If you didn't know, this book is hard. I am a first year engineering student, and I felt lost through most of it. I gather it was intended for full-fledged physicists, but I was intrigued to read it anyway because of a philosophical thread running through the work. But beware--get ready for some Immanuel Kant and Einstein in only the introduction. This book is as much about the physics of time as the philosophy concerning subjectivity of time. Even though I didn't understand a lot of the probability or almost any of the quantum mechanics math, I still got some pleasure out of some of the more bizzare conclusions of the book. Did you know that for an isolated system (one not interacting with any others), time can't be said to have any direction? Furthermore, time as we know it is just a statistic. Another interesting fact is that on the quantum mechanical level, there is no such thing as time! If these things intrigue you (and you know what a double Riemann sum is) go for this book. Otherwise, be very afraid...