A 1.3B-light-year-across ring of galaxies has confounded astronomers
cosmosmagazine.com
cosmosmagazine.com
https://youtu.be/fwRJGaIcX6A?t=173
Here's an in-depth seminar on the findings of the Giant Arc in the Sky, her work prior to the Big Ring discovery:
https://www.youtube.com/watch?v=-zkGk6EPMC8
She was also featured in a pop-sci BBC Four documentary:
https://www.youtube.com/watch?v=S36MqEzUzIw
Unfortunately all videos are of quite bad quality, but the explanations are a good introduction to the work.
My other thought, with all respect to the expertise of the scientists involved, is that when we observe the universe at this massive scale it may be inevitable that structures will just appear out of the data, even with very high statistical significance. I don't know if this is a scientifically defensible position to take though.
Again - I'm not a scientist and I don't know what I'm talking about. Just musing, but interested in the opinions of others more informed than me.
[1] I'm aware that determining distance over cosmological distances is very difficult
Galaxies. And determining the approx relative distance of distant galaxies is in fact easy thanks to cosmological redshift (the z values the article refers to). 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.
The article also mentions that either the circle or the arc in itself could be just a statistical coincidence – as long as we dok’t find more such structures – but the existence of both the circle and the arc, in the same part of the sky, is highly suspicious.
> 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)
[2] And also, I guess, from a similar point on the other "side" of the ring
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.
There will almost certainly be more discoveries like this as we continue surveying the cosmos with increasingly sensitive instruments.
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.
Actual structure no. But, random chance can make things look like a structure on this scale.
> 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.
I would generally assume it to be random. In galaxies stars move around far to much for any structure from their initial formation to remain for long, and forming a ring long after creation would just be happenstance.
But its not, it has structure - it looks like ring or arc. The universe should be homologous at this scale.
Random processes can appear to have meaningful structure, but that’s just because we value some outcomes more than others.
> The universe should be homologous at this scale.
That doesn’t mean we’re going to perceive it as homologous. A true random number generator spitting out 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 would be freaky as fuck to see, but that doesn’t make it non random.
I’m just talking without actually having done a close reading or done the statistics for myself, so I could be quite wrong.
It’s less impressive when looking at the background data than how it’s described.
No. It's because some structures are much much much less likely to form randomly than other structures.
If you throw 1000 dices, is it possible to get all one? Yes. Is it likely? Not at all.
Why do planets look like a sphere (approximately)? Because that's the most probable shape if things happen randomly. If a pyramid-shaped planet was found, scientists would freak out. This galaxy ring phenomenon is similar to that (but not that crazy).
Actually, you would have a hard time producing this set in such way that no "circles" like that are found at all. It would have to be a very artificial distribution of points in space for you not to observe this, like all of them arranged in a single line, or a giant rectangle, idk.
It depends on the size of the circle, though. The smaller the size, the more likely the probability is. But that’s only for a particular combination of 50 dots. Now we have to average out of all possible circle sizes and all combinations of 50 dots. Can someone do the math (or the simulation)?
I'm thinking, the larger the space, the larger the number of points contained within it, so the larger the probability of them being arrange in such way that blah blah ...
We need a math guy to chime in. I have a hunch there may be a theorem about something like this already.
That's literally as likely as any other possible outcome.
Let's simplfy this to a coin toss, which is more likely:
HHHHHH
or
HHTHTT
or
HTHTHT
They all have the exact same odds of appearing, we might just tell ourselves one formation is more special than any other.
In the dice example, it's obvious that the probability of getting at least one dice facing two is much more likely than the probability of getting all dice facing one.
Similarly, in the planet shape example, I hope you don't think that a pyramid-shaped planet is as likely to form as a sphere-shaped planet.
However that doesn't mean that a sphere is any more or less likely than any specific other structure. It's an small but important distinction.
No, a pyramid shaped planet is not as likely to form as a sphere shaped pyramid. Definitionally a pyramid shaped planet is impossible.
A shape/structure doesn't have an intrinsic probability. Your sentence is underspecified. Shape of what under what process?
In the context of the shape of galaxies, I think we can agree that if we found galaxies forming a shape like this sentence: "WE ARE COMING", everyone would freak out. So yeah, in this context, some shapes are more likely to form (randomly) than others.
Again I think you are confused. Assuming random distribution, 'We Are Coming' is just as likely as any other similarly long structure to form. You just happen to care about that structure more than others - however that doesn't make it more or less likey to form.
That message, in morse code is .-- . / .- .-. . / -.-. --- -- .. -. --..
There are 200B to 2T galaxies in the obeservable universe. If you found lines of galaxies and interperated them as morse code, I'm sure you'd find some interesting words/phrases being said.
You'd expect that phrase in every 2^28 = 268,435,456 random 28 digit binary strings - which is not very many. Keep in mind a galaxy could be part of many, many strings (different index position, different orientation of string).
You are confused. How could we be back to square one? We've discussed it before. I'm not arguing that "WE ARE COMING" is more likely than, for example, "WE RAE COMING". Of course, they are as likely.
Suppose you have a machine that generates 15-char strings. Yes, "INTERCHANGEABLE" is as likely as "YSVQEPQVIGXOQSR" to come out—but that’s not the point. My point is that the probability of getting a proper English word is very unlikely. Most of the time, you'll get gibberish strings.
Also, I didn't say the sentence to be encoded in morse code. Instead, the galaxies form the literal shape of "W", "E", and so on. I hope you can see that in this case, it's borderline impossible to happen.
Sure, but given a large enough sample both will likely exist. So the fact that one happens to be english should not surprise anyone nor does it suggest meaning.
> Also, I didn't say the sentence to be encoded in morse code. Instead, the galaxies form the literal shape of "W", "E", and so on. I hope you can see that in this case, it's borderline impossible to happen.
I used morse as its easy to reason about. There's no reason to think shapes are impossible - you just have to define what makes a shape and then look for patterns that match.
Humans have been finding patterns in clouds, stars and even toast since time immemorial.
This applies to every event with nonzero probabilities. What's your point?
> Humans have been finding patterns in clouds, stars and even toast since time immemorial.
I knew this—humans love finding patterns. But our discussion is not about that. It's about the very basic thing in probabilities, which is some event is not as likely to happen as others. This is so trivially true.
The probability of getting a proper English word from a random string generator is much less likely than the probability of not getting it. Thus, getting a proper English word should be surprising. It is as surprising as getting any string from a set of gibberish strings with the same cardinality of English vocabularies.
> So the fact that one happens to be english should not surprise anyone
What should surprise you, then? I'm surprised that we need to talk about this very basic thing three times.
Similarly finding any shape in a random set of points is much more likely than the odds of any one shape.
So you need to adjust for both things people are looked for correlations and the entire class of things that would notice not just the odds of what you happened to see. A random process you run spitting out a famous quote would be low, but you would also be surprised Pi is 3,14 or Pi is 3.14 etc etc.
Thus someone else hitting a random process and getting “To be or knot to be” is now looking at the odds that anyone anywhere would get something that’s close to something memorable which should actually be quite high.
TLDR; https://xkcd.com/882/
Obviously. But that’s not the point (no pun intended). My point is that most of the "shapes" would be just an unstructured shape—if you can even call it a shape. "Familiar" shapes will be much much unlikely to form that "uncommon" shapes. (Hopefully this is obvious because the number of familiar shapes are much much fewer than uncommon shapes.)
Let me use another example to help you understand the point. Suppose a monkey is given a typewriter and a sheet.
Is the probability of getting The Declaration of Independence is as likely as the probability of getting one particular gibberish sequence of characters? Yes.
Should we surprise if the monkey types any proper one-page English essay? Yes.
In case it's not obvious, that's because the number of possible ways to write a proper one-page English essay, albeit humongous, is nothing compared to the number of possible ways to arrange characters in one page. In other words, it's very very very unlikely to happen.
You can’t exclude non English languages being you would still be surprised if it was in Spanish etc. If your test is if anything surprising happens, then you must consider every possibility that you would find surprising.
Also, this isn’t some mathematically perfect shape it’s a points in a clump that we’re classifying as a shape.
As such a monkey typing someone vaguely like a proper one-page essay in any language or encoding would still be surprising, but is probably 10^1,000 or so times more likely than any specific sequence.
I'm not saying that the only surprising result is an English esssay. But sure, let's add all languages in the world. Getting a proper one-page essay is still surprising, because the absurd number of ways to arrange characters in one page. It's much much much larger than even the number of particles in the universe.
> but is probably 10^1,000 or so times more likely than any specific sequence.
Obviously. Your point? If the probability of an event is so low, it doesn't really matter if it's 1 in 10^1000 or 1^1000000. If that event happens, it is surprising.
---
Anyway, I'm not arguing that the galaxy ring is a rare occurrence, hence surprising. I don't know even an approximate probability of it to happen.
I'm arguing against those who shrug and say "Well, it's random, so even a complex structure can form." Not necessarily. It all depends on the processes behind it.
Case in point: Darwin's evolution. The only reason that it's plausible that random processes can transform basic living organisms into complex ones like mammals is DNA replication.
Without DNA replication, random mutations between generations would be independent, just like random key presses by a monkey. You need to start over every time. This makes it essentially impossible to form complex organisms over time, considering how long DNA of complex organisms is.
Except that's not a given.
Any equally long random string is as likely as any other equally long random string.
Different length sets of random strings may differ in probability.
Finding what might appear to be meaningful structures in large data sets, e.g. shapes in 2T galaxies, doesn't inherently suggest anymore than chance.
Before I give up on this discussion that's always back to square one, maybe this question (that I've similarly asked) will help set a baseline:
What are a few examples of probablistic events that should surprise you?
The ring may be possible but, so far, it's the only example so despite being a potential random outcome of randomness, the sheer singularity of its existence proves it's incredibly low likelihood of occurrence - perhaps such a low % chance of actually occurring that it may be easier to believe that the ring had help in its formation, whatever that may be.
I'm not going to deny obvious things just bc they challenge my worldview - especially if I have to defend my viewpoint semantically
You can easily build a compression scheme for any one of these values, but not one that encapsulates all values while using less data than the raw values themselves.
> That's literally as likely as any other possible outcome.
???
If you want any outcome, they're equally likely.
But the prev post chose a particular outcome, and any particular outcome is rare.
There's no contradiction.
So what's the insight?
This distinction is popularly represented by the "Monty Hall problem": should you take the offer of the other door.
The problem involves 3 doors with a prize behind only one, where you choose 1 of the three, then Monty shows you what's behind 1 of the remaining 2, which is not the prize, then asks you if you would like to switch to the remaining door.
You might think that your odds won't change because nothing behind the doors has changed, or might get worse because the offer is a second chance to pick the dud.
But instead of 3 doors, imagine 1000 doors. You pick 1. Monty shows you what's behind 998 that aren't the prize and asks you if you want to switch.
By switching, your 1-of-1000 odds become 1-of-2.
The particulars matter.
No they should become 999 out of 1000. If your door is 1 in 1000 then the other door must have all other possibilities.
Also, the Monty haul problem is counter intuitive because it depends on the exact rules under which he operates. Suppose the classic 1 in 3 odds of a win, but an evil Monty haul where he only gives the option if you would win, now swapping is a guaranteed loss. Mathematically the answer is obvious when all the rules are guaranteed, but people’s internal heuristics don’t automatically trust rules as stated.
No, we first observed a particular outcome (the giant ring). This would be like running coin flips for long enough, spotting some interesting sequence that wasn’t decided beforehand, then deciding it must not be random because that sequence should have been incredibly rare.
Sure, that sequence was rare but it was just as likely as all the other sequences which we didn’t end up seeing.
It's not 50/50. That means you had a 50% chance to get the door correct on the first guess out of 1000. By showing the non-winning doors, the odds collapse into the remaining door. You had a 1/1000 chance of getting it right the first time, after the reveal all 998 are now assigned to the remaining door.
That has actually nothing to do with randomness, and everything to do with gravity. https://spaceplace.nasa.gov/planets-round/en/
Randomness only favors something over noise if there is a non random process determining the structure
A lot of these questions are much more clearly addressed in the previous paper by the same authors, which is much more layperson-friendly: https://academic.oup.com/mnras/article/516/2/1557/6657809?lo...
That makes sense, thanks for actually explaining the core idea.
That doesn’t mean it was put there intentionally, just that given enough random samples any pattern will appear.
You can never absolutely prove that something isn’t random. However:
Galaxy distributions are pink noise, not white noise. Large scale structures are less probable.
The Komolgorov complexity of large structures is lower than random noise, and lower Komolgorov complexity usually indicates some non-random process.
A random process is less likely to produce structure than a non-random process.
Here's the idea. The expansion of the universe is currently accelerating. If this continues indefinitely, we get the https://en.wikipedia.org/wiki/Big_Rip model. What happens if the Big Rip proceeds to the point where a lot of https://en.wikipedia.org/wiki/Vacuum_energy gets released, and that release stops the Rip by creating the next Big Bang? This could form a cycle since the next Bang creates cosmos that in turn will Rip.
It doesn't sound entirely crazy to me. The Casimir effect shows that you should release vacuum energy when you constrain the volume that a particularly bit of space can interact with. The incredible expansion of a Rip should constrain such interactions. So a large release of vacuum energy seems expected. And who knows how releasing vacuum energy interacts with the acceleration of the expansion of the universe?
Let's do a back of the envelope estimate. Theory estimates vacuum energy at something like 10^113 joules per cubic meter of vacuum energy. For comparison the visible universe is estimated at 10^53 kg. Using Einstein's E = mc^2, that's around 10^70 joules. Current cosmological models say that at the hottest part of the Big Bang, the universe must have already been larger than a cubic meter. Yes, there is a lot of energy not in the form of visible matter. Even so, there's a lot of room for a release of vacuum energy to explain the energy density needed at the beginning of a Big Bang.
We at least pass the most basic sanity check.
This would offer interesting answers to some key cosmological questions.
Current Big Bang models struggle with how a large volume started out very uniform. Inflation has been proposed for this, but it has some problems. But in this model, extreme uniformity over a large volume is predicted. If you add in quantum fluctuations starting the vacuum release, that have spread out before we go from Rip to Bang, then you can also explain arbitrarily large structures in the universe.
This also explains the arrow of time. How could we start off with such low entropy when entropy is always increasing? Well as the universe expands, entropy increases. But volume increases faster. We wind up with a giant universe filled with very low entropy/volume. When a small piece of that forms a new Big Bang, it again starts with very low entropy.
Unfortunately, this involves an insane lack of conservation of energy. But GR provides no easy way to even state what conservation of energy means. At least not outside of limited classes of models. Which this is not one of. So the idea of energy not being conserved at cosmological scales is at least not entirely unprecedented by current theory.
Of course we would? This is absolutely backwards.
A random plot of billions of points will have all sorts of coincidental shapes and clusterings. A uniform field might look more random but would actually demand explanation, as lacking those coincidental clusterings is strong evidence for structure.
And as I understand the topic, the scales involved preclude those galaxies physically interacting and being able to form structure. So they should appear randomly distributed.
Edit: To be clear I’m assuming my own ignorance here. I presume there is a reason this is significant, I just don’t understand it. But arguments like yours aren’t convincing to me because we should expect to see random structure, the same way a series of a billion coin flips is likely to have a giant run of alternating heads and tails.
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.)
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.
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.
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.
I don't kno why ppl believe that it is. It's very big, we have no frame of reference bc it literally contains all possible known frames of reference and even with that in mind, we need a bigger thing to grasp how big it is, we won't ever have that perspective.
That doesn't make the universe infinite tho. Even if the universe is expanding at a rate greater than we could ever catch the other galaxies and this expansion limitlessly expands the universe, THAT is still not infinite.
There is no infinite thing bc nothing is infinite for real, it's an idea
If you think about it, it doesn't matter which point of view it works on, if the thing is an actual circle that's interesting on its own, or presumably a sphere(?) but they don't even touch on that because "3D is hard"? Anyway, for some reason they implicitly choose our point of view as the "interesting one", funny (/s, actually lame and sad) to see the geocentric model is still alive after two millennia!
They also didn't check if other stars would form circles from any arbitrary point of view (how many circles are actually up there, not just the apparent ones), which would be a trivial calculation, but I guess "matrix transformations are hard" as well?
The whole paper is pretty weak. They calculate the "thickness" of this "circle", i.e. the distance from the galaxy closest to us to the galaxy further from us if you undo the projection; and they come up with a value of ~400 Megaparsecs. Now, you may be inclined to think "yeah, but the universe is HUGE and on that scale they may be kind of tighly packed?". Nope! It's on the order of the largest (actual) cosmological structures that we have identified, so, pretty much, they are as further away as they can be from each other, lol.
This is pretty much astrology.
Source: I read the paper.
Would the perspective difference be significant even if it were far out into the solar system?
Spin up your mental model of a circle in 3D space, look at it from a vector perpendicular from its diameter, rotate it 90 degrees in any other axis but the one you're looking at it; on that 2D projection, it will be a line.
Right, and as a matter of fact that's exactly what we DO see with the Milky Way galaxy. It can be conceived of as a circular disc, more or less, but in our sky we see it from the side, as a streak or a band rather than a disc.
> They also didn't check if other stars would form circles from any arbitrary point of view (how many circles are actually up there, not just the apparent ones),
I think (not sure of the proof) that any set of points that form a circle from a specific PoV would, from any arbitrary PoV form a regular shape (ellipse) or a straight line.
So we can probably tell if any group of stars/galaxies/bright-lights-in-the-sky form a "structure" (i.e. a regular shape).
Not a professional one in the field, sure. But scientist? Most assuredly.
Of course he's not a professional scientist!!!
To be one you have to partake in academic politics, with its legendarily low stakes, in a publish or perish environment ... for little more than minimum-wage.
I mean, even if you were a scientist[1], odds are good you're not that kind of scientist.
Sort of like "I'm not a lawyer, but even if I were, I'm not YOUR lawyer."
[1] I was a scientist, and but not this kind of scientist, so your musings look just as plausible, if not more, than my own would.
> The tangent-plane distribution of Mg II absorbers in the redshift slice z = 0.802 ± 0.060.
the ring is visible in the slice, which corresponds to a distance range based on those redshift values and cosmological parameters. I think this is effectively a spherical shell of a certain thickness.
Could a region of space be engineered to allow for a limited form of time travel?
In short, this seems to say the exact opposite of your claim: https://en.wikipedia.org/wiki/Dust_solution
> I could be wrong but I think you're outside your field on this one.
And in contrast what would that make of you??
I'm saying that if there in some point in the future (because we can see it now) is sufficient mass density in the region of space of that big ring, and it is rotating, we tick every box we know of to theoretically allow for an eternal circle. "Engineering" it would mean that someone wanted some type of eternal existence, which is the profound idea at play here.
Engineering things without the technology to manufacture it happens all the time. Just because we can't imagine how to build it does not mean we can't calculate if it could exist.
That "only" is important but unintuitive. It means space and time can not be separated from mass.
Light travels very fast but space is very big, so the light from stars we see is very old - some of the lights have outlived their stars, so I assume you meant the past but tbh I'm unsure
What we're talking about here are closed timelike curves. There's models which suggest they could exist inside a singularity, but they're not going to outside without something which seriously breaks other areas of physics (Tipler cylinders etc).
A singularity is a dimensionless point. It has no inside. Did you mean a black hole? If so, the Kurtzgesagt cartoon explains this.
The second part of you sentence seems to have a broken sentence structure. Can't make sense of it.
...but [closed time-like curves are] not going to [exist] outside [of a singularity] without something which seriously breaks other areas of physics (Tipler cylinders etc. [are examples of such theoretical instances which would break other areas of physics]).
https://mphitchman.com/geometry/section8-3.html
(I think I read about it first in “The shape of space” book)
In the other hand, complexity sometimes lead to unexpected regularities, maybe things were not so even around the Big Bang.
Dr. Becky covers these sorts of phenomena in an accessible format:
What is to stop the star from just crashing into the sphere?
Obviously if it's not reflective you could absorb the energy and use it as needed
Unlikely configurations could be interpreted as communication from beings more advanced than typically imagined, or as cosmic engineering projects, or perhaps more likely, the shape of the universe is just different than previously imagined.
I think the fact that the arc has a similar focus to the ring is going to turn out to be something.
Can you go into how you would predict it without homogeneity? Without homogeneity you don't get the FLRW metric, so you won't get the big bang or expansion, so no hot dense state in the past, thus no CMB.
> In a strictly FLRW model, there are no clusters of galaxies or stars, since these are objects much denser than a typical part of the universe. Nonetheless, the FLRW model is used as a first approximation for the evolution of the real, lumpy universe because it is simple to calculate...
So unless there's a really strong dependency on the size of the lumps, what breaks on the path from there to something observationally close-enough to the CMB? I mean, I know inflation is a factor there, but that very much postdates the first ideas of the big bang so it can't invalidate the basic idea.
Ed: basically what I'm saying is, there are a lot of routes to a CMB-like prediction based on our observations, and I very much doubt they all get broken by lack of a cosmological principle.
> The temperature of the gas at the time of condensation was 600 K., and the temperature in the Universe at the present time is found to be about 5 K. We hope to pub- lish the details of these calculations in the near future.
https://en.wikipedia.org/wiki/Discovery_of_cosmic_microwave_... describes the kinda-accidental confirmation of this theory.
The current universe conditions have existed for about 12.8 billion years, and while it might have taken 4.5 billion years for vertebrates to evolve on earth, other planets might have taken faster paths to self-awareness.
I figure an "intelligent sludge" could easily have evolved within a billion years of planet formation. Something that wasn't even fully multicellular, but could work together to produce intelligence in a community of loosely connected homogeneous cells. And if that lifeform gained the ability to intelligently manipulate its own DNA (or equivalent), it could bypass the whole next stages of evolution. Or it could go straight for technology.
The light we are viewing now was emitted billions of years ago, we don't know what it looks like today.
The ring we see is how it looked 9 billion years ago. The universe is 14 billion years old. So, when the universe was still a baby.
An elongated circle can be the letter O or perhaps zero. You can similarly compose other letters visually using galaxy dots, and that's presumably what the original poster meant when talking about writing out a Shakespeare. If the universe was infinite, this would be a possibility.
But the fact we got a circle rather than something funny suggests it is probably a phenomenon that causes circles responsible. Circles are far more common in nature than statistics might suggest. Nature well knows circles.
> Using the Convex Hull of Member Spheres (CHMS) algorithm, we estimate that the annulus and inner absorbers of the BR have departures from random expectations, at the density of the control field, of up to 5.2σ.
5 sigma is the gold standard at which we can safely exclude the noise explanation.
* Actually quite interesting reasons, but which take a lot of maths to explain that I'm not going in to here.
** In this case, defined as a thing or set of things in a mathematically simple shape - spheres, rings etc.
*** Assuming any bit of the universe is roughly like any other bits, and we didn't just happen to fluke on literally the only place where these exist, and there's two.
The shortest, simplest way I can think to explain it is that we expect the universe to look alike, anywhere we look. Think of it like a biopsy - we assume that anywhere we look should be much like anywhere else, because there's no reason to think any area of the universe has special conditions where physics plays by different rules.
That sets up some implications around what we think the universe should look like, at different scales. However, we recently have been running into structures which are bigger than we'd expect.
Where we get into the maths is to do with the value of the cosmological constant. We currently think it's positive, because the universe is expanding, and its rate of expansion is accelerating. To look into the maths for this, have a Google around the maths behind the accelerating expansion of the universe.
Yeah, bs.
Provide sources to support you argument, that's entry level discourse.
Have fun! It's quite interesting.
I actually read the article, as you can see by the other comments I've made, and found none of that, but please feel free to correct me and cite here the portions of the paper where that is mentioned.
And sure, I could specialize in cosmology and find out the reasons on my own, but also, the burden of proof on that argument is not on me.
>The multiple discoveries of LSSs made throughout the past few decades are well known to challenge our understanding of the Standard Cosmological Model (ΛCDM) [2, 8–12], in particular due to a possible violation of a fundamental assumption, the Cosmological Principle (CP), which states that our Universe is both homogeneous and isotropic on large scales
That gives you a couple papers and a few terms that you can get started with. Unless your goal is to argue, instead of learn, which it seems like it might be.
>For reasons*, there's a soft limit on the scale that you'd expect structures** to scale to.
The content you cited acknowledges the premise of the Cosmological Principle, but it does not say anything about what these "reasons" could be.
So, nope, that's not an adequate argument.
Again, I could waste my time on a PhD in Cosmology to come back and actually make a good argument for why homogeneity in structure is favored at large cosmological scales ... but why should I? I didn't bring that particular argument into the conversation [1].
1: https://en.wikipedia.org/wiki/Burden_of_proof_(philosophy)
I'm not trying to argue, lol. You're asking for more information but in such a weirdly aggressive way.
The reason there is a soft limit (in our current theories) is because of the cosmological principle
Big lol at the wiki linking of burden of proof. Not every conversation is an argument, holy.
As much as I love HN, this type of aggressiveness and desire to converse as if defending a dissertation can get bloody exhausting.
What? That's a circular argument.
HN is definitely not the place for "me vs. you" grudges, so I stick to making arguments and try to drive the conversation forward, however,
>Have fun! It's quite interesting.
>Unless your goal is to argue, instead of learn, [...]
>Big lol at the wiki linking of burden of proof.
You don't seem to be the one arguing in good faith, though. "You're being aggressive", laughable.
The rest was probably a bit uncalled for, you're right. I was immediately put on edge by "Yeah, read the site guidelines, yo." (which, uhh, not sure how that is focused on moving the conversation forward but lets leave it at we were both touchy!)
Or a weak wifi signal.
There might be some, so it could be lucky and just random chance, but the stats seem to say that it's very unlikely
> cosmological neighbours
These structures are more than halfway across the observable Universe. It's ludicrous to claim that they are neighbours.
They are close enough to each other.
That's as if Paris had a second Eiffel tower three blocks away.