York PhysSoc lecture
Quantum mechanics has replaced Newton's classical mechanics as the true picture of how matter moves and interacts. In quantum mechanics, objects do not have definite positions or definite speeds, but are “fuzzy” in the sense that different results can be obtained when a measurement is made. We have to discard our familiar notions of matter being composed of “particles”, and instead replace the particles with “wave functions” that are more akin to sound waves or light waves than to point particles. Among the strangest of wave phenomena in quantum mechanics is “tunnelling” of matter through a barrier, something that is absolutely impossible in classical mechanics. I shall explain how tunnelling arises from the concept of a wave, and how quantum tunnelling of matter is exploited in ultra-powerful microscopes, and offers the prospect of future ultra-high-density computer-chip technologies.