(for simplicity, we assume spatial flatness). This is generally written at present time t0 in terms of the critical energy density ρc ≡ 3H2 0 /(8πGN ) (H0 being the value of the Hubble parameter today):
(for simplicity, we assume spatial flatness). This is generallywritten at present time t0 in terms of the criticalenergy density ρc ≡ 3H20 /(8πGN ) (H0 being the value ofthe Hubble parameter today):