Yep, it was not LIGO. LIGO uses Michelson inteferometer, while I'm looking for Sagnac interferometer results. As far as I remember, I started with that article: https://arxiv.org/pdf/gr-qc/0401005v3.pdf , then started searching of articles about rotation sensing mentioned in the article. It looks like that it: http://porto.polito.it/2460498/1/G_GranSasso_18.pdf (or a newer paper).

I looked at FIG. 10: The rotation rate of the Earth measured with the G ring laser as a function of time. Averaging over 2 hours was applied to a corrected dataset, where all known geophysical signals have been removed

But their measurements were done with up to 1E-11 accuracy, which is just not enough, because (IMHO) signal will be 10-100x weaker than gravitational wave, so, IMHO, 1E-21 accuracy is required. So my comment, which started that discussion, is just wrong. :-(

About war: war is still here. We are switched to professional army (hence no new conscription) and situation is stable enough (1-7 killed, 3-15 injured every day). Crimea is still captured. Next week will be hard because I will have meeting with my killers. But, after 2 month of preparation, I forgot about one small but important detail, so I am basically unprepared now. Unfortunately, I cannot stop my play because I want to free Crimea next year, and lot of people are already involved, and contact with Russians is important in this case, so I will try to improvise, like before, when I was unprepared. I will delete that text tomorrow.

To develop intuition, first you must understand that we are not moving through space, we are propagating through space, because we are waves. Actually, nothing is moved, hence no drag between material objects and space.

I will use video above as example. If you measure speed of sound in water between waves around droplets, you will found that speed of sound is constant, regardless of speed of droplet, because water is not moving at all. Water is contracting and expanding in place. We can perceive «lower» speed of sound in water in case of really big waves, because distance to travel will increase slightly. This is how gravitational waves are caught. Otherwise we are out of luck: we are counting waves to measure distance and time, and that count is not changing when space contracts and expands.

So the only two solutions I see to prove that space is real thing, like water, using waves only, is to:

1) cool vacuum below 0K — cooled vacuum will have slightly different speed of light (someone in USA is already working on that, shortly after discussion about „frozen vacuum“ at HN ;-). It's possible to cool or heat water using acoustic, but we are propagating through space, so cooled vacuum will be left in place while we will propagate away. Hard task. Can be done in interstellar space if ship will be able to stand at same place, or if large enough setup will be used quickly.

2) measure tiny asymmetry of front vs back of pilot wave using Sagnac effect to show that there are small deviations between predicted values and actual values, which are varying over year, as direction of movement and our position in Solar system changes (Solar system already had that asymmetry as measured by Voyagers). I saw (or I think that I saw) paper with exactly that information: experiment with large Sagnac interferometer conducted for over year with high precision which was focused on these deviations, but I still cannot find it. :-(