Hi Im new here, and have begun to read this book. I dont have any science qualification but I've read a few books on evolution. I'm making notes as I go along and here are 2 difficulties I have. 1) It says gravity is for large scale and quantum is at the small scale. Im just wondering what are the scales relative to ? I would have thought size is relative ? 2) It says there is no absolute speed, however surely the guy on the train's speed is = speed of train + speed of Earth + speed of Milky Way + speed of Universe. His eyes tell him he's not moving (if he doesnt know he's on a train) but our eyes didnt evolve to read accurate speeds , certainly not at a planetary level so I dont agree that different observers are just as right as each other. I dont know if that make sense but if you assume the universe is moving in relation to a nothingness , then there is an absolute speed. Thats as far as I've got so far, just finishing off the chapter on Relativity , it is very interesting stuff.