But malicious attacks can. Suggestive as the new theory is, other scientists are finding that the picture may not be so simple. In a paper published in October in the Proceedings of the National Academy of Sciences, Dr. Luis A. Nunes Amaral and his colleagues at Boston University analyzed a number of networks, including some of those studied by the Barabasi group. The list also included the hubs and spokes of the world airport system and two small friendship networks formed by a group of Mormons and by junior high school students. They concluded that while some networks obey power laws, in many others the pattern is distorted or nonexistent.
Airports can only support so many new flights a day.
Because of such complications, a network may fall somewhere on a spectrum between the extremes of randomness and order. Researchers are optimistic that they will sort out the details of a discipline that is still in its infancy. More important than any particular study, Dr. Watts said, is that scientists finally have the computer power to study real networks instead of just speculating about idealized ones. Ask questions about Nutrition , Health , Science News and more. Get answers and tell other readers what you know, in Abuzz, new from The New York Times.