why do we need a viewing screen in order to see interference patterns? why can we see interference patterns through our fingers when we look at a distant light source and we don't need a screen in that case?
what do we mean by visible light? can we see the wave itself, crests and toughs as we see in water waves? If we don't see it, is it because the wavelength is too small or because electromagnetic fields are invisible? if electric and magnetic fields are invisible then what are the light fringes in interference patterns?