Quantum physics is commonly characterized as an “ab initio” model due to its reliance on fundamental principles and equations, such as the Schrödinger equation, derived from first principles that elucidate the behavior of quantum particles.
In a similar vein, classical mechanics can be deemed an ab initio model as it builds upon foundational principles, including Newton’s laws of motion and the principle of energy conservation, governing the dynamics of macroscopic entities.
Classical electromagnetism is typically not regarded as an ab initio model since it emanates from Maxwell’s equations, which do not themselves constitute fundamental principles but instead serve as empirical observations and mathematical representations of electric and magnetic fields.