Smell is a physical process used by us all, but fully understood by none. A physicist seeks to understand the mysterious phenomena of nature and so it is natural to apply physics to this problem. There is a reluctance in the field of olfactory science to explore the physical processes of fundamental interactions in odorant recognition because the system is complex. However, nature is often compliant to our simple models, and part of the art is to reduce the problem to a soluble one, and part of the beauty of science is often that the simple model with the simple answers give the right ones. This article reviews the applicability of some physical models to olfaction and looks in particular at one theory within the realm of olfactory science. This theory was first endorsed by Turin in 1996, that smell signalling may be based on a form of Inelastic Electron Tunnelling (IETS). This review looks at the mystery of olfaction and the physical principles that may unveil such mysterious phenomena.