1991 Lectures in Complex Systems, Eds. L. Nagel and D. Stein, Santa Fe Institute Studies in the Sciences of Complexity, Proc. In junior high, I remember reading a book called The Seven States of Matter . The original three, by now, have become multitudes. In important and precise ways, magnets are a distinct form of matter.
Metals are different from insulators.
Superconductors and superfluids are striking new states of matter. We'll discuss this more in lecture two. Much of these two chapters will discuss the properties of crystals. Crystals are surely the oldest known of the broken-symmetry phases of matter, and remain the most beautiful illustrations. It's amazing that in the past few years, we've uncovered an entirely new class of crystals.