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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?

Deschele Schilder
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You can reverse the time and find the situation in which these Gravitational Waves can be absorbed like in Binary systems that originally made it if this comment is right it means these binary systems will get larger and can act like a Gravitational-wave detector. at least it is what comes to my mind.

Reza Naderi
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  • That's a nice thought (+1)! One thing though. Where do the gravitational waves approaching the binary system originate? – Deschele Schilder May 24 '21 at 21:12
  • binary systems in the neighborhood I guess – Reza Naderi May 24 '21 at 21:15
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    The incoming waves are spherical : they come from every direction with some coherent phase. I am not sure any reasonable physical system could produce such waves – SolubleFish May 25 '21 at 08:08
  • I agree with your view @SolubleFish but consider the time when these waves are created by some binary system this system itself does not have spherical symmetry, so how can we expect the waves it propagates have a spherical shape? I think of them as spiral-like shapes, However, creating this kind of configuration and focus it on a local place is too hard if not impossible I guess. I thought of an example of a close universe and a binary system inside it, so these G waves can come back at some finite time in the configuration mentioned earlier and absorb again. – Reza Naderi May 25 '21 at 18:40