Space elevators face wobble problem

"If an elevator stretching from Earth into space could ever be built, it could slash the cost of space travel. But a controversial new study suggests that building and maintaining one would be an even bigger challenge than previously thought, because it would need to include built-in thrusters to stabilise itself against dangerous vibrations."

http://space.newscientist.com/article/dn13552-space-elevators-face-wobble-problem.html?feedId=online-news_rss20