Sunday, June 23, 2002

Lessons From Networks, Online and Other
ELBERT-LASZLO BARABASI, a professor of physics at the University of Notre Dame, became fascinated with the structure of the Internet in 1998. He and his student researchers designed software robots that went out on the Net and mapped as many of its nodes, hubs and links as they could. He then began studying other networks and found that they had similar structures. The Internet in particular, he found, had taken on characteristics of a living ecosystem.

That made for a valuable insight in itself. But Professor Barabasi went a step further and analyzed the genetic networks of various living organisms, finding that their genes and proteins interacted in much the same networked way as the Internet.

This conclusion, described in Professor Barabasi's new book, "Linked: The New Science of Networks" (Perseus Publishing, $26), could alter the way we think about all the networks that affect our lives. Those networks may be Hollywood power brokers, Vernon E. Jordan Jr.'s corporate board directorships or Al Qaeda terrorists. The Apostle Paul had a network of cities to spread Christianity.

Professor Barabasi's well written book will be understandable to most readers, but its core concept takes a moment to absorb.

Start by thinking of a highway map of the United States before the advent of the Interstate System. Each city, or node, was connected pretty much at random to others in the network of American cities. Each city has the same relative weight, or "scale," in Professor Barabasi's terminology. Knocking out one city doesn't disrupt the network. Traffic can be rerouted easily.

In contrast, consider the airport hub-and-spoke system that dominates the nation's airline transportation. A few nodes like Chicago, Atlanta and Dallas-Fort Worth have become far more important than, say, Lincoln, Neb. Knocking out the important nodes has serious cascading effects throughout the network.

This is similar to a disruption on the Internet. Because the nodes of these networks do not have the same scale, Professor Barabasi calls them scale-free, a concept that permeates the book.

Once you understand that concept, you're off on an intellectual detective journey. Professor Barabasi has invented a vocabulary to talk about the structure of networks.

"We are witnessing a revolution in the making as scientists from all different disciplines discover that complexity has a strict architecture," he writes. These networks do not operate at random, the author contends; there are laws that govern their behavior.

There are many examples of scale-free networks. Even a cocktail party can be mapped that way: the most sociable people are the "hubs" that link all the guests in a pattern that can be drawn. Other scale-free networks include the electrical power grid, companies and consumers linked by trade and the nervous system of living creatures.


Business writers have long talked about "network effects," meaning that a network generates more power than individual parts can do by themselves. That was part of the intellectual case against allowing Microsoft to dominate so many personal computers using its operating system.

But Professor Barabasi has put more flesh on the relatively primitive concept of the network effect. His work is relevant not only to physicists and mathematicians, but also to business executives, computer scientists, sociologists and biologists.

Networks have strengths and weaknesses, and Professor Barabasi contends that we have to understand both. On the positive side, because of the multiplicity of connections, some things happen quickly. A good idea can win rapid acceptance.

Professor Barabasi uses the example of Hotmail's explosion in popularity. Created on July 4, 1996, by Sabeer Bhatia and Jack Smith, it had one million users within a year. By the time Microsoft came knocking on the door to buy it a year later, it had 10 million. "Innovations and products with a higher spreading rate have a higher chance of reaching a large fraction of the network," he argues.

By contrast, networks have what he describes as an Achilles' heel. Knocking out a single major hub can cripple the network, which the Sept. 11 attacks almost succeeded in doing. In the United States, the airline system, financial markets and telecommunications networks all suffered grievous blows.
http://www.nytimes.com/2002/06/23/business/yourmoney/23VALU.html

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