Friedmann Equation Density Parameter. 3 32 thus a flat k 0 universe requires i 1 at all times whatever the form of the contributions to the density even if the equation of state cannot be decomposed in this simple way. The variable k is the curvature parameter of the universe and can be either 1 0 or 1 for a closed flat and open universe respectively.
Besides the density and gravitation constant g the equation contains the hubble parameter h a scaling parameter r and a factor k which is called the curvature parameter. The density parameter the first of the friedmann equations defines a density parameter useful for comparing different cosmological models. The first friedmann equation is often seen in terms of the present values of the density parameters that is h 2 h 0 2 ω 0 r a 4 ω 0 m a 3 ω 0 k a 2 ω 0 λ.
For a matter dominated universe the density varies as.
Besides the density and gravitation constant g the equation contains the hubble parameter h a scaling parameter r and a factor k which is called the curvature parameter. The variable k is the curvature parameter of the universe and can be either 1 0 or 1 for a closed flat and open universe respectively. Negative ω 1 positive ω 1 flat ω 1 rewriting the friedmann equation in integral form. In this equation g is the gravitational constant 6 67 10 11nm2 kg2 ρris the radiation density of the universe ρmis the matter density of the universe and ρdis the dark energy density of the universe.
