There's a series of books by Ray Spangenburg and Diane Kit Moser called The History of Science. Actually, there are two -- one produced in the late 90s, and one produced in the mid-late 2000s. The second is just a shiner update of the first. Anyway, it's an excellent series for getting "caught up" in science, especially if you feel out-of-date. I read both series during two summer breaks from college to keep my scientific literacy polished. Should provide a basic refresher, from which you can look into more detailed books.
Other history-of-science books are good, too: Dan Falk's Universe on a T-Shirt
is a popular read, while Theories for Everything
is a more substantial volume.