Talk:CMB cold spot

message: I was reading this article on Yahoo about the cold spot and what the Spanish and British astronomers suggested. I understood it all. Then I come to Wikipedia and all I see is a bunch of formulas, without explaining their context, added to the article. Excuse me, but what do those formulas mean? If you must add them, then at least add them later into the article. First, you should take the time to explain the phenomenon to the common folks, because we're not all scientist here. --Thus Spake Anittas 16:35, 27 October 2007 (UTC)
thread_title: Article for common folks

message: With such a big hole in the sky,  is the cosmological principle still valid? Is the universe still considered homogemeous and isotropic? If this assumtion is false, is the Big bang thoery false as well?  —Preceding unsigned comment added by 202.42.202.67 (talk) 06:43, 30 November 2007 (UTC)
thread_title: Is the Cosmological Principle still valid

message: 'Position' says:
Southern hemisphere of the Celestial sphere.
Yet, the 'Parallel universe' Attempted Explanation also says:
"If the parallel universe theory is true there will be a similar void in the Southern hemisphere of the Celestial sphere."
Well, that's handy. It already exists!
But then, I read the source for the 'Parallel Universe' item. It says that the WMAP cold spot exists in the Northern Hemisphere. Hum.
Source: http://www.theblogofscience.com/evidence-for-a-parallel-universe/
Supposedly Revision 179775771 had it correct, per 'The Blog of Science', that the WMAP cold spot exists in the Northern Hemisphere
http://en.wikipedia.org/w/index.php?title=WMAP_cold_spot&oldid=179775771
Revision 181053980 changed the text to read WMAP existed in the Southern Hemisphere
http://en.wikipedia.org/w/index.php?title=WMAP_cold_spot&oldid=181053980
For now, I'm not going to touch the article because I'm not cosmologist. I may come back in several days and change if I get the time to read through some of the sources. Washii (talk) 06:33, 14 February 2008 (UTC)
replies: text: I was just about to comment on the same thing. It's a rather glaring contradiction. RobertM525 (talk) 10:57, 15 February 2008 (UTC)

text: I have edited the article to 'Northern hemisphere' from 'Southern hemisphere' Washii (talk) 07:05, 27 February 2008 (UTC)
thread_title: Positional contradiction

message: Here is Dr Mersini's second paper which predicts the second void of one degree http://arxiv.org/abs/hep-th/0612142.
Notpayingthepsychiatrist (talk) 16:21, 22 March 2008 (UTC)
thread_title:  Professor Mersini Radio Broadcast

message: No mention is made for the angular size of the object. The article only mentions “large”.
CielProfond (talk) 14:09, 13 November 2008 (UTC)
thread_title:  Angular Size 

message: I have removed the 'Koch' section as it was completely unsourced, unreferenced, and so far as I could possibly determine, incomprehensible. --Tdent (talk) 20:40, 12 March 2009 (UTC)
thread_title:  Koch - ? 

message: What does the phrase in the title mean?  I can understand temperature fluctuations and the order of magnitude of these, but what does the term fractional temperature fluctuations mean?  All I can figure is that it refers to the reciprical of the order of magnitude so that it is less than unity, however; the degree of typical fluctuation is given as as being less than one, so that doesn't make sense.  Does the term fractional have a meaning in this article's sentence or is it a mistake?--Δζ (talk) 07:02, 23 August 2010 (UTC)
replies: text: This term usually means (delta T)/T, where delta T is the fluctuation, and T is the mean CMB temperature of 2.73 K. Amaurea (talk) 19:02, 15 May 2011 (UTC)
thread_title:  The typical fractional temperature fluctuations 

message: The Kolmogorov-based things are presented a bit too matter-of-factly here, in my opinion. As the recent controversy around low-variance rings in the CMB has shown, the authors disagree with the rest of the world about how to simulate the CMB. Amaurea (talk) 19:25, 15 May 2011 (UTC)
thread_title:  The Kolmogorov stuff 

message: It is stated that temperature fluctuations at the time of recombination lead to CMB anisotropies.  That much is clear, but wouldn't helium density fluctuations also cause anisotropies?  A helium-poor region would be colder, I would think, based on helium having higher ionization energy than hydrogen.  Is helium expected to be completely uniform in the early universe?
Spope3 (talk) 03:55, 11 September 2011 (UTC)
replies: text: Helium would be largely absent in the earliest stages of the universe, after temperatures were low enough to permit matter to form atoms. Hydrogen would predominate, eventually fusing to form helium and heavier elements. It all depends on which epoch you're looking at.Wzrd1 (talk) 22:04, 14 March 2012 (UTC)
replies: text: The primordial helium-4 abundance from Big Bang nucleosynthesis is about 25%.  It's mostly hydrogen, but there's enough helium that I wouldn't call it "largely absent."  As for the original question, there have been studies of the possibility that the helium abundance might vary .  I don't find anything more recent.  I think that adiabatic fluctuations are unlikely to change the helium abundance much, so there may not be a good mechanism for generating a spatial variation in the helium abundance.  --Amble (talk) 23:18, 2 June 2012 (UTC)
thread_title:  Helium density fluctuations 

message: The "supervoid" explanation contains the line "A 2015 study shows the presence of a supervoid that has a radius of 1.8 billion light years [...] This would make it the largest void detected, and one of the largest structures known." However the article on Eridanus (constellation), says "At a diameter of about one billion light years it is the second largest known void, superseded only by the Giant Void in Canes Venatici." But then the article on the Giant Void says "It is the largest confirmed void to date, with an estimated diameter of 1 to 1.3 billion light years [...] Even the hypothesized "Eridanus Supervoid" corresponding to the location of the WMAP cold spot is dwarfed by this void." Clearly something is incorrect here. 72.196.122.46 (talk) 15:45, 10 May 2016 (UTC)
thread_title:  Void size contradictions with other articles 

message: The article didn't seem to have anything about this theory which I think is a separate theory, as their papers don't cite  Laura Mersini-Houghton and a recent paper just published cites Chang et al and doesn't cite her. I have added a one sentence mention with cites. Perhaps this can be expanded on by experts? Robert Walker (talk) 11:53, 15 May 2017 (UTC)
thread_title:  Colliding bubble universes before inflation 

message: If one follows reference [6] to the following: https://arxiv.org/abs/0908.3988 
it seems the entire cold spot hypothesis rests upon use of a Mexican Hat function.
This is similar to turning on HDR mode on a consumer camera - it enhances edges
and produced false features.
Why is there no consensus that this is the entire origin of the purpouted cold spot?
It seems clear from the evidence.
Spope3 (talk) 07:05, 4 September 2022 (UTC)
thread_title:  Mexican Hat function displays cold-spot feature not in the data