How many baryons are there in the universe?

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Discussion Overview

The discussion revolves around estimating the number of baryons in the universe, specifically focusing on the claim that 4% of the universe's energy is baryonic. Participants seek to clarify the absolute number of baryons and reference existing literature for estimates.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • Fran inquires about the absolute number of baryons in the universe, noting a lack of clear sources.
  • George estimates the number of baryons in the observable universe to be about 1080, referencing a problem from Barbara Ryden's book on cosmology.
  • Some participants express skepticism or challenge the relevance of the responses, indicating a potential disagreement on the interpretation of the estimates provided.
  • A later post humorously references "Coors Cosmology," suggesting a light-hearted take on the complexity of the topic.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the number of baryons, and there are competing views regarding the relevance and clarity of the estimates provided.

Contextual Notes

Limitations include the reliance on existing literature for estimates and the potential ambiguity in the interpretation of the calculations referenced.

franoisbelfor
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Many articles and papers say that 4% of all energy in the universe is baryonic. How many baryons does that make? I do not seem to find any wikipedia article or paper that gives an absolute number. Can anybody help?

Thank you!

François
 
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Then number of baryons in the observable universe is usually estimated to be about 1080. See, for example, the solution to problem 6.8,

http://www.physics.ucsb.edu/~tt/PHYS133/hws5.pdf ,

from Barbara Ryden's excellent book Introduction to Cosmology.
 
Last edited by a moderator:
Coors Cosmology, I like it.
 
Good answer, Nabeshin, whatever that meant. Fran asked for a number, George gave the best current estimate. Do you have a rebuttal or are you just sniping?
 
Chronos said:
Good answer, Nabeshin, whatever that meant. Fran asked for a number, George gave the best current estimate. Do you have a rebuttal or are you just sniping?

The document to which I linked calculates the number, and after the calculation writes:

"*COORS COSMOLOGY*
The number of baryons in the observable universe is roughly equal to the number of
baryons in a bottle of beer, cubed."
 

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