Chaos

"James Gleick is a former science writer for the New York Times and in this book he describes the science of chaos, and how complex systems can also be interpreted in terms of simple rules and simple (but interacting) behaviours. For example, he examines Edward Lorenz’s butterfly effect. I love this part because it is something that pretty much everyone has experience of in everyday life, but never in their introductory physics class. Get the weekly Five Books newsletter The cliché is the weather where you can imagine that the tiniest, tiniest change in the weather in New Jersey would affect the weather in London down the line because the entire system is linked. If one system has slightly lower pressure, the rest of the system reacts. Another example is, imagine you are on the top of a pyramid-shaped mountain and you put a little ball on top. The tiniest wind will determine which side of the pyramid the ball rolls down. The theory basically says that many systems will respond completely differently depending on tiny changes in their initial conditions. And this idea is something we have to keep in mind, for example, when we study Earth history. For example, if we look at climate change, the tiniest change can alter things and, most importantly, the size of the change doesn’t have to scale with its consequences. A relevant example today is the stability of the Greenland and West Antarctic Ice sheets. So far, they have remained stable while the climate has warmed over the last century. Will a small change somewhere on Earth destabilise one of the ice sheets, cause a chain reaction, and flood coastal cities around the world? In my group we don’t practise chaos theory mathematically, but we practise it when it comes to creativity and observation all the time. We just keep in mind that not every process is some simple isolated linear system that you can set up as a physics experiment."

"Chaos theory is pretty new. Elements of it have been popping up over the last century but as a solid thing it’s really from the late 70s and 80s. Different equations describe different phenomena. People have always looked at these equations and said if we had a powerful enough computer we could solve the problems, make certain predictions. But it turns out that even simple equations can have such complicated behaviour that, in practice, it’s impossible to predict the outcome, which is described as ‘chaotic’. And what’s interesting is that we’ve found this in lots of different areas: from biology to genetics, to computer science and physics, and even in evolutionary systems. So then you ask if there’s anything in common between these random chaotic behaviours: what is the common thread? And that’s where the science of chaos came from, trying to pick up essential aspects that come out of this. Complexity is going one step further and saying that sometimes out of simple equations you can get complex behaviours that may not be random but perhaps structured. So the question then is how it is possible to predict where complexity emerges? Complexity the book is concerned with the creation of an institute in Santa Fe to address these questions. It’s applying things from evolutionary systems to cities, to financial markets. Since the great explosion of interest in chaos theory in the 80s and early 90s I haven’t seen anything of significance for the last decade or so, but in the field of complexity people are doing amazing things. I’ve got a friend working at Santa Fe who has been creating massive simulations of megalopolises – big cities – and he’s made this discovery that quality of life goes up the bigger a city is, which goes very much against what people expect."