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Complexity: a guided tour – Melanie Mitchell ****

This book made me want to cheer, because with this title OUP has got it right. I dearly love Oxford University Press, and time after time they come up with popular science books that sound really interesting. Only, when you read them they can be dull and not very well written, often, I’m afraid, because the author is an academic. But this time, in this fascinating guide to complexity, emergent systems, networks and more, they’ve found an author with just the right tone who has the ability to make the subject interesting while still conveying her own interest and involvement in the field.
You may have come across complexity as an adjunct to chaos theory – and chaos is covered in here, but there are so many other things too. In looking at the background, Melanie Mitchell includes the theory of information and computation, plus tying this theory into evolution. She introduces us to genetic algorithms and other computer-based mechanisms for systems to evolve, including the potential for using these approaches in problem solving. We discover cellular automata and an attempt to get computers to understand analogy. And there’s a whole section on the hot topic of networks, from the World Wide Web to the human brain. Time and again we see how simple rules and structures can evolve into complex results that can be difficult to predict in their real world forms.
If I’m picky, Mitchell does occasionally give us too much detail, falling into the ‘boring lists’ trap – and some of the items she covers are presented in too technical a way. There’s also a statement at one point ‘Given a room full of air, at a given instant in time each molecule has a certain position and velocity,’ that would have a physicist cringing – for quantum particles, there aren’t values for the properties until a measurement is taken, and even then the uncertainty principle ensures we can’t know both with any accuracy. But the statement is made in the context of some classical statistical physics, so is almost forgivable.
The reader is probably left with a slight sense of doubt. There seems to be a lot of science here that’s fascinating, but can’t really be used for anything. But that’s not the author’s fault, it just reflects the nature of complexity – at least in our present level of understanding – and Melanie Mitchell’s book will certainly ensure that the reader has a good picture of what it’s all about.
Review by Brian Clegg


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