# Hubble Parameter

## Homework Statement

For a κ=0 universe with no cosmological constant, show that H(z)=H0(1+z)3/2

## Homework Equations

Friedmann equation: H2=$\frac{8*\pi*g}{3c^2}$-$\frac{κc^2}{r^2}$*$\frac{1}{a(t)^2}$

## The Attempt at a Solution

I know that R(z)=R0/(1+z) but I do not know where this comes from. Following this, I should be able to take a density ρ(z)=ρ(now)*(1+z)^3 and input it into the Friedman equation but I am not sure how to proceed

## Answers and Replies

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cepheid
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