One of the characteristics of the modern media age — at least for anyone who uses the web and social media a lot — is that we are surrounded by vast clouds of rapidly changing information, whether it’s blog posts or news stories or Twitter and Facebook updates. That’s great if you like real-time content, but there is a not-so-hidden flaw — namely, that you can’t step into the same stream twice, as Heraclitus put it. In other words, much of that information may (and probably will) disappear as new information replaces it, and small pieces of history wind up getting lost. According to a recent study, which looked at links shared through Twitter about news events like the Arab Spring revolutions in the Middle East, this could be turning into a substantial problem.
The study, which MIT’s Technology Review highlighted in a recent post by the Physics arXiv blog, was done by a pair of researchers in Virginia, Hany SalahEldeen and Michael Nelson. They took a number of recent major news events over the past three years — including the Egyptian revolution, Michael Jackson’s death, the elections and related protests in Iran and the outbreak of the H1N1 virus — and tracked the links that were shared on Twitter about each. Following the links to their ultimate source showed that an alarming number of them had simply vanished.

In fact, the researchers said that within a year of these events, an average of 11 percent of the material that was linked to had disappeared completely (and another 20 percent had been archived), and after two-and-a-half years, close to 30 percent had been lost altogether and 41 percent had been archived. Based on this rate of information decay, the authors predicted that more than 10 percent of the information about a major news event will likely be gone within a year, and the remainder will continue to vanish at the rate of .02 percent per day.