Talk:Galaxy filament

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fringe[edit]

Since the content of the http://www.the-electric-universe.info/Scripts/filament.html link seems to me to be quite on the fringe, I replaced it with http://pil.phys.uniroma1.it/twiki/bin/view/Pil/GalaxyStructures, which also has nice pictures, a useful list of reverences, and seems to be a bit more sane [Marfisa].

By sane you mean anything you agree with. --BlueRider12 (talk) 14:30, 10 August 2010 (UTC)[reply]

In this case it's also much closer to what the vast majority of professional physicists would agree with. The removed link contains stuff like "the electrons have a 43 times higher velocity in a given temperature related to that of the protons of the same temperature, therefore, the core [of a star] will be positively and the surface negatively charged" which is simply not how plasmas work. The editor was quite right to remove it. Olaf Davis (talk) 17:37, 10 August 2010 (UTC)[reply]
The electric universe is a well known crackpot fringe theory. Good job removing this nonsense. --Cyclopiatalk 22:31, 10 August 2010 (UTC)[reply]

Largest structures[edit]

On Superclusters: "No clusters of superclusters are known, but the existence of structures larger than superclusters is debated (see Galaxy filament)."

On Galaxy filament: "In physical cosmology, filaments are the largest known structures in the universe,..."

Do filaments exist or not? Are they or are they not the largest structures?

125.236.131.166 04:01, 29 December 2006 (UTC)[reply]

They exist, and are the largest known structures. See this article. (Which could probably be used as a citation for filament size, although I think it disagrees with the one in the article.) --Starwed 08:04, 21 May 2007 (UTC)[reply]

old list[edit]

* Sloan Great Wall
* CfA2 Great Wall

This list was replaced by the new tablular list. 70.51.8.75 (talk) 08:44, 7 October 2008 (UTC)[reply]

"SCl" numbers[edit]

76.66.196.139 (talk) 13:00, 16 September 2009 (UTC)[reply]

List[edit]

some more info from SIMBAD: search for "wall" ; curiously, the Cetus Wall is just called "The Wall" in SIMBAD...

76.66.197.30 (talk) 14:38, 24 September 2009 (UTC)[reply]

Filaments image[edit]

I am concerned about this image and its caption:

File:Local galaxy filaments 2.gif
The present day dark matter distribution in a slice cut through a simulation of a flat universe with cosmological constant. The distribution reveals fine, filamentary structures. The slice has a side length of 520 million light years, and a thickness of 100 million light years. It contains the so-called "supergalactic plane". The major nearby clusters, like Coma, Virgo, Perseus cluster, are labelled.[1]

If it is indeed a simulation slice, it is not a depiction of our real universe, and as such the labels are nonsense. If it is not a simulation slice, but a map, why it is labeled as a simulation? --Cyclopiatalk 12:53, 23 December 2009 (UTC)[reply]

Interesting... it is from the Max Planck Institute for Astrophysics. See [1] and [2]. 70.29.210.242 (talk) 10:06, 30 January 2010 (UTC)[reply]
Since you can't see dark matter, it would need to be a simulated distribution... 70.29.210.242 (talk) 10:09, 30 January 2010 (UTC)[reply]
Thanks for the links, I'm looking at the pages now, it seems this quote from the source clarifies much the issue: the initial conditions of the simulations shown below were constrained to match the overall pattern of structure in our cosmic neighbourhood. .--Cyclopiatalk 12:37, 30 January 2010 (UTC)[reply]

References

  1. ^ http://www.mpa-garching.mpg.de/galform/data_vis/

Contradictions?[edit]

Part of the article seems to contradict itself in the relative size of certain very large objects. One point says the two great walls are the largest, another says lyman alpha blobs are bigger than both, and the Pisces-Cetus Supercluster Complex article has dimensions that point to it being between the two walls in size. Do we need a different article for a list of extremely large and/or massive objects? The relative size problem may be in my reading of the rather dense article, or may stem from outdated source material. --Nutarama (talk) 08:50, 22 March 2010 (UTC)[reply]

File:Local galaxy filaments 2.gif Nominated for Deletion[edit]

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The illustration mentioned above was deleted. I've hidden it as it is rather confusing to have the caption without the illustration. Is it possible to find a replacement illustration? Njaelkies Lea (d) 07:21, 25 August 2011 (UTC)[reply]

Filaments[edit]

I feel this article would benefit from a description of the physical nature of filaments: what kinds of processes are known to create filaments, and how does one recognize the qualitative features of a filament? 70.247.171.190 (talk) 14:33, 6 July 2012 (UTC)[reply]

Description[edit]

I found it odd that the article for CfA2 Great Wall had a better description of a galactic filament than this article did. Specifically, it says,

In the standard model of the evolution of the universe, such structures as the Great Wall form along and follow web-like strings of dark matter.[3] It is thought that this dark matter dictates the structure of the Universe on the grandest of scales. Dark matter gravitationally attracts baryonic matter, and it is this "normal" matter that astronomers see forming long, thin walls of super-galactic clusters.

Is there any reason this would be inappropriate to include in the introduction of this article? RobertM525 (talk) 19:18, 12 March 2014 (UTC)[reply]

The meaning on the article of CfA2 Great Wall includes all structures in general. Filaments are not only the large-scale structures, there are superclusters, complexes, walls, and LQGs. In addition, the phrase tells a structure's formation, not its characteristics. Johndric Valdez (talk) 00:21, 4 April 2014 (UTC)[reply]

Help![edit]

Someone deleted the entire list of galaxy walls. It is very comprehensive, and has more than 5 Kb data. I have no time to revert it. Help me! Johndric Valdez (talk) 00:32, 4 April 2014 (UTC)[reply]

Galaxy filaments and neuronal networks[edit]

Some interesting facts to implement into this Wikipedia article: https://aaaummm.wordpress.com/2012/03/29/neural-networks-and-the-universe/

--81.6.59.42 (talk) 15:13, 22 September 2015 (UTC)[reply]

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External links modified (January 2018)[edit]

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Distances are Confusing[edit]

While browsing the list of filaments and walls, I (a non-physicist) got very confused by the “Distance” column and distance data in other places.

Sometimes distances are given in km/s, which, to my knowledge is a unit of velocity. It is very unclear how this relates to other better-known distance units like AU or lightyears or Parsecs. Also, why a unit of velocity can be used to indicate distances. The term “redshift space” is used, but neither explained nor linked.

Then in other places, nothing but a z-value (such as z=2.38) is given, which to me (and probably any other non-cosmologist) is utterly useless without clarification in what context this z value is used.

I hope someone can clear this up, this topic is fascinating!

2A02:8071:BB4:8100:0:0:0:A468 (talk) 14:49, 9 June 2020 (UTC)[reply]

MPC vs. LY[edit]

So, in the article it includes that most filaments fall between 50-80 megaparsecs. Then it says that this is the order of 200-500 million light years. But 50mpc is only 165 million light years and 80 is less than 300 million light years. Especially since the rounded numbers don't come from the source, there is no reason to have this discrepancy when converting to light years. We should either round to the nearest 50 million or 100 million.

Also: I'm unsure of the source for the lengths. The paper cited looked at a specific set of regions where filaments were 50–70mpc and another region where they were 80mpc. While it does generalize an upper bounds at around 80mpc, the lower bound is not as well defined there. — Preceding unsigned comment added by Cwallenpoole (talk • contribs) 18:27, 25 March 2021 (UTC)[reply]

I just added those numbers back. There are a dozen reputable sources who say a MPC = 3.26 * 106 ly. Cwallenpoole (talk) 14:48, 15 April 2021 (UTC)[reply]

Star formations that are dense and form straight sided rectangular shapes with straight sided inside the shape[edit]

What is this? 2601:586:D026:2F06:8520:C9FD:E9A6:19D7 (talk) 19:09, 16 January 2023 (UTC)[reply]

Is the text in your heading referring to something in the article? I can't find that wording so it's unclear what part of the article you're questioning. Schazjmd (talk) 19:11, 16 January 2023 (UTC)[reply]

Removed gravitationally bound in the lede[edit]

I removed gravitationally bound in the lede, added a bit backed up by a forbes article discussing how these structures are not gravitationally bound. They used to be 6 billion years ago, but when dark energy took over the expansion of space changed that. Now these structures are expanding, and essentially will dissolve in the far future.

The only structures in the universe that will remain together in the dark energy dominated future will be groups and clusters of galaxies. Not even superclusters will survive. Take for example the Lanakea supercluster. All of the individual galaxy groups (like the local group) and clusters (like the Virgo cluster) are being blasted apart. We're not even that far away from the Virgo cluster, and it's moving away from us at around 1,100 km/s. In 100 billion years even the virgo cluster will be 20 billion light years away from us, as the scale factor will be 300 or so. Beyond our cosmological event horizon it'll appear to freeze in place/time and get redshifted to nothing.

Just wanted to say this in case anyone disagreed with that change or thought they are gravitationally bound, as they aren't. If you want sources see https://www.skyatnightmagazine.com/astrophotography/galaxies/galaxy-clusters-groups which says "Galaxy clusters are collections of gravitationally-bound galaxies and are the largest known structures held together by gravity in the Universe." Or the forbes source I quoted in the changes. Feel free to change the wording, or if you disagree post here. Chuckstablers (talk) 19:42, 13 November 2023 (UTC)[reply]

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