**Demetre Kazaras,
Duke University**

**Title:**
If Ricci is bounded below, then mass is in control!

**Abstract:** The ADM mass of an isolated gravitational system is a
geometric invariant measuring the total mass due to matter and other
fields. In a previous work, we showed how to compute this invariant
(in 3 spatial dimensions) by studying harmonic functions. Now I'll use
this formula to consider the following question: How flat is an
asymptotically flat manifold with very little total mass? We make
progress on this problem and confirm special cases of conjectures made
by Huisken-Ilmanen and Sormani. The main results asserts that in the
class of reasonably-behaved asymptotically flat manifolds with
non-negative scalar curvature satisfying a uniform lower bound on
Ricci curvature, small mass implies Gromov-Hausdorff closeness to flat
space.