Our guest on ST is Harold McGee, who writes about the science of food and cooking. His earlier books include "On Food and Cooking: The Science and Lore of the Kitchen" and "Keys to Good Cooking: A Guide to Making the Best of Foods and Recipes." He joins us to discuss his new book, "Nose Dive: A Field Guide to the World's Smells." As was noted of this work by Booklist: "In his detailed survey of scents, food writer and cooking scientist McGee elegantly explains olfaction.... His exploration of