Firstly I have to say that Mr.Greene knows how to write for people like me. I'm intelligent and inquisitive but need books on such complicated subjects to keep my attention, as this does.  He keeps it simple and makes his illustrations and narrative captivating and page-turning.<br><br>Of course string theory is just that, a theory. After reading the Elegant Universe I have concluded that perhaps Hubble was wrong about the big bang and if that's so then I have a good idea what dark matter is. Unfortunately I don't know any physicists to discuss this with!  The ideas are certainly fascinating, especially when he postulates that eventually our universe might go as far as it can and start shrinking back on itself,eventually disappearing up it's own existence!<br><br>I think I'll read another book on Zen Buddhism after this, because none if it matters anyway, even if the theory does turn out to be correct.