Welcome to Phys 155, 2012!

Welcome to Solid State Physics!

In this course, you will learn both very fundamental and very practical knowledge about how the world around us works. First, about "practical." This is quite obvious. Solid state physics is concerned with magnets, conductors, semiconductors, insulators, superconductors, semi-metals, etc. They are clearly practical stuff, since they permeate to all corners of our materials industry. Second, about "fundamental." This is also quite obvious if you give it a little thoughts. However, some of the fundamental aspect is indeed very deep. Virtually all phenomena in solids are the result of interactions between electrons and photons. This involves quantum mechanics, which is quite fundamental. In particular, one particle in a periodic potential problem -- a rather simple and easy problem -- occupies the heart of solid state physics. However, under this deceivingly simple fundamental problem is hidden another fundamental mechanism at work. Namely virtually all of what happens in solids (and condensed matters in general) is due to the interaction of very (dauntingly) many particles. This is the reason why there are so many phases of matter, with surprising and useful new phases being discovered continually. Interactions are also a key element in truly understanding what we call simple particles in solids -- electron, holes, phonons, etc.