# Infromation extracting from Friedmann equation

In cosmology, we are using the Friedmann equations for the evolution of the universe. And we are using this equation a lot.

$$\frac{H^2}{H_0^2} = \Omega_ma^{-3} + \Omega_{\Lambda} + \Omega_ra^{-4}$$

If we write $$a(t)$$ in terms of z,

$$H(z) = H_0\sqrt{\Omega_m(1+z)^{3} + \Omega_{\Lambda} + \Omega_r (1+z)^{4}}$$

I wonder by evaluating this function, for different omega values, what kind of different information(s) we can obtain

• This like a near duplicate of Equation for Hubble Value as a function of time. Certainly Pulsar's answer largely addresses this question. – John Rennie Nov 27 '19 at 16:20
• @JohnRennie I know those things I actually wondered more information then that. For example where can we use $H(z)$. Changing $H(z)$ changes which values (rather then the age of the unvierse) – Layla Nov 27 '19 at 17:06