 Einstein–de Sitter universe

An Einstein-de Sitter universe is spatially flat and contains only pressureless matter. In conformal time, $a\propto {\tau }^2$ and $\mathcal{H}=a^{\prime }/a=2/\tau$.

The Einstein–de Sitter universe is a specific cosmological model that describes a particular type of expanding universe within the framework of general relativity.