So I came across a question where a light source is shined on a mirror attached to a spring which is attached to a rigid support. Now, in the solution the question has been solved by equating the change in momentum of the photons to the change in momentum of the mirror. However, what escapes ...

I was reading an article (forgot the link) but it said "The energy levels of the electron in a hydrogen atom are quantised". What do they mean by the term quantised?

$F\Delta t=m\Delta v$, is the equation of impulse, lets say that I push a wall with my hands, we can have $0$ change in velocity therefore $F\Delta t=0$, since I'm pushing the wall there is force, the only way the equation equals zero is that $\Delta t$ equals zero, applying force in zero seconds...

I'm a laywoman in physics and recently found myself pondering about the matter reflected in the title of this post. To make my question more precise from the mathematical standpoint, let's suppose you are given a 3D image of the momentary positions of the nuclei of all atoms of an unknown monoat...