Kirk Pflaum, of Middleton Grange School, asks :-

What is chaos theory?

Mark McGuinness, a mathematician at Victoria University of Wellington, responded.

Scientists had been used to having rules for how things behave, nice tidy rules with nice predictable results. Then along came chaos theory, which says that you can get very complicated results even when the rules are simple.

For example, try this. Take a number between -2 and 2, square it, then subtract 2. Write down the answer. Using the answer, do it again. And again. Keep doing it until you know what will happen, or you get tired.

If you start with 2, you keep getting 2 back. What happens if you start with a whole number? You can predict the result. Can you say what will happen if you start with a number that has a fractional part? Probably you will get tired first. Even though you are doing a very simple thing, the result is hard to predict. Computers are good at doing things over and over again, so they are used in chaos theory.

With chaos theory there is the good news and the bad news. The bad news is that you might get complicated results when you hope for simple ones. The good news is that even though the world around us looks very complicated, maybe there are some simple explanations.

Scientists are using these ideas in studies of clouds, rivers, coastlines, the weather, lungs, hearts, brainwaves, flames, freezing, fluid flows, blowflies, transistors, rusting, chemistry, the stock-market, the planets and asteroids, lasers and earthquakes.