What Einstein Told His Cook, volume 1 and volume 2, by Robert Wolf, discuss the physics and chemistry of cooking. It's question and answer format creates a friendly, informal tone that is accessible to all cooks, new and experienced. McGee's On Food and Cooking is a much more complete discussion of the science behind cooking, but is not nearly as easily understandable for the average reader.
Neither volume of What Einstein Told His Cook is really intended to be read through from cover to cover. Rather Wolf really sees his book more as a reference book for cooks. Of course, I read both through cover-to-cover (and back-to-back); this way, I could find out what he discussed in each book and know where to go later if need be.
For the most part, the science is clearly and well-explained. Wolf's scientific training and experience as a teacher-- ahem -- college professor shine through. His explanations do not assume that you understand more science than what most junior high school students have had. I like this approach; it reduces the chance you will misunderstand his explanations.
One of my favorite discussions in both volumes was his discussion of fats. I came into the discussion understanding what a saturate fat was and what an unsaturated fat was. I also understood that hydrogenation adds hydrogen molecules to an unsaturated fat. Thanks to Wolf, I now understand what a trans fat is and why that is bad -- something McGee was unable to do.
Each section contains some recipes that underscore the points he made in that section. The recipes are easy to find and relatively easy to follow. I haven't tried any of them yet, so I can't speak to how tasty they are.
Like any book, it has its weaknesses. Volume 2 is definitely the weaker of the two volumes. His answers aren't quite as clearly written and I have had some serious questions about a few of the scientific claims. Still, there is good information in it, so it is worth reading at least once.