A theory, first developed during late Industrial Age and Atomic Age Old Earth, that describes the interactions of subatomic particles, combining several basic discoveries, such as the observation that energy is absorbed or radiated in discrete quantities (quanta) and the Heisenberg Uncertainty Principle stating that it is not possible to know both the exact position and momentum of a particle (e.g. an photon or electron) at the same time. Quantum mechanics is a very solid theory in many ways; it is on the same order of fundamentalness as thermodynamics. Some of its applications like quantum field theory became quite messy even during the information age, a lot of the original associated concepts such as the "Copenhagen Interpretation" were rendered irrelevant by the so-called Physics Whizz Babies of the early Interplanetary period. An understanding of the workings of quantum interactions remains an essential prerequisite of any minute-scale ultra tech.