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I'm no physicist either. Maybe I wish I were, though. And no, your ideas here are everything but simple-minded, imho. On the contrary, being a non-expert lets you play with things with much more freedom than otherwise (like sci-fi authors), and then actual physicists can take over, sort out the testable and go with their own gut feeling.

(note: I assume TFA = Trend Filtering Algorithm, please correct if I'm wrong).

> galactic rotational axes are correlated on extremely large scales

I think "correlation does not imply causation". While this is a plague in economics, psychology, sociology, biology (non-exact sciences), it also applies in physics. We really don't know in this case, we just observe what you said but "correlation" is bias that typically hinders actual research, experiments — it's the idea that you'll see what you want to see and even design the experiment to show it, which is a very slippery slope, basically a form of "confirmation bias".

I want to stress that I in fact agree with you, in sentiment and analysis, but I'm just voicing my internal "devil's advocate" voice here: mental models and frameworks that are wrong, and not only make my intuition thus false, but deeper than that prevent me from seeing other solutions, from 'forking' every step of the way according to new data.

I guess I'm prefacing my conclusions here:

- there is no "dark matter", there is X that explains a bunch of discrepancies between theory and observation. Each such discrepancy could be explained by a different X (Y, Z...) or a sub-part of X (like mass relates to gravity, but also density, thus heat profile, etc).

- there is always a "fundamental correlation" between literally everything (aren't each and every organ of our body, every inch of this Earth the literal 'children' of supernovae and neutron stars explosions and black hole cataclysms?)

The hard part is to find first-degree (i.e. direct) relations, of the kind described by physics equations. It's not always discrete and binary, but it can be done — for instance I can tell you that "hunger" among the population is as certain a path as it gets to revolution. Not sadness, not lack of freedoms, not violence physical or mental, not even cataclysms have a firmer grasp on rebellion than the empty stomach of our children. It's as direct a path from A (hunger) to B (revolution) as you can get, statistically in all of history (you have days before people rebel, a very few weeks at most).

The alignment of galaxies are obviously related to something, which might yet leave individuals otherwise independent — like metal rods align, each of their own "volition", with a magnetic field; there is no correlation between the rods but rather a macro phenomena. Functionally a vector space wherein rods exist, not a function from rod i to rod j for any (i,j). Galaxies might work this way too — this is my intuition. No spooky supraluminal action at a distance, just a "gravitational polarity X" that averages to orienting space locally at large-enough scales. At a higher scale in 3D, it's probably more about tangents lines (i.e. said "polarity" is of the flow, the streams of galaxies, possibly "dark matter" which is a Y here, possibly distinct from the X phenomena) than a macro-universal sense of rotation (although it's a perfectly valid solution too, indeed many symmetries are broken for our cosmos to exist, namely anti/matter, causality, or chirality.)

Rotation discrepancy could be related to X and/or Y or yet another Z phenomena (my money is on the supermassive blackhole in the center, which I think we're not fully understanding all effects yet, far from it, but meh it's bias and subjectivity on my part).

[Btw, since you seem to like this kind of discussion, I'd strongly recommend you follow Anton Petrov on YouTube[1]. He's a wonderful young scientist who makes short 5-15 minutes videos on new astrophysics / astronomy papers every day or so. For me, it's just the best way I've ever had to 'quickly' keep track of the latest observations and theories, while hearing the explanation and questions of an expert. Dr Becky[2] is another newcomer in the field of intelligent vulgarization, and she's on a path to awesomeness as well.]

I've been into these things since my teenage years (late 1990s) and it's incredible how much more observation we have now, how much more material there is to think about. It's a truly great time for space amateurs.

[1]: https://www.youtube.com/channel/UCciQ8wFcVoIIMi-lfu8-cjQ

[2]: https://www.youtube.com/channel/UCYNbYGl89UUowy8oXkipC-Q



Sorry. TFA is "this f... article".

I agree about the "correlation does not imply causation" plague. It's especially problematic for purely observational sciences, where experiments are impossible or unethical. Prototypically for epidemiology, but also for astronomy and cosmology. And yes, it's a slippery slope, even for experimental sciences.

I get what you say about the alignment of metal rods in magnetic fields. So yes, there could be some gravitational polarity over extremely large scales.

I see that I was getting stuck on the idea that changes can't propagate faster than light, no matter what the mechanism. But now I get how arbitrarily separated stuff can be similarly affected by a given source. For example, there was a recent article about hot gas "sloshing" in a galaxy cluster.[0]

And thanks for the YouTube links :)

0) https://phys.org/news/2020-01-sighting-hot-gas-sloshing-gala...


Aha, TFA, right :p

Yeah, the faster-than-light topic is actually a very, very tricky one, even for seasoned astro-peeps it seems.

I didn't mention PBS Spacetime[1] but it's probably the best place to start for best-in-class high level mojo in astrophysics. Tons of back-catalog. Really great quality production. Less 'newsy', more 'substance' than the other two I mentioned (these are my trio on the topic).

Case in point: they do a fantastic job at explaining, notably time shenanigans. They basically made it click for me, notably for FTL (Faster-Than-Light) space expansion, cosmic inflation, etc. Fantastic-everything about them, can't recommend enough.

One thing, though: my best way of framing the FTL limit is in terms of a speed limit (c) to transfer "information". This is why entanglement is a valid principle, it does not violate c because entanglement cannot be used to transfer information faster than light[2].

So "structure" can change arbitrarily fast, from the perception of its objects, its contents; but "information", the contents, the objects, they are bound by c and all the rules actually defined by said structure.

I really don't know if that's the correct view, but it seems to work to explain (actually rule out) most light-speed paradoxes, so...

[1]: https://www.youtube.com/channel/UC7_gcs09iThXybpVgjHZ_7g

[2]: I think this vid does a good job at explaining why: https://youtu.be/2_4l5_G3dnM




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