Talk:CfA2 Great Wall

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reqdiagram[edit]

what is it?[edit]

Yes, wonderful. But what the heck is it? I see no mention of what the wall actually is or what it's made of.

  • Galaxies. Just like any other large-scale cosmic structure. Nickptar 01:45, 30 Mar 2005 (UTC)

Cosmic filaments should be mentioned here!

Dark Matter Speculation[edit]

I removed the phrasing that suggested the existence of dark matter was hotly debated. From the article on Dark Matter,

Together with Rubin's findings for spiral galaxies and Zwicky's work on galaxy clusters, the observational evidence for dark matter has been collecting over the decades to the point that today most astrophysicists accept its existence as a matter of course. As a unifying concept, it is one of the dominant features considered in the analysis of structures on the order of galactic scales and larger.

It is perfectly acceptable to talk about dark matter as if it is accepted by the scientific community in general, because it is. True, there are possible other plausible explanations for the observations which are taken as evidence for dark matter, but the idea of dark matter is nonetheless well accepted. The primary focus of debate is on the nature of dark matter.

I disagree with this abuse of the consensus. Dark matter is accepted because there is no other explanation apart declaring falsified the Standard Model. You should be more precise than "generally accepted", this is misleading. The fact is that the Standard Model cannot allow such large structure so dark matter is only generally accepted as "fuzzy words" but it stands for "the reason why Standard Model fails". I ask to avoid amatorial sci-fi.83.103.38.68 (talk) 09:33, 19 August 2008 (UTC)
What is the "standard model" you are talking about? LambdaCDM, a universe with a large amount of cold dark matter and a cosmological constant _is_ the standard model right now. There are alternatives (such as MOND, modified newtonian dynamics), but the majority of cosmological models assume the existence of dark matter. There is a substantial body of evidence for invisible mass and it makes sense dynamically, explaining the existence of structures such as these vast walls of galaxies. Dark matter is not a brand new revolutionary theory - it has been around for over twenty years and is just part of the current consensus. If you read any modern textbook or go to any astronomy conference then you will see that dark matter is not "sci-fi" - it is a model that is currently our best explanation for what happens in the universe on large scales. There might not be _direct_ evidence of it - but there is no _direct_ evidence of nuclear fusion happening within the sun either... —Preceding unsigned comment added by AstroDave (talkcontribs) 14:45, 15 April 2010 (UTC)

Broken link[edit]

This link appears to be broken, now moved here: [1]Ylai 07:55, 27 August 2006 (UTC)

Discrepancies[edit]

This article states that the CfA2 Great Wall is 500 million light years long, but the article on the Sloan Great Wall states that the SGW is 1.37 billion light years long and 80% longer than the CfA2 Great Wall. This article also says the SGW was discovered in 2004, whereas the SGW article states that the SGW was discovered in October 2003. Which article is right?

--Pagw 16:01, 12 September 2006 (UTC)

It depends on who's doing the measuring, on which galaxy clusters they choose to include or not, on what Hubble constant they use, etc. 70.51.11.219 (talk) 12:33, 4 August 2008 (UTC)

Volume of the CnA2 Wall[edit]

I just moved the text with the mention of the Wall's volume from the see also section to the main body (and improved the formatting). When trying to convert the volume to cubic parsecs, I found that that volume is equal to Roughly 7% of the volume of a small dwarf galaxy. I'm by no means an expert in the field of cosmic megastructures, but doesn't that seem a bit... small for something referred to as a great wall? Julesmazur (talk) 19:49, 1 June 2013 (UTC)