Quantum physics is referred to as an “ab initio model” because it is based on fundamental principles like the wave-particle duality and the uncertainty principle, which cannot be simplified further in the context of quantum phenomena. Similarly, classical mechanics is considered an ab initio model since it relies on Newton’s laws of motion, providing a foundational understanding of how objects move. Classical electromagnetism also fits this category as it is grounded in Maxwell’s equations, which describe how electric and magnetic fields interact.