In a current thread the book http://www-thphys.physics.ox.ac.uk/p...ney/QBhome.htm [Broken] is recommended... I skimmed the first chapter and like the explanation and style...I'm printing and reading more carefully now... but I already have a "burning" question (perhaps 2 ) maybe someone can address. The first sentence of the book is this: How do we know that's ALWAYS true?? (Ever since I found out Einstein discovered time and distance are NOT fixed I'm suspicious of all obvious assumptions...) Is the past absolutely certain?? How do we know that??