It is the beginning of the twenty-first century, and we are living on the cusp of change. Reality has already spawned one alternate state, and for many people virtual reality is now where they are most at home. But what happens when virtual worlds become indistinguishable from what we consider to be the real world? When you wake up from a dream, how do you know that you are not still dreaming? And if the reality we're in is virtual, who is doing the...