 The unrelenting symmetry of the FLRW models makes them quite simple geometrically and dynamically. Rather than a set of coupled partial differential equations, which generically follow from EFE, in the FLRW models one only has to deal with 2 ordinary differential equations (only two of \((\ref{eq:Fried})\)–\((\ref{eq:cons})\) are independent) which are determinate once an equation of state \(p = p(\rho)\) is given.