Critical density

  • Thread starter LSulayman
  • Start date
  • #1
LSulayman
42
0
What exactly does the critical density mean?
In articles they keep comparing the desity of the universe to the critical density and what the consequences are but nobody explains what exactly the critical density is and where it comes from.
 

Answers and Replies

  • #2
Nabeshin
Science Advisor
2,207
16
The critical density is the density required to have a spatially FLAT universe. It comes from... well, requiring that the universe be spatially flat!

Does that answer your question?
 
  • #3
LSulayman
42
0
Yes it does! A rather simple answer, but very logical actually.
 
  • #4
Chalnoth
Science Advisor
6,197
447
I think I'd also like to point out that the critical density depends upon the rate of expansion. A larger rate of expansion requires a greater density for spatial flatness. Specifically:

[tex]\rho_c = {3 H_0^2 \over 8\pi G}[/tex]
 

Suggested for: Critical density

  • Last Post
Replies
10
Views
3K
  • Last Post
Replies
7
Views
10K
  • Last Post
Replies
1
Views
3K
  • Last Post
Replies
9
Views
1K
Replies
6
Views
307
  • Last Post
Replies
2
Views
2K
  • Last Post
Replies
4
Views
3K
Replies
1
Views
1K
Replies
4
Views
3K
Replies
4
Views
2K
Top