Posted by instagraham 5 days ago
Related question: the horizon of a black hole is expanding when the mass increases. Could this map to the expansion of our universe, which seems to expand faster and faster?
So many unanswered questions.
But if objective spin directions are roughly evenly split because the universe is isotropic, the spins from our viewpoint ought to be evenly split as well.
If they're not evenly split, the universe must have a preferred axis, which would be an amazing discovery. I guess if the preferred axis just happens to align with our own galaxy, that would support the alternative theory that it's due to an observation effect such as doppler shift.
Either way, it's incredibly cool to have such a simple but totally unexpected observation pop up out of nowhere.
Note that this is not that easy to determine:
When done manually, the determination of the direction of rotation of a galaxy can be a subjective task, as different annotators might have different opinions regarding the direction towards a galaxy rotates. A simple example is the crowdsourcing annotation through Galaxy Zoo 1 (Land et al. 2008), where in the vast majority of the galaxies different annotators provided conflicting annotations. Therefore, the annotations shown in Fig. 1 were made by a computer analysis that followed a defined symmetric model (Shamir 2024e).
I can’t think of any that would make much sense as top/bottom would mean that there needs to be a relative universal point to reference and as far as I know, that doesn’t exist.
If the distribution was truly random, and the universe is isotropic, we should see roughly 50/50.
Or maybe not, anyways back to work.
It should be fairly easy to determine the rotation direction of any (spiral) galaxy we can see, based on reasonable assumptions about the relationship between rotation and the configuration of the spiral arms. There should be thousands or millions of visible galaxies for which this could be determined (out of the estimated 2 trillion galaxies in the observable universe). Perhaps I'm missing something, but why bother reporting a result from such a tiny sample?
It should also be possible to derive more detailed information that just clockwise vs. counter-clockwise. The rotation of a galaxy defines a direction (the galaxy's rotational north pole) and a point on the surface of an imaginary sphere. This could be determined by the galaxy's apparent rotational direction, its orientation, and its position in the sky. It would be interesting to see a plot of those points. In principle, they should be random. (If the points spell out "Go stick your head in a pig", I'll be very sorry that Douglas Adams didn't live to see it.)
Or maybe they're just billboard sprites, always facing the camera, with clockwise animations.
Study is at around 3σ (like 62 heads in 100 flips). It is more likely that future studies disprove it, and this is an issue with the methods, if I am of the betting type... :-)
https://www.comsol.com/blogs/why-do-tennis-rackets-tumble-th...
Spiral galaxies spin, they do not tumble unless hit by another galaxy.
Elliptical galaxies are like gravitational convection and don't really have cohesive "rotation", however.