The principle of gauge invariance states that the Lagrangian of a physical theory must be invariant under gauge transformations
based on Hamiltonian Equation and The Action Principle
Adding an arbitrary derivative to the action does not affect the motion of the particle
This is a principle of symmetry used to describe fundamental natural interactions such as Electromagnetism, Weak force, and Strong force.
Gauge invariance means that physical laws do not depend on a specific reference frame or background structure, and through this, theories such as the standard model of particle physics have been developed. Gauge invariance has made significant contributions to the development of quantum field theory.
자연에 속한 힘들을 통일하는 것에 역할을 한다. 전자기력이라는 자연의 근본적인 힘이 발생하는 이유는 전자의 동역학을 기술하는 슈뢰딩거 방정식이 위상각 변환에 대해서 변하지 말아야 하기 때문