= Curvature radius of a constant-curvature space
{title2=$R_c=|K|^{-1/2}$}
A space with nonzero constant <sectional curvature> $K$ has <curvature radius of a constant-curvature space> $R_c=1/\sqrt{|K|}$. Scaling a <metric tensor> by $a^2$ divides its <sectional curvature> by $a^2$. In an <FLRW metric> whose spatial normalization is $k=\pm1$, the <spatial curvature of an FLRW universe> is $K=k/a^2$, so its <scale factor> equals $R_c$. For $k=0$ there is no finite intrinsic curvature length.
Back to article page
