Introduction and Overview (1): Selected Questions in Quantum Mechanics

We set off on our journey to semiclassical problems with a very brief introduction to some concepts of quantum physics, which are unavoidable in the succeeding presentation. We discuss the quantum behavior of atomic and subatomic particles described by de Broglie waves and how it is different from that of classical objects. Semiclassical physics is an intermediate model in which quantum effects are taken into account yet considered small. We look at the Schrödinger equation as the principal equation of quantum mechanics, the analog of Newton’s law in classical physics. We also address the Heisenberg uncertainty principle, which in general gives the maximum possible precision of the classical description of any object in nature. As a special case, we consider a Gaussian wave function with the least possible uncertainty.