i'll try...:
movement of all matter distorts space-time. when something moves it creates gravitational ripples, that squish everthing in their path along one axis (and strech about the mutually orthogonal axis)
unless you're looking at an incredibly large mass (i.e. a black hole), these distortions are unbeleivably small, and so rather difficult to spot.
i think the idea is we'll get to learn more about massive objects, if these waves can be 'seen'.
(feel free to correct this, anyone!)
