Talk:CMB cold spot

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Article for common folks[edit]

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)

Is the Cosmological Principle still valid[edit]

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 (talk) 06:43, 30 November 2007 (UTC)

Positional contradiction[edit]

'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:

Supposedly Revision 179775771 had it correct, per 'The Blog of Science', that the WMAP cold spot exists in the Northern Hemisphere

Revision 181053980 changed the text to read WMAP existed in the Southern Hemisphere

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)

I was just about to comment on the same thing. It's a rather glaring contradiction. RobertM525 (talk) 10:57, 15 February 2008 (UTC)
I have edited the article to 'Northern hemisphere' from 'Southern hemisphere' Washii (talk) 07:05, 27 February 2008 (UTC)

Yes that is very confusing - best not to rely on popular magazines, I think the astronomical publications say southern hemisphere. Notpayingthepsychiatrist (talk) 14:42, 25 October 2010 (UTC) ex Notpayingthepsychiatrist (talk) 14:50, 25 October 2010 (UTC) Here is another citation from an academic journal which says 'south' Mon. Not. R. Astron. Soc. 390, 913–919 (2008). It looks like the article in New Scientist was wrong.Notpayingthepsychiatrist (talk) 18:33, 26 October 2010 (UTC)

Just thought I'd include this as someone else will wonder the same thing... If you are at the south pole and look up, you will only see the southern celestial hemisphere. If you are at Parks radio telescope in Australia, you will be able to see some of the north and some of the south hemispheres. So it is feasible for the raddio telescopes in New Mexico to be able to measure something in the south celestial hemisphere, but just because the telescope is in the north doesn't mean the cold spot is in the northern celestial hemisphere.Notpayingthepsychiatrist (talk) 04:08, 7 November 2010 (UTC) Roughly speaking, if you draw a tangent to the earth to where you are, your own 'hemispere' will be above that line and, for example, above the equator you could see half northern and half southern hemispheres.Notpayingthepsychiatrist (talk) 04:26, 7 November 2010 (UTC)

Professor Mersini Radio Broadcast[edit]

Here is Dr Mersini's second paper which predicts the second void of one degree Notpayingthepsychiatrist (talk) 16:21, 22 March 2008 (UTC). In that paper the writers refererence this paper as indicating the small void in the southern hemisphere Notpayingthepsychiatrist (talk) 16:36, 22 March 2008 (UTC) This paper attributes assymetry, planarity and alignment in CMB power between hemispheres as explained by assymetry of voids between hemispheres which seems to be were the prediction of a small void in the opposite hemisphere comes from. Notpayingthepsychiatrist (talk) 05:04, 23 March 2008 (UTC)

It seems the large void near the horizon of the universe verified predictions of the string theory landscape high scale inflation birth of the universe where, I think, long waveforms of different universes entangled and decohered (understandable radio broadcast as at 23-03-08), radio broadcast archived as at 07-04-08 and the small void is simply to understand the CMB power. Notpayingthepsychiatrist (talk) 08:10, 23 March 2008 (UTC)

As yet the theory has not been adopted by high impact magazines like Science, Nature or PNAS. Notpayingthepsychiatrist (talk) 19:49, 29 March 2008 (UTC) The significance of Laura Menisi-Haughton's prediction can't be understated, the cold spot could have been dark matter. Notpayingthepsychiatrist (talk) 06:58, 5 April 2008 (UTC)

But the Wikipedia article doesn't give any competing theory Notpayingthepsychiatrist (talk) 10:47, 31 March 2008 (UTC). A competing theory was proposed on 5 March, where the cold spot is regarded as a gateway to extra dimensions: Notpayingthepsychiatrist (talk) 23:46, 6 April 2008 (UTC)

At three physicists are commended for using mathematical proofs. This is a translation from the German using AltaVista Babel Fish: Are there infinitely many beside our universe still different university verses, possibly? The answers to this question are speculative - and most disputed. There are proofs none. But one must admit one: Researchers such as Alex Vilenkin, Laura Mersini and Leonard Susskind do not establish her theory buildings PAGE 10 page 10 by any means on that to nothing. They quite move with their computations on the ways its that is mathematically possible. —Preceding unsigned comment added by Notpayingthepsychiatrist (talkcontribs) 09:14, 6 April 2008 (UTC)

This report dated December says it is actually a group of extrema and not one, prefers not to use wavelet analysis as a measure of Gausinnity and also examines whether there are other cold spots. (They conclude - using their different technique - that: "clustering of the extrema of the ILC III and WCM signals is a typical feature of the morphology,..." (p9) Notpayingthepsychiatrist (talk) 00:52, 7 April 2008 (UTC)

Here are the title of the article, it's authors and their positions:

Title: The mystery of the WMAP cold spot Authors: Pavel D. Naselsky (1), Per Rex Christensen (1), Peter Coles (2), Oleg Verkhodanov (3), Dmitry Novikov (4,5), Jaiseung Kim (1) ((1) Niels Bohr Institute, Copenhagen, Denmark; (2) School of Physics and Astronomy, Cardiff University, Wales, United Kingdom; (3) Special astrophysical observatory, Nizhnij Arkhyz, Russia; (4) Imperial College, London, United Kingdom; (5) AstroSpace Center of Lebedev Physical Institute, Moscow, Russia) —Preceding unsigned comment added by Notpayingthepsychiatrist (talkcontribs) 03:39, 8 April 2008 (UTC)

However, does this refute figure 5 in (which is quoted in the Wikipedia article itself)? Notpayingthepsychiatrist (talk) 04:10, 8 April 2008 (UTC). This study was designed, presumably, on radio waves, while the other one mentioned by Wikipedia on background temperature.Notpayingthepsychiatrist (talk) 05:17, 8 April 2008 (UTC)

However, the wikipedia article is not entirely easy to follow, as the article on detection by radio telescope proposes "modest redshift" objects - implying they are further away? - eliminating the need for Gaussinity. But isn't it true that the smaller the redshift, the slower and closer the galaxy? I now understand it is the integrated Sachs-Wolfe effect (of a hot spot before a void in the line of sight), which is why the article mentions modest red shifts, but doesn't change the size of the void. Notpayingthepsychiatrist (talk) 11:21, 8 April 2008 (UTC)

Angular Size[edit]

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

Page Title ("WMAP" -> "CMB" Cold Spot)[edit]

A few weeks ago I moved this page to "CMB Cold Spot" from "WMAP Cold Spot." I should have solicited other opinions on this; I apologize for acting unilaterally, but I'm glad the change has so far stuck. Unfortunately, much of my reasoning for the change was cut off in my edit summary, so I repeat it here. While the cold spot was discovered in data from the WMAP satellite, WMAP itself is peripheral to the cold spot's significance. Calling this the WMAP cold spot would be a bit like including the name of the telescope used to discover Neptune in its name! When other instruments observe the CMB, such as the upcoming Planck satellite mission, WMAP's significance to the cold spot will diminish further.

Still on the subject of the page title, in my opinion, the parapsychological "cold spot" "phenomenon" should not be the default Wikipedia destination for "Cold Spot," but a disambiguation page should be. Anyone agree?

Koch - ?[edit]

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)

The typical fractional temperature fluctuations[edit]

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)

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)

The Kolmogorov stuff[edit]

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)

Helium density fluctuations[edit]

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)

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)
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 [1]. 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)

Void size contradictions with other articles[edit]

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. (talk) 15:45, 10 May 2016 (UTC)