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Comment by worldsayshi | Hacker News Reader

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

Or is it just relative to all the other galaxies?

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.

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?

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.

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

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"

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.

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?

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.

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

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.

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

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”.

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

This comment doesn’t make sense… You can’t change your opinion into a fact just via reptition.

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

> 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.

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).

> 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.

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

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?

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

It seems to have caught on, but one could still doubt its applicability to all phenomena at all scales.

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.

My best guess would be using a standard coordinate system such as https://en.m.wikipedia.org/wiki/Supergalactic_coordinate_sys...

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."

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