Insights What Is the Cosmic Background Radiation?

AI Thread Summary
The discussion centers around a new PF Insights post titled "A Poor Man's CMB Primer. Part 2: The Birth of a Cosmic Background Radiation." Participants express appreciation for the article's insights and the quality of the content. A key point highlighted is the requirement for the number of neutral atoms to exceed the number of electrons by approximately 100:1 for the universe to become transparent. There is also an offer of collaboration to improve the cosmological chapter of a book. Overall, the conversation emphasizes the significance of understanding cosmic background radiation in cosmology.
bapowell
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bapowell submitted a new PF Insights post

A Poor Man's CMB Primer. Part 2: The Birth of a Cosmic Background Radiation

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Continue reading the Original PF Insights Post.
 
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Houahhh! You did a great redaction work! Let me know if you want sometimes help me improve the Cosmological chapter of my book ;-P

It would be a pleasure to collaborated with a talented guy like you! :ok:
 
Nice insights article, bapowell. I had no idea that the number of neutral atoms had to exceed the number of electrons by ~100:1 before the universe became transparent.
 
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Thread 'Matter density right after the decoupling'

https://en.wikipedia.org/wiki/Recombination_(cosmology) Was a matter density right after the decoupling low enough to consider the vacuum as the actual vacuum, and not the medium through which the light propagates with the speed lower than ##({\epsilon_0\mu_0})^{-1/2}##? I'm asking this in context of the calculation of the observable universe radius, where the time integral of the inverse of the scale factor is multiplied by the constant speed of light ##c##.
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Thread 'Rutgers finds a transparent Einstein Cross - apparently a dark matter "halo".'

The formal paper is here. The Rutgers University news has published a story about an image being closely examined at their New Brunswick campus. Here is an excerpt: Computer modeling of the gravitational lens by Keeton and Eid showed that the four visible foreground galaxies causing the gravitational bending couldn’t explain the details of the five-image pattern. Only with the addition of a large, invisible mass, in this case, a dark matter halo, could the model match the observations...
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Thread 'Big Bang and Infinite Universe'

Hi, I’m pretty new to cosmology and I’m trying to get my head around the Big Bang and the potential infinite extent of the universe as a whole. There’s lots of misleading info out there but this forum and a few others have helped me and I just wanted to check I have the right idea. The Big Bang was the creation of space and time. At this instant t=0 space was infinite in size but the scale factor was zero. I’m picturing it (hopefully correctly) like an excel spreadsheet with infinite...
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