Closed radiation-dominated Friedmann solution
= Closed radiation-dominated Friedmann solution
{title2=$a=A\sin\tau,\quad t=A(1-\cos\tau)$}
With positive curvature, zero <cosmological constant> and radiation density $\rho_0a^{-4}$ in units $8\pi G=1$, $A=\sqrt{\rho_0/3}$. The <scale factor> is positive for $0<\tau<\pi$, reaches its maximum at $\pi/2$, and has a <Big Crunch> at <conformal time> $\pi$ or <proper time> $2A$. This complements the <closed matter-dominated Friedmann solution>.