To completely understand how a living organism works one would have to take it apart, the great physicist Niels Bohr once observed — but then the organism would certainly be dead1. In general, systems of high complexity, including living things but ranging from the Internet to social networks, are often impossible to track in all their details.
But what if you didn’t have to? Network-theory researchers now have come up with some clever mathematics that reveals complex systems by tracking a selected few of their components.
Influential few predict behaviour of the many : Nature News & Comment.