I was reading a book on solid state physics. Sibylla gave it to me for my birthday because it said inside the front cover that the extension of our understanding of the properties of solids at the microscopic level is one of the important achievements of physics this century and because she had found a damaged copy on sale for £2.99. Unfortunately it wasn’t quite the bargain it looked, because the blurb went on to say: Dr. Rosenberg’s book requires only a fairly basic background in mechanics, electricity, and magnetism, and atomic physics along with relatively intuitive ideas in quantum physics. Sibylla thinks no one is put off by difficulty only by boredom and if something is interesting no one will care how hard it is; it is certainly an absorbing subject but to follow it you really need at least some kind of introductory materials on the above-mentioned subjects. I was getting rather frustrated but I thought I would rather die than sell the heart, not because I wanted to keep it but because it would be horrible to take money for it.

[...] I was thinking about the Umklapp process, or thinking about it as much as you can think about it if you don’t have a fairly basic background in mechanics, electricity, and magnetism, and atomic physics along with relatively intuitive ideas in quantum physics.