Saturday, March 14, 2009

What is a soliton?

To help me explain, I want you to think about these situations:

Situation #1: Imagine jumping in to the water. Waves would spread out in all directions around you, making bigger and bigger circles.

Situation #2: Now imagine that the when you jump in the water, waves only spread in one direction. There’s no circle getting bigger, just a line of waves traveling in one direction at a constant speed.

I’ve jumped in water lots of times, and the waves have always acted like situation #1. Situation #1 is also how waves have acted when I’ve thrown things in the water or seen fish jump out of the water. It’s just how waves act.

Solitons are a special kind of wave that acts like situation #2. Really. This is one of those times when science gets weird. It doesn’t happen often, but if the tides are just right, the time of year is just right, and the location is just right, solitons will form.

One of the really wonderful things about being a scientist is that I’m allowed to forget everything else for a while to study just one thing. Imagine the most interesting thing you’ve done in school all year and getting to do that for as long as you like. That’s what I’ve been doing for the last few days with solitons. I’ve been looking at figures, equations, and maps, trying to understand everything that has happened.

An important thing to know about solitons is that they’re internal waves. That means that they’re not on the surface of the water, but they’re inside the water where colder and warmer water meet (7th & 8th grade science club: remember the tank experiment?). Most of our measurements have to be below the water. However, there is a sign on the surface of the water that a soliton is going by: a band of breaking waves in an otherwise calm sea. It looks so unusual that sailors back in 1922 wrote about it but had no idea why it happened. Here’s what it looks like:

The whitecaps (those breaking waves) might not look big, but they were stretched out in a huge line across the horizon. It didn’t look like anything I’d ever seen before.

Don’t worry if you don’t really understand what a soliton is, or why they're important. Most college students don’t even know what an internal wave is, and certainly don’t know what solitons are. So you’re already ahead of the game.

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