An alternate hypothesis which seems equally interesting, albeit for different reasons, is at the end of the article:
> Another explanation for why the JWST may have seen an overrepresentation of galaxies rotating in one direction is that the Milky Way's own rotation could have caused it.
> Previously, scientists had considered the speed of our galaxy's rotation to be too slow to have a non-negligible impact on observations made by the JWST.
> “If that is indeed the case, we will need to re-calibrate our distance measurements for the deep universe," Shamir concluded. "The re-calibration of distance measurements can also explain several other unsolved questions in cosmology such as the differences in the expansion rates of the universe and the large galaxies that according to the existing distance measurements are expected to be older than the universe itself."
perihelions 1 hours ago [-]
I'm utterly confused what's going on. They're measuring galaxies' rotations by looking at images of the subset that are spiral galaxies, and checking which direction the arms spiral. They describe their image processing algorithm in their paper [0]. (it's around figure 3)
How can local movement of stars within the Milky Way affect which way spiral galaxy arms are pointing?
There is no absolute direction for a galaxy’s spin—it’s always relative to the observer’s perspective.
So I’d suspect they’re saying time and distance would need to be factored in rather than just looking at static images relative to our position today since our own spin may have caused a particular galaxy to appear to have been spinning in a different direction at another point in space-time
tremon 47 minutes ago [-]
I don't understand this logic. To me, that's equivalent to saying "there's no absolute direction for which way a wheel spins, it's relative to the speed of the observer". Which makes no sense to me, because my definition of spin is measured against the axis of rotation of the object itself.
I don't see how time-intermittent frame captures from our own position affect that interpretation. Or are we using an astonomy-specific definition of spin here?
d1sxeyes 6 minutes ago [-]
It’s the same as saying you can only work out how fast something is moving in relation to something else. Your car is doing 50mph on the highway, but the earth is spinning round the sun and the sun is moving around the centre of the galaxy and the galaxy is moving compared to other galaxies and so on.
jacksnipe 36 minutes ago [-]
But what if you, the observer, are also rotating? What if you’re rotating faster than the thing you’re observing?
Georgelemental 1 hours ago [-]
Read section 5.2 of the paper
perihelions 54 minutes ago [-]
Do you or other HN commenters understand it in a satisfying way?
The author writes about the Doppler effect creating a systemic bias in brightness depending on which way the galaxies are rotating. I don't understand that argument either, but it's moot, because they state categorically that that effect would be too small to explain their results. ("This explanation is challenged by the fact that the effect of the rotational velocity have merely a mild impact on the brightness of galaxies, and therefore is not expected to lead to the dramatic difference of 50 per cent in the number of galaxies as observed through JADES.")
That's the only explanation I recognized as an explanation. Then I lost track of their argument following that. They refer to several speculative physics theories like MOND, but I don't understand them to be saying something that concretely predicts distant galaxies to appear to be rotating differently.
I'm appealing to anyone on HN who knows enough about this field to understand the meat of this argument.
perihelions 25 minutes ago [-]
It's a moot point, but I *really* don't understand the Doppler-shift bias mechanism either. Help?
This one of the author's other papers they cited in this one,
I'm completely lost how they're eliding between the rotation orientation of the Milky Way galaxy, and relative linear velocities with stars in other galaxies. In the special relativity argument, where does the rotation axis of the Milky Way enter?
sigmoid10 2 hours ago [-]
This newsblog takes one piece of the paper [1] and blows it up like it's the most obvious thing ever and completely hand-waves away the alternative, while the paper itself actually provides some compelling evidence for the alternative explanation: This asymmetry is because of our own galaxy's rotation. It would be an insane coincidence to have the large scale structure of our universe be more asymmetric towards the poles of our galactic plane and the further you go away from our galaxy (especially when velocity blue shifts would obviously make one type of rotation for galaxies more visible in the high-z regime where JWST primarily looked). Forget black hole cosmology, if you believe what this article suggests, then special relativity itself may be wrong. The data is pretty sound and perfectly in line with earlier observations that found no asymmetry if you believe our own galaxy's rotation is the culprit. So if I had to bet, I'd say we misunderstood galaxies and not the universe as a whole. Mostly because galactic physics is incredibly complicated and has very whimsical empirics, whereas we have some really solid theories and data on the universe as a whole.
Thanks for link. Amazing work. I'm less than noob, so barely comprehend this topic, much less this paper.
ELI5: Per "5.2 Physics of Galaxy Rotation", could the Milky Way's relative movement, in addition to its spin, also effect the observed assymetry? In Figure 10, is the Milky Way also moving toward the blue and away from the red?
Thanks for humouring my question. Everything about astronomy and JWST just blows my mind. Like how Figure 10 sorta resembles yinyang. What a time to be alive.
jagged-chisel 2 hours ago [-]
> These [baby] universes would be unobservable to us because they are also behind an event horizon, a one-way light-trapping point of no return from which light cannot escape, meaning information can never travel from the interior of a black hole to an external observer.
Also meaning that “our” blackhole (the one containing us) is unobservable from the parent universe for the same reason. So where is all this extra light/energy going in our universe? Should we not have detected an increase of energy in our universe?
alabastervlog 2 hours ago [-]
I figure our whole universe so far has existed in the first nanosecond (or whatever) after the creation of the black hole in the parent universe, so very little energy or light has had time to enter.
By one or two seconds in the parent universe’s time scale, our universe will have settled down to its extremely long state of being a cold, dark void of slowly decomposing subatomic particles.
No good reason to think this, just feels right.
Aerroon 1 hours ago [-]
Scales are a very interesting thing to think about. There's a theory that the universe didn't really 'start' with the big bang, that it was always there, but at a different scale. The big bang was essentially an increase in the scale of the universe, possibly in terms of time and space.
dghughes 1 hours ago [-]
Our universe may be a rotating detonation engine only it's our universe being made not combustion.
jagged-chisel 2 hours ago [-]
The relative time part is a really interesting thought. Thanks!
lostmsu 1 hours ago [-]
Time in high gravity usually flows slower than in flat regions, not faster.
jagged-chisel 53 minutes ago [-]
With our math, yes. But maybe that’s because we are the imaginary part of the equation.
itronitron 50 minutes ago [-]
what exactly is a flat region in high gravity?
flowerthoughts 2 hours ago [-]
(Complete hypothesizing from a very cursory understanding.)
Perhaps that's dark energy or vacuum energy? If mass and time truly switches places when crossing into a black hole, it would make sense that the spacetime size of this universe translates into observable mass outside it. Which might tie it to the expansion of the universe.
nextaccountic 2 hours ago [-]
> If mass and time truly switches places when crossing into a black hole
What do you mean by that?
bilekas 41 minutes ago [-]
> "The discovery by the JWST that galaxies rotate in a preferred direction would support the theory of black holes creating new universes, and I would be extremely excited if these findings are confirmed.
Its an interesting theory but to be honest, given the conditions of the event horizon, I don’t see HOW it could be proven.. That said I do feel this will turn out to be a nuance of the measurement itself but maybe that’s just my mind not comprehending the scales of what’s being measured here.
gchamonlive 27 minutes ago [-]
Does this mean we could look at deep space for clues about the physical rules that govern what happens beyond a black hole's event horizon?
rocqua 2 hours ago [-]
How does this work with matter falling into 'our' black hole and hawkins-radiation leaving our black hole?
Heck, Hawkins radiation means black holes can evaporate. Does that correspond to a universa collapsing?
Would matter falling into our black hole come shooting out of the white-hole we see?
Would time on either side of the event horizon even be related?
cryptonector 52 minutes ago [-]
> How does this work with matter falling into 'our' black hole and hawkins-radiation leaving our black hole?
We would see that at the edge (if we could see it) there's new mass and energy, but that would be obscured by what appears as the CMB for us.
> Heck, Hawkins radiation means black holes can evaporate. Does that correspond to a universa collapsing?
No, it corresponds to stuff disappearing from our universe, until someday nothing is left.
> Would matter falling into our black hole come shooting out of the white-hole we see?
We'd see it as being part of the Big Bang, behind the CMB, so we wouldn't see it.
> Would time on either side of the event horizon even be related?
Er, not in any way that we could observe, so it's not a question we could answer. But we could receive information from the outside, except that the CMB would hide it from our prying eyes.
rocqua 42 minutes ago [-]
Hawking radiation can't just be stuff dissapearing, because the actual singularity can dissolve. Besides, where would the stuff even leave from? I could imagine the mass flux through our event horizon being related to the energy driving space expansion (or contraction). That only makes sense if time on the inside is related to time on the outside though.
The idea that any mass that will ever fall into our black hole all simultaneously appeared at the big bang doesn't feel correct. That suggests a very specific relationship between time on the inside and outside. There are at least two moments that are distuinishable on both sides. The singularity appearing, and the singularity dissapearing. Compressing all time on the outside into the big bang means weird things for the timing of when the singularity dissapears.
Aerroon 2 hours ago [-]
Perhaps dark energy is hawking radiation. We just see what it's like from the inside.
Something to consider is a possible time scale difference. Eg time could be dilated for us for being around so much density.
rocqua 38 minutes ago [-]
It would need to be the other way around, dark energy being matter falling into our black hole. Hawking radiation should 'suck' energy out of our universe. I can't think of a satisfying source of this energy.
The best I can imagine is either space contracting (but that is gravity) or entropy increasing (but that doesn't leak energy, just free energy).
cvoss 1 hours ago [-]
> Would time on either side of the event horizon even be related?
I think that's exactly the right question to ask. And ask it for space too. Perhaps the entire history of the interior universe unfolds between the black hole's formation and its final evaporation. Perhaps a heat death of the interior universe, where everything spreads out until nothing interesting is left, can fit inside this ever shrinking volume.
vitiral 36 minutes ago [-]
Some confusion in this thread. I think it would help folks to know that in addition to conservation of energy, our universe has conservation of angular momentum, aka mass spin.
Hope that helps!
api 58 minutes ago [-]
It'd be neat if the universe were essentially a nested Russian doll of black holes. Our universe is a black hole with black holes inside and black holes inside them and so on, and the larger universe outside ours is also an even bigger black hole. Some of the really huge black holes in our universe might be big enough to host interesting things within, but the smaller ones probably just contain "toy" universes without much happening.
I recall reading about our universe as a black hole once -- one thing posited is that everything that is happening and what we think of as space is really information processing occurring just at the surface of the event horizon. There was some possible way of explaining non-local phenomena like entanglement that way, but I forget the details.
It's fascinating to think about how the actual universe might be something quite alien from our ordinary perception. It's not that our ordinary perception is wrong. What we're perceiving is just one perspective on something much larger and weirder. In this case our perspective would be from within this information substrate. It's almost universe-as-simulation, except that the simulation does not have a builder. It's a naturally occurring phenomenon. The Matrix has no architect, or if it does it's something fully outside the event horizon of this object and thus un-observable.
Of course at this point we're well into physicists smoking pot territory.
dingnuts 2 hours ago [-]
at the bottom of the article the mundane hypothesis is presented that the measurement seen by JWST might be a calibration error caused by the rotation of the Milky Way making it appear that other galaxies have a preferred rotation.
sadly, this is likely the real explanation, but that's not very exciting
This result is a big deal, and actually seems under-hyped. None of the explanations make any sense.
Sharlin 2 hours ago [-]
Something something Betteridge's law of headlines.
m3kw9 2 hours ago [-]
Ok but then the theory of black holes are wrong because this isn’t dense at all.
rocqua 2 hours ago [-]
Black holes aren't really infinitely dense. The matter isn't concentrated at the centre, its spread out over the event horizon. As i understand the theory, they effectively suggest you could glue another universe onto the event horizon of a black hole. From the outside that is indistinguishable from 'just a black hole'.
nextaccountic 2 hours ago [-]
Only the infinitesimally small singularity that is in the future of all objects inside the event horizon is supposed to be very dense. The space inside the event horizon is supposed to be normal-ish
Aerroon 2 hours ago [-]
If such a singularity exists at all. The thing we "observe" about black holes is the event horizon. It could be that space inside a black hole is just regular space.
nextaccountic 45 minutes ago [-]
Yep! Generally speaking singularities only appear because the math is deficient in some way. Other areas of physics successfully got rid of unphysical singularities by employing better math, it's just that we don't know how to fix this aspect of general relativity (maybe quantum gravity will?)
ShinTakuya 2 hours ago [-]
Black holes need not be dense. The black hole at the centre of galaxy M87 has the density of air in our atmosphere. The larger the black hole, the less dense it is. So that alone doesn't preclude us existing inside of one.
m3kw9 3 minutes ago [-]
That’s news to me, I was taught that the mass collapses into it self it creates more gravity and more matter gets sucked in because the mass is so dense. So at which point does it become less dense?
jpalawaga 2 hours ago [-]
An entire universe crammed inside the event horizon seems pretty dense to me! Makes you wonder how much matter would be in the parent universe.
Rendered at 15:55:35 GMT+0000 (Coordinated Universal Time) with Vercel.
> Another explanation for why the JWST may have seen an overrepresentation of galaxies rotating in one direction is that the Milky Way's own rotation could have caused it.
> Previously, scientists had considered the speed of our galaxy's rotation to be too slow to have a non-negligible impact on observations made by the JWST.
> “If that is indeed the case, we will need to re-calibrate our distance measurements for the deep universe," Shamir concluded. "The re-calibration of distance measurements can also explain several other unsolved questions in cosmology such as the differences in the expansion rates of the universe and the large galaxies that according to the existing distance measurements are expected to be older than the universe itself."
How can local movement of stars within the Milky Way affect which way spiral galaxy arms are pointing?
[0] https://academic.oup.com/mnras/article/538/1/76/8019798.
So I’d suspect they’re saying time and distance would need to be factored in rather than just looking at static images relative to our position today since our own spin may have caused a particular galaxy to appear to have been spinning in a different direction at another point in space-time
I don't see how time-intermittent frame captures from our own position affect that interpretation. Or are we using an astonomy-specific definition of spin here?
The author writes about the Doppler effect creating a systemic bias in brightness depending on which way the galaxies are rotating. I don't understand that argument either, but it's moot, because they state categorically that that effect would be too small to explain their results. ("This explanation is challenged by the fact that the effect of the rotational velocity have merely a mild impact on the brightness of galaxies, and therefore is not expected to lead to the dramatic difference of 50 per cent in the number of galaxies as observed through JADES.")
That's the only explanation I recognized as an explanation. Then I lost track of their argument following that. They refer to several speculative physics theories like MOND, but I don't understand them to be saying something that concretely predicts distant galaxies to appear to be rotating differently.
I'm appealing to anyone on HN who knows enough about this field to understand the meat of this argument.
This one of the author's other papers they cited in this one,
https://www.mdpi.com/2073-8994/15/6/1190
I'm completely lost how they're eliding between the rotation orientation of the Milky Way galaxy, and relative linear velocities with stars in other galaxies. In the special relativity argument, where does the rotation axis of the Milky Way enter?
[1] https://academic.oup.com/mnras/article/538/1/76/8019798
ELI5: Per "5.2 Physics of Galaxy Rotation", could the Milky Way's relative movement, in addition to its spin, also effect the observed assymetry? In Figure 10, is the Milky Way also moving toward the blue and away from the red?
Thanks for humouring my question. Everything about astronomy and JWST just blows my mind. Like how Figure 10 sorta resembles yinyang. What a time to be alive.
Also meaning that “our” blackhole (the one containing us) is unobservable from the parent universe for the same reason. So where is all this extra light/energy going in our universe? Should we not have detected an increase of energy in our universe?
By one or two seconds in the parent universe’s time scale, our universe will have settled down to its extremely long state of being a cold, dark void of slowly decomposing subatomic particles.
No good reason to think this, just feels right.
Perhaps that's dark energy or vacuum energy? If mass and time truly switches places when crossing into a black hole, it would make sense that the spacetime size of this universe translates into observable mass outside it. Which might tie it to the expansion of the universe.
What do you mean by that?
Its an interesting theory but to be honest, given the conditions of the event horizon, I don’t see HOW it could be proven.. That said I do feel this will turn out to be a nuance of the measurement itself but maybe that’s just my mind not comprehending the scales of what’s being measured here.
Would matter falling into our black hole come shooting out of the white-hole we see?
Would time on either side of the event horizon even be related?
We would see that at the edge (if we could see it) there's new mass and energy, but that would be obscured by what appears as the CMB for us.
> Heck, Hawkins radiation means black holes can evaporate. Does that correspond to a universa collapsing?
No, it corresponds to stuff disappearing from our universe, until someday nothing is left.
> Would matter falling into our black hole come shooting out of the white-hole we see?
We'd see it as being part of the Big Bang, behind the CMB, so we wouldn't see it.
> Would time on either side of the event horizon even be related?
Er, not in any way that we could observe, so it's not a question we could answer. But we could receive information from the outside, except that the CMB would hide it from our prying eyes.
The idea that any mass that will ever fall into our black hole all simultaneously appeared at the big bang doesn't feel correct. That suggests a very specific relationship between time on the inside and outside. There are at least two moments that are distuinishable on both sides. The singularity appearing, and the singularity dissapearing. Compressing all time on the outside into the big bang means weird things for the timing of when the singularity dissapears.
Something to consider is a possible time scale difference. Eg time could be dilated for us for being around so much density.
I think that's exactly the right question to ask. And ask it for space too. Perhaps the entire history of the interior universe unfolds between the black hole's formation and its final evaporation. Perhaps a heat death of the interior universe, where everything spreads out until nothing interesting is left, can fit inside this ever shrinking volume.
Hope that helps!
I recall reading about our universe as a black hole once -- one thing posited is that everything that is happening and what we think of as space is really information processing occurring just at the surface of the event horizon. There was some possible way of explaining non-local phenomena like entanglement that way, but I forget the details.
It's fascinating to think about how the actual universe might be something quite alien from our ordinary perception. It's not that our ordinary perception is wrong. What we're perceiving is just one perspective on something much larger and weirder. In this case our perspective would be from within this information substrate. It's almost universe-as-simulation, except that the simulation does not have a builder. It's a naturally occurring phenomenon. The Matrix has no architect, or if it does it's something fully outside the event horizon of this object and thus un-observable.
Of course at this point we're well into physicists smoking pot territory.
sadly, this is likely the real explanation, but that's not very exciting
To cross her course
Are swallowed by
A fearsome force
Through the void
To be destroyed
Or is there something more?
Atomized — at the core
Or through the Astral Door —
To soar…"
https://www.rush.com/songs/cygnus-x-1-book-one-the-voyage/