> First off, thanks for engaging in a bit of debate. I came off a bit needly when I was trying to allude to a technical point.

Totally got that, no worries. And yes, I do see where you're coming from. But I base my argument not on the concept of the quasi-static potentials of a field theory with infinite speed of potential propagation (i.e. Newton).

> Even in a classical case, an external observer witnesses a periodic gravitational potential

But this assumes instantaneous propagation of the potential.

In every field theory in which changes (i.e. disturbances) of the field propagate with limited speed any accelerating movement of the generating sources of the field will create waves in that field.

Wiggle around some electric charge and you get EM waves carrying away energy. Einstein's first (and failed) attempt toward a relativistic theory of gravity was to apply the concept of retarded potentials. Didn't work out, something was missing. But even in such a retarted gravitational potentials theory, gravitational waves do show up.

> and cause Mercury to precess.

Isn't the precession of Mercury an effect of contraction of space by mass and that at the radii of perihel and apehel the metric of space is different?

Even the tiniest spec of dust moving at Mercury's orbit should experience the same precession, yet will radiate much less energy away through gravitational waves, as far as I understand it.

> but that's not what we typically mean by "gravitational waves" which are, formally, metrics admitting a covariantly null vector field.

Yes I know, GR permits for additional wave modes, that you don't have in e.g. electrodynamics in the vacuum. But I think it's dishonest to dismis the more "mundane" modes to be not gravitational waves.

As far as I see it, in any field with limited propagation delay, any disturbation propagating through the field is a true wave in a its right in that field. If you want to reach a fundamental theory which can be applied universally without the requirement of a-priori choices being made on the system modelled, all aspects of the theory must be "enabled" all the time.

> As such, we can safely analyze it within the realm of Newtonian mechanics which only admits DC offset "gravitational waves"

… which is what I was saying by having long integration times. And as far as nature goes, in any real system there is no true DC offset, because that would require integration from -inf to +inf. Yes, I did mention "DC", but in a practical sense DC just means "frequency which interval is an order of mangitude longer than the integration time of the observation".

Here's a little food for thought: Say you have an mechanical shutter and shine some long coherene (= narrow bandwidth) laser through it. Then you quickly close and open the shutter. How does the spectrum of the light look like after the shutter? Integrating over the spectrum before and after the shutter does the power change? If so where did the delta in energy go / come from?

This is some practical wave dynamics engineering we laser guys do on a regular base and solely rests on the fact that in a universe of finite age there is no such thing as a true DC component; you can get infinitesimally close to DC, but never reach true DC in the first place. So for example we use (fast) modulators to create spectral sidebands and even do things like carrier and single sideband suppression to shape the light to our bidding; becomes really interesting if you throw nonlinear effects into the mix that allow to all sorts of up-/downconversion.

> I'm not sure what you are referring to with the "flipping" procedure, but I'd guess it's more about homogonizing erros rather than generating "force pulses".

You're remembering right. What you do in the Cavendish experiment is to rotate the big masses by 90° so that the torsion pendulum is twised in the opposite direction, so that offsets in the pendulum cancel out. However consider this: Instead of moving the big masses at descrete times, let them (slowly) oscillate, maybe at the resonance frequency of the pendulum. If the pendulum has a high Q factor it will eventually reach quite the significant oscillation amplitude.

So what is this? I'd say this is energy transfer through gravitational waves in the near field.