I have recently been thinking about some "paradoxes" about mirrors, such as this one .
Yet I still have not found a mathematical (or physical) full description of an ideal mirror (no adsorption, no distortion, etc.).
Let's say that I have a 2D image in front of a mirror: How can I can I describe it and how can I describe its reflection?
I suppose there must be some kind of operator that acts on it and I suppose it is a reflection or rotation of $\pi$ around a given axis; but what axis?