←back to thread

Is our universe trapped inside a black hole? This JWS Telescope discovery

(www.space.com)
81 points janandonly | 3 comments | 15 Mar 25 13:03 UTC | HN request time: 1.327s | source
Show context
fprog ◴[15 Mar 25 14:18 UTC] No.43372696[source]▶
An alternate hypothesis which seems equally interesting, albeit for different reasons, is at the end of the article:

> Another explanation for why the JWST may have seen an overrepresentation of galaxies rotating in one direction is that the Milky Way's own rotation could have caused it.

> Previously, scientists had considered the speed of our galaxy's rotation to be too slow to have a non-negligible impact on observations made by the JWST.

> “If that is indeed the case, we will need to re-calibrate our distance measurements for the deep universe," Shamir concluded. "The re-calibration of distance measurements can also explain several other unsolved questions in cosmology such as the differences in the expansion rates of the universe and the large galaxies that according to the existing distance measurements are expected to be older than the universe itself."

replies(2): >>43372859 #>>43373645 #
perihelions ◴[15 Mar 25 14:44 UTC] No.43372859[source]▶
I'm utterly confused what's going on. They're measuring galaxies' rotations by looking at images of the subset that are spiral galaxies, and checking which direction the arms spiral. They describe their image processing algorithm in their paper [0]. (it's around figure 3)

How can local movement of stars within the Milky Way affect which way spiral galaxy arms are pointing?

[0] https://academic.oup.com/mnras/article/538/1/76/8019798.

replies(3): >>43372891 #>>43372933 #>>43374338 #
1. Georgelemental ◴[15 Mar 25 14:48 UTC] No.43372891[source]▶
Read section 5.2 of the paper
replies(1): >>43372961 #
2. perihelions ◴[15 Mar 25 15:01 UTC] No.43372961[source]▶
Do you or other HN commenters understand it in a satisfying way?

The author writes about the Doppler effect creating a systemic bias in brightness depending on which way the galaxies are rotating. I don't understand that argument either, but it's moot, because they state categorically that that effect would be too small to explain their results. ("This explanation is challenged by the fact that the effect of the rotational velocity have merely a mild impact on the brightness of galaxies, and therefore is not expected to lead to the dramatic difference of 50 per cent in the number of galaxies as observed through JADES.")

That's the only explanation I recognized as an explanation. Then I lost track of their argument following that. They refer to several speculative physics theories like MOND, but I don't understand them to be saying something that concretely predicts distant galaxies to appear to be rotating differently.

I'm appealing to anyone on HN who knows enough about this field to understand the meat of this argument.

replies(1): >>43373149 #
3. perihelions ◴[15 Mar 25 15:31 UTC] No.43373149[source]▶
It's a moot point, but I *really* don't understand the Doppler-shift bias mechanism either. Help?

This one of the author's other papers they cited in this one,

https://www.mdpi.com/2073-8994/15/6/1190

I'm completely lost how they're eliding between the rotation orientation of the Milky Way galaxy, and relative linear velocities with stars in other galaxies. In the special relativity argument, where does the rotation axis of the Milky Way enter?