What is a wave?
Waves are everywhere, from the ripples in your coffee to the light bouncing off this screen. But what exactly is a wave? It's one of those things most people can point out but struggle to define. Let's dive into the science and surf of waves.
At its core, a wave is a disturbance that propagates energy through a medium. A short definition, but huge consequences. To understand why, it’s best to break it down with some real-life examples.
Let's start with ocean waves, the kind we love to ride. In their simplest form, far offshore, waves are smooth and evenly spaced from trough to trough and peak to peak. These waves are born when wind drags across the water's surface. Once a tiny ripple forms, the wind keeps pushing, adding more energy - like giving a well-timed push to someone on a swing.
Here's the cool part (if you’re a nerd, which I assume y’all are): while waves can travel enormous distances across entire oceans, the water itself barely moves. Individual water molecules actually move in small circles, ending up almost exactly where they started after the wave passes. They get pushed up by the wind, get pulled back down by gravity a little too far, and get rebounded back up to get pushed by wind again.
It's like when The Wave™ goes around a stadium during a game. People stand up and sit down, but they're not actually traveling around the field. And maybe counterintuitively, the speed at which everyone stands up and sits down doesn’t change the speed of the wave - the timing between you and your beer-spilling neighbor determines that.
This concept holds true for all sorts of waves. Take sound waves, for instance. They're just pressure fluctuations bumping air particles that bump other air particles that eventually bump your eardrum. Light waves? They're variations in the electromagnetic field that our eyes have evolved to detect. The material is not actually moving far.
Waves follow what scientists call a wave equation. One version looks like this:
I am sorry that to startle your Monday morning with an equation - the important thing is that this equation describes a simple wave moving in three dimensions at a certain speed given by the variable “c”.
Various forms of this equation are how we oceanographers understand the waves that we surf. That swell we're eyeing has traveled hundreds, maybe thousands of miles to reach us. It's carried energy across the ocean without moving much water as it has passed, following a wave equation the entire way. Until, that is, it breaks and gives us that ride we have been hoping for.
Waves are the rhythm of our oceans and the backbone of our comprehension of the universe. And it is freaking awesome that we've figured out how to balance on a chunk of foam and ride them.
Further Reading: