Why Time FliesFor more than two thousand years, the world's great minds have argued about the true essence of time. Is it finite or infinite? Is it continuous or discrete? Does it flow like a river, or is it granular, proceeding in small bits like sand trickling through an hourglass? And most immediately, what is the present? What is time, exactly? Why does it seem to slow down when we're bored and speed by as we get older? How and why does time fly? In this witty