Séminaires

The symmetrized Asymptotic Mean Value Laplacian \tilde{\Delta}, is obtained as limit of approximating integral operators \tilde{\Delta}_r, and is an extension of the classical Euclidean Laplace operator to the realm of metric measure spaces. We show that in the limit as r->0, as the operators eventually admit isolated eigenvalues defined via min-max procedure  on any compact uniformly locally doubling metric measure space. Then we prove L^2 and spectral convergence of \tilde{\Delta}_r to the Laplace-Beltrami operator of a compact Riemannian manifold, imposing Neumann conditions when the manifold has a non-empty boundary.

The Hawking energy is one of the simplest quasi-local energy definitions in general relativity. Despite its simplicity, the Hawking energy has faced challenges due to ambiguities when applied to general surfaces. In this talk, I will present recent results demonstrating that the Hawking energy exhibits key physical and mathematical properties—non-negativity, rigidity,
and monotonicity—when evaluated on a generalization of  area-constrained Willmore surfaces  (Hawking surfaces). In particular such properties hold for area-constrained Willmore surfaces on manifolds with nonnegative scalar curvature.  These results establish Hawking surfaces as a useful tool for evaluating the Hawking energy and reinforce its potential as a meaningful tool for understanding gravitational phenomena.