There´s an ongoing debate if gravitational waves (or gravity?) contains energy.
But what if a very strong gravitational wave hits an atom. Let´s for simplicity say a hydrogen atom. Not a wave that is supposed to have hit us recently (that´s too faint to bring about a modification in the hydrogen´s energy levels), but let´s say the same wave very close to the it´s origin (the two black holes), and put the hydrogen atom there.
I assume that the energy (the hydrogen is in the ground state) of the hydrogen during the passage of the wave is tilted a little bit because of the asymmetric space surrounding the atom (as in a very strong static field). Shall after the passage the electron emit a photon, to restore the minimum energy, or shall the energy disappear again in the curved spacetime of gravity? I find it hard to believe that afterwards the energy is again put back in the gravitational field. Of course is after the passage of the wave the situation again the same as before, but maybe in the short time the wave passes, the atom decays to a lower state and afterwards get´s a bit energy from the vacuum, to restore again the normal ground state.
Is this the same as saying that the gravitational waves (and the same can be said about gravity: just put a hydrogen atom in a very strong curved spacetime) possess energy? So not only energy passes through spacetime, but spacetime also possesses energy?