Far as I know, 7 (6 actually, 7th day is rest) day creation is not a theory at all. What branch of science would that be?

Alchemists don't consider alchemy a psuedo science do they? It's a science. They work with theories, they mix stuff together, sort of like chemistry. Alchemy is to chemistry like evolution is to biology. They just haven't figured out the formula for gold, or whatever, yet. But they keep trying.