If you like this sort of thing, you might enjoy the book "Physics of the Impossible", which examines the feasibility of various science fiction technologies (such as FTL) from a pop-sci level.
All of Michio Kaku's physics books are pretty solid, even if there's a bit of overlap among them. "Physics of the Future," for instance, is a decent examination of what he believes will actually be realized in 10, 20, 100, 1000, etc., years. It's a good companion piece to "Impossible."
