1: Introduction to Quantum Mechanics

One normally makes a distinction between quantum mechanics and quantum physics. Quantum physics is concerned with those processes that involve discrete energies, and quanta (such as photons). Quantum Mechanics concerns the study of a specific part of quantum physics, those quantum phenomena described by Schrödinger’s equation.

Quantum physics plays a rôle on small (atomic and subatomic) scales (say length scales of the order of 1 0− 9 m) and below. You can see whether an expression has a quantum-physical origin as soon as it contains Planck’s constant in one of its two guises

\begin{array}{l}
h=6.626 \cdot 10^{-34} \mathrm{Js} \\
\hbar=h / 2 \pi=1.055 \cdot 10^{-34} \mathrm{Js} .
\end{array}

Here we shall shortly review some of the standard examples for the break-down classical physics, which can be described by introducing quantum principles.

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