<p>Looking at a few more sources:</p>
<p>Astrophysicist and author Prof. Ethan Siegel describes all Superclusters as, essentially, artifacts of their times, with none of them actually being gravitationally bound.  There is insufficient mass to overcome the expansion due to Dark Energy.</p>
<p><a href="https://www.forbes.com/sites/startswithabang/2020/02/04/our-home-supercluster-laniakea-is-dissolving-before-our-eyes/" rel="nofollow noreferrer">https://www.forbes.com/sites/startswithabang/2020/02/04/our-home-supercluster-laniakea-is-dissolving-before-our-eyes/</a></p>
<p>The NASA post here (<a href="https://science.nasa.gov/universe/galaxies/large-scale-structures/" rel="nofollow noreferrer">https://science.nasa.gov/universe/galaxies/large-scale-structures/</a>) states that Superclusters &quot;... are not typically gravitationally bound to each other.&quot;</p>
<p>The Center For Astrophysics; Harvard and Smithsonian, state explicitly that &quot;Galaxy clusters are the largest objects in the universe that are held together by their own gravity.&quot;  Not, you will note, Superclusters.
<a href="https://pweb.cfa.harvard.edu/research/topic/galaxy-clusters#:%7E:text=Galaxy%20clusters%20are%20the%20largest,amount%20of%20invisible%20dark%20matter" rel="nofollow noreferrer">https://pweb.cfa.harvard.edu/research/topic/galaxy-clusters#:~:text=Galaxy%20clusters%20are%20the%20largest,amount%20of%20invisible%20dark%20matter</a>.</p>
<p>That the Superclusters appear to exist at all is explained as an incident of our observing time.  In the future they will disperse due to the effects of Dark Energy.  For now they are just galaxy-cluster ships which are passing in the night.</p>

CC BY-SA 4.0
2024-10-06T08:01:33.233Z
2024-10-06T08:01:33.233Z
JohnHunt
<p>According to this answer in another website <a href="https://www.quora.com/Are-the-Laniakea-Supercluster-the-Perseus-Pisces-Supercluster-both-moving-in-the-same-direction" rel="nofollow noreferrer">Are the Laniakea Supercluster the Perseus-Pisces-Supercluster both moving in the same-direction</a></p>
<p>(Not sure how reliable it is)</p>
<blockquote>
<p>No. The Laniakea Supercluster is not a gravitationally bound set of
galaxies. Eventually all galaxies in it will go their seperate ways.</p>
</blockquote>
<p>How is it determined when a supercluster is gravitationally bound? Is there a known size/density relation which determines this, is it done through observation or how?</p>

CC BY-SA 4.0
2024-09-24T21:59:28.773Z
Looks legit https://arxiv.org/abs/1502.04584
Mithoron
<gravity><supercluster>
How is it found when a supercluster is gravitationally bound?
Pablo
# How is it found when a supercluster is gravitationally bound?

(Asked by: username_0 on 2024-09-24)

According to this answer in another website [Are the Laniakea Supercluster the Perseus-Pisces-Supercluster both moving in the same-direction](https://www.quora.com/Are-the-Laniakea-Supercluster-the-Perseus-Pisces-Supercluster-both-moving-in-the-same-direction)

(Not sure how reliable it is)

> No. The Laniakea Supercluster is not a gravitationally bound set of
> galaxies. Eventually all galaxies in it will go their seperate ways.

How is it determined when a supercluster is gravitationally bound? Is there a known size/density relation which determines this, is it done through observation or how?

**Tags:** gravity, supercluster

> **Comments:**
> **username_1**: Looks legit https://arxiv.org/abs/1502.04584  

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## 1 answers

### Answer by username_2 on 2024-10-06. Score: 2

Looking at a few more sources:

Astrophysicist and author Prof. Ethan Siegel describes all Superclusters as, essentially, artifacts of their times, with none of them actually being gravitationally bound. There is insufficient mass to overcome the expansion due to Dark Energy.

<https://www.forbes.com/sites/startswithabang/2020/02/04/our-home-supercluster-laniakea-is-dissolving-before-our-eyes/>

The NASA post here (<https://science.nasa.gov/universe/galaxies/large-scale-structures/>) states that Superclusters "... are not typically gravitationally bound to each other."

The Center For Astrophysics; Harvard and Smithsonian, state explicitly that "Galaxy clusters are the largest objects in the universe that are held together by their own gravity." Not, you will note, Superclusters.
[https://pweb.cfa.harvard.edu/research/topic/galaxy-clusters#:~:text=Galaxy%20clusters%20are%20the%20largest,amount%20of%20invisible%20dark%20matter](https://pweb.cfa.harvard.edu/research/topic/galaxy-clusters#:%7E:text=Galaxy%20clusters%20are%20the%20largest,amount%20of%20invisible%20dark%20matter).

That the Superclusters appear to exist at all is explained as an incident of our observing time. In the future they will disperse due to the effects of Dark Energy. For now they are just galaxy-cluster ships which are passing in the night.


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