How everything on the web is connected by just 19 clicks
London: The internet may appear to be an almost random mass of information, but researchers said that in fact, there is a 'Kevin Bacon' effect - meaning a web page is connected to others by just 19 clicks.
The statistic echoes the famous 'Six degrees of Kevin Bacon' game, which claims anyone on Earth can be linked to the actor through just six people.
The Opte project is one of several aiming to show the web graphically.
In the image, based on 2005 data, red lines represent links between web pages in Asia, green for Europe, the Middle East and Africa, blue for North America, yellow for Latin America and white for unknown IP addresses.
"As the Web began to grow in the 1990s, it was thought that it most probably had the properties of a random network," the Daily Mail quoted Hungarian physicist Albert-Laszlo Barabasi as saying.
The researchers originally determined this by constructing algorithms that collected all the links on a Web page and then followed them to their destinations, and repeating the process over and over again.
His team found that in fact, any page on the web can be linked to any other via a surprisingly small number of clicks, known as the 'small world property'.
It says that two nodes are likely to be connected, even in such a very large and sparse scale-free network as the Web, by a relatively short path of nodes-in the case of the Web, the path length is about 19, Professor Barabasi said.
He claims the key to the web's fast expansion yet small 'Kevin Bacon number' is the emergence of massive 'hubs' such as Facebook and Google.
"Such networks are in effect held together by a small number of highly connected hubs," he wrote.
This scale-free property is an important organizing principle for the Web. Rather than virtually all nodes having more or less the same degree, we should expect a few nodes to be very highly connected, and the vast majority to have smaller degree than the average, he said.
However, he warns that the system may cause problems should the 'superhubs' such as Facebook and Google be attacked by hackers.
"The flip side of this is that, in the event of a targeted attack, where the most connected nodes are deliberately removed first, then the network will be destroyed very quickly. This is the Achilles' heel of a scale-free network," he added.
The research, first published in Nature in 1999, has now been expanded and published in the prestigious Philosophical Transactions Of The Royal Society.