It's the web media equivalent of the central cosmological constant: does the universe of personal sites expand ad infinitum, or else collapse under its own weight? And we may finally have an answer. The number of active blogs tracked by Technorati has stalled at about 15 million. Now that's still a remarkable number, even before one adds in quasi-blogs, such as pages on social network sites such as Myspace. But, compared with the conventional wisdom — that every human, and household pet, will eventually have a blog — the reality is sobering.(The irony: these numbers on active blogs were provided by Dave Sifry of Technorati, whose state of the blogosphere reports have created the illusion of limitless growth; and the data emerged because the blog index boss was asked to distinguish between active and inactive sites by a reporter at Business Week, the magazine that has done more than any other to hype up the medium.) After the jump, your take. I have my theories, but, first, why do you think the number of active bloggers is flat?