Talk:Cosmic microwave background
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| A summary of this article appears in Big Bang. |
The CMB is not completely smooth and uniform
This paragraph needs references. It also conflicts with statements elsewhere in the article, that the microwave background is a perfect black body spectrum. Aoosten (talk) 18:11, 13 August 2024 (UTC)
- The vast majority of this article is about this issue and contains many references. We don't typically put citations in the lead unless the topic is controversial. However I see we have some citations in the lead, so maybe we should remove these to be consistent. The concept is that the lead is a summary of the content and the content is referenced.
- I did not find the claim that the CMB is a "perfect black body spectrum" but I did find "almost perfect black body spectrum". This matches the statement "The CMB is not completely smooth and uniform" to me. Johnjbarton (talk) 18:59, 13 August 2024 (UTC)
- Ok I moved the refs into the body of the article. Is there something else we might do to improve this issue? Johnjbarton (talk) 19:20, 13 August 2024 (UTC)
- It matches a black body spectrum to five orders of magnitude, which is pretty close to perfect by most Earthly standards. By comparison, the Earth differs from a sphere by a third of a percent. I'd say that "almost perfect black body spectrum" is accurate. Praemonitus (talk) 23:12, 13 August 2024 (UTC)
- @Praemonitus Yes, but the issue I guess is how to clear state this and yet also get across that the differences below fiver orders of magnitude are very significant. Johnjbarton (talk) 01:02, 14 August 2024 (UTC)
WMAP or Planck map
The WMAP heat map of the CMB has been superseded by the Planck map. The Planck heat map has been published by NASA so it is free of copyright. Shouldn't we use the latest heat map here? See for example Astronomy Picture of the Day 2018 July 22 Aarghdvaark (talk) 07:00, 25 June 2025 (UTC)
Done Johnjbarton (talk) 15:52, 25 June 2025 (UTC)
"2.725" listed at Redirects for discussion
The redirect 2.725 has been listed at redirects for discussion to determine whether its use and function meets the redirect guidelines. Readers of this page are welcome to comment on this redirect at Wikipedia:Redirects for discussion/Log/2025 July 5 § 2.725 until a consensus is reached. Rusalkii (talk) 21:11, 5 July 2025 (UTC)
Image 3
The x-axis units in image 3;
"The horizontal axis ("1/cm") corresponds to the reciprocal of the microwave wavelength (in cm), which is proportional to the microwave frequency"
could not be more confusing. Why can't the units just be frequency or wavelength? ~2025-31361-68 (talk) 02:27, 5 November 2025 (UTC)
- The text quoted above does not appear in the article. The caption in does have that text but it is not relevant here. The frequency units are 1/cm. Johnjbarton (talk) 15:31, 5 November 2025 (UTC)