Sort of kidding with the title here. But seriously I am having trouble making progress in my study of QFT because I can't see where it is going. Please give me an example of something to calculate with QFT that corresponds to a measurable quantity, hopefully something which cannot be calculated with regular QM (non-relativistic or relativistic). No computational details required. I'll look it up and figure it out myself. But right now I'm like learning to read musical notation without ever having heard music.