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Woops. Yes, galaxies. Too late to edit. > Anyway, given the number of galaxies in the ring, being at different distances but their projections just happening t

Woops. Yes, galaxies. Too late to edit. > Anyway, given the number of galaxies in the ring, being at different distances but their projections just happening to form a rough circle would be even more astonishing than the galaxies in fact sharing a causal history due to some unknown early-universe mechanism. I don't understand what you mean by this. Why would it be "more astonishing" than an actual causal connection? Surely astronomers are more interested in causal connections than observational coincidences? To illustrate: the stars making up the constellation of Norma [1] form a rough square when seen from earth, but as their distances from Earth vary greatly this is just an illusion caused by Earth's relative orientation to them. Given the Copernican principle (which I accept is not a physical law) I'm struggling to see why a group of galaxies that form a circle only when seen from "near" earth [2] are actually cosmologically significant. I accept that the ring contains more than four galaxies, and this makes the ring more statistically significant than a square of galaxies. But it still implies a privileged viewpoint in order for it to be actually significant. I still have the gut feeling that this potential significance is more than offset by the enormously greater observational scale. tl/dr: why is this more than just naming a new constellation? (Just to re-iterate: I'm interested in understanding the errors in my mental model - and I'm not trying to poke holes in the work of scientists more qualified them me.) [1] https://en.wikipedia.org/wiki/Norma_(constellation) https://en.wikipedia.org/wiki/Norma_(constellation) [2] And also, I guess, from a similar point on the other "side" of the ring

_xerces_ 2y ago
I think of it in terms of degrees of freedom and statistical likelihood. If I throw a bunch of marbles on the floor and a few of them form a interesting shape that is one thing as they can only move on a plane. If I throw them in the air it is less likely to form a circle as now they are free to move in multiple directions and are not constrained to the plane. If 4 of those marbles align that is less likely than 20 of them happening to do so in a recognizable shape. 20 marbles in the air, each one being in just the right place relative to the 19 others in order to look like a circle when they can be in any position in space (vs. limited to a flat plane) is exceedingly unlikely. Even more unlikely is that an arc appears next to the ring, that would make me start to wonder if something is affecting the marbles I throw into the sky.
- financypants 2y ago
  Is it less likely even if we can view the marbles in the air from any angle?
- jjk166 2y ago
  But your view is a 2D projection, so you are eliminating that degree of freedom. It's equivalent to forcing them all to fall to the floor. If they form an actual ring in 3D space, that is far less probable.
mannykannot 2y ago
It does not seem very plausible that professional astronomers have twice made this rookie mistake and no-one has noticed yet. Furthermore, if they were just doing what amounts to drawing circles and lines on a map of galaxies, they could have discovered thousands by now!
- mentalpiracy 2y ago
  The rate at which we are collecting data far, far outpaces the speed at which it is being analyzed. There will almost certainly be more discoveries like this as we continue surveying the cosmos with increasingly sensitive instruments.
  - mannykannot 2y ago
    Well, yes, but my point is that, if these astronomers are finding circles and other structures without doing basic checks such as distance, they could find thousands right now, using nothing more than a chart of the known galaxies - and even bigger ones than they are reporting here. Thus, it is not plausible that they are omitting these basic checks.
alfiopuglisi 2y ago
> Woops. Yes, galaxies. Too late to edit. Not even galaxies, but massive galaxy clusters. The spatial smoothing used for the ring image is a 2D gaussian with an equivalent width of 11 Mpc, or 37 million light years, big enough to contain all the 2000 galaxies in the nearby Virgo cluster with room to spare. That's for each point in the ring (and that's why they all look so nice and round. These astronomers are playing a statistical game where a pixel combines information from trillions of stars) It's called the Big Ring for a reason. Our own Laniakea supercluster [1], whose dimensions are bigger than anyone imagined up to a few years ago, can be tiled inside the ring several times over. At that spatial scale, the Universe is supposed to be homogeneous. We do not have plausible mechanisms to generate structures on such a massive scale. Regarding your analogy with a constellation, yes you can always draw arbitrary squares and triangles among bright stars. But if you had 20+ stars arranged in a circle like that ring, no one would think it was a chance projection, you would demand a physical explanation. We do in fact have such a ring around us: the Gould Belt [2], made of young stars all around the Sun. It is difficult to recognize precisely because we are inside it, and its stars are spread all around the sky. And, of course, some kind of physical explanation is invoked for this ring as well. Moreover we do know it's an actual ring, and not some chance alignment, because we can derive the distance of each point from its redshift, and it turns out that they are all quite similar. The authors spend quite a few pages describing the 3D ring structure, showing that it's a ring only when seen from our direction, and how it would appear like an arc or a strange shape from other viewpoints. It would still be a kind of overdense structure, but maybe more difficult to recognize. BTW the mechanism used to detect the ring is quite clever: it's not a sky image, but rather an absorption map: thousands of background quasars provide a sort of uniform illumination, and they look where this light is removed by clumps of matter. [1] https://en.wikipedia.org/wiki/Laniakea_Supercluster https://en.wikipedia.org/wiki/Laniakea_Supercluster [2] https://en.wikipedia.org/wiki/Gould_Belt https://en.wikipedia.org/wiki/Gould_Belt
- andyjohnson0 2y ago
  Thank you for taking the time to write such an informative response.
- deleted 2y ago
  [deleted]
vikingerik 2y ago
There is also the multiple-endpoints principle to think about. The likelihood of this particular set of galaxies forming a ring is very low. The chance of some set of galaxies among all the billions in the sky doing this is much higher. Then we notice and cherry-pick only the one interesting data point, we never notice all the mundane ones. It's always difficult to tell if a popular-science article is really describing something unusual or if it's using selective perception to create the illusion of one. (I have no idea in this case.)
- SubiculumCode 2y ago
  It's unusual, at the very least. Because it's relatively close to us.
- beltsazar 2y ago
  > The chance of some set of galaxies among all the billions in the sky doing this is much higher. Of course in relative terms it's much higher, but it doesn't matter—what matters is the absolute value. 10^-100 is much larger than 10^-10000, but if something with the probability of 10^-100 happens, it's still "astonishing." The probability of a particular planet has a shape of pyramid is so low. And yes, the probability of finding any planet in the universe that has a shape of pyramid is much higher, but still very low. If one was found, scientists would freak out.
szvsw 2y ago
The infinite does not necessarily contain everything. I would be surprised to find an even number in an infinite list of odd numbers. I would be even more surprised to find cantor’s diagonalized number in a list of rational numbers. And yet even more surprised to find Hamlet encoded within Pi. Structure is still interesting. In re: the non-causal alignment being even more astonishing - a simple argument to illustrate this is to ask- would you be more amazed if you threw 100 bouncy balls in a room, took a photo and they formed a perfect circle in mid air at that instant from that angle, or if you went and placed the marbles one by one in a perfect circle on the ground and took a photo? The latter might be more meaningful, but the former is more miraculous - not in a religious sense of course, but just in the sense of the extraordinary unlikelihood of catching such a moment of chance alignment in noise, apophenic divinity, in how it seems to violate the second law, etc etc. It might be instructive for you to try look up Piero Della Francesca’s method of generating perspective images from a point cloud (from the 14th century no less - he invented 3D face scanning then!) and try a few manual examples to really wrap your head around how difficult it would be for a perfect circle to emerge from a truly random point cloud.
- gcanyon 2y ago
  If Pi is normal, which we haven't proven but do suspect to be true, then it contains Hamlet, and indeed the entire works of Shakespeare in chronological order, an infinite number of times. https://en.wikipedia.org/wiki/Normal_number https://en.wikipedia.org/wiki/Normal_number
  - szvsw 2y ago
    Of course! But we haven’t been proven it yet. And in any case, knowing something exists is quite different than actually observing it. I know every night in Vegas, so many people will hit my lucky number (7, boring I know) on a roulette wheel that it is a perfectly ordinary event with no significance, and yet I would be ecstatic if it happened to me and would certainly be feeling lucky (and so I don’t gamble!). Even if Pi is indeed normal, it would still certainly be beyond surprising to stumble across the complete works of Shakespeare. In fact, from a cultural point of view, it would be a somewhat earth-shattering event! Imagine the headlines! Maybe not, maybe no one would care. It would certainly be shocking to anyone with half a brain cell, even if they knew it had to be somewhere… to find one such particular region is just so improbable that it would be undeniably… cool? My point is that structure emerging out of noise, even if by mere coincidence, is still deeply interesting on a human, psychological level. Another commenter described the original paper as astrology, essentially arguing that it is bad science… maybe that is the case, but I think there is still room for some form of… confusion, estrangement, awe? in observing these sorts of phenomenon, even in scientific discourse every now and then. It’s vaguely like a piece of meaningless but none-the-less captivating art emerging out of the complex technological and discursive apparatuses of science.

_xerces_ 2y ago

I think of it in terms of degrees of freedom and statistical likelihood. If I throw a bunch of marbles on the floor and a few of them form a interesting shape that is one thing as they can only move on a plane. If I throw them in the air it is less likely to form a circle as now they are free to move in multiple directions and are not constrained to the plane. If 4 of those marbles align that is less likely than 20 of them happening to do so in a recognizable shape. 20 marbles in the air, each one being in just the right place relative to the 19 others in order to look like a circle when they can be in any position in space (vs. limited to a flat plane) is exceedingly unlikely. Even more unlikely is that an arc appears next to the ring, that would make me start to wonder if something is affecting the marbles I throw into the sky.

financypants 2y ago
Is it less likely even if we can view the marbles in the air from any angle?
jjk166 2y ago
But your view is a 2D projection, so you are eliminating that degree of freedom. It's equivalent to forcing them all to fall to the floor. If they form an actual ring in 3D space, that is far less probable.

mannykannot 2y ago

It does not seem very plausible that professional astronomers have twice made this rookie mistake and no-one has noticed yet. Furthermore, if they were just doing what amounts to drawing circles and lines on a map of galaxies, they could have discovered thousands by now!

mentalpiracy 2y ago
The rate at which we are collecting data far, far outpaces the speed at which it is being analyzed. There will almost certainly be more discoveries like this as we continue surveying the cosmos with increasingly sensitive instruments.
- mannykannot 2y ago
  Well, yes, but my point is that, if these astronomers are finding circles and other structures without doing basic checks such as distance, they could find thousands right now, using nothing more than a chart of the known galaxies - and even bigger ones than they are reporting here. Thus, it is not plausible that they are omitting these basic checks.

alfiopuglisi 2y ago

> Woops. Yes, galaxies. Too late to edit. Not even galaxies, but massive galaxy clusters. The spatial smoothing used for the ring image is a 2D gaussian with an equivalent width of 11 Mpc, or 37 million light years, big enough to contain all the 2000 galaxies in the nearby Virgo cluster with room to spare. That's for each point in the ring (and that's why they all look so nice and round. These astronomers are playing a statistical game where a pixel combines information from trillions of stars) It's called the Big Ring for a reason. Our own Laniakea supercluster [1], whose dimensions are bigger than anyone imagined up to a few years ago, can be tiled inside the ring several times over. At that spatial scale, the Universe is supposed to be homogeneous. We do not have plausible mechanisms to generate structures on such a massive scale. Regarding your analogy with a constellation, yes you can always draw arbitrary squares and triangles among bright stars. But if you had 20+ stars arranged in a circle like that ring, no one would think it was a chance projection, you would demand a physical explanation. We do in fact have such a ring around us: the Gould Belt [2], made of young stars all around the Sun. It is difficult to recognize precisely because we are inside it, and its stars are spread all around the sky. And, of course, some kind of physical explanation is invoked for this ring as well. Moreover we do know it's an actual ring, and not some chance alignment, because we can derive the distance of each point from its redshift, and it turns out that they are all quite similar. The authors spend quite a few pages describing the 3D ring structure, showing that it's a ring only when seen from our direction, and how it would appear like an arc or a strange shape from other viewpoints. It would still be a kind of overdense structure, but maybe more difficult to recognize. BTW the mechanism used to detect the ring is quite clever: it's not a sky image, but rather an absorption map: thousands of background quasars provide a sort of uniform illumination, and they look where this light is removed by clumps of matter. [1] https://en.wikipedia.org/wiki/Laniakea_Supercluster https://en.wikipedia.org/wiki/Laniakea_Supercluster [2] https://en.wikipedia.org/wiki/Gould_Belt https://en.wikipedia.org/wiki/Gould_Belt

andyjohnson0 2y ago
Thank you for taking the time to write such an informative response.
deleted 2y ago
[deleted]

vikingerik 2y ago

There is also the multiple-endpoints principle to think about. The likelihood of this particular set of galaxies forming a ring is very low. The chance of some set of galaxies among all the billions in the sky doing this is much higher. Then we notice and cherry-pick only the one interesting data point, we never notice all the mundane ones. It's always difficult to tell if a popular-science article is really describing something unusual or if it's using selective perception to create the illusion of one. (I have no idea in this case.)

SubiculumCode 2y ago
It's unusual, at the very least. Because it's relatively close to us.
beltsazar 2y ago
> The chance of some set of galaxies among all the billions in the sky doing this is much higher. Of course in relative terms it's much higher, but it doesn't matter—what matters is the absolute value. 10^-100 is much larger than 10^-10000, but if something with the probability of 10^-100 happens, it's still "astonishing." The probability of a particular planet has a shape of pyramid is so low. And yes, the probability of finding any planet in the universe that has a shape of pyramid is much higher, but still very low. If one was found, scientists would freak out.

szvsw 2y ago

The infinite does not necessarily contain everything. I would be surprised to find an even number in an infinite list of odd numbers. I would be even more surprised to find cantor’s diagonalized number in a list of rational numbers. And yet even more surprised to find Hamlet encoded within Pi. Structure is still interesting. In re: the non-causal alignment being even more astonishing - a simple argument to illustrate this is to ask- would you be more amazed if you threw 100 bouncy balls in a room, took a photo and they formed a perfect circle in mid air at that instant from that angle, or if you went and placed the marbles one by one in a perfect circle on the ground and took a photo? The latter might be more meaningful, but the former is more miraculous - not in a religious sense of course, but just in the sense of the extraordinary unlikelihood of catching such a moment of chance alignment in noise, apophenic divinity, in how it seems to violate the second law, etc etc. It might be instructive for you to try look up Piero Della Francesca’s method of generating perspective images from a point cloud (from the 14th century no less - he invented 3D face scanning then!) and try a few manual examples to really wrap your head around how difficult it would be for a perfect circle to emerge from a truly random point cloud.

gcanyon 2y ago
If Pi is normal, which we haven't proven but do suspect to be true, then it contains Hamlet, and indeed the entire works of Shakespeare in chronological order, an infinite number of times. https://en.wikipedia.org/wiki/Normal_number https://en.wikipedia.org/wiki/Normal_number
- szvsw 2y ago
  Of course! But we haven’t been proven it yet. And in any case, knowing something exists is quite different than actually observing it. I know every night in Vegas, so many people will hit my lucky number (7, boring I know) on a roulette wheel that it is a perfectly ordinary event with no significance, and yet I would be ecstatic if it happened to me and would certainly be feeling lucky (and so I don’t gamble!). Even if Pi is indeed normal, it would still certainly be beyond surprising to stumble across the complete works of Shakespeare. In fact, from a cultural point of view, it would be a somewhat earth-shattering event! Imagine the headlines! Maybe not, maybe no one would care. It would certainly be shocking to anyone with half a brain cell, even if they knew it had to be somewhere… to find one such particular region is just so improbable that it would be undeniably… cool? My point is that structure emerging out of noise, even if by mere coincidence, is still deeply interesting on a human, psychological level. Another commenter described the original paper as astrology, essentially arguing that it is bad science… maybe that is the case, but I think there is still room for some form of… confusion, estrangement, awe? in observing these sorts of phenomenon, even in scientific discourse every now and then. It’s vaguely like a piece of meaningless but none-the-less captivating art emerging out of the complex technological and discursive apparatuses of science.