Baby universes = awesome

ricevermicelli recently posted an awesome quote by Sean Carroll: "...a universe could form inside this room and we’d never know." Sean is a cosmologist at Caltech whom I knew when we were both at Chicago, and if you ever have the chance to see him speak, do it: he's fantastic. (He's got a few talks online, some with video.) I offered to give a capsule summary of what he was talking about, but I figure it might be of broad enough interest to give it its own entry rather than burying it as a comment.

Because this is turning out to be less "a capsule" and more "three capsules and a blender", I'll put the details behind a cut.

( I'll try to keep it short, I promise! )