This is a fantastic book that gives me hope for humanity's future. There's nothing bad that can possibly be said about this book, which is the only thing actually impossible about it. Each chapter goes through a subject that would normally be considered science-fiction for the normal everyday person, but then explains it in simple terms that most people should be able to understand, explaining why it could really happen and even giving examples of real experiments with each thing in labs. This book is inspiring. It's like reading a magical adventure story when you were a kid that made you really excited, except everything's real. I have Physics of the Impossible and Parallel Worlds on my shelf, right between The Demon-Haunted World and A Briefer History of Time. Kaku is well-deserving of being between the likes of Carl Sagan and Stephen Hawking.One thing, though. In the notes and bibliography section, Kaku uses his own previous books a couple times as a source reference. Why? How's it make sense to use yourself as your own source? I could write any book of total drivel and then make another book afterwards and say I sourced it, because I used myself as a source. Using yourself as a source is INCREDIBLY tacky and a *lot* of authors seem to do it.