Hi! This might very well be a silly question. In many courses I've been presented as an obvious fact that it won't work to use (e.g.) light with a wavelength larger (at least, not much larger) than the thing you want to resolve. Why is this exactly? Thinking of photons I could find no obvious explanation, but I couldn't really get my head around it thinking of classical waves either. Wouldnt you be able to, say, work out the position of a pole planted in water by examining the refraction pattern of water waves with wavelengths longer than the pole diameter? Might not be a useful analogy but that's what came to mind. Hope somebody can enlighten me!