[sulam]

Mass is energy. As I understand it, the waves are created because of the rapid acceleration of large masses, either black holes or neutron stars. These waves do transmit energy and the final resulting body will be less massive at least partially because of that.

[dwaltrip]

I believe all accelerating masses emit gravitational waves, but that most do so on an absurdly small scale. As if the 10^-20 scale of the black hole merger gwaves isn't small enough...

[lou1306]

You are correct. In fact, Einstein predicted gravitational waves but considered them un-observable, and the LIGO interferometer is 1km long exactly to magnify the effect.