Percent area of the universe is galaxy?

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Discussion Overview

The discussion revolves around estimating the percentage of the universe's area that is composed of galaxies. Participants explore various approaches to quantify this aspect, including calculations based on the number of galaxies and their volumes in relation to the observable universe.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant seeks to determine the percentage of the universe's area occupied by galaxies, indicating a lack of available information.
  • Another participant suggests considering the critical density of the universe as a relevant factor.
  • A later reply provides an estimation of the number of galaxies in the observable universe and calculates the total volume occupied by these galaxies, comparing it to the volume of the observable universe.
  • The discussion includes a quote emphasizing the vastness of space, highlighting the relative scale of galaxies within the universe.

Areas of Agreement / Disagreement

Participants do not reach a consensus on a specific percentage or method for calculating the area occupied by galaxies, and multiple approaches are presented without resolution.

Contextual Notes

The calculations presented depend on assumptions regarding the average volume of galaxies and the total volume of the observable universe, which may not be universally agreed upon.

sketchd2
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%area of the universe is galaxy?

Hi.
I'm trying to determine the approximate percentage of the universe's area that is made up of galaxies for a question I was asked earlier this week. I have been looking everywhere and can not find any information of use. Can someone please help?
 
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Try critical density of the universe.
 


Thank you. That is just what I needed
 


Estimated number of galaxies in observable universe is N = 175 X 109, assuming average volume of each 22/7*100000*100000*30000 i.e. v = 9.25 X 1014 cubic light years. Total volume occupied by galaxies = N X V = 1618.75 X 1023 cubic light years.

Compare this with volume of observable universe = 4.1 × 1032 cubic light years.

The Hubble Ultra Deep Field shows 10000 galaxies, but still the photo is mostly black (space).

Space is big. Really big. You just won't believe how vastly, hugely, mindbogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space - Douglas Adams, The Hitchhiker's Guide to the Galaxy
 

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