Thread: Fridman's equation help View Single Post

## Fridman's equation help

Hi there. My interest in cosmology is purely amateurish, so bear with my ignorance. I have some questions regarding following Fridman's equation:

$$H^{2}=\frac{8\pi G\rho}{3}-\frac{kc^{2}}{a^{2}}+\frac{\Lambda c^{2}}{3}$$

1. Lambda is usually given in units of s-2, or in units of m-2. When given in s-2 is it already multiplied with c2, so the last term is λ/3, right or wrong?

2. What are the units of k - normalized spatial curvature? I can't find it anywhere. It is just given as 0,1, or -1. It can't be unitless or equation wouldn't end in 1/s, required units for Hubble parameter. It must also be in m-2, right or wrong?

3. What is exactly Hubble parameter? Same thing as Hubble constant, or to say, Hubble constant is current value of Hubble parameter?

Any help would be appreciated, thanks.

sm
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