It's an interesting feeling to spend four years studying the English language only to find out that it's led you into a room where people make small talk by discussing anti-equinox software and the going rate for a TI-89 Titanium calculator. So walking into Disque 109 for a Dean's Seminar on nonlinear waves with the knowledge that I'd soon have to write an article explaining the content of the lecture was quite the daunting task.
To his credit, however, Professor J. Douglas Wright did a fine job of explaining the basic concepts of non-linear waves to his audience on April 9th, 2008. With such a complex topic and an audience that wasn't accustomed to the technical terms of the field, the simplicity with which he explained the various topics was as impressive as his extensive knowledge of them.
To the average nonlinear wave enthusiast, terms like shock, diffusion, and dispersion are considered commonplace. However, Wright described them in everyday terms, referring to shock as a traffic jam effect, diffusion as a drop of dye's color spreading through water, and dispersion as the ripples from a rock landing in a pond.
I often lost myself in the terms and equations of the subject, but found myself suddenly understanding the basic concept through the help of Wright's video clips. In one short clip, a group of students was studying the effects of solitons, or solitary water waves, which can be defined as a single wave that maintains its shape and speed while traveling through a body of water. In their experiment, the students had a long box of still water about the length of a shuffleboard table and then released a sudden rush of water from one end. With the transition of the wave from potential to kinetic form, it rushed down the box, through the calm water, and left the same calmness in its wake, never disturbing the water for more than a few moments.
As an upgrade to that experiment, the students then released the same sized wave, but followed it with a bigger wave. As they traveled down the canal of calm water, three separate stages took place. The bigger wave traveled faster than the smaller wave, then they combined into one wave, which sped up quite a bit, and then the bigger wave reappeared in front of the smaller wave, as if it had passed it without ever affecting the size or speed of either wave at the starting point.
Wright explained that the taller the wave, the faster it moves. So while they are separate, the big wave will move faster than the smaller wave, and then when they're combined, the waves will move faster than either one could on its own, which leads to the intriguing natural disaster of tsunamis.
Tsunamis are a particularly catastrophic incidence of solitary water waves. When they're at sea, the waves aren't very large in amplitude (height), but are as much as a few kilometers wide. The problem comes when the waves reach the shore and the shallow water causes the waves in front to lose speed, as the faster waves behind them to "pile up" and become very large. These facts contribute mightily to their destructiveness.
In all honesty, the subject of nonlinear waves seemed very foreign to me at the start of the lecture. But no matter the topic, when presented by someone with enough enthusiasm about what they're doing, anything can be interesting. Hats off to Professor J. Douglas Wright.
