Well-distributed great circles on S^2

Abstract

Let $C_1,\dots ,C_n$ denote the $1/n-$neighborhood of $n$ great circles on ${\mathbb{S}}^2$. We are interested in how much these areas have to overlap and prove the sharp bounds $$ \sum_{i, j = 1 \atop i \neq j}^{n}{|C_i \cap C_j|^s} \gtrsim_s \begin{cases} n^{2 - 2s} \qquad &\mbox{if}~0 \leq s < 2 \\ n^{-2} \log{n} \qquad &\mbox{if}~s = 2\\ n^{1- 3s/2} \qquad &\mbox{if}~s > 2. \end{cases} .$$ For $s=1$ there are arrangements for which the sum of mutual overlap is uniformly bounded (for the analogous problem in ${\mathbb{R}}^2$ the lower bound is $\gtrsim \log n$) and there are strong connections to minimal energy configurations of $n$ charged electrons on ${\mathbb{S}}^2$ (the J. J. Thomson problem).