I like to read science books as the content interests me. Whenever I pick out a new book, I may or may not be familiar with the author, but I always hope that the book mainly contains scientific fact, and not just the personal opinion of the author. Usually, you can tell when the author may be generalizing, or drawing conclusions based on incomplete facts. Sometimes, you know for sure that you are just exploring a theory. For instance; a book dealing with string theory. Other times though, it does not seem so clear. I’ve read a couple books by Carl Sagan. I know that he was and still is a respected scientist. In some of his books, he talks about global warming, and how the burning of fossil fuels contributes to increases in greenhouse gasses in the atmosphere. However, other sources like to claim that the sun is responsible for “global warming”, and that ALL the planets are warming, not just the Earth. How does one decide what to believe? How do we know when something is based on absolute fact, and when something might not be?