Quantum mechanics is considered an ab initio model because it is based on fundamental principles, such as the Schrödinger equation, which describes the behavior of quantum systems. The behavior of quantum systems is determined by the wavefunction, which describes the probability of finding a particle in a given location.
Similarly, classical mechanics can be considered an ab initio model because it is based on fundamental principles, such as Newton’s laws of motion, which describe the behavior of macroscopic objects. The behavior of macroscopic objects is determined by the forces acting on them, which can be calculated based on their positions and velocities.
Classical electromagnetism, on the other hand, is not typically considered an ab initio model because it is based on the experimental observations of electric and magnetic fields and their interactions with charged particles.But fundamental of classical electromagnetism is depend on maxwells equation to describe behavior of electrica and magnetic field