says who, and how did they prove it? (i am not a nobel winning scientist so im probably going to have problems understanding the actual answer if there is one, but all opinions count and are welcomed as far as im concerned)
Another good book, which I got out of the library - In Search of the Edge of Time (John Gribbin), which is fascinating and explains the concept of curved space-time very well. Um and, I'm afraid, I have to disagree with Woofgang - I'm pretty sure "The Globe" is about evolution, it's the first Science of the Discworld you want for an explanation of how the universe works.