Talk:Cosmic microwave background radiation

I moved here the contents of CBR because the term is more general that the CMBR, that this article describes. --AN

I'm starting some discussion on Talk:Sunyaev-Zeldovich effect which relates to recent changes and reversions of Cosmic microwave background radiation as well. If anyone watching here has anything to say on the relevance of the Dirac sea to the SZ effect please take a look. --EddEdmondson 09:45, 25 Mar 2004 (UTC)

Contents

1 Reionization Period? 1.1 WMAP data reviewed (early 2004), casts doubt on anisotropy 2 Confusing 3 CMB prediction 4 "Large-scale structure of the cosmos" category 5 Style, coordination 6 Features Question 7 APOD

Reionization Period?

I'd like to see discussion either here or at reionization about how the reionization period related to the CMB. --zandperl 03:56, 9 Jul 2004 (UTC)

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No it doesn't....

WMAP data reviewed (early 2004), casts doubt on anisotropy

See here (http://www.ras.org.uk/html/press/pn0401ras.html) for a recent reappriasal of the WMAP data by Professor Tom Shanks of the University of Durham that casts some doubt on some of the anisotropic evidence.

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Confusing

The line: "During the mid-1990s, the lack of detection of anisotropies in the CMB led to some interest in nonstandard cosmologies (such as plasma cosmology) mostly as a backup in case detectors failed to find anisotropy in the CMB. The discovery of these anisotropies combined with a large amount of new data coming in has greatly reduced interest in these alternative theories"

....does not make sense. During the mid 90's? Didn't we know about anisotropy since COBE's results in early 1992?--Deglr6328 04:59, 27 Dec 2004 (UTC)

CMB prediction

I thought the CMB was predicted long before George Gamow, Ralph Alpher, and Robert Hermann in the 1940s, as follows:

• 1926: Sir Arthur Eddington estimates the thermal background radiation temperature as 3.2K.
• 1930s: Cosmologist Ernst Regener calculates that intergalactic space has a background temperature of 2.8K
• 1938: Nobel Prize winner (1920) Walther Nernst estimates 0.75K
• 1946: Robert Dicke predicts an MBR (microwave background radiation) temperature of 20K (ref: Helge Kragh)
• 1946: Robert Dicke predicts an MBR temperature of "less that 20K" but later revised to 45K (ref: Stephen G. Brush)
• 1946: Gamow estimates a temperature of 50K
• 1948: Ralph Alpher and Robert Herman re-estimate Gamow's estimate at 5K.
• 1949: Ralph Alpher and Robert Herman re-re-estimate Gamow's estimate at 28K.
• 1960s: Robert Dicke re-estimates a MBR (microwave background radiation) temperature of 40K (ref: Helge Kragh)

"Large-scale structure of the cosmos" category

Should this article be placed in the "Large-scale structure of the cosmos" category? —Vespristiano 02:50, 8 Jan 2005 (UTC)

Style, coordination

As a lot of other cosmology related articles, this article has a very large "See also" list. I'd to propose trimming this down:

• Don't link to articles which are already linked in the prose.
• Don't link to articles, which are not centrally related. They can be reached via the category.

What's the opinion of the other contributors?

Also, I'd like to ask, whether it would make sense and find interest contributors, to set up a "cosmological coordination", a WikiProject to have an eye on consistency, missing and duplicated articles.

Pjacobi 19:22, 2005 Jan 29 (UTC)

Features Question

Could someone describe how the 700 km/s velocity, described as the basis for the dipole shift in the CMB, was measured/inferred? Is it the inferred velocity of the Local Group that would cause the observed dipole shift? Does this dipole pattern induce a "preferred coordinate system" for the universe? Dan Watts 19:00, 26 Apr 2005 (UTC)

It is actually a dipole due to the motion of the Earth wrt the CMB -- that's all components including the motion of the sun through the galaxy and the motion of the galaxy toward the great attractor. It introduces a preferred Galilean reference frame which jives fine with GR since GR just requires Lorentz invariance. The feature looks like a giant hotspot and a giant coldspot on the sky due to the velocity-related redshift. See this picture of it (http://antwrp.gsfc.nasa.gov/apod/ap010128.html).Joshuaschroeder 06:27, 15 May 2005 (UTC)

Therefore, shouldn't the CMBR section state that it is consistent with such motion instead of being worded such that it appears to be an independent statement of the galactic motion? Instead of "It is mostly due to the motion of the observer against the CMB, which is some 700 km/s ..." shouldn't it be a more accurate statement such as "This feature is consistent with the observer moving at some 700 km/s relative to the CMB." ? Dan Watts 14:41, 15 May 2005 (UTC)

APOD

Congratulations are in order. This article is linked to NASA's Astronomy Picture of the Day feature for May 8th. http://antwrp.gsfc.nasa.gov/apod/ap050508.html Fire Star 05:35, 8 May 2005 (UTC)