I can imagine that wobbliness comes from chaotically passing strong gravity waves of very high wavelengths coming from outside of the observable universe and from before times of Big Bang.

There's no specific reason that forces us to believe that Big Bang was the actual beginning of everything. It might have been "local" high energetic event happening in much larger structure.

For example try to imagine how the collision of two dense clusters of trillions of black holes each traveling at nearly light speed would look like from the point of view of the dust swirling in-between and around them. I can't imagine it would be very different from what we observe in our universe.

Don't you think that we would be able to observe some anisotropy in the data if that were the case? (Note: I have no clue, but it seems unlikely...)

Maybe? I don't know. I imagine we don't have any good ways to observe gravitational waves, even fairly strong ones with periods of millenia or even centuries which are still very short times on a galactic scale.

And apart from that, I think that we can only look at CMB and conclude that it's a bit wobbly. Must be quantum fluctuations, sure, why not, but is it only the quantum fluctuations? Or maybe the spacetime between us and CMB source is a bit wobbly too?

Another thing is large scale structure of our universe. Visualizations look like foam. Planty of chaos that wobblines can safely compose into.

I think the work of those scientists is very important because it might allowed us to pinpoint how strong distortions of the spacetime would need to be to explain what we see and maybe we could narrow down the range of frequencies which might gives us ideas how to look for them.

Simplistic and grandiose assumptions make our current best model of the universe a bit restrictive. To the point that we are starting to find direct counterexamples for our theories derived from it. Mature galaxies way too old. Megastructures way too large. CMB fluctuation not exactly fitting best theoretical models. Unreconcilable differences between Hubble constant measured from CMB and that measured from galaxies.

I think accepting a bit of chaos beyond what we currently believe is an inevitable way out.

> I can imagine that wobbliness comes from chaotically passing strong gravity waves of very high wavelengths coming from outside of the observable universe and from before times of Big Bang.

Could gravitational waves from outside the observable universe actually reach us? I thought the same limitations apply as with any other information.

Why wouldn't they be able to reach us if they started traveling in our direction before the event of the Big Bang?

Even though the spacetime expands if they started their journey early enough they might have been arbitrarily close to us at the moment spacetime within our observable universe started expanding.

For example the front of some gravitational wave originating from outside could be near the times of Big Bang as close to us as the matter that eventually formed Andromeda galaxy. As waves travel with the speed of light it would passed us very long time ago.

The limitations you speak of are calculated with assumtion that both all the matter in the whole universe and the spacetime itself started at the moment of Big Bang.

If there was matter outside our bubble of observable universe and time before the Big Bang those limitations are not valid for anything originating there.

Is that the "postquantum" bit? i.e. not that spacetime is quantized as such, but that it's not a uniform continuous medium at all scales, that classical mechanics would assume.