[TheUniverseYou]

This is more of a discussion question than a the-person-asking-the-question-doesn't-know question.List of notable theories: * Astronomy: Big Bang Theory * Biology: Cell theory — Evolution * Chemistry: Atomic theory — Kinetic theory of gases * Climatology: Theory of Global Climate Change (due to anthropogenic activity) * Computer science: Algorithmic information theory — Computation theory * Economics: Decision theory * Education: Constructivist theory — Critical pedagogy theory — Education theory — Emotional education theory — Multiple intelligence theory — Progressive education theory * Engineering: Circuit theory — Control theory — Signal theory — Systems theory * Film: Film Theory * Games: Game theory — Rational choice theory * Geology: Plate tectonics * Humanities: Critical theory * Literature: Literary theory * Mathematics: Catastrophe theory — Category theory — Chaos theory — Graph theory — Knot theory — Number theory