Tuesday, October 14, 2025

From "Math for Poets..."

16 Oct 2025

Mathew Gluck

The Method of Moving Spheres



Abstract. The method of moving spheres is a powerful and versatile method for analyzing partial differential equations with conformal symmetry. At the core of this method is the amazing fact that one can classify all suitably nice functions f  defined on Euclidean space for which both of the following properties hold:

1.  For all points x there is a sphere centered at x about which f  has inversion symmetry, and

2.  for all directions e, there is a hyperplane with normal direction e about which f  has reflection symmetry.

I will give some examples of functions for which both properties hold, and I will discuss the historical development of the classification of all such functions. Finally, I will overview the method of moving spheres and provide some applications of the method in the analysis of conformally covariant partial differential equations.