They have no idea. And neither do the rest of us.

"We Have No Idea" is a new book out from roboticist/comic artist Jorge Cham and physicist Daniel Whiteson that covers the big picture of our cosmic ignorance.  A couple of chapter's in, it's pretty darned good, good enough to go ahead and post up a recommendation for it.  Here's the trailer link for it, and here's the comic-format trailer:

Cosmic ignorance: admitting that you have this problem is the first step toward the cure.