4 ms·

Structures yes, but not at this sort of scale. For reasons*, there's a soft limit on the scale that you'd expect structures** to scale to. There's no technical

Structures yes, but not at this sort of scale. For reasons*, there's a soft limit on the scale that you'd expect structures** to scale to. There's no technical reason why they can't get bigger, it just becomes spectacularly unlikely that you'd ever get one. The fact that we've found two so far means 1. There's probably more we haven't found yet, and thus they're probably*** more common than we'd expect, and 2. There may be some mechanism we don't yet understand which leads to the emergence of astronomical structures at this sort of scale. * 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.

fsloth 2y ago
Can you give references on the *reasons? Would love to try to do some maths reading in a long while.
- pwatsonwailes 2y ago
  If you want to do some research on the subject, you're looking for violations of homogeneity, as implied by the Lambda-CDM model of the universe. The lambda in this case is the cosmological constant. You'll need to read up on that too. 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.
moralestapia 2y ago
>but which take a lot of maths to explain that I'm not going in to here Yeah, bs. Provide sources to support you argument, that's entry level discourse.
- ziddoap 2y ago
  If you follow the link from this article to the preprint, you'll find some explanations, references to other papers, as well as enough terminology to do some Googling. Have fun! It's quite interesting.
  - moralestapia 2y ago
    Yeah, read the site guidelines, yo. 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.
    - ziddoap 2y ago
      Introduction, paragraph 2: >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.
      - moralestapia 2y ago
        Context, as it seems to have been missed: >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) https://en.wikipedia.org/wiki/Burden_of_proof_(philosophy)

fsloth 2y ago

Can you give references on the *reasons? Would love to try to do some maths reading in a long while.

pwatsonwailes 2y ago
If you want to do some research on the subject, you're looking for violations of homogeneity, as implied by the Lambda-CDM model of the universe. The lambda in this case is the cosmological constant. You'll need to read up on that too. 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.

moralestapia 2y ago

>but which take a lot of maths to explain that I'm not going in to here Yeah, bs. Provide sources to support you argument, that's entry level discourse.

ziddoap 2y ago
If you follow the link from this article to the preprint, you'll find some explanations, references to other papers, as well as enough terminology to do some Googling. Have fun! It's quite interesting.
- moralestapia 2y ago
  Yeah, read the site guidelines, yo. 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.
  - ziddoap 2y ago
    Introduction, paragraph 2: >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.
    - moralestapia 2y ago
      Context, as it seems to have been missed: >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) https://en.wikipedia.org/wiki/Burden_of_proof_(philosophy)