This question made me think. It was asked why matter is transparent for gravitational waves. it was said (more or less) that because the waves interact with mass very weakly, mass makes them pass easily.
But What physical circumstances can absorb gravitational waves? Are there situations thinkable that can absorb gravitational waves? Or, at least, the major part of it? All massive objects react to their presence, so aren't there configurations of masses that absorb them, like a photon is absorbed by an atom? I don't mean black holes, obviously.
The situation depends both on the configuration of mass and the form of the wave. Let's not be imparted by the reality of what's in our universe. we can imagine every possible configuration of matter and every possible form of gravitational waves, regardless if they truly exist in the visible universe. Is it possible, when we let imagination run wild, to find a scene in which waves are for the major part absorbed?
will a very short wave be absorbed by a thick layer of mass? Obviously (if the layer is thick enough). I was thinking along the lines of masses that start to vibrate and dissipate the kinetic energy in some kind of way. Maybe a plasma that turns the vibration into electromagnetic radiation.
Can we somehow create a configuration of mass for which "eigenstates" for the gravitational waves exist, more or less for, say, the energy eigenstates of the hydrogen atom? When the right electromagnetic radiation is fired at the hydrogen atom, the radiation is absorbed. Can we make something similar occur for certain gravitational waves and certain matter distributions that are "fit for" the waves?