I just finished a trilogy that made the list of my favorite books. Hominid, Human and Hybrid by Robert Sawyer. Hard SciFi that uses current concepts in physics and neuroscience. A physicist from a parallel universe visits us. In his universe, Neanderthals predominate and are more advanced than us. They are in complete balance with their environment, and have a natural form of socialism with little crime and widespread happiness. The heroine from our universe is a good Catholic girl who falls in love with him. Throughout the series, we watch her examine and cast aside her religious beliefs. I really liked the examination of our culture from a totally different perspective. One of those 'can't put down- reading marathon series'.