5 ms·

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

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.

xeornet 2y ago
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?
- schoen 2y ago
  https://en.wikipedia.org/wiki/Copernican_principle 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.
- andrewaylett 2y ago
  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.
MichaelZuo 2y ago
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?
- namaria 2y ago
  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.
  - MichaelZuo 2y ago
    There doesn’t need to be a reason, just random chance from gasses shifting around is sufficient.
    - hnaccount_rng 2y ago
      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"
      - MichaelZuo 2y ago
        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.
        namaria 2y ago
        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?
        MichaelZuo 2y ago
        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.
worldsayshi 2y ago
> 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.
- deepsun 2y ago
  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).
  - worldsayshi 2y ago
    > 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.
okdood64 2y ago
So it would've been more "broadly" true to say: JWST discovers that most galaxies rotate in the _same_ direction?

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.

xeornet 2y ago

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?

schoen 2y ago
https://en.wikipedia.org/wiki/Copernican_principle 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.
andrewaylett 2y ago
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.

MichaelZuo 2y ago

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?

namaria 2y ago
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.
- MichaelZuo 2y ago
  There doesn’t need to be a reason, just random chance from gasses shifting around is sufficient.
  - hnaccount_rng 2y ago
    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"
    - MichaelZuo 2y ago
      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.
      - namaria 2y ago
        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?
        MichaelZuo 2y ago
        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.

worldsayshi 2y ago

> 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.

deepsun 2y ago
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).
- worldsayshi 2y ago
  > 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.

okdood64 2y ago

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