A lower bound for the number of elastic collisions

Krzysztof Burdzy, Mauricio Duarte

Published 2018-03-02Version 1

We prove by example that the number of elastic collisions of $n$ balls in $d$-dimensional space can be greater than $n^3/27$ for $n\geq 3$ and $d\geq 2$. The previously known lower bound was of order $n^2$.