Gravitational waves are ripples of gravity created when large objects move through space and time.Space.com: Cosmic Superstrings Might Sing in Gravity Waves (January 9, 2008) Objects that have more mass create larger gravitational waves and the faster an object moves, the more gravitational waves it will produce.NASA: On the Edge: Gravitational Waves

"As far as we know, the Universe began 13.7 billion years ago. We have the dream of listening to that Big Bang itself by detecting and studying gravitational waves. It will give us a chance of listening to the dark, invisible side of the Universe."—Karsten Danzmann, Investigator at the Max-Planck-Institut fur Gravitationsphysik in Hanover, Germanyesa: Observing Einstein's gravitational waves (April 8, 2005)