energy density are dominant in the Friedmann equation. Equivalently, in the radiation-dominated period of late cosmology, this can be stated as $\r_r(t)/\m <1$, or ł[2ca]{} == &lt;1 ,where we used that $\m M^2_{pl}/M^3\simeq 1$ [@mi1; @mi2]. Taking $\m \sim 10^{-12} 
GeV$, we find that the approximation of late cosmology is valid up to the temperatures of order $5\cdot 10^2 GeV$.

In the leading approximation, in which the bulk energy-momentum tensor is set to zero, from the system of the 5D Einstein equations and junction conditions on the brane is obtained the unique extension of the metric the components from the brane to the bulk [@BDL2] ł[21b]{} &&a\^2 (y,t) =,and ł[21c]{} n(y,t)= .

Without the Weyl radiation term the function $a^2 (y,t)$ is [^6] ł[21a]{} a\^2 (y,t) =,where $a(0,t)$ is a solution of the Friedmann equation on the brane. $a^2 (y, t)$ (\[21a\]) As a function of $y \,\,a^2 (y, t)$ (\[21a\]) has the minimum equal to zero at the point $|\b{y}|$ ł[mp]{} e\^[2||]{} =1+. The function $n(y,t)$ has no zeroes. At the point $\b{y}$ the scalar curvature $R^{(5)}$ is finite. The function (\[21b\]) has no zeroes, but the function $n(y,t)$ has a zero. Again this zero is a coordinate singularity.

