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James Webb Space Telescope reveals that most galaxies rotate clockwise

smithsonianmag.com

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Re: James Webb Space Telescope reveals that most galaxies rotate clockwise

#11

Post by misja111 »

Everybody here is talking about the black hole hypothesis, but to me it seems that the other explanation, a wrong assumption about the rotation of our own galaxy, is more likely: because it could explain 2 other problems as well.

> "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.”

Re: James Webb Space Telescope reveals that most galaxies rotate clockwise

#14

Post by exe34 »

0xEF wrote: post #7
d--b wrote: post #4

> This preferred direction of spin might be due to one of two reasons: either our entire universe exists in a black hole, or astronomers have been measuring the universe’s expansion incorrectly This is the subtitle of the article. It’s such a great summary!

I'm not well versed in celestial mechanics, but I see a lot of "we're in a black hole" comments so far, and I'm super curious as to whether or not we know why black holes prefer a direction of spin. Can you (or anyone, really) shed light on that?

I think it would be more that the entire universe is in a black hole spinning in a certain direction.

Re: James Webb Space Telescope reveals that most galaxies rotate clockwise

#16

Post by zurfer »

Complete layman's question: If we would indeed be inside a black hole wouldn't we be able to observe new energy and matter entering?

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?

Re: James Webb Space Telescope reveals that most galaxies rotate clockwise

#17

Post by iainmerrick »

snitty wrote: post #6

If we were on the other side of those galaxies, wouldn't they look like they were spinning counter-clockwise? Or are they measuring spin some other way?

I was wondering the same thing -- "direction of spin" is ambiguous on its own, you also need to pick which direction is up.

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.

Re: James Webb Space Telescope reveals that most galaxies rotate clockwise

#18

Post by perihelions »

misja111 wrote: post #11

Everybody here is talking about the black hole hypothesis, but to me it seems that the other explanation, a wrong assumption about the rotation of our own galaxy, is more likely: because it could explain 2 other problems as well. > "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 gal…

I don't understand how the 1e-16 Hz rotation of the Milky Way affects how we perceive other spiral galaxies' orientations.

Re: James Webb Space Telescope reveals that most galaxies rotate clockwise

#19

Post by like_any_other »

> Due to an effect called the Doppler shift, astronomers expect galaxies rotating opposite to the Milky Way’s motion to appear brighter

How does this work? The page it links to doesn't explain why rotation would matter.

Edit: To clarify - one side of the galaxy would be moving towards us, and one away from us, no matter which direction it spins in, so this should not affect the average brightness of the entire galaxy.

The original paper (https://academic.oup.com/mnras/article/538/1/76/8019798?logi...) links to a few papers discussing this, among them https://www.mdpi.com/2073-8994/15/6/1190 It doesn't answer my question (or if it does, I didn't understand it), but it gives a magnitude for the expected effect on brightness - 0.6%. I do not think that would explain the 1:2 ratio of observed spin directions.

Re: James Webb Space Telescope reveals that most galaxies rotate clockwise

#20

Post by iainmerrick »

0xEF wrote: post #7
d--b wrote: post #4

> This preferred direction of spin might be due to one of two reasons: either our entire universe exists in a black hole, or astronomers have been measuring the universe’s expansion incorrectly This is the subtitle of the article. It’s such a great summary!

I'm not well versed in celestial mechanics, but I see a lot of "we're in a black hole" comments so far, and I'm super curious as to whether or not we know why black holes prefer a direction of spin. Can you (or anyone, really) shed light on that?

It's not that black holes prefer a direction, it's just that they have a direction at all. It's one of the very few observable properties of a black hole.

If I'm following correctly, the "we're inside a black hole" idea is a major reach, connecting at least two unrelated concepts (black holes could contain baby universes; black holes have spin). But it's a really interesting idea and not obviously wrong.

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