I have three questions about QFT. I know you can answer this questions, sure you can. - How does a standing wave look like in 3 dimensions (x,y,z). I mean an electro magnetic oscillation between two walls or in free space. I can't really imagine that thing and looked for pictures (google) but coudn't find what I searched for. - Let's say we have an electromagnetic oscillation with quantum number n=3. Then this has energy of 7/2*w*h(bar) and contains 3 particles (photons). Here we say this particles make the field oscillating. And thus the oscillation of this particles can go from earth to moon. But if we describe this 3 photons as wave packets they don't have such an influence (from moon to earth). Something has to be false, but what? - Consider two plates. Between that plates there is a harmonic oscillation with energy 7/2*w*h(bar). How can we describe this oscillation with formulas. I tried to solve this with 2 wave functions. One comes from left and one from the right side and they interfer. But my wave functions don't involve the energy, arghhhhh. Can someone give me a guess? Thanks for any help.