Isodiametry, variance, and regular simplices from particle interactions

Series
PDE Seminar
Time
Tuesday, October 1, 2019 - 3:00pm for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Tongseok Lim – ShanghaiTech University – Tlim@shanghaitech.edu.cnhttp://ims.shanghaitech.edu.cn/ims_en/2018/1110/c4742a35950/page.htm
Organizer
Xukai Yan

We study the geometry of minimizers of the interaction energy functional. When the interaction potential is mildly repulsive, it is known to be hard to characterize those minimizers due to the fact that they break the rotational symmetry, suggesting that the problem is unlikely to be resolved by the usual convexity or symmetrization techniques from the calculus of variations. We prove that, if the repulsion is mild and the attraction is sufficiently strong, the minimizer is unique up to rotation and exhibits a remarkable simplex-shape rigid structure. As the first crucial step we consider the maximum variance problem of probability measures under the constraint of bounded diameter, whose answer in one dimension was given by Popoviciu in 1935.