The Primers on different subjects
mechanical_fish: Ironically, I have a Ph.D. in Physics, so I will have trouble recommending a decent primer. ;)You can't go wrong with Feynman's stuff. But his Lectures really are notorious for being the books that physics grad student wish were the standard primers, rather than books that are known to be easy for beginners to learn from. On the other hand, if you're gonna get lost, getting lost with Feynman is always more fun.I've had good luck so far with the Very Short Introduction series -- specifically, the one on quantum mechanics didn't offend me too much, which says a lot. (Once you've actually learned a bit of real quantum mechanics the popular treatments will tend to drive you to drink.)http://www.amazon.com/Quantum-Theory-Short-Introduction-Intr...If you're looking for intellectual stimulation I wouldn't go toward medicine, per se. For practical medical skills I've been thinking of dabbling in first aid and EMS classes, but for intellectual stuff what you really want is biology and chemistry. I think it's been long enough since I last plugged Molecular Biology Made Simple and Fun on HN, so let me recommend it again:http://www.amazon.com/Molecular-Biology-Made-Simple-Third/dp...It's corny but the science is solid, and it is so much lighter, more readable, and cheaper than The Molecular Biology of the Cell, which is a classic text and a book that I still intend to read someday, by god, whenever I have something like three entire months of spare time and a very solidly designed reading desk. [1]Incidentally, have you looked at the online courses you can get for free these days? The other day on MIT Open Courseware I found an intro biology course taught by none other than Bob Weinberg and Eric Lander:http://ocw.mit.edu/OcwWeb/Biology/7-012Fall-2004/CourseHome/...It's a bit tricky to listen to in the car, or even to watch, as the slides for this particular class are hard to see and some of the topics are necessarily visual. But, still, these guys are star professors for a reason.---[1] Or when the Kindle version comes out. MBoC is a book designed for that big Kindle. If I tried to read the print version in bed I'd probably crush myself to death.