Theory

To understand theoretical physics, one must understand the concept of theory. Theories are simple models of complex systems. The universe is a complex system. In order to analyze the universe as the science of physics does, it must be broken down into simple principles and basic ideas that create a visualization or model. A theory must be useful in that it should approximate reality and make it understandable, measurable, and predictable.

Aristotle realized, there must be propositions that do not need, for whatever reason, to be proven. Such propositions he called the first principles (archai, principia) of demonstration.

To create a theory, one must begin with assumptions or postulates. An assumption is something accepted without proof. The assumptions are therefore the weak point of any theory. Due to this fact, William of Ockham circa 1300 A.D., a medieval English philosopher, emphasized that the fewer the assumptions, the more useful the theory.

The assumptions should then lead to a theory that contains explanations of reality and the observations of reality should be able to be explained and even predicted by the theory. Therefore the predictions of the theory can be tested.