alt.hn

3/31/2025 at 10:31:39 AM

James Webb Space Telescope reveals that most galaxies rotate clockwise

 https://www.smithsonianmag.com/smart-news/james-webb-space-telescope-reveals-that-most-galaxies-rotate-clockwise-180986224/

by instagraham

3/31/2025 at 10:27:02 PM

> The same solo author (a computer scientist) has made many similar claims based on a variety of datasets. Often coming to completely contradictory conclusions. Some of these claims have been followed up by astronomers, who found errors in his analysis and poor statistical tests. His claims have been discussed in this sub before. Independent studied have found no significant evidence of anisotropy.

https://academic.oup.com/mnras/article/534/2/1553/7762193

https://ui.adsabs.harvard.edu/abs/2021ApJ...907..123I/abstra...

https://ui.adsabs.harvard.edu/abs/2017MNRAS.466.3928H/abstra...

>Take his claims about JWST as an example. In 2024 he wrote a paper about some early data, claiming to find more galaxies rotating with the Milky Way. He claimed based on a sample of just 34 galaxies that the signal was significant. Now he has looked at a wider dataset of the same area, which should allow him to verify his analysis. But it shows exactly the opposite, more anti. So he writes a paper saying this new result is definitely significant but doesn't reflect on the fact he has written two papers which contradict each other. He has failed to reproduce his own result. The take away is that his results are not as significant as he claims. He's also looking at a tiny area, and nearby galaxies can have correlated spins. He doesn't take this into account either. There are multiple JWST fields in different directions he could examine in different directions to test his claims, there are two JADES fields, but he only publishes one.

>I do wish the MNRAS editors would take measures to stop publishing low quality claims like this without more robust review. If you look at the text, it’s largely repeating results from his old papers. There’s very little discussion of the new results.

source: https://www.reddit.com/r/cosmology/comments/1ja9i53/the_dist...

by nabla9

3/31/2025 at 10:42:16 PM

Thank you. That's a shame, it was a cool-sounding story, just unlikely enough to sound plausible.

by iainmerrick

4/1/2025 at 2:33:15 AM

Clockwise? To which observer?

by datavirtue

4/1/2025 at 2:42:03 AM

It's arbitrary, but that's fine. The important part would be any asymmetry. The Big Bang implies that there shouldn't be one.

by jfengel

4/1/2025 at 5:40:29 AM

Just to be clear, it's not fine at all in any "this is a fine physical theory".

A statistically unlikely arrangement of cosmic objects relative to earth only - earth in particular, violates not just the properties of the big bang but "the cosmological principle" and common sense. It's a garbage theory, a headline that makes a math person just have a "how stupid do they expect the average person to be" reaction.

by joe_the_user

4/1/2025 at 8:17:28 AM

No, I don't think you have this right. There was no physical theory claimed, just a very surprising observation (though of course it turns out to be bogus). If it were true it would require an incredible explanation, but that's not at all the same as just proposing an outlandish theory with no motivation.

If you take the approach you describe, I think you'd have incorrectly dismissed the observation that distant continents look as if they could fit together like jigsaw pieces, as it implied the impossible theory of continental drift. Isn't that just the same sort of outlandish, clearly ridiculous observation as "there's an asymmetry in the way galaxies rotate"? Except of course that one observation is correct, and the other isn't. You can falsify it just by checking the observation, rather than dismissing it out of hand as impossible.

Edit to add: maybe a better comparison would be to the violation of parity conservation in the weak force, as proposed by Yang and Lee, although I just learned from wikipedia that the actual experiment was performed by Wu. If you think that isn't a valid analogy, I'd be really interested to learn why.

by iainmerrick

4/1/2025 at 8:05:14 PM

TL;DR; all your analogies are less extreme than the claimed observation because they don't violate the principle that physical laws apply uniformly throughout space/time.

Theory or data/observation is a sort of layered thing. The lowest data level is the data that the Webb or whatever telescope gets, then you have the theory that what's being represented in galaxies and you have all suppositions of standard cosmology and in that you have a posited theory that galaxies as viewed from earth rotate in a "given direction".

The thing about this theory/observation/whatever is that it's a pattern that, if true, would only be visible on earth (or in vanishingly small area relative to the claimed area of the pattern). If such a thing were happening, it wouldn't just contradict current physical laws. It would contradict the paradigm science has had since Newton that physical laws apply uniformly throughout the cosmos and especially that the earth isn't the "center" of the universe. The observation of continents fitting together or violations of parity conservation aren't analogous because they involve things that can be meaningfully observed anywhere.

All this is to say "extraordinary claims require extraordinary evidence". As far as investigating. I could or someone could, spend the effort needed to investigate this. But science actually should have one level of claim+evidence that's "interesting, let's investigate" and another that's "oh dear, that's really crank stuff and you'd need to truly vast evidence before I'd even look". Other science would be overwhelm by bullshit.

by joe_the_user

4/1/2025 at 7:16:25 AM

?? he's saying "it's fine" if it's defined as "clockwise" arbitrarily.

by thrdbndndn

4/1/2025 at 2:57:32 AM

Us?

by pests

4/1/2025 at 6:10:57 AM

On pictures Milky Way is usually shown to rotate counterclockwise. As is solar system.

by GoblinSlayer

3/31/2025 at 11:33:57 PM

The author is also a proponent of tired light theory, which has been thoroughly refuted.

by antonvs

4/1/2025 at 11:29:21 AM

I was prepared to be mindblown. He lost all credibility to me

by pal9000i

3/31/2025 at 10:47:04 PM

Wow and not even 24 hours after Trump takes aim at the Smithsonian.

*) The article is from March 17.

by twothreeone

3/31/2025 at 11:28:09 PM

Is this just word association, or you saying there’s some notable connection here?

by khazhoux

4/1/2025 at 12:42:03 AM

If I was an editor at the Smithsonian, I'd be worried about peddling bogus theories for clicks at a time my employer is under scrutiny from the government. Apparently, they are not worried though, which astonishes me, hence my comment.

by twothreeone

4/1/2025 at 12:59:24 AM

Out of all of the things, this government is scrutinizing, factual, accuracy, and quality of reasoning don’t seem to be of particular importance.

by brookst

4/1/2025 at 2:42:59 AM

No, but having people call you out would make you feel even more vulnerable than you already are.

by jfengel

3/31/2025 at 10:59:35 AM

Potentially a very dumb question, but seeing the difference between cyclones and hurricane on earth (clock-wise, anti-clock-wise)...

Does it mean that we are, potentially, on one of two poles(?) of the observable universe, if we're observing most galaxies around us rotating a certain way?

by keyle

3/31/2025 at 8:27:50 PM

Dumber question: would a galaxy that appears to spin clockwise appear to spin counter-clockwise when viewed from the other side? Does this imply that the real question is why galaxies' relative orientations seem to favor more spinning in one direction than the other?

by kmoser

3/31/2025 at 9:52:02 PM

Yes, that's it exactly. There's a net asymmetry in the distribution of galaxy axes. "Clockwise" by itself is a relative term. This seems to be the paper in question: https://academic.oup.com/mnras/article/538/1/76/8019798

That said: I'd wait a bit here. This is a single-author paper by a non-astronomer (he's a CS professor). The sample size seems small (N=263), and the measurement coarse (he's just bucketing galaxies into "rotating in the same/different direction as the Milky Way"). And the technique may be too novel for its own good. The gold standard here would be to look at differential redshift, but all he's doing is applying a ML filter to detect the "twirl" direction in the image of the spiral galaxy. Which... might be amazingly effective or might fall on its face because of bugs in the filter.

But the signal seems strong, though (158 vs. 105 galaxies in each direction).

Basically, I'd wait a bit for someone to try to replicate with more data and more conventional measurements.

by ajross

4/1/2025 at 2:45:12 AM

Wouldn't it be biased towards nearby galaxies? A net rotation of the local cluster would be reasonable. But it would be very wrong to extrapolate that to the whole universe.

by jfengel

4/1/2025 at 4:20:23 AM

Look, if the visible universe is expanding, as we think it is, that is already a direction. Viewing galaxies “from the other side” is not the same in an expanding bubble. It’s like being surprised that many things are redshifted no matter where you look. As for rotations — you could perhaps have some local coriolis force.

The visible universe is redshifted and galaxies are getting further and further away. So jumping straight to “we are in a black hole” is weird

It is far more plausible that there is some coriolis like spinning effect in a higher dimension, even if the universe is flat it could have similar effects to how the earth’s spin makes cyclones all spin in the same direction.

Problem solved. Next?

by EGreg

4/1/2025 at 1:36:47 PM

> Look, if the visible universe is expanding, as we think it is, that is already a direction.

Could you point in that direction?

by antonvs

4/1/2025 at 1:08:07 AM

> when viewed from the other side?

Nobody has done it so far. We have only theories and hypothesis.

by MoonGhost

4/1/2025 at 2:10:05 AM

I'm not sure I understand this response -- basically all of cosmology involves theories based only on somewhat subjective interpretations of sensor data targeting far-off objects. So I don't necessarily disagree.

But what could possibly happen other than they act like all other physical objects do? It boggles the mind to think how broken physics would have to be to accommodate a second correspondence principle for the big-but-not-too-big scale...

I feel like maybe I'm misunderstanding your sentiment, because this seems like a basic shared fact: a clock anywhere in the universe is still a clock.

by bbor

4/1/2025 at 3:53:06 AM

Except most theory can be observed where this one can’t until we find a wormhole to travel through or break c

by reactordev

4/1/2025 at 2:56:53 PM

I guess I'm saying that we also can't observe any proof for the theory that anything exists beyond the solar system instead of a giant screen run by aliens built to trick us. I appreciate the empirical mindset, but taking it this far is not leaving room for the usual amount of parsimony-based reasoning!

by bbor

3/31/2025 at 9:38:46 PM

This is exactly the dumb question I came here to ask. So now I wait with you for a less dumb person to reply.

My clock certainly seems to tick in the opposite direction when I look at it from behind.

by smeej

3/31/2025 at 10:06:03 PM

Answering to your and original question above: there are no poles (or axes of rotation) in the Universe. On large scales (think distances to include thousands and millions of galaxies each with billions of stars with even more planets) the Universe is uniform - isotropic and homogeneous [1]. It is expanding with acceleration in all direction in each and every point of its space, so there is no preferred direction thus in average we should have 50% of clockwise and 50% of counter-clockwise galaxies since orientation of those should also be absolutely random in average, unless something when the Universe was being created or evolving affected that balance.

1. https://en.wikipedia.org/wiki/Cosmological_principle

by nuccy

3/31/2025 at 11:49:13 PM

Dumb question time continues: The majority of the solar planets rotate in the same way, and the majority of the large moons rotate in the same direction as their planets. I assume this is influenced by the rotation of the relevant accretion disks. And I assume this is common for stars within a galaxy?

I don't think the universe is considered to have any significant rotation, however. Is this due to scale for us to measure, and/or having nothing external to compare against?

by prawn

4/1/2025 at 12:30:23 AM

That's exactly it. Solar systems and galaxies have net rotation, and maybe even galactic clusters.

But there is no reason to think that the universe has a net rotation. It could have one; you don't need a frame of reference to detect rotation. (The same way you feel centrifugal force.)

It would be huge if it were shown to have a net rotation. So huge that I take this claim with skepticism until heavily confirmed.

by jfengel

4/1/2025 at 2:52:12 AM

Hemispherical Power Asymmetry (HPA) observed in the Cosmic Microwave Background (CMB) temperature fluctuations [1]

"We conclude that the hemispherical power asymmetry still remains as a challenge to the standard model." [1]

1. https://arxiv.org/abs/2411.15786

by gjs4786

3/31/2025 at 11:43:04 PM

So it makes about as much sense to ask why 2/3rds of the galaxies are "upside-down" from our vantage point, because there's no clear reason it should be something other than 50% in a sample size this large?

by smeej

4/1/2025 at 2:49:55 AM

Correct. On the largest scales it should be 50-50.

If it's not that would add a significant term to the Big Bang that nobody had previously expected. It would be a rather big deal... if it holds up.

by jfengel

3/31/2025 at 12:03:08 PM

That would be super cool to find out! And then it also begs the question, is there something at the center that unites the two poles? If so then what is it!

It would also imply that our whole universe is rotating - the only reason this happens on Earth is because of our planets rotation and the Coriolis effect.

by fennecfoxy

3/31/2025 at 12:16:27 PM

I've been following this news for the past couple of weeks-- in essence your statement is what they are hypothesizing, and that the "something at the center that unites the two poles" might be that we are within a black hole. https://en.wikipedia.org/wiki/Black_hole_cosmology for the curious.

by thunder-blue-3

3/31/2025 at 12:30:25 PM

It was my understanding that if two black holes collide, they just form a bigger black hole, but we know there's a black hole in our universe, which then would mean that there's a black hole inside of a black hole that did not merge with the parent black hole, right? Is that something that is considered possible?

by askonomm

3/31/2025 at 1:37:51 PM

I'm under the impression that we really have no clue what's going on inside of black holes, so the most we can really say with confidence is that when two black holes collide they appear from the outside to now be a single black hole.

by lupusreal

3/31/2025 at 4:48:39 PM

It’s a reasonable assumption. If two solar masses collide, their masses tend to combine[^]. Just “look” at planets that smash into each other. Ergo, a more massive black hole.

[^]: Ignoring ejections. But black holes also don’t “eject” mass. Or maybe they do? Hawking Radiation is weird.

by colejohnson66

3/31/2025 at 5:42:41 PM

Actually, they can shoot out relativistic jets at the poles. https://www.nustar.caltech.edu/page/relativistic-jets

by soulofmischief

3/31/2025 at 6:57:11 PM

But there, the black hole is ejecting other mass near it, not its own.

by colejohnson66

3/31/2025 at 7:05:13 PM

Mm, I didn't correctly interpret their comment. You're absolutely correct.

by soulofmischief

3/31/2025 at 7:41:45 PM

Yeah. I could've worded it better. By "ejections" I meant how, when two planets/moon sized masses collide, rocks shoot out into space. But because black holes have so much gravitational pull, everything theoretically just falls in.

by colejohnson66

4/1/2025 at 7:54:22 AM

When two black holes collide, gravitational radiation shoots out into space. The origin of the radiation is in the dynamical spacetime outside each black hole's horizon, however. This is what the gravitational wave detectors operated by LIGO, Virgo, KAGRA, and others look for.

Similarly, the dynamical spacetime around a black hole not near any other black hole can couple with quantum fields -- even fields in a no-particle "vacuum" state as measured by an observer, for example one in orbit around the black hole -- with the result that Hawking radiation is produced.

Both gravitational radiation and Hawking radiation carry away energy (in the sense of ability to do work, per the "sticky bead" argument) from the environment immediately around a black hole. This in turn means that the horizon radius will be less than it could be.

So as a Hawking-radiating isolated black hole will tend to shrink (if it's not fed by hotter cosmic microwave background radiation, for example), the mass of a post-merger binary black hole will be less than the sum of the unmerged binary.

Just because things can't cross from the inside of a black hole horizon to the outside doesn't mean the horizon is always the same -- the horizon can grow and shrink dynamically when interacting with other self-gravitating bodies, with matter like dust or starlight, or with "the quantum vacuum".

by raattgift

3/31/2025 at 12:47:31 PM

The inner black hole did not come from the outside, it formed inside and if i had to guess, it is stuck in the inside together with all the other matter, unable to interact with the outside of the outer black hole.

by blueflow

3/31/2025 at 12:51:36 PM

Just thinking about this infinite recursion gives me the mental equivalent of a stack overflow.

by askonomm

3/31/2025 at 2:31:19 PM

I don't think it is infinite - each universe can only have that mass/energy that fell into the outer black hole in the parent universe. At some level you'll inevitably have black holes with universes that do not have enough mass to form another inner black hole.

by blueflow

3/31/2025 at 5:40:41 PM

Unless, although there's no reason to currently believe this, the energy requirements for physics are relative within each black hole, sort of (but not strictly) like how the speed of light is relative for all observers. And we can get a little crazier, and imagine a meta universe that is sort of like a Klein bottle in that it doesn't just recurse all the way down but somehow folds back into itself. Again, no current reason to believe anything like this but it's a mind-boggling to visualize.

by soulofmischief

3/31/2025 at 2:59:06 PM

How much mass is required to form a black hole in a new universe with perhaps different physical constants? It could be that 'ability to make black holes' is a prerequisite for successful universes in the way way that good genes are a prerequisite for successful organisms. The universes that fail to spawn black holes are 'dead ends' so any life is statistically likely to find itself in a black hole spawning universe.

Maybe there is an 'incentive' for universes to form with physical constants tuned to produce black holes with the available energy in that universe.

by idiotsecant

4/1/2025 at 2:53:28 AM

The trick is that bigger black holes are less dense. Supermassive black holes can have the density of water. If the universe is gravitationally closed, it would have the density of... well, just look up at night. (Actually much less than that; you see more stars because you're inside a galaxy.)

The density makes the scale recursion less mysterious.

by jfengel

4/1/2025 at 5:56:46 AM

That’s interesting! When you are referring to density, are you referring to average density within the event horizon? Isn’t most (effectively all) matter concentrated in the singularity? Would love to hear you elaborate on this thought further.

by drusenko

4/1/2025 at 12:15:44 PM

We can't really talk about what's inside a black hole. From outside, it has a volume and a mass, and that's all there is to know.

We can say that any particle inside the horizon is inevitably headed to the center. (That's why we can't say any more: no other information can escape.) That does lead to a problem in that all of the mass would be concentrated at a single point at the center, whose density is division-by-zero.

But I wouldn't put too much weight on that. We already know from quantum mechanics that there isn't really any such thing as a "point". The math is still a problem, but the solution almost certainly lies in that direction.

by jfengel

3/31/2025 at 8:03:21 PM

Maybe generating a stack overflow was the true depiction of God!

by jug

3/31/2025 at 12:22:48 PM

“The universe is an orb and that orb is rotating causing all the other stuff to spiral.” This was a long held theory of mine because I could not understand why a galaxy would spiral.

I think there is a men in black scene, where an alien is rotating the universe globe like a toy they are playing.

by nashashmi

3/31/2025 at 1:54:08 PM

> This was a long held theory of mine because I could not understand why a galaxy would spiral.

I think in general it would be unusual if they didn’t rotate. Any large non-uniform mass of gas or rocks when colliding will induce some rotation. What is odd though is that for galaxies we see more of them spinning one way than another.

by rdtsc

3/31/2025 at 5:43:19 PM

Ok but what is making the universe spin? This kind of theory is turtles all the way down.

by soulofmischief

3/31/2025 at 8:32:11 PM

Is this getting into questions like "Where did the singularity come from?" and "What came before the singularity?". We don't have a way to answer these kinds of questions.

by irrational

3/31/2025 at 11:24:34 PM

My point is that it's not much helpful to say, "galaxies spin a certain way because the universe spins", because it shifts the problem without actually answering the "why". "Turtles all the way down" is a saying about such infinite regress. https://en.wikipedia.org/wiki/Turtles_all_the_way_down

And yes, I'm familiar with Dawkins' famous retort when someone asked how magnets repel things.

by soulofmischief

4/1/2025 at 8:05:10 AM

> And yes, I'm familiar with Dawkins' famous retort when someone asked how magnets repel things.

I'm not. I was unable to substantiate that anyone named Dawkins, Richard or otherwise, made or is popularly associated with a comment about magnets. What was the retort?

by thaumasiotes

3/31/2025 at 3:16:26 PM

Doesn’t it have to spiral? Think of the gravity well, anything not orbiting is just falling. The only things not racing towards the black hole at the center of the galaxy are the ones that are orbiting.

by eightysixfour

3/31/2025 at 3:58:04 PM

It can be directly sucked into the center. A spiral implies a lateral movement plus a centripetal force

by nashashmi

3/31/2025 at 5:59:39 PM

Right, I guess what I am saying is if it didn't spiral, it wouldn't be a galaxy for "long." It would just be a super massive black hole.

by eightysixfour

4/1/2025 at 1:15:44 PM

The trick to having a galaxy is for mass to fall towards the black hole and miss it all the time.

by lolc

4/1/2025 at 2:50:47 PM

From what I remembe of Undergrad physics this isn't actually possible. According to GR, within an event horizon, space-like pths become "time-like" which effecitvely means the singularity is unavoidably "in the future". No matter how big a black hole is, you can't just drift around inside it as literally all paths lead downward (hence even light not escaping)

If you were inside a black hole you wouldn't be able to see light from "deeper" because it wouldn't be able to travel towards you.

This is not what we see within the universe, so I don't think we can be inside a black hole

by bencyoung

4/1/2025 at 6:40:25 PM

All paths _eventually_ lead downward. Is there any limit to how long? Can't we just be near the outside of the blackhole and can't see the doom yet?

by kadoban

4/3/2025 at 8:01:34 AM

There are no stable orbits inside the event horizon, and my understanding is even things like atom vibration can't move further from the sigularity so I'm guessing timespans would be limited!

by bencyoung

3/31/2025 at 3:01:32 PM

*raises the question

by whamlastxmas

3/31/2025 at 11:16:03 PM

Off-topic, so I hope not to spark too much side discussion here.

While I agree with your correction and this always bugs me, the common usage of the phrase "begs the question" seems to have become synonymous with "raises the question", as opposed to what I understand to be its former — and perhaps original — meaning which was associated with the informal logical fallacy by the same name.

by g4zj

3/31/2025 at 11:46:50 AM

Regardless of if this is the case, the idea certainly blew my mind

by Gooblebrai

3/31/2025 at 12:45:47 PM

lol, I’m glad it wasn’t just me that thought “woah wait. wtf did you just say??!”

by alfiedotwtf

3/31/2025 at 6:46:47 PM

IIRC the Virgo Supercluster is gravitationally bound. Pure speculation but my guess would be that galaxies are revolving around the center of the Virgo Supercluster and this creates the galaxy-level Coriolis effect.

by MichaelDickens

3/31/2025 at 12:07:24 PM

My own dumb question …

How does cyclones/hurricanes relate to being “on one of two ‘poles’”?

Do you mean hemisphere?

by tiffanyh

3/31/2025 at 12:55:59 PM

If all of the galaxies we see rotate the same way, are we “looking down” from a pole and seeing only those with the same rotation we have, as opposed to a more equatorial view that would be evenly split.

by jeffdn

3/31/2025 at 1:59:26 PM

But the universe isn’t spherical. I’m not sure I understand this hypothesis as explained.

by vlovich123

3/31/2025 at 2:24:06 PM

This along blows my mind: I picture this bin bang and everything expanding from that point and... that everything is now a sphere. In my mind. But it isn't? Yes, I know next to nothing but love thinking about all of this.

by Contax

3/31/2025 at 8:29:01 PM

It is often presented this way because models generally mix up the observable universe and the universe. One key notion is that we are at the center of the universe. Not the Milky Way, not the Sun, Earth is. Yet we know that Earth isn't at the center, so what is that? Because it is defined as our ability to travel from where we are at. Each of us could be considered at the center of our own observable universes, but this is a distinction we don't make because they overlap so closely that we don't have tools with the precision to tell them apart. I would guess that even aliens on the other side of Milky Way have an observable universe that overlaps so closely with our that they are equal to whatever level of precisions our tools allow for. Once you get to someone in a different galaxy, especially one that is moving away from us and not closer, then they have a different observable universe.

But then, what is the universe? One way to think of it is to imagine that every galaxy has at least one intelligent species with their own observable universe. The universe is the sum of all observable universes. The very nature of how to sum them together, what it means to combine multiple sets of thing which include items that don't exist relative to other items in the set, is a question we can't really answer yet. Because of this, even a question like the size of the universe is unknown, and even the question of if more of the universe exists outside of the observable universe isn't simple to answer and gets into the nature of what it means to exist. If someone exists in the universe, but not in the observable universe, it becomes an instance of Russell's Teapot.

by SkyBelow

3/31/2025 at 3:23:05 PM

Picture an infinitely long piece of elastic. Now stretch that elastic.

by jon_richards

3/31/2025 at 7:56:47 PM

OOMkilled

by stouset

3/31/2025 at 4:12:39 PM

Isn't this a 1d or 2d simplification?

by bigmadshoe

3/31/2025 at 5:21:13 PM

Yes, 1d. But it's easier to go from a strip to a sheet to a block than trying to imagine an infinite block from scratch.

The important part is that at any given point on the elastic strip, both sides are getting further away. Everything else is getting further away.

You might think if A-B-C-D are points on the tape and A-B are expanding and C-D are expanding, then B and C must be squished together, but the distance between them is also expanding. You have infinite elastic, but you also have infinite room to stretch it (even along the direction it already occupies). You now have A--B--C--D.

It's tempting to think about that stretch from the point of view of the floor/table beneath the elastic, in which case some parts of the elastic move faster than others as they stretch, but if you always think from a point on the elastic, then the speed of the rest of the elastic depends on how far away it is. Stuff twice as far away moves away twice as fast. Stuff infinitely far away moves away infinitely fast. That's true for every point on the elastic. No bunching up.

by jon_richards

3/31/2025 at 5:32:29 PM

I usually just imagine an n-dimensional space and then substitute n as needed

by kirubakaran

3/31/2025 at 2:16:23 PM

But the observable universe roughly is.

by pests

3/31/2025 at 7:21:50 PM

The observable universe is an illusory artifact of being an observer traveling at less than the speed of light. A constant distance in every direction is a sphere. That tells us nothing about the actual structure of the universe.

In other words, your observable universe is different than mine and that's both spheres we're in the middle of. That suggests the universe itself probably isn't a sphere.

by vlovich123

3/31/2025 at 8:32:17 PM

Is it an illusory artifact or is it all that exists? If it can't be observed, it can't be tested, it can't be verified in any way or ever interacted with, then isn't it just an instances of Russell's Teapot and thus does not exist? What does it mean for science if existence isn't a binary property or one that we set as a truth yet is entirely untestable?

by SkyBelow

4/1/2025 at 5:35:28 AM

We definitely have reason to believe that there’s universe outside the observable universe. The CMB uniformity suggests that that’s the case as do our theoretical models. The mere fact that two observers have different observable universes indicates it is indeed an illusory artifact.

Just because something is untestable today doesn’t mean it will be for all time. However, the untestability problem has started to creep much more deeply into cosmology and high particle physics in particular - our technology and models aren’t staying enough ahead to provide a lot of fertile testable ground.

by vlovich123

4/1/2025 at 12:39:23 PM

>Just because something is untestable today doesn’t mean it will be for all time.

This is generally true, but such ideas are kept outside the realm of science until they are. In this case specifically, all our knowledge points to this remaining untestable as it would require FTL travel which is on par with violating conservation of energy or time travel. It even allows solving the halting problem (Turing machine in timeloop until it halts, you outside of the timeloop can then check if the Turing machine in the timeloop ever left it).

It is entirely possible that there are things which are true which science cannot verify because of the underlying philosophy by which science operates. Things that exist outside of the observable universe, if FTL travel is truly impossible, would fall outside the realm of science.

>The mere fact that two observers have different observable universes indicates it is indeed an illusory artifact.

Do they? The nature of the observable universe is that, if you can communicate with someone else, any information they can receive and pass on to you is part of your observable universe as all information travels at the speed of light or slower. If they can receive information and cannot pass it on to you, they are not part of your observable universe any longer and no longer exist (exception if FTL interactions are discovered). Thus the only observers that exist in a way you can interact with, can make any testable hypothesis concerning, and thus can be considered by science, are observers in your observable universe.

by SkyBelow

4/1/2025 at 2:30:23 PM

> Do they? The nature of the observable universe is that, if you can communicate with someone else, any information they can receive and pass on to you is part of your observable universe as all information travels at the speed of light or slower. If they can receive information and cannot pass it on to you, they are not part of your observable universe any longer and no longer exist (exception if FTL interactions are discovered). Thus the only observers that exist in a way you can interact with, can make any testable hypothesis concerning, and thus can be considered by science, are observers in your observable universe.

The observable universe is defined as natural light reaching us. It says nothing about repeaters. If someone id at the edge of your observable universe they could still send you a message. They’re observable universe would necessarily include light that wouldn’t reach you due to expansion. Of course, it is possible we’re within a black hole or some other weird space time geometry in which the universe folds in on itself in which case it is possible the observable universe is the universe. I’m not saying that’s impossible since we don’t know. I’m simply stating my Bayesian priors based on my understanding of the evidence collected so far about the CMB and what it and the theoretical models we have suggest. It doesn’t make other theories less valid, it just means where I’d make a wager if I had to. As you say, right now it’s not capable of being a scientific theory and it’s a stretch to even be called a hypothesis.

Still, this is just a reversion to our natural state where we have philosophical ideas grounded in the best knowledge we have trying to find ways to unlock the secrets, not unlike ancient Greeks. We might succeed or we might not but I still think it’s a scientific pursuit grounded in the scientific method in some way. For example, we have no way of really confirming whether our models are correct about estimating the distance to stars. Still, we think it’s true enough because it works locally. Science is and always has been a fuzzy endeavor of truth seeking and only local models of simple interactions have a “nonexistent” amount of error.

by vlovich123

4/1/2025 at 6:17:25 PM

>It says nothing about repeaters. If someone id at the edge of your observable universe they could still send you a message. They’re observable universe would necessarily include light that wouldn’t reach you due to expansion.

I don't think it does once accounting fully for relativity (and assuming perfect sensors, so the idea of information being too redshifted to be detected isn't a factor until that information no longer exists within the universe, and immortality of participants, and near light speed travel).

Say Alice and Bob can communicate X years apart at near C speed. At any time, Alice can jump on a spaceship and reach Bob in ~X years. Therefore, anything in Bob's observable universe at that time counts as also being in Alice's observable universe.

If the distance is so far apart that one day space will expand too fast, then there is a moment where Alice stops being able to travel to see Bob ever again. At that moment, Bob's observable universe is now distinct for Alice's, but they also can no longer communicate.

Bob could get on a spaceship going near C away from Alice and access information that is outside of Alice's observable universe, but Bob only crosses that barrier when he moves far enough away from Alice that he exits her observable universe. (Technically I think you get some sort of infinite sphegettification of Bob leaving as he crosses Alice's observable universe's event horizon, where he never fully leaves and sends back photos that become more and more red shifted until their wavelength equals the diameter of the observable universe.)

So Bob has an observable universe that is different from Alice's, but it is predicated on him exiting from Alice's observable universe to access it. Either he accesses it and stops existing to Alice, or he doesn't access it and eventually it falls out of what he can possible access. The only part he can access and still communicate back to Alice is the part within Alice's universe. It is a bit like a superpower to turn invisible only when no one is looking... sorta kinda...

Given enough time, Alice and Bob either drift together until they clearly share the same observable universe, or eventually drift apart to the point expansion of space shifts them into two separate unrelated observable universes and they stop existing relative to each other.

by SkyBelow

4/1/2025 at 11:34:49 PM

It’s not possible for Alice and Bob to be within each other’s light cones but observe galaxies that aren’t in the other’s light cone? That seems wrong - there are galaxies that disappear from our light cone due to the expansion of the universe and they have neighbors that are still visible to us which would imply that the neighbors can still see the galaxy that became invisible to us.

I’m willing to concede I don’t know enough about the actual math of cosmology and relativity to say. How certain are you in your reasoning? I’m willing to admit either case could be possible and neither is a testable prediction at this time but maybe my first principles reasoning is outright flawed?

by vlovich123

4/2/2025 at 12:47:18 PM

It is about when they are or aren't in the light cones. If we remove relativity for a moment and define some time T=0, then Alice and Bob do see different things. The thing is that at 0, Bob and Alice aren't in each other light cones. Future Bob is in Alice's light cone and future Alice is in Bob's light cone, but at current they aren't. So you in the case of Alice, it is a question of what is in Bob's light cone.

There is also the matter of possible verses actual light cones. Assuming we had a ship that could go near C, imagine Alice doing three things. Alice v1 stays home. Alice v2 goes racing off near C to the left. Alice v3 goes racing off near C to the right. Each of these will have different light cones, but Alice v0 who hasn't made a decision could make any one of these decisions and thus all three light cones are in her possible light cones if she chooses to pick each action. Eventually each Alice will be so far away from each other that expansion of space splits their light cones into entirely separate ones from that point on.

>How certain are you in your reasoning?

Not at all. This is just based on my understanding of the very basics. The reason I'm sticking to it like I am is because, if I'm wrong and someone can point out where, it becomes a really good learning opportunity for me. And if I'm not wrong (at least given the layman level of detail of the conversation), the better I can explain my reasoning the better someone else might gain new ideas from it.

by SkyBelow

3/31/2025 at 2:24:39 PM

How do you know?

by x3n0ph3n3

4/1/2025 at 2:09:58 AM

Because measurements confirm a homogeneous and isotopic universe. A spherical universe would imply a special point, the center, which would go against these cosmological principals.

by paulrouget

4/1/2025 at 2:33:42 PM

Could be a universe that folds in on itself in multidimensional space so that every point looks like the center. But it almost certainly isn’t a 3d sphere.

by vlovich123

3/31/2025 at 1:04:46 PM

We're equidistant from the edge of the observable universe in all directions. One would think that puts us at the center.

(But the same is true for someone sitting on another planet).

by analog31

3/31/2025 at 2:52:27 PM

> equidistant from the edge of the observable universe in all directions

That seems like an example of "streetlight effect." The streetlight effect, or the drunkard's search principle, is a type of observational bias that occurs when people only search for something where it is easiest to look.

https://en.wikipedia.org/wiki/Streetlight_effect

by adolph

3/31/2025 at 4:51:35 PM

It's not. Rather it's that every observer in the universe is at the center of their own light cone.

The fact that we can not observe anything outside our light cone is well understood.

by jordanb

3/31/2025 at 1:12:44 PM

Some of that is a semantic thing about how one defines "distant", but this is not really required by GR. In fact the insight behind the emerging "timescape" theories is that the universe isn't flat or homogenous on large scales and that different regions have expanded at different rates. Their "edges" are equally old, but may not be not equally "distant".

by ajross

3/31/2025 at 8:14:16 PM

We're in the centre of the observable universe.

The observable universe is the only true sphere.

The observable universe is expanding into the unobservable universe.

What would be interesting is to run a diff on the cosmic microwave background and the pictures from the James Webb space telescope to figure out where the true centre of the universe is, and derive the poles from there.

by peterburkimsher

3/31/2025 at 8:21:50 PM

> The observable universe is expanding into the unobservable universe.

Is that so? My understanding is that it doesn't expend into something. And that it expend so fast that the edge of it becomes unobservable.

by jenadine

3/31/2025 at 9:37:45 PM

Thats just a distinction between the Observable Universe and the Universe. The observable universe should be labeled "Our" Observable Universe as what is observable depends on where you are. Imagine a sphere growing outward at the speed of light, this is what is observable this region is aka the Hubble Volume. Right beyond the edge there just hasn't been enough time for the light to reach our location. No woowoo required.

There are ongoing debates whether the actual Entire Universe is infinite or not.

by vonneumannstan

3/31/2025 at 10:51:36 PM

There is only one Entire Universe; it's not a multiverse. And we observe it as a sphere, sized by the speed of light in every direction.

Trying to see beyond the edge would be like trying to peer out of a black hole. It would probably look blue, like Cherenkov radiation. (but I'm biased, due to having blue eyes).

If the Entire Universe is infinite, then it's eternal in time. And then we get philosophical again.

by peterburkimsher

4/1/2025 at 4:13:30 PM

Again there needs to be a distinction between the Observable Universe and the Universe. No Physicist thinks the actual Universe ends at the edge of the Observable section. Most estimates put the Actual Universe as ~250x larger than the Observable Universe, if it is finite at all.

by vonneumannstan

3/31/2025 at 8:40:56 PM

Space and time are related, and expanding rapidly since the Big Bang (though there was a time in the early universe when the expansion rate was faster).

https://cds.cern.ch/images/CERN-HOMEWEB-PHO-2022-023-1

Observing the edge is effectively looking back in time, to see the conditions of the universe closer to the time of the Big Bang.

New telescopes keep expanding that edge, and new particle colliders (such as those at CERN or Fermilab) keep "bashing 2 rocks together to make fire" - recreating the conditions of the Big Bang to see what comes off.

What I'm not sure about is whether the speed of light (assumed to be constant) is correlated with the size of the observable universe. Perhaps a physicist could shed some light on that question. Relativity means that galaxies that are moving at the speed of light away from one another (one travelling at c, another travelling at -c) have a relative velocity of higher than the speed of light (|c| + |-c| = 2c).

There's also the theory of the One Electron Universe, which I quite like (though that reveals my bias as an electronic systems engineer). Perhaps what we see is the One photon universe. https://en.wikipedia.org/wiki/One-electron_universe

Hopefully this rambling makes sense to someone!

by peterburkimsher

3/31/2025 at 9:32:20 PM

I thought the expansion of space which is faster towards the event horizon has no impact on the Lorents factor. But I might be wrong.

by holoduke

3/31/2025 at 10:45:57 PM

I think you're right, except for the spelling of Lorentz factor.

The equation is on Wikipedia. https://en.wikipedia.org/wiki/Lorentz_factor

The terms are: v is the relative velocity between inertial reference frames, c is the speed of light in vacuum, β is the ratio of v to c, t is coordinate time, τ is the proper time for an observer (measuring time intervals in the observer's own frame).

If we could compare the time as we know it (based on the SI unit of seconds using an atomic clock) against the time at the singularity at the centre of the universe, we could figure out whether we're in a black hole, whether we're at the event horizon, or whether we're outside.

But we would have to assume space is a vacuum, which isn't entirely true.

by peterburkimsher

3/31/2025 at 9:11:42 PM

Wait, I get space expanding and accelerating.

I never considered time expanding (and accelerating?).

Is that even possible? What does that imply?

by ck2

3/31/2025 at 10:40:19 PM

Finding a way to reverse the expansion of the universe would imply time travel being possible. It hasn't happened yet, but perhaps that's just a technological limitation. And if you ask my Mac, then Time Machine is very much possible - that's just the name of the backup system.

The question starts to become very philosophical if there is a backup system for this universe. Everything being saved, for eternity, in infinite time. It would require very advanced computational power and storage, but it would probably work in binary (but that's just the kind of thing a computer engineer would say).

Maybe, though, the observable universe is rotating clockwise around a centre that is in the unobservable universe, and time is just a measure of how many rotations have been made since the Big Bang.

by peterburkimsher

3/31/2025 at 12:07:27 PM

maybe this is a stupid question, but is it possible that the big bang simply had some kind of clockwise angular momentum to it? how different is that idea from the black hole cosmology concept? I don't really understand how the two fit together

by permo-w

3/31/2025 at 12:29:22 PM

I don't believe the current consensus is that motion from big bang imparted a spin on objects. Rather, that dark matter (mass) was "dropped" all over as a result of the bang, making gravitational hot spots. Millions of years of dark energy progression affects those hotspots, making a sort of ever expanding (yet perceptively slowing down) sink drain with water pouring into it.

by Reubachi

3/31/2025 at 1:47:24 PM

It’s different because it’s simpler to assume that the total angular momentum of the universe is zero. If one black hole is rotating one way there must be other stuff rotating the other way to counterbalance. If you assume instead that the whole universe has angular momentum, well, where did that come from?

by ziofill

3/31/2025 at 2:04:06 PM

> If you assume instead that the whole universe has angular momentum, well, where did that come from

Would that be same kind of question as “where did the Big Bang come from?”. That’s a lot of energy that came from somewhere as well seemingly for no good reason.

I also wondered immediately about dark matter; could it be that’s where the counter-balance of momentum went? Like most galaxies spin one way and most dark matter would then have to spin the opposite way.

I am not a physicist so this is all random guessing of course.

by rdtsc

3/31/2025 at 6:30:57 PM

> That’s a lot of energy that came from somewhere as well seemingly for no good reason.

I never finished the book, but this reminds me of God's Debris by Scott Adams which explores a philosophy of pandeism (where God annihilated itself and became the universe).

by RandomBacon

3/31/2025 at 8:16:41 PM

Some say god is light. maybe it was a high energy photon that met its antiphoton.

by exe34

3/31/2025 at 10:47:15 PM

I say that god is just the universe

by permo-w

4/1/2025 at 8:08:00 AM

Why not just say the universe?

by exe34

4/1/2025 at 11:37:31 AM

why not just say say?

by permo-w

4/1/2025 at 2:33:24 PM

> why not just say say?

that’s exactly how it all started, at least according to john 1:1

by rdtsc

4/1/2025 at 3:22:19 PM

was the word kaboom?

by exe34

3/31/2025 at 2:55:16 PM

Where did the the values of the coupling constants between the various fields come from?

There are many parameters that do not have a reason for their value.

by platz

3/31/2025 at 3:23:15 PM

>If you assume instead that the whole universe has angular momentum, well, where did that come from?

You can say the exact same thing about mass. Obviously it came from somewhere. And it could have taken angular momentum with it.

by weberer

4/1/2025 at 2:13:02 AM

It split. The counter part is antimatter. And there’s more matter than antimatter.

So it’s a similar question. Where does this asymmetry come from.

by paulrouget

3/31/2025 at 6:14:06 PM

Which also implies the universe, or our section of it, is rotating. Which raises the question: where did that angular momentum come from?

by JumpCrisscross

3/31/2025 at 8:11:23 PM

Non-expert here, but I think any imperfect mass distribution with any attractive force would lead to a rotation. Which would mean, essentially, as soon as any imbalance happened in the early universe, some rotation was inevitable.

by twojacobtwo

3/31/2025 at 9:32:33 PM

The same place the rest of the universe came from. A slight imbalance in the Matter-Antimatter distribution in the early universe

by vonneumannstan

3/31/2025 at 12:06:32 PM

Potentially a very good question!

by wjSgoWPm5bWAhXB

3/31/2025 at 7:48:13 PM

Thanks for asking my question 8 hours in advance and allowing me to revel in the answers! :tada:

by thebeardisred

3/31/2025 at 11:49:04 AM

Wow, interesting thought

by blackhaj7

3/31/2025 at 12:00:11 PM

Universe of left-handed people.

by xtiansimon

3/31/2025 at 12:49:15 PM

https://mapoftheuniverse.net

While we don't believe we're the center of the universe, I believe we're limited by instrumentation to determine its size. Best guess now is 100B LY in diameter.

by eagerpace

3/31/2025 at 1:02:41 PM

100B LY is a little bit larger than the observable universe.

But the observable universe is a fraction of the whole thing. The "best guess" right now is that the total universe is flat and has no end.

If it's bounded, 100B LY is orders of magnitude below the most conservative lower-bound estimates, which I believe start at around 300-500x that size. (With huge error bars on all sides.)

by A_D_E_P_T

3/31/2025 at 2:44:15 PM

that's the neat part, it is though

by cozyman

3/31/2025 at 11:22:28 AM

Seems like we've got a few of these imbalances now where you'd expect 50:50 but instead it's skewed to one side where nature had a different idea

Matter-antimatter ratio

Left vs right handed molecules

Now galaxy spin directions

Maybe there are others I missed too

by over_bridge

3/31/2025 at 11:30:52 AM

For the matter-antimatter ratio, you would not expect 50:50, or would you? Because 50:50 would be a highly unstable system? In any case, you would expect that unstable states would be highly unlikely, and it would converge into a stable state.

I'm not sure about the other examples. But maybe it's a similar reason that it is not a 50:50 ratio?

by albertzeyer

3/31/2025 at 11:34:55 AM

A 50/50 matter/anti-matter system could still house stable local pockets of mostly matter or anti-matter. The problem is, from what I understand, that the universe seems to have sprung into existence with way more matter than anti-matter, and we don't know why.

by hhjinks

3/31/2025 at 1:25:03 PM

Could it be that the observable universe is one of these stable local pockets and the antimatter to balance it out is simply not observable to us?

by nabakin

3/31/2025 at 7:48:05 PM

Mathematically possible.

If you flip 2n fair coins, you expect n+δ heads and n-δ tails, where δ is (IIRC) sqrt(n/2). Going much away from that becomes infintessimally unlikely.

Probability is a subject famously easy to get wrong, so be careful with what I'm about to suggest: I *think* you could argue that in the moment prior to the inflation epoch spreading everything out just enough that pair production stops*, any given particle in our horizon is a coin toss of matter or antimatter.

Number of observed atoms in the universe is about 6e79 (http://www.wolframalpha.com/input/?i=how%20many%20atoms%20in...), so 6e79 = sqrt(n/2) -> n = 7.2e159 due to protons, and the same again for electrons; as we don't see significant signs of antimatter, any around must have annihilated a long time ago, so in this scenario we should expect to see ~7e159 (red-shifted) photons from the supermajority of particles which have annihilated.

It's outside my field to know how that compares to cosmologist's observations.

* won't that be at different times for protons/neutrons and electrons?

I can't get good answers on the expectations for either "why are protons and electrons counts the same" or "what is the observable consequence if they're not?"

by ben_w

3/31/2025 at 1:48:44 PM

Potentially, but it seems like an untestable hypothesis by itself.

by SkyBelow

3/31/2025 at 12:08:46 PM

Not a physicist, but here is my understanding of the cosmology physics:

High energy can spontaneously form matter antimatter pairs. In the early universe, the heat of the universe was very high, so this was common, constantly happening.

The problem as always if fine tuning. If the early universe was 60-40, that would be understandable. If the early universe was precisely 50-50, that’s fine too. But the universe was 50.0001-49.9999 or something like that, and then all annihilated. It’s too big a difference to easily be random chance, and too small a difference to be easily explained by a starting condition what wasn’t precisely tuned by some mechanism.

by BlarfMcFlarf

4/1/2025 at 8:43:51 AM

Not a physicist either but pair production also occurs in "non extreme" conditions and is still quite common.

If find this question fascinating. Matter can only ever exist with respective anti-matter. Question is where has all the antimatter gone? Are there processes were it does indeed behave different from matter? So where is it? Since a photon and antiphoton are the same and do not absorb each other, we should be able to see it, shouldn't we?

I still want to believe in the antimatter universe where there is some evil twin of mine.

by raxxorraxor

3/31/2025 at 3:33:28 PM

In all known physical processes, the baryon number is conserved. Particles with a positive baryon number are the heavy particles in matter. Think protons, neutrons, and so on. Particles with a negative number are antimatter. Think antiprotons, and antineutrons. And particles with a 0 baryon number are not made of quarks. Think leptons like electrons and neutrinos, or bosons like photons and the Higgs boson.

This means that all known ways to create or destroy matter, also creates or destroys an equal amount of antimatter.

It turns out that most attempts to extend the Standard Model allow violations of baryon conservation. This could explain the dominance of matter in our universe. However none of those attempts have been able to make any predictions that matched experiment. And so it remains true that all known physical processes perfectly conserve the baryon number.

(It is also possible that baryon number really is conserved, and dark matter is actually dark antimatter. But we lack a theory of what dark matter could be that predicts this.)

by btilly

3/31/2025 at 4:07:26 PM

Even if in the strong, weak and electromagnetic interactions the baryon number is conserved, there is the interesting fact that for the 8 particle set composed of the 3 kinds of u quarks, 3 kinds of d quarks, 1 electron and 1 neutrino, the sum of all kinds of quantities that are expected to be conserved, like electric charge, color charges and spin sum to zero. This set of 8 particles is also equivalent with the set of the components of one proton, one neutron, one electron and one neutrino.

This property of this set of 8 particles is analogous to the similar property of the set of 2 particles composed of a particle and its anti-particle, and to the similar property of the sets of 4 particles that can be involved in a weak interaction (the intermediate weak bosons convert one 4-particle interaction into a couple of 3-particle interactions, but when looking at the overall inputs and outputs, all the weak interactions are 4-particle interactions), which ensure the conservation of various quantities over such interactions.

This means that it is possible to conceive an additional kind of interaction, which unlike electromagnetic interactions between 2 particles and weak interactions between 4 particles, involves 8 particles, so it has a much smaller probability of occurring, i.e. it is a much weaker interaction than the weak interaction, and through which, when provided with enough energy, quarks + electrons + neutrinos could be generated simultaneously without generating anti-matter.

While there is no evidence yet for such an interaction, it is conceivable that at least during the circumstances of the Big Bang, such an interaction could have existed, so all the quarks and leptons could have been generated from some unknown bosons, just with enough initial energy and with conservation of all quantities for which there are solid reasons to believe that they must always be conserved, like energy, linear momentum, angular momentum, electric charge and color charges. (Unlike for the baryon number, for which there is no other reason to believe that it must be conserved, except that the strong, weak and electromagnetic interactions happen to have this behavior.)

by adrian_b

3/31/2025 at 4:33:48 PM

You would expect a 50/50 ratio because when energy is converted into matter, it's typically in the form of matter/antimatter pairs.

There's nothing special about matter or antimatter. Same energy, just opposite charge. All else being equal, they should be created in equal amounts. As far as we're aware, there is no special property that would make the universe preferentially create more matter than antimatter.

There's also no requirement that the configuration of matter and antimatter be "stable" for whatever definition you want to apply. The only rule is that conserved quantities stay conserved.

by mystified5016

3/31/2025 at 12:11:45 PM

but I was under the impression that equal parts of matter and antimatter annihilate, which would make a 50:50 system remain as such, which is why its such a mystery?

by permo-w

3/31/2025 at 11:26:41 AM

Isn’t there a different observation for why planets tend to orbit in the same direction in a solar system?

by anomaloustho

3/31/2025 at 11:57:58 AM

It's easily provable that any matter rotating other way gets expelled or thrown to center (Sun). So majority wins.

by deepsun

3/31/2025 at 1:30:45 PM

> Left vs right handed molecules

Organic chemistry found on meteors shows that non-terrestrial sources are equally left vs right-handed.

However, the rest might be caused by one or more errors in our premise. The most likely culprit being cosmological principle.

by Ygg2

3/31/2025 at 2:06:11 PM

I honestly start thinking that the idea "everything should be symmetric in some way..." is completely wrong, and an example of wishful thinking "...because it would be cool if it did". Even if nature is in some way balanced on a scale large enough, it's extremely unlikely for us not to be in some local pocket. Most likely we're a part of some bigger structure that has certain properties, and this affects our perception of the laws of physics.

by anal_reactor

3/31/2025 at 2:20:41 PM

> Most likely we're a part of some bigger structure that has certain properties, and this affects our perception of the laws of physics.

Which would also be the reason we have the laws of physics we do in general.

Anything seemingly ad hoc in our universal (from our vantage) viewpoint is potentially explainable as a pocket among all other possible distributions/combinations of relations.

by Nevermark

3/31/2025 at 1:37:50 PM

there's also that famous experiment by Chien-Shiung Wu, veritasium did a video on it somewhere

by stainablesteel

3/31/2025 at 1:18:58 PM

Dark matter / regular matter

by gerad

3/31/2025 at 12:10:47 PM

But rotation direction depends on the observer. If i see galaxy spinning clockwise, this means someone observing galaxy from behind it sees it rotating counter clockwise. So are we just located so in the universe that we see 2/3 spinning clockwise and another counter?

by vincnetas

3/31/2025 at 12:12:50 PM

The actual paper makes more sense: "the number of galaxies in that field that rotate in the opposite direction relative to the Milky Way galaxy is ∼50 per cent higher than the number of galaxies that rotate in the same direction relative to the Milky Way."

by Patient0

3/31/2025 at 12:27:54 PM

So 1/3 MilkyWay-Wise, 2/3 Counter-MWW?

Or is it? I hate these percent-relative word games things...

- Let x = "num MWW"

- then "num CMWW" = 1.5x ("50% higher than x")

- x + 1.5x = 1

- x = 0.4

So 40% is MWW, 60% CMMW?

by floatrock

3/31/2025 at 1:41:04 PM

Correct, I guess. 40/100 x 1.5 = 60/100. For 1/3 and 2/3 it must have been 100% higher.

by wruza

3/31/2025 at 1:13:09 PM

It just occured to me that "rotation direction" is a pretty coarse measurement. Actually, you could look at the angle of a galaxy relative to ours, where (let's say) 0° is viewed exactly from "above" (rotating clockwise), 180° is viewed exactly from "below" (rotating counterclockwise), 90°/270° is viewed side-on etc. How about some stats based on this parameter?

by rob74

3/31/2025 at 9:43:10 PM

What does "above" or "below" even mean in the context of something without a top or bottom? Or are you defining "above" to mean "the vantage point from which the galaxy appears to be rotating in the direction of earth clocks" for the purpose of this question?

by smeej

4/1/2025 at 2:30:37 AM

Not to disagree with your justified Socratic questioning, but this sparked my interest and I figured I'd share my (novice!) TIL: it appears the IAU uses a coordinate system based on our solar system on January 1st 2000, 00:00 AM, or "J2000.0". Thus (0, 0, 0) is at the ~center of Sol and the x and y are within Earth's orbital plane, which means the z axis is orthogonal to that. In other words, it seems like "above"/"up" in a astronomical sense denotes the same approximate direction as "Northward"/"North", which is pretty fascinating!

Of course as an arrogant computer scientist I think they're downright kooky for not basing it on the galaxy, but ce la vie. Presumably there's one of those too, and this just wins for boring social inertia reasons as much as for any technical ones.

image: https://geoscienceaustralia.github.io/ginan/images/ICRF-75pc...

wiki: https://en.wikipedia.org/wiki/International_Celestial_Refere...

Of course this doesn't really matter for the above musing since top/bottom would purely be conventional based on our viewpoint, but otherwise illuminating on the issue of understanding rotation directions across the universe.

by bbor

4/1/2025 at 6:47:55 AM

Yes, I was arbitrarily defining the side that rotates clockwise as "top" and the other side as "bottom".

by rob74

3/31/2025 at 8:50:53 PM

This is actually why rotational math is more complicated in 3d than you would expect. It's something game developers get used to, because accessing and modifying a rotation requires knowing what the orientation is relative to a fourth axis. That's what a quaternion is. In the situation of this story, it's in reference to the milky way's vertical axis.

by q_andrew

3/31/2025 at 3:45:22 PM

This was my thought too

by kevinb9n

3/31/2025 at 12:22:38 PM

this is a hard one for me to instinctively understand spatially, so I’m imagining myself stood in a room with arrows pointing left and right. if I have 3 arrows facing left in front of me and behind me I have 3 arrows facing left -- from my perspective when I turn around -- then I step past one of the arrows and now I have 2 left facing on one side and then in front of me what was now a left arrow is a right arrow, so now there's 5 lefts and 1 right. so extrapolating that, the observation is possible, but it still doesn't explain the imbalance, does it? you would expect most places in the universe to have a roughly even distribution from any perspective, I think?

by permo-w

3/31/2025 at 12:30:01 PM

No I don’t think so

Once you have a few dimensions on a normal or other distribution there’s not a lot of content that’s in the middle.

by jncfhnb

3/31/2025 at 11:01:39 AM

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.”

by misja111

3/31/2025 at 11:05:50 AM

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

by perihelions

3/31/2025 at 11:19:13 AM

>Due to an effect called the Doppler shift, astronomers expect galaxies rotating opposite to the Milky Way’s motion to appear brighter, which could explain their overrepresentation in telescopic surveys.

I found this a little surprising as well

by scythe

3/31/2025 at 11:22:15 AM

- "Doppler shift, astronomers expect galaxies rotating opposite to the Milky Way’s motion to appear brighter"

But how does that work?

by perihelions

3/31/2025 at 11:33:37 AM

I'm not an astronomer, but my intuition is this: When the source of the light is moving towards the observer, each successive photon emission happens from a position closer to the observer than the previous photon. Hence, from the observer's perspective, the time between photons is reduced, meaning more photons are observed in a given time, and the brightness is increased. When we observe a galaxy that is rotating opposite to us, not only is the source of the light moving closer to us, but we are also moving closer to it.

by z33k

3/31/2025 at 2:33:06 PM

From the perspective of us looking directly down on a parallel “plate” of a galaxy (with the other galaxy viewing us in the same way), relative differences in speed for the situation of same direction of rotation will be much smaller than for opposite directions.

But between any point in one galaxy to another, just as much matter will be moving closer as moving away. Regardless of same or opposite rotations.

But perhaps greater red shift and greater blue shift (as apposed to lesser of both) as a practical matter of telescopes vs. their cross spectrum sensitivities, means more light detected.

by Nevermark

3/31/2025 at 12:15:52 PM

I would assume that they're talking about redshift.

by IsTom

3/31/2025 at 12:23:08 PM

Yes, but one half of a galaxy would get redshifted, and the other blueshifted, no matter which direction it spins in. So why would that change its overall brightness?

(Though one of the papers notes that the tiny change in brightness this causes isn't enough to explain the large difference in spin directions)

by like_any_other

3/31/2025 at 2:04:47 PM

The close and far sides get shifted too, and those have different brightness.

by marcosdumay

3/31/2025 at 2:12:49 PM

No, 'like_any_other has it right: any physical system is 1-to-1 isomorphic with its mirror image, which is spinning the opposite direction.

Whatever asymmetry you're visualizing for one galaxy, its mirror-image galaxy is equally physical, and possesses the same asymmetry.

by perihelions

3/31/2025 at 1:26:33 PM

Relative motion to the center. 230 km/s is fast.

by tomrod

3/31/2025 at 7:46:40 PM

But then on the other side (hemisphere) we'd move the other direction (towards vs away), so wouldn't the opposite effect be expected there, more counterclockwise galaxies?

by Aardwolf

3/31/2025 at 1:32:11 PM

Then how does linear motion do it?

by perihelions

3/31/2025 at 11:15:35 AM

that's trivial to model... if anyone looking for a phd topic that sounds complex but only involves basic trig. (conclusion will probably be a No)

by 1oooqooq

3/31/2025 at 11:02:12 AM

Clockwise relative to what? Does the universe have an "upwards" direction?

Or is it just relative to all the other galaxies?

by worldsayshi

3/31/2025 at 11:11:41 AM

Clockwise relative to our viewpoint, while we would expect that we'd see an equal number rotating in either direction no matter which way we looked or where we were looking from.

by andrewaylett

3/31/2025 at 11:29:54 AM

> relative to our viewpoint

That would seem way more surprising than relative to a arbitrarily selected common upwards direction and it would imply that we are somehow at the center/top of the universe.

by worldsayshi

3/31/2025 at 12:04:05 PM

You are correct, we are indeed at the center of the universe.

Hence the farther we observe stuff, the earlier in time it happens. And if an observer moves to a different location, they will still be at the center of the universe (aka light cone).

by deepsun

3/31/2025 at 1:42:41 PM

> And if an observer moves to a different location, they will still be at the center of the universe (aka light cone).

That doesn't make sense for this particular context though. The direction of "up" of another galaxy doesn't change depending on where you are as an observer...

Then again, it's only two-thirds of the galaxies that have "up" facing us - which isn't that surprising. If something like 99% of their "up" was facing us it would seem more special.

by worldsayshi

3/31/2025 at 7:59:23 PM

Sorry if it's a dumb question, by why would we expect an equal number? Doesn't that assume that we consider ourselves at the centre of our observable universe?

by xeornet

4/1/2025 at 9:31:08 AM

If the orientation of galaxies is totally random, we would expect no bias in orientation. If you look at an arbitrary galaxy that's face on to us, it could be rotating either way. And we had no reason to set our prior at anything other than 0.5: why would one direction be more common than the other?

But we observe a bias. Now, that could just be chance — but it's more likely that we've missed something somewhere so our assumption was wrong. One specific possibility is that the universe has an intrinsic spin, which might be because (per the article) we're inside the event horizon of a black hole which is spinning.

Also, yes: we are at the centre of our observable universe.

by andrewaylett

3/31/2025 at 3:01:26 PM

So it would've been more "broadly" true to say: JWST discovers that most galaxies rotate in the _same_ direction?

by okdood64

3/31/2025 at 11:19:41 AM

How does that follow?

I imagine there was already a preferred spin of gases immediately after the big bang, just due to random chance, so why wouldn’t that be preserved more or less?

by MichaelZuo

3/31/2025 at 11:22:47 AM

That's the thing, we don't know any reason for a preferred spin and assumed it would be equally distributed. So this is an interesting fact.

by namaria

3/31/2025 at 7:37:37 PM

There doesn’t need to be a reason, just random chance from gasses shifting around is sufficient.

by MichaelZuo

3/31/2025 at 9:16:50 PM

I think you are misunderstanding the point being made: The _only_ random chance that is part of current models is "quantum uncertainty at big bang time" and we can give upper bounds for the variations that can be explained from that. So what's really being said here is "We found a significantly larger discrepancy between Milkyway-corotating galaxies and Milkyway-counterrotating galaxies than can be explained by ~initialisation randomness"

by hnaccount_rng

3/31/2025 at 9:56:46 PM

That doesn’t make sense, they can’t be assumed to have behaved like ideal gasses, thus turbulence alone can cause significant uncertainties.

Let alone all other possibilities combined.

by MichaelZuo

4/1/2025 at 8:07:20 PM

No it can't. Turbulence does not introduce net-angular momentum. It just (re)distributes it. And the scale on which that "mixing" can happen is limited (essentially the speed of sound is smaller than the expansion of the universe in the early universe). So on large enough scale, it (~any vector value) must be add up to ~zero (up to the initialisation uncertainties). Or one of our fundamental assumptions is wrong. And that's why this is so interesting

by hnaccount_rng

4/2/2025 at 2:24:53 AM

Can you link the proof for these claims?

I don’t see any obviously titled ones on Google Scholar, such as proving it’s impossible for turbulence to “introduce net angular momentum”.

by MichaelZuo

4/2/2025 at 7:21:23 AM

I don't have anything more than Newton's third law for you and that its effects also hold in general relativity. The "far away parts of the universe are disconnected" is from my astrophysics courses back in university and the number of lectures to the cosmic microwave background, mostly coming from people discussing the Planck mission.

But.. no, I don't have a convenient citation for you. And at least for the "angular momentum is conserved thing", I'd be surprised if you'd find a google scholar paper, this is early GR

by hnaccount_rng

4/1/2025 at 7:14:52 AM

I don't get it, why did you ask for clarifications about why this was not expected if you're just going to be adamant it should have been expected?

Is it really your honest position that everyone has been doing cosmology wrong and you would have known better?

by namaria

4/1/2025 at 12:21:06 PM

I didn’t ask for clarifications… I asked how it followed…

Are you sure you understood the comments completely?

It’s my honest opinion that anyone assuming away phenomena like turbulence, without credible proof, cannot be relied upon to have accurate insights.

So yes whenever I do have better insights, than by definition that’s more than 100% of the population who do not.

by MichaelZuo

4/1/2025 at 8:05:07 PM

Right. I guess I did not understand your comment at all then. I am sorry I engaged.

by namaria

4/2/2025 at 2:23:05 AM

Then why stick around for another reply that can only detract, or at best be neutral…?

It seems impossible for this to add to your argument.

by MichaelZuo

3/31/2025 at 11:29:07 AM

It's still of great interest to understand why exactly symmetry broke, and how this news might affect the cosmological principle.

by soulofmischief

3/31/2025 at 12:13:51 PM

The actual paper makes more sense: "the number of galaxies in that field that rotate in the opposite direction relative to the Milky Way galaxy is ∼50 per cent higher than the number of galaxies that rotate in the same direction relative to the Milky Way."

by Patient0

3/31/2025 at 11:09:08 AM

> 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.

by like_any_other

3/31/2025 at 2:50:16 PM

Well, I don't know physics, but from I heard of it, there are two kinds of phenomena that are sensitive to a rotation. One is quantum particles, they have fixed spin, but won't delve into that topic, because I suspect that their "spin" is like the charm of the charm quark, probably physicists just liked the sound of a word and used it. But there is one other thing I heard about: electromagnetism. If you run charged particles in circles, they create magnetic field that is directed perpendicularly to the circles, and the magnetic field feels different depending on the side of the circles being observed.

I see no way it influences the light emitted, but maybe I heard just too little of physics? BTW, does the direction of magnetic field of galaxies correlate with the direction of their rotation?

edit: Ah, maybe magnetic field can polarize the light? And when you have two magentic fields they polarize in one direction or in two different, and maybe it influences observed brightness of the light? Or maybe it is just an uninformed guess?

by ordu

3/31/2025 at 1:27:19 PM

I think this may be a subtle reference to what is usually called "relativistic beaming" or "Doppler beaming" [0], though I normally associate this effect with matter that is moving quite close to the speed of light.

[0]: https://en.wikipedia.org/wiki/Relativistic_beaming

by tomr_stargazer

3/31/2025 at 2:27:25 PM

perihelions [1] phrased it best - a galaxy spinning clockwise is just the mirror image of one spinning counter-clockwise. So why should mirroring change brightness? I don't really understand why Doppler beaming would cause this (though one of the papers did also mention it).

The other question is - what does the rotation of our own galaxy have to do with it? Let's keep the Solar system as is, and mirror the rest of the Milky Way around it, so that it is now spinning the opposite direction. Why should this affect the apparent brightness of other galaxies? Especially since the Solar system is effectively moving in a straight line, on the scale of a human lifetime.

[1] https://news.ycombinator.com/item?id=43535285

by like_any_other

3/31/2025 at 8:51:28 PM

This is only obvious when you yourself are not moving on a curved trajectory.

In GR curved trajectories lead to "weird" observations. For instance, I'd expect the side of the remote galaxy that is closer (visually, for you as an observer) to the center of your galaxy to be gravilensed slightly more than the other side. Because the effect is non-linear, it does not just compensate when sides are reversed.

P.S. Not claiming this has any significant effect on the described phenomenon, just that mirror symmetry does not apply.

by lostmsu

3/31/2025 at 11:12:38 AM

One side is moving away from us, the other towards. This means their relative speeds are different, detectably so.

by ceejayoz

3/31/2025 at 11:23:24 AM

I went to give a similar answer and realized that - in the instance that the two galaxies are sideways facing each other and with the text saying “it gets brighter” not “one side gets brighter” - I’m not sure if this is the actual answer.

I can’t figure out why the Doppler Shift would make the entire galaxy brighter. I assumed it would make the rotation side spinning towards us brighter. But also redshift the side spinning away.

by anomaloustho

3/31/2025 at 11:16:51 AM

How are you linking that effect to the spin orientation of the Milky Way galaxy? Where is the all-sky anisotropy coming from?

by perihelions

3/31/2025 at 1:30:21 PM

Fascinating.

Did it require JWST to notice this, or did we just _not check_ until now?

Is there a notable asymmetry in, say, the spin directions of galaxies contained in the Hubble XDF?

EDIT:

This doesn't make a lot of sense. Lior Shamir has written that a lot of unrelated sky surveys recently have shown an asymmetry in the past few years, but only down around ~2%.

https://www.mdpi.com/2073-8994/16/10/1389

https://aas.org/sites/default/files/2020-05/lior_aas236.pdf

JWST's asymmetry in both early work and more recent deep fields is more than an order of magnitude stronger.

EDIT2: Notably they show anisotropic asymmetry: The galaxies are different rotations when you look in different directions, with something like +6% in one direction and -5% in another. But still nothing like the +50% now being reported as a general feature.

by mapt

3/31/2025 at 10:51:59 AM

> 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!

by d--b

3/31/2025 at 10:57:50 AM

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?

by 0xEF

3/31/2025 at 11:11:08 AM

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.

by iainmerrick

3/31/2025 at 11:16:24 AM

Is inside the article:

"A preferred axis in our universe, inherited by the axis of rotation of its parent black hole, might have influenced the rotation dynamics of galaxies, creating the observed clockwise-counterclockwise asymmetry,” Nikodem Poplawski

by f1shy

3/31/2025 at 11:02:08 AM

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

by exe34

3/31/2025 at 11:12:17 AM

Exactly and anything new entering the spinning black hole is likely to inherit its spin.

by kingsleyopara

3/31/2025 at 11:31:39 AM

Of all the mind-boggling answers explaining this direction-of-spin thing, they picked the one saying "Hey actually you know what, our entire (mind-boggingly large) universe itself is located in a black hole. That'll explain things nicely."

by pandemic_region

3/31/2025 at 9:06:49 PM

I mean the universe in a black hole is one of the more common ideas in physics, though we don't have any evidence for it. So it's not surprising people pick it up and run with it.

With that said, when the universe was younger things were way way closer so would it be possible for things like very early massive quasars to inject powerful magnetic fields in the otherwise dark universe at this time and bias matter falling into galaxies to one direction or another?

by pixl97

3/31/2025 at 11:56:23 AM

The convenience of black-boxy things!

by d--b

3/31/2025 at 11:03:14 AM

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?

by zurfer

3/31/2025 at 11:11:34 AM

I don’t think we know enough about relative time from outside our universe. Our 15 billion years could be the parent universe’s one second.

by jagged-chisel

3/31/2025 at 2:07:16 PM

What about black hole new mass/energy converting into orthogonal space ??? ( ..is it part of Principia Unitas ??).

by thro1

3/31/2025 at 10:55:33 AM

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?

by snitty

3/31/2025 at 10:58:11 AM

The point is that you’d expect a roughly even distribution of clockwise and counterclockwise spins, not all of them to rotate in the same direction.

by scribu

3/31/2025 at 11:20:43 AM

wouldn't it be the case that you would see almost exactly 50/50 if all galaxies had parallel axes and rotated in the same absolute direction?

by throwawaymaths

3/31/2025 at 11:23:04 AM

why? if you subscribe to big bang then all matter got the same "initial kick". would be easier to assume same spin?

by 1oooqooq

3/31/2025 at 12:08:29 PM

From my understanding, the big bang requires that the proto-universe was in a completely homogenous state that was then pushed out of that equilibrium for some reason. But that reason doesn't require non-zero angular momentum. It only requires that a the proto-universe was homogenous and now the universe isn't. And that is what separates pre and post big bang. I could be wrong, I am not a cosmologist. Would be happy to hear from one though.

by mnky9800n

3/31/2025 at 12:07:36 PM

So what caused the "initial kick" to favor one side?

by aurareturn

3/31/2025 at 7:50:44 PM

What causes a perfectly symmetric ball on top of a perfectly symmetric hill to roll down via one side? (Probably quantum randomness if everything else is perfectly symmetric)

by Aardwolf

3/31/2025 at 8:53:42 PM

What caused this universe to favor matter over anti-matter?

So many unanswered questions.

by pixl97

3/31/2025 at 11:04:43 AM

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.

by iainmerrick

3/31/2025 at 11:29:56 AM

That is correct, "clockwise" only makes sense relative to a single observer: on Earth we set up out coordinate system so that the Milky Way's directed axis of rotation points one way, and most galaxies have it pointing the other way. "Clockwise / counterclockwise" makes sense for images coming from telescopes but it's not cosmologically meaningful.

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).
The point is that we would typically assume a 50-50 ratio regardless of where you are in the universe.

by RotationPedant

3/31/2025 at 12:14:35 PM

The actual paper makes more sense: "the number of galaxies in that field that rotate in the opposite direction relative to the Milky Way galaxy is ∼50 per cent higher than the number of galaxies that rotate in the same direction relative to the Milky Way."

by Patient0

3/31/2025 at 1:12:34 PM

I wonder if it’s already April’s Fools Day in some parts of the world. The hands of a clock move clockwise if seen from the front, but counterclockwise if seen from the back.

by credit_guy

3/31/2025 at 1:15:51 PM

Coming from a place of complete ignorance, are there indicators in galaxies that determine a top/bottom for lack of better words?

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.

by coffeecantcode

3/31/2025 at 9:55:43 PM

The article states that the problem is that they looked at random galaxies, 1/3 were moving one way and 2/3 the other.

If the distribution was truly random, and the universe is isotropic, we should see roughly 50/50.

by tiagod

3/31/2025 at 12:39:32 PM

The result is only significant to 3.39 sigma. Pretty good chance this is just a random fluctuation that will go away if you look at more galaxies.

by symmetricsaurus

3/31/2025 at 12:47:04 PM

This was also my thought, since selection bias seemed like a good explanation as well. The survey only covers 220 square arcminutes out of a total of about 148 million. Interesting data point though, definitely seems like something that one should measure!

by BlackFly

4/1/2025 at 4:53:53 AM

The study is based on 263 galaxies.

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.)

by _kst_

3/31/2025 at 12:47:01 PM

I was reading this and thinking, what if there’s no such thing as scale. Like, obviously there is in some sense, but what if there’s some kind of theory of relativity for scale as well, maybe scale is relative to gravity and gravity isn’t constant or something like that. So for example a universe as detailed as ours with sentient beings and all that could exist inside a quark, and we could in fact be living inside a proton or something, seen from someone else’s perspective. And it’s that level of detail, forever, in every direction.

Or maybe not, anyways back to work.

by CPLX

3/31/2025 at 11:01:15 AM

Unless you're looking at them from the other side, in which case they rotate counter-clockwise!

Or maybe they're just billboard sprites, always facing the camera, with clockwise animations.

by DonHopkins

3/31/2025 at 10:50:55 AM

At this point I'm open to believing our Universe is in a black-hole-like structure.

by alenrozac

3/31/2025 at 11:57:44 AM

This study does not conclusively prove most galaxies rotate clockwise...Just has a somewhat strong observation of asymmetry. Other studies that the paper mentions, and criticizes, did not observe it.

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... :-)

by belter

3/31/2025 at 3:00:16 PM

Spin a coin on top of a glass table. Observe it from the top, and it spins either clockwise or anticlockwise. Observe it from the bottom and it's the opposite. There are no tables in space. Objects tumble while rotating. It seems we are measuring rotations using a fixed perspective when there is no reason to do so

https://www.comsol.com/blogs/why-do-tennis-rackets-tumble-th...

by 1970-01-01

3/31/2025 at 3:17:09 PM

If there were 10 pennies and 7 of them were spinning the same direction, you might say one direction appears to be favored.

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.

by hnuser123456

3/31/2025 at 3:05:31 PM

The paper measures rotation relative to the Milky Way galaxy.

by richwater

3/31/2025 at 3:31:02 PM

must be something left out, because a galaxies r/l rotation is dependent on which side it is bieng viewed from, and since the are unlabled as to face and back, what is the basis for the handedness of something spinning in the void, with presumably most of the galaxies tilted at every angle and orientation possible other than aligned with ours. and 263* galaxies is zero galaxies when divided by the minimum number of galaxies, it's not a significant sample * number in study

by metalman

3/31/2025 at 1:04:24 PM

The linked article is written in an absurd way. Clockwise is not a fundamental measurement, it's relative to the viewer.

What the original article explains, is that this is relative to our observer point of view (obviously).

It's still very interesting, since, disregarding any potential interaction in our local group, randomness was expected and we should see around 50/50 rotating either way unless one of the explanations came into play.

by wtcactus

3/31/2025 at 1:40:47 PM

Is this a robust finding? I heard something about this apparent discrepancy a week or so ago, and it was dismissed as probably just an artifact of dodgy classification and the paper's author was a bit of a kook, a computer scientist who was delving into cosmology to find evidence of the simulation hypothesis.

by lupusreal

3/31/2025 at 12:57:13 PM

approximately 60% of the 263 galaxies examined were found to rotate clockwise, while about 40% rotated counterclockwise. The study’s results have a significance level of approximately 3.39 sigma, indicating a moderate chance that the findings could be due to random fluctuations

by singularity2001

3/31/2025 at 12:56:16 PM

I used to read a lot about the history of science as a kid.

The one thing that stuck with me is how frequently things we believe to be true are disproven.

This does not surprise me:

> “If that is indeed the case, we will need to re-calibrate our distance measurements for the deep universe,”

by gwbas1c

3/31/2025 at 12:40:07 PM

Another potentially dumb question: what does it mean for a 3d body to rotate clockwise? Doesn't a clock, viewed from its back, turn counter-clockwise? So is this just from James Webb's perspective that they rotate clockwise?

by kerkeslager

3/31/2025 at 2:00:59 PM

Yeah, the headline is misleading for just that reason. But rotation in 3d does have an unambiguous orientation which we call right-handed or left-handed (the "right hand rule" if you're unfamiliar with this). I don't know which orientation our galaxy's rotation has, the article only says it's opposite the majority in this sample.

by abecedarius

3/31/2025 at 12:37:46 PM

I was disappointed that the article only once mentioned “from our perspective” in relation to the spin of galaxies. One of the most fascinating things that you first learn about when you try to understand relativity, is the fact that there is no “still” point in the entire universe. Out in space, the point in space one foot in front of your space suit’s helmet can be called still by you, but it is just as reasonable to call a rock racing by you at a million miles an hour the central still point, where all other motion in the universe can be measured against. Because there is no absolute still anywhere. And when you understand that, that’s when all these cool concepts can then be described, related to time changes that happen between two locations when the relative speed difference between the two objects or locations approaches the speed of light. (So you can return from your trip to Alpha Centuri and meet your great great grandson who is older than you.)

And just like there is no still point in the universe, there is no up or down. So yes, it may be true that, IF you select a couple of arbitrary points in the universe to be up and down, THEN you can count how any galaxies spin left vs right. And it is way cool to find out that it doesn’t appear to be 50/50, and to wonder about why. But I think the article author did the readers a disservice by glossing over the “no up or down” fact.

by BubbleRings

3/31/2025 at 9:26:28 PM

They analysed only a small patch of sky, which could have a local relative rotation compared to our region of space.

Real science will be when they survey the entire sky, with many small deep-field images.

by jiggawatts

3/31/2025 at 11:18:36 AM

Time and time again, we are beginning to come to the realization that our entire observable universe is not the whole picture, and we are almost certainly seeing only a localized portion of a much larger and grander universe.

by andrewclunn

3/31/2025 at 10:41:14 PM

Several folks here have recognized that the spin direction depends on whether you look at the plane of the galaxy from ‘above’ or ‘below’. One thing I didn’t see in the article is how the two types of galaxies are distributed across the 3D spherical coordinates when viewed from the earth (or rather from the JWST).

Im thinking: what if there are a bunch of massive objects like black holes in certain directions that are causing the light to bend in a certain way. So what would normally be light coming from the top of the galaxy plane, is actually light reaching us from the bottom of that plane. Would this slew the distribution of the spin one way - I don’t know.

by smath

3/31/2025 at 11:46:45 AM

1. Are they really saying "Because we are in a universe with a preferred spin and black holes have spin, we must be inside a black hole?" Tenuous, no?

2. If we are inside a black hole, where is the singularity?

by damnitbuilds

3/31/2025 at 12:41:20 PM

Inside a black hole just means inside its event horizon. The singularity can still be arbitrarily far away from that horizon (if the black hole is correspondingly large). The volume enclosed by the event horizon may be larger than our cosmological horizon (i.e. how far the speed of light allows us to see, given the finite age of the universe.) And the singularity of a black hole isn’t “where”, it’s “when”. The singularity of a black hole is in the future of all particle trajectories inside the event horizon.

by layer8

3/31/2025 at 12:11:02 PM

If the universe is bounded by regions that are further away than the speed of light has time to reach us then that would be an ideal place to look for a singularity. unfortunately it is unmeasurable since so far the speed of light is a hard boundary for what we can measure.

by mnky9800n

4/1/2025 at 2:20:59 AM

Should we expect the big bang to have been completely symmetrical? If not, wouldn't most galaxies spin one way versus the other?

by mbac32768

3/31/2025 at 1:36:03 PM

so i guess the underlying assumption is that this looks out from out perspective in a single static orientation, because this says nothing to me about their orientation which i think is what they're trying to convey by saying clockwise?

or i suppose this is clockwise/counterclockwise in regards to the direction they're moving in?

2/3 doesn't seem that significant if they think it should be a 50/50 split, we might just not be seeing enough

by stainablesteel

4/1/2025 at 5:50:29 AM

So do the galaxies rotate clockwise, or did we make clocks that rotate in the direction the galaxies choose? :)

by nottorp

4/1/2025 at 8:59:34 AM

Sundials are really really cool, and the shadow sweeps in the clockwise direction at mid-latitudes in the northern hemisphere, but

https://en.wikipedia.org/wiki/Sundial#In_the_Southern_Hemisp...

So "clockwise" is because the Earth's axis of rotation about itself is not too far from perpendicular to its orbital plane of rotation around the sun, and because the Earth rotates counter-clockwise from the perspective of someone hovering above the planet's north pole. This is the right-hand rule.

Earth's axis of rotation (and orbital plane) is fairly well aligned with most of the round bodies in the solar system, except notably for oddball tilted Uranus and anti-aligned Venus (and the pretty different orbital planes of the minor planets like Pluto and Eris).

The sun's north pole (following the right-hand rule) and south pole do not point to anywhere particular in the galaxy, and its axis of rotation is highly tilted with respect to the axis through the central bulge of the Milky Way. A nice diagram that seems to have originated from the European Southern Observatory: <https://www.physicsforums.com/attachments/motion-of-earth-an...>

Most disc-like structures we've found tend to be randomly oriented compared to each respective host galaxy's polar axis.

For spiral galaxy rotations we have much better data from mostly edge-on views because we can measure the doppler shifts of molecular clouds at their margins; the advancing side will be less red-shifted than the trailing side. Spectral lines also broaden with the magnitude of rotation. AFAIK there is nothing at all unexpected about the distribution of trailing vs leading edges on our sky; the mystery is in the magnitude of the rotation of these outer gas clouds compared to things like their galaxy's apparent optical brightness or other markers of mass.

Also fun is that for elliptical galaxies, these gas clouds don't rotate around the equatorial bulge of those that have them. They instead tend to move mostly radially deeper and shallower within their host galaxy.

So if galaxies don't choose the rotation of their internal components like star systems or radio-loud objects like pulsars and relativistic-jet-equipped black holes, why (accepting for the sake of this argument that this garbage paper is correct about there being a bias in face-on spiral galaxies) would a distant galaxy affect us more than our own?

by raattgift

4/1/2025 at 9:42:59 AM

Heh I was joking but you can trust HN to have someone come up with a comprehensive explanation for anything :)

by nottorp

3/31/2025 at 12:00:11 PM

So, there is a visible order about this matter. That they are "rotating", instead of, for example, "Z-Pattern" movement. Amazing.

by pushreply

4/1/2025 at 5:45:10 AM

Candidate for hardest collective fall for an April Fool's Day joke in Hacker News history?

by herdrick

3/31/2025 at 8:43:20 PM

US left-handed presidents are also over-represented. This is another reason to feel special in our neighborhood.

by wojo1206

3/31/2025 at 1:57:58 PM

Everything turns clockwise from a specific perspective... that's what is interesting here, perspective and consistency.

by RobertRoberts

3/31/2025 at 11:19:21 AM

Does it need to be that the whole universe started with rotation, or that our visible part of the universe has a common ancestor?

by seydor

4/1/2025 at 2:11:21 PM

Does that mean we're in the northern or southern unisphere ?

by Mekaniko

3/31/2025 at 1:57:06 PM

Could this be related that the weak force only interacts with left-handed particles (and right-handed antiparticles)?

by tlogan

3/31/2025 at 5:46:18 PM

What if we're just upside down? :)

by soulofmischief

4/1/2025 at 4:02:32 AM

A sample size of 263 galaxies isn’t enough to draw any conclusion.

by wwarner

3/31/2025 at 8:53:16 PM

Correction: Oops, The Telescope Was Just Spinning Counter-Clockwise, Our Bad

by GuinansEyebrows

3/31/2025 at 7:07:54 PM

sorry if someone already asked this, but what is clockwise when there's no "up"? The earth axis is like 60 degrees off the axis of milky way, so it's not clear what the frame of reference is.

by 93po

3/31/2025 at 8:59:40 PM

In theory it doesn't matter what the frame of reference is.

Instead of thinking of it like spin, think of it like heads or tails. Both are binary measures and frame of reference doesn't matter. For example if you're flipping a penny on a glass table and someone is looking from the bottom, they'll see the same ratio as you.

In a fair universe you'd expect pretty much a 50/50 heads/tails clockwise/anti-clockwise outcome. But instead we something like 66/34 or 75/25. The actual direction of spin doesn't matter. The fact the measurement is unbalanced does.

by pixl97

4/1/2025 at 4:37:01 PM

That makes sense, but the article title says "clockwise". Why did they choose that word instead of "counter-clockwise"? They must be some threshold of "this 180 degrees is up and this other 180 degrees is down" for them to have chosen one word over the other.

by 93po

3/31/2025 at 9:37:11 PM

isn’t counterclockwise same as clockwise whe viewed from the other side?

by wokewombat

3/31/2025 at 4:10:44 PM

If you look at the galaxy from the other side, wouldn’t it be counterclockwise?

by tagami

3/31/2025 at 4:17:10 PM

Yes, but I think the interesting thing is that there are a greater number of galaxies spinning one way than another.

by bigmadshoe

3/31/2025 at 1:16:15 PM

On the antipodal side of the universe they mostly rotate counterclockwise. ;-)

by gerad

3/31/2025 at 9:03:33 PM

My clock also runs clockwise, when seen from one of two sides...

by martini333

4/1/2025 at 9:31:06 AM

Wait - even if seen from the opposite side?

by DrNosferatu

3/31/2025 at 2:29:50 PM

Could an equivalent of the Coriolis Force be at play here?

by slicktux

3/31/2025 at 7:42:45 PM

Maybe anti matter galaxies would spin the other way

by bilsbie

3/31/2025 at 12:49:36 PM

So the universe is left handed?

by klysm

3/31/2025 at 4:08:32 PM

We’re six black holes deep

by sivm

3/31/2025 at 11:01:57 AM

Did they also check in the northern hemisphere of the observable universe?

by dodslaser

3/31/2025 at 11:44:22 AM

This to me indicates the primordial particle was spinning clockwise.

by brador

3/31/2025 at 12:14:55 PM

How would you even define what is clockwise or not if there is no other particle as a reference? You can look at it from the other side and say it's spinning in the opposite direction.

I think it's enough to say that it was spinning. There was an imbalance tending toward a direction.

by lioeters

3/31/2025 at 7:23:14 PM

got it.

by rambojohnson

3/31/2025 at 8:38:21 PM

Shouldn't the galaxies in the northern and southern hemispheres spiral in opposite directions? /s

by rezmason

4/1/2025 at 2:22:48 AM

[dead]

by atkailash

3/31/2025 at 12:21:18 PM

[flagged]

by nwaf

3/31/2025 at 12:21:28 PM

[flagged]

by nwaf

3/31/2025 at 12:21:42 PM

[flagged]

by nwaf

3/31/2025 at 10:52:21 AM

Now if only we could see inside a black hole.

by bustling-noose