The shape of the past in the World Wide Web: Scale-free patterns and dynamics

Human societies accumulate a great deal of information about past events. People make reference to things that happened in time in different ways and record them in multiple media. We have studied the current use of this information by analysing the frequency of occurrence of numbers associated with years in the World Wide Web (WWW). We found a consistent scale-free reduction in the number of web pages referencing events occurred in increasingly older years. This was found for the entire WWW and separately for web pages written in 12 different languages. From year 2005 to 2006 the increase on the number of web pages associated to each year also decayed as a power-law from recent to old years. Such general pattern reveals that time elapsed to present is the best predictor of the interest or the amount of information on a particular year in the WWW. Moreover, the power-law increase from one year to the next shows that the scale-free shape of past in the WWW is dynamically maintained.