Book: Small World: Uncovering Nature's Hidden Networks

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Small World: Uncovering Nature's Hidden Networks

Author: Mark Buchanan
Publisher: Orion

Most of us have had the experience of running into a friend of a friend far away from home—and feeling that the world is somehow smaller than it should be. We usually write off such unlikely encounters as coincidence, even though they seem to happen with uncanny frequency. According to some physicists, it turns out that this ‘small-world’ phenomenon is no coincidence at all. Rather, it is a manifestation of a hidden and powerful design that binds the world together. The Internet, the brain, power-grids and the global economy are all networks that seem to have evolved a ‘small-world’ geometry—with properties independent of the nature of the things themselves.

Small World argues that this underlying pattern may be one of nature’s greatest design tricks, and the book shows us how scientists are putting this new insight to work.

This book was also published under the title Nexus: Small Worlds and the Groundbreaking Science of Networks.


On reading Mark Buchanan’s new book, Small World, you can see Kevin Bacon has a lot to answer for. As anyone who has visited The Oracle of Bacon will know, the actor is well connected: only two or three handshakes separate him from every other actor on the Internet Movie Database. Is Mr Bacon special? No. We are all of us—all six billion of us—only about six “degrees of separation” away from each other. Whenever coincidence prompts to say that “it’s a small world”, we have, says Buchanan, stumbled upon a piece of mathematics as fundamental to the natural world as Fibonacci numbers and the Golden Mean. “Small world networks” are everywhere, underlying diverse cultural, biological and even physical systems.

Buchanan has been quick off the mark with this book: the mature study of small world networks is barely four years old; so, naturally enough, the same pioneering names recur often as he outlines the field’s development. But there is nothing contingent or flimsy about Buchanan’s arguments as he stakes out the numerous areas for which this new science is already providing surprising insights.

One of the great surprise strengths of this book is Buchanan’s grasp of social policy and the behaviours of governments and organisations. In an account that does its level best not to shortchange any application of a new science, it’s good to see Buchanan addressing ordinary human applications with such authority and enthusiasm. This approach should reassure those readers who tremble at the idea that this might turn out to be “a book about maths”. As far as that goes, the maths is pretty easy territory (spectacular, too)—and Buchanan is an excellent guide. —Simon Ings

Barnes and Noble

A former editor of Nature with a Ph.D. in physics, Mark Buchanan brings the new science of networks to life, one that explains spooky correlations between how we function and how other complex systems function—from individual cells to the global Internet.

Buchanan identifies crucial features shared by networks with apparently little in common, notably the “small-world” phenomenon. (Think of “six degrees of separation,” whereby you’re just six links away from any other human being on earth.) This idea may explain how your brain works. In aristocratic small-world networks, certain elements maintain huge numbers of links, while most maintain far fewer. This principle describes everything from ecosystems to wealth distribution.

Relatively simple computer models are shedding surprising new light on complex systems and making intriguing—if preliminary—predictions. Promoting commerce will tend to level income distribution, but instabilities in investment returns lead to massive, sudden disparities. Ecosystems will weather the loss of some species, but lose the wrong species, and collapse follows almost instantly. You’ll get your next job through some guy you haven’t seen in years, not your best friend.

If you were fascinated by Malcolm Gladwell’s The Tipping Point, read this next. Buchanan places Gladwell’s ideas—and many others—in a broader context, showing how scientists are beginning to make sense of the crucial interactions that define our lives. (Bill Camarda)

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