In general, engineering and scientific disciplines (including mathematics) have a theory wing. Commonly I encounter people in the trenches who seem to think theory is useless and that only heuristics get things done. I'm fairly sure this is false, but I want to know what other people think. I'm posting this in the career section because I personally avoided pursuing theory in physics because I wasn't sure it was relevant, in some way, to applications. Some people of course will argue that its relevance to applications isn't necessary, and I'm curious about that too.