My research has led me to look into the idea of bubble universes which I don't know very much about. The first thing that I am looking for is understanding or visualising how could many bubbles co-exist geometrically, assuming each bubble universe is like ours (that is, a flat euclidean geometry). Are we talking about an n-manifold that has multiple bubbles embedded in it? Submanifolds? Or can we extend the idea of branes to the notion of bubbles? Is it perhaps a 3-sphere that houses multiple 2-spheres? Put simply, what is the theoretical geometry that engulfs all the bubbles and how would they be connected?