ABSTRACT
A number of fields of science have felt the impact of a development in statistical mechanics in response to some strange observations on a variety of magnetic alloys of little or no technical importance but of long-recognized scientific interest. These fields are: statistical mechanics itself, both equilibrium and non-equilibrium; computer science, both special algorithms and general theory of complexity; evolutionary biology; neuroscience, especially brain modelling; and there are speculations about possible applications to protein structure and function and even to the immune system. In each case the behavior of a system is controlled by a random function of a very large number of variables. The first such function of which the properties came to be understood was the model Hamiltonian. Stein has proposed a spin glass Hamiltonian to describe the distribution of conformational energies of these proteins about a fixed tertiary structure as a first step toward making the analogy between proteins and spin glasses explicit.
