👉 In physics and mathematics, a sub-discipline is a specialized area of study that focuses on a particular aspect or topic within a broader field. Sub-disciplines are often related to each other in terms of their focus areas. For example, if you're studying quantum mechanics, sub-disciplines might include topics like quantum electrodynamics (QED), which deals with the behavior of electrons and photons at the atomic and subatomic level; quantum chemistry, which focuses on understanding the properties of atoms
