Great work! It seems that the approach is similar to the stochastic collapse, but the nonlinearity here is effective, due to the feedback loop between quantum and classical, is that right? Would that still cause any observable features due to this effective nonlinearity, apart from possibly heating?

We're not really sure. There are many theory predictions: like stochastic background from phase transitions in the early universe, inflation, etc. From the compact objects, these could be light primordial black holes or exotic stuff like Q-balls, gravastars or boson stars.

We'd need to adapt calibration and data acquisition techniques, but we could already add this in LIGO or GEO600! Why not? That would be fun!

Have a look: www.nature.com/articles/s41...

We compute the sensitivies of different detectors and show that all modern detectors hare quite comparable to the dedicated high-frequency detectors. We could also build small-scale detectors which have good sensitivity in a broad band.

In fact, the sensitivity of the detectors depends on the point on the sky from where the signal is coming from. Usually, we assume the signals to come from zenith. And for such signals we're indeed not sensitive above a few kHz.

Not the case for other points on the sky (like on the image here)!

Published in Scientific Reports, we explore the sensitivity of the detectors at high frequencies. Funny enough, it's actually been known for decades, but not to the broad community, and many colleagues assumed that detectors are limited to a few kHz.

www.nature.com/articles/s41...

Thank you!

That's a good point! My thinking was that the set of 3 detectors is synchronized "two-way" with light, but then detects GWs arriving uniformly from various directions, and then any anisotropy would appear as deviations from this "average" two-way value. But I'm really out of my depth here...

That's a good point, I've also been reading up on it since, but it's not so clear in the case of a different carrier (GWs)...I mean, the clock synchronization in this case is directional (the detectors are in different places), but the GW is not. Thus we kind of show the isotropy already.

...alternative theories with direction-dependent speed of light, but that's a curious application of GWs, I think. Unless the logic is flawed, of course :)

[1] journals.aps.org/prd/abstract...

we have two independent measurements: the speed of gravity is equal to c, and the one-way speed of light is equal to the speed of gravity. Thus, one-way speed of light is equal to c! To within ~1% or so, whatever the current statistics would be. Not sure if that's enough to exclude...

From statistics of GW events, as it's shown in [1], we can independently estimate the speed of gravity to be equal to the speed of light to within ~1-2%. That is based on the first 50 detections. Now we have seen over 200 events, and I'm sure new statistics will pin this down well below a %.

So...

...found that the speed of gravitational waves equals the speed of light up to the ~8th decimal digit. But that in itself doesn't tell anything about the speed of light!

Luckily, we have another way to measre the speed of gravity: using the delay in arrival of a GW to different detectors.

...I think :)

Curiously, I haven't found this argument anywhere in the literature. So I want to argue that we actually have measured the one-way speed of light. Using...gravitational waves!

In 2017, we saw GWs and light coming from the neutron star merger GW170817. From this measurement, we...