In this video, snakes are forced to slither between two boards. The boards are placed successively closer together until the poor snake is wriggling. But this isn’t about annoying a snake — it’s about physics.
Take a frail beam, a straw or a piece of wood, put one finger on each end, and compress the thing. You’ll see it buckles in a distinctive way. Scientists have analysed the way oblong physical objects buckle under pressure, but physical reality had endless variations. So far, we’re short on data about how a straw would buckle if you were to place it between two boards and repeat the experiment.
That’s where this “snake race” comes in. Usually snakes move using a wide, sinuous movement, but according to a paper by Junfeng Xiao and Xi Chen, “when a snake crawls between two parallel walls, its body takes a unique rectangular wave-like shape which also depends on the wall spacing”.
A compressed beam takes on the same rectangular shape as more and more pressure causes it to buckle into sections, some of which are pressed against the walls. If the beam were rigid, it would snap into pieces, but like the snakes, these model beams are elastic. The diagram on the left shows how collapsing causes them to shift into different “modes”, making narrower and narrower rectangles as they compress down.
This is a good example of how one dynamic motion can serve as a model for another. As the snakes stretch out, they give us a look at how another object might squish down.