Degree of Separation on Web 2.0

What is the degree of separation of World Wide Web? Albert-Laszlo Barabasi had presented a 19-degree of separation on the web according to his best-selling book---Linked. This study, though remarkable, was based on a traditional web structure, in which links were rigidly hardcoded by webmasters. This scene of hardcoded linkes is closer to the leftmost regular network in the following figure because the link-specifiers must have pre-requisite knowledge about the existence of destination pages. Therefore, these hardcoded links are mostly linked to the neighbors on the basis of single-direction acquaintance.



Beginning with the Web 2.0, however, this picture changes. One important difference between Web 2.0 and the traditional web (which we may harmlessly address as Web 1.0) is the prevalence of human-specified tags. These tags, however, may have dramatically shortened the distance of arbitrary two web pages by linking them together without pre-acquainting. On Web 2.0, two web pages have a significant greater chance than before to be linked by a distance of only 2 by sharing a common tag without the need of knowing the existence of each other beforehand. Therefore, this scene becomes closer to the middle small-world network on the figure above. According to the Watts-Strogatz model, by adding a few random links into a regular network, we may signficantly reduce the diameter of the network. It thus means the further decreasing of the degree of separation on the web.

Beyond Web 2.0 and with the emergence of semantic web, the degree of separation on the web is going to be more and more close to the degree of separation among humans in the real world, while the latter one is also decreasing by the prevalance of the WWW. Traditionally, the degree of separation among humans is often regarded as 6 based on the famous theory of six degree of separation. Recently Thomas Friedman declared in his book "The World is Flat" that the relational distance between arbitrary persons was shortened when the world got flattened. Eventually, anyone who share common interest can become acquaintances to each other disregarding their physical distance in a flattened world. The web pages in a flattened world will become closely linked to each other as long as their human masters are acquaintances. Hence the degree of separation among web pages will basically equal to the degree of separation among real humans, which will be greater than 2 but less than 6 in a flattened world.