FRW from spaces of constant cuvature

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In summary: I will try to find another source that is accessible.In summary, the conversation discusses the derivation of the Friedmann Robertson Walker metric with constant curvature, in order to satisfy the cosmological principle that space is the same everywhere. The speaker is looking for help in understanding the derivation, particularly equation 2.11 and the role of S() in Fig 2.1. They have not been able to find a clear explanation and are asking for assistance.
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Mike2
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FRW from spaces of constant curvature

I'm reading how the Friedmann Robertson Walker metric (with its k=-1,0,+1) is derived by considering spaces of constant curvature in order to satisfy the cosmological principle that space is the same everywhere. But I'm not able to find any derivation of these metrics of constant curvature. And that's where we get k=-1,0,+1. Any help out there? Thanks.
 
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Try chapter 2 of this lectures:
http://astro.uwaterloo.ca/~mjhudson/teaching/phys787/
 
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  • #3
hellfire said:
Try chapter 2 of this lectures:
http://astro.uwaterloo.ca/~mjhudson/teaching/phys787/

Thanks for the tip. I'm trying to go through it. Where did he come up with equation 2.11? What is S() in Fig 2.1? Thanks.
 
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  • #4
I don't seem to be able to find it.
 
  • #5
Mike2 said:
I'm reading how the Friedmann Robertson Walker metric (with its k=-1,0,+1) is derived by considering spaces of constant curvature in order to satisfy the cosmological principle that space is the same everywhere. But I'm not able to find any derivation of these metrics of constant curvature. And that's where we get k=-1,0,+1. Any help out there? Thanks.
The best I've been able to find is statements like the following:
"An N dimensional Riemannian space is of constant curvature if its curvature tensor obeys

[tex]\[R_{\mu \nu \gamma \lambda } = \frac{R}{{N(N - 1)}}(g_{\mu \gamma } g_{\nu \lambda } - g_{\mu \lambda } g_{\nu \gamma } ),\,\,\,\,\,\,\,R = const.,\][/tex]

where R/N(N-1) = [tex]\varepsilon\[/tex]K-2 is called the Gaussian curvature."

Can someone show me how that calculation was derived? Or would it more appropriate to post this question to the Tensor Analysis & Differential Geometry forum? Thanks.
 
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  • #6
hellfire said:
Try chapter 2 of this lectures:
http://astro.uwaterloo.ca/~mjhudson/teaching/phys787/

Unfortunately they are blocking access to this.
 
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  • #7
I am sorry, when I posted the link the access was free to all chapters of the lectures.
 

What is FRW from spaces of constant curvature?

FRW (Friedmann-Robertson-Walker) models are mathematical descriptions of the expansion of the universe. They are based on the assumption that the universe is homogeneous and isotropic on a large scale, and that the expansion is driven by the energy density of matter and radiation. Spaces of constant curvature refer to the geometry of the universe, which can be flat, open, or closed, and is determined by the amount of matter and energy present.

What is the significance of FRW models in cosmology?

FRW models are used to study the large-scale structure and evolution of the universe. They provide a framework for understanding the expansion and density of the universe, as well as the behavior of matter and energy over time. These models have been crucial in developing our current understanding of the universe and its origins.

What are the key assumptions of FRW models?

FRW models make several key assumptions, including the homogeneity and isotropy of the universe, the validity of the cosmological principle, and the presence of dark matter and dark energy. These assumptions allow for simplified mathematical descriptions of the universe and its evolution, but they may not accurately reflect the true nature of the universe.

How do FRW models differ from other cosmological models?

FRW models are based on the assumption of a homogeneous and isotropic universe, while other cosmological models may consider a more complex or irregular universe. FRW models also take into account the expansion of the universe and the effects of matter and energy, while other models may focus on different factors or phenomena.

What are the limitations of FRW models?

FRW models are limited by their assumptions, which may not accurately reflect the true nature of the universe. They also do not account for certain phenomena, such as the effects of dark energy, and may not be able to fully explain other observed phenomena, such as the acceleration of the expansion of the universe.

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