Register to reply

Ricci scalar and curveture of FRW metric

by sadegh4137
Tags: curveture, metric, ricci, scalar
Share this thread:
sadegh4137
#1
Nov16-12, 02:13 AM
P: 73
hi

we know that our universe is homogenous and isotropic in large scale.
the metric describe these conditions is FRW metric.
In FRW, we have constant,k, that represent the surveture of space.
it can be 1,0,-1.
but the the Einstan Eq, Ricci scalar is obtained as function of time! and this leads to Frideman Eq.
I sonfuse about this. the curveture of universe is constant or not!
Phys.Org News Partner Science news on Phys.org
Scientists develop 'electronic nose' for rapid detection of C. diff infection
Why plants in the office make us more productive
Tesla Motors dealing as states play factory poker
TrickyDicky
#2
Nov16-12, 02:53 AM
P: 3,043
Quote Quote by sadegh4137 View Post
hi

we know that our universe is homogenous and isotropic in large scale.
the metric describe these conditions is FRW metric.
In FRW, we have constant,k, that represent the surveture of space.
it can be 1,0,-1.
but the the Einstan Eq, Ricci scalar is obtained as function of time! and this leads to Frideman Eq.
I sonfuse about this. the curveture of universe is constant or not!
You must make a distinction between the curvature of the spatial three dimensional hypersurface, that has constant curvature in the FRW universe, and the 4-dimensional spacetime curvature that doesn't have constant curvature in that model.
sadegh4137
#3
Nov16-12, 10:23 AM
P: 73
yes i know
in The early universe is written by kolb in chapter 3
auther stayed that Ricci tensor in the special space is 6k/a(t)
I can't understand this!!

Bill_K
#4
Nov16-12, 11:36 AM
Sci Advisor
Thanks
Bill_K's Avatar
P: 4,160
Ricci scalar and curveture of FRW metric

"Constant curvature" means that the curvature of a space section is the same everywhere, i.e. independent of x,y,z. At a given instant, it's the same everywhere, like a sphere. In cosmological models the curvature of the space section varies with time.


Register to reply

Related Discussions
Double contraction of curvature tensor -> Ricci scalar times metric Special & General Relativity 2
Need to find the Ricci scalar curvature of this metric Special & General Relativity 5
Need to find the Ricci scalar curvature of this metric Advanced Physics Homework 1
From the scalar of curvature (Newman-Penrose formalism) to the Ricci scalar Special & General Relativity 8
Ricci scalar Special & General Relativity 2