"The search for gravity waves has been a century long epic. They are a prediction of Einstein's General Theory of Relativity but for years physicists argued about their theoretical existence. By literally squeezing light on a quantum level, scientists are refining detection instruments to an extent never seen before.
If you want to place bets on the date of first detection of some gravity wave then some physicists would bet on 2016, probably the majority would bet 2017. A few pessimists would say that we will discover unexpected problems that might take a few years to solve."
Do read the book, it is well written.