Asimov's Guide to Science
Asimov tells the stories behind the science: the men and women who made the important discoveries and how they did it. Ranging from Galilei, Achimedes, Newton and Einstein, he takes the most complex concepts and explains it in such a way that a first-time reader on the subject feels confident on his/her understanding.
"What is the book that changed your life? (not novels or religious texts)"
I think it's a wonderful way to connect in a less superficial way and learn a little more about each other. It's also a wonderful way to discover new books worth reading.
This is one of them. The full list is here.