998 for a look at Faith Hill’s top ten crossover hit, “This Kiss,” written by Beth Nielsen Chapman, Robin Lerner and Annie Roboff.

Although it’s a very lighthearted, poppy song, “This Kiss” actually makes a few different scientific references in its three-minute runtime. In between the narrator’s lover sending her “shooting across the sky” like a rocket ship and giving her a “subliminal” sensation, the kiss the song is about is said to create a feeling of “centrifugal motion.” Since the other two references are pretty straightforward, let’s dive into that last one. There’s a lot to unpack there.

In the corresponding music video, Faith Hill sings the lyrics, “It’s centrifugal motion” while spinning around on top of a flower. Considering that the rest of the video consists of Hill doing things like swinging around while riding a giant peach Miley Cyrus-style, this may seem like a relatively mundane moment to most viewers. Believe it or not, it’s actually quite the head-scratcher. 

The entire concept of “centrifugal motion” is pretty dubious. First of all, it’s a misnomer. Because she’s turning around in a circle as she sings, it’s reasonable to believe that Hill presumes she’s singing about the feeling of circular motion. It can be inferred that the songwriters are actually talking about the hotly–contested concept of “centrifugal force.” The only other thing she could likely be referencing is “centripetal force.” Although both of these concepts are essentially referring to the same phenomenon, they are completely opposite descriptions of what’s happening. Both “centrifugal” and “centripetal” use the prefix “centri-,” which can be traced back to the Latin word “centrum,” which means “center” in English. The former combines this prefix with a form of the Latin “fugio,” which translates to “I flee.” The latter, on the other hand, pairs “centri-” with “peto,” meaning “I seek/aim.” That is why centrifugal is defined as moving outward from the center, whereas centripetal equates to being directed towards the center. Kind of funny to think Faith Hill is really saying that a supposedly blissful kiss is pushing her away, huh?

How can these contrasting terms be describing the same thing? It’s all from the point of view you’re considering. Imagine you’re driving your car down the road. You reach an intersection and begin to turn left. Because of inertia, an object’s tendency to continue being in motion in the same direction it’s been traveling in, you will continue moving straight (relative to your position before you made the turn) until your seatbelt restricts you, causing you to move with the circular motion of your car. From a bird’s-eye view, you would appear to have been pulled towards the center of the circle your car is tracing (centripetal force). However, you might attest to feeling the sensation of an outward pull (centrifugal force). Because inertia is really what made you feel like you were being pulled away, many physicists will claim that centrifugal force is simply not real. Others will argue that there’s no harm in describing the pushing sensation with this term. Well, other than causing Faith Hill to unwittingly sing about being repulsed by a kiss, that is.

It’s important to note that after the first time “this kiss” is likened to “centrifugal motion,” this sensation is also called “impossible.” So, based on this technicality, if we were to assign “This Kiss” an accuracy rating (as it pertains to the world of STEM) on a five-star scale, I would have to give it four-and-a-half stars (the other four mentions are not described as impossible). By many accounts, centrifugal force (and more so, centrifugal motion) is in fact impossible. After all, what could be more scientific than immediately (and correctly) re-examining your own theory?