Gravity waves perpetual motion?

[wolram]

I have tried to find out how gravitational radiation can be suppressed or decay, there may be some thing in the literature but i can not find it, also is it possible for gravity waves from different distances and times to merge?

[AEM]

I have tried to find out how gravitational radiation can be suppressed or decay, there may be some thing in the literature but i can not find it, also is it possible for gravity waves from different distances and times to merge?

For your second question, do a Google search on Colliding Plane Gravity Waves. You'll find plenty of references to papers on the subject.