Does anyone know any good information on the science of love and/or the science of attraction?

I want to know why certain people are attracted to each other. Is it the smell, the looks, the personality? Any stories that anyone has would be appreciated. This interests me so much and I'm thinking it would be such a cool job to go into. Also, how did you know when you fell in love with someone? Did you go after them? Did you unknowingly pass them up until you realized later that they were what you wanted? Did it take you long to know that you were in love? Have you been in love and fallen out of it? And lastly, whats the difference between being in love and loving someone? Any story relating to these types of things would be awesome. Thanks!