Age of the Universe at the recombination?

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Discussion Overview

The discussion centers on the age of the universe at the epoch of recombination, specifically the commonly cited figure of 379,000 years. Participants explore the definition of recombination, the methods used to calculate this age, and the implications for understanding the cosmic microwave background radiation.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants assert that the age of the universe at recombination is reported as 379,000 years and seek references for this calculation.
  • Others clarify that recombination refers to the epoch when neutral atoms first formed, allowing the universe to become transparent.
  • One participant mentions that the value of 379,000 years is derived from fitting the Lambda-CDM model to cosmic microwave background measurements, specifically referencing the Planck collaboration's work.
  • There is a discussion about the potential confusion in terminology, with some participants suggesting that "recombination" may be misleading and should be clarified.
  • Another point raised is that recombination took a significant amount of time relative to the age of the universe at that epoch, which affects the analysis of the cosmic microwave background.
  • A mathematical approach is suggested, where integrating the parametrized Friedmann equation with the redshift of recombination (z = 1100) can yield the age of the universe at that time.

Areas of Agreement / Disagreement

Participants express varying degrees of understanding and interpretation regarding the age of the universe at recombination, the definition of recombination, and the methods of calculation. No consensus is reached on the clarity of terminology or the best approach to derive the age.

Contextual Notes

Some limitations include the dependence on specific models and the need for a working knowledge of modern cosmology to fully understand the calculations and implications discussed.

mbond
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The age of the universe at the recombination is reported everywhere on the internet as 379,000 years.
I would be grateful if someone could point me towards the paper where this is calculated.
 
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What is this "recombination"? What was recombined?
 
The epoch when neutral atoms start to reform. It is a preliminary stage to the surface of last scattering

One can find the details here
www.astro.utoronto.ca › E...PDF
Web results
Emberson Qualifier Solutions - Department of Astronomy ...
 
http://www.astro.utoronto.ca/~cczhu/EmbersonQual.pdf&ved=2ahUKEwiA58SvxqPjAhWNwMQHHSQ0AzIQFjAAegQIAhAB&usg=AOvVaw2ObN_IA6lZhynuI8ifg24m

Sorry previous link is incorrect grr can't get the link correct on this phone. I will post later but simply Google " epoch of recombination pdf"

That will pull up several references
 
mbond said:
The age of the universe at the recombination is reported everywhere on the internet as 379,000 years.
I would be grateful if someone could point me towards the paper where this is calculated.
I think it would be more correct to say that this value has been measured. This is done by fitting a model, called the Lambda-CDM model to the measurements of the cosmic microwave background radiation. In the Wiki article this parameter is called t*. The most recent and accurate measurement of this parameter is from the Planck collaboration. You can read their paper at this link. Figure 1 on page 7 shows how well the model fits the data. The parameter z*, in Table 2 on page 15, basically gives this value, although you have to understand the model well enough to be able to convert from redshift to time to get the age. Do you have a working knowledge of modern cosmology? If not, you will probably not be able to follow the paper.
 
Mordred said:
The epoch when neutral atoms start to reform.
Recombination and reformation is a bit misleading. This the time when neutral atoms first formed and the universe became transparent.
 
Fair point should have stated recombine
 
As an aside, one interesting thing about recombination is that it took a fair amount of time to occur (roughly 10-15% of the age of the universe at that time). This fact is important for analysis of the cosmic microwave background (which was emitted during recombination), as it causes small-scale variations to be blurred.
 
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mbond said:
where this is calculated
Does your question mean how we got the age of the universe at recombination? If so, all you need is to integrate the parametrized Friedmann equation with the redshift of the recombination which is z = 1100. The integration will give you the age of the universe at that time(event).
 

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