A political theory that holds that control of Eurasia and Africa (the World Island) is achieved via control of the countries bordering the Soviet Union

(physics) A theory developed in the early 20th century, according to which nuclear and radiation phenomena can be explained by assuming that energy only occurs in discrete amounts called quanta.

(philosophy) Theory in medieval Europe to explain then-modern events from an Aristotelian context.

(mathematics) The study of differentiable functions, where the domain of each is a manifold and the codomain is the real line.

(biology) A theory of evolution, especially the scientific theory of evolution through natural selection. / (by extension) Any model of disequilibrium or accumulating change.

An interdisciplinary field of science which studies the nature of complex systems in nature, society and science, and studies complex parts of reality as systems.

(chemistry) Any theory that relates collisions among particles to reaction rate; reaction rate depends on such factors as concentration, surface area, temperature, stirring, and the presence of either a catalyst or an inhibitor.

A theory of how people positively and negatively value things and concepts, the reasons they use in making their evaluations, and the scope of applications of legitimate evaluations across the social world.

(chemistry) An obsolete scientific theory of combustion.

(physics) A supposed theory uniting all fundamental physical phenomena into a single framework.