Network scientists study networks: collections of people or objects connected to each other in some way. Think of the 1.5 million Manhattan residents or the 30,000 genes inside a human cell. Such networks, scientists argue, behave in ways that can’t be understood solely in terms of their component parts. Without knowing what every single person or object within the network is doing, they say, it’s nevertheless possible to know something about how the network as a whole behaves.
Stated that way it sounds simple. But as an intellectual approach, network theory is the latest symptom of a fundamental shift in scientific thinking, away from a focus on individual components – particles and subparticles %u2014 and toward a novel conception of the group. As Mr. Barabasi, a professor of physics at the University of Notre Dame, put it: “In biology, we’ve had great success stories – the human genome, the mouse genome. But what is not talked about is that we have the pieces but don’t have a clue as to how the system works. Increasingly, we think the answer is in networks.”