A casual discussion on a very complex topic.  I'm about 2/3 way done.  I'll say this.. this books is as well written as can be for such an abstract topic. I'm writing this review before finishing the book since I'm afraid at my pace, by the time I'm done, the theories, and these are theories only, discussed may have changed.  To a complete non-scientific person like myself, this book seems written in a foreign language, for a different species.  One much smarter than me.  But at a pace of 5 pages or so per reading session, I'm slowly digesting it.  And so far it's a worthwhile read...or punishment as I some times feel.