When two stars collide, or a massive star blows up, the fabric of the universe warps and springs back sending gravitational waves across the cosmos. So Einstein predicted. The wave motion would be very tiny. But to watch it, scientists must build very large instruments, like the 4km long Laser Interferometer Gravitational-Wave Observatory (LIGO).
If it works, it should make headlines worldwide. But more importantly, it opens up a new way to observe distant phenomena like black holes, supernovae, neutron star collision, galaxies tearing one another apart and much more.