Good article.

http://www.grantland.com/story/_/id/6760031/is-fastest-human-ever-already-alive

The central question fans of track and field have always wanted to know: is there a ceiling to how fast a man can run? Will there be a day — maybe in 50 years, or maybe in 500 — when someone runs the 100-meter dash in 8.99 seconds?

In order to answer this question, you have to think like a sprinter. "And sprinters believe that — someday — somebody will run the 100 meters and the clock will read 0.00" Ato Boldon tells me over the telephone.