LINKS:

Physics at Notre Dame

Nature magazine

The relatively close proximity is the result of hyperlinks found on Web pages. Some sites have hundreds, but the average per page is seven, according to the study.

Barabasi and two graduate students — Reka Albert, a doctorate student, and Hawoon Jeong, a postdoc — measured what they call the "diameter" of the Web (the shortest path between two points) using a software "robot" they developed to track and count hyperlinks. The information they gathered helped them develop a topological model of the Web's growth.

In an article published in the September 9 issue of the journal Nature, the researchers say this model could help "in developing search algorithms or designing strategies for making information widely accessible on the Web." The 19-click parameter, for instance, could tell search engines how deep to dig before they would begin covering the same ground.

Even if the Web grows by 1,000 percent, as is expected over the next few years, the degrees of separation will increase only from 19 to 21 clicks, the researchers predict.

The researchers say they were surprised at how small the diameter of the Web is. Also surprising is that while the Web has been left to grow unregulated, its growth has not been random but has followed a self-organized pattern like that found in the liquid-solid phase transition of water into ice. Just as water molecules move randomly in water and then take on an ordered structure as ice, so too does the Web exhibit a definite non-random structure even though people have been creating Web pages and links seemingly without regard to what other people are doing. Says Barabasi, "The Web doesn’t look anything like we expected."

C Ed Cohen

Return to winter 1999-2000 contents
Notre Dame magazine home page