Is Wikipedia a Victim of Its Own Success?

The online encyclopedia is suddenly adding fewer articles and has fewer editors. Has all knowledge been summarized, or does Wiki have a problem?

Looking back, it was naive to expect Wikipedia's joyride to last forever. Since its inception in 2001, the user-written online encyclopedia has expanded just as everything else online has: exponentially. Up until about two years ago, Wikipedians were adding, on average, some 2,200 new articles to the project every day. The English version hit the 2 million — article mark in September 2007 and then the 3 million mark in August 2009 — surpassing the 600-year-old Chinese Yongle Encyclopedia as the largest collection of general knowledge ever compiled (well, at least according to Wikipedia's entry on itself).

But early in 2007,...