Theoretical Physics explains, rationalizes, and predicts natural phenomena with two primary tools: abstractions of physical objects and mathematical models. Theoretical physics is a separate branch from Experimental Physics, which is based on experiments. Generally, science advances uses both branches. Theory often comes first, and the simplest explanations of theories are tried and proven with experimental study. Current physical theories can be categorized as mainstream theories, proposed theories, and fringe theories.
Theory is used to model physical events. Theories are weighed by their predictions’ agreement with empirical observations. They are also judged by their ability to make new physical predictions which can be validated by newly gathered data. A mathematical theory has an axiom that doesn’t need to agree with experimental results, whereas physical theories must.
An axiom in theoretical physics is a postulation or an assumption which is assumed to be true. It is a premise, a statement, which acts as a starting point for further argument and reasoning. The etymology of the word axiom is Greek. It means that which is thought worthy or fit, and that which commends itself as evident.
One of the advantages of theoretical physics is that it can be practiced with sheer mathematical rigor, cutting out the time and resources of experimentation. Conversely, Albert Einstein was awarded the Nobel Prize for using theoretical physics to explain the photoelectric effect, a scientific observation found through experimentation, which lacked a coherent theory.
The best physical theories are not only the simplest and the truest scientific explanations, but they can be applied most widely to the physical phenomenon of our universe. New physical theories are few and far between, as they must not only make correct predictions of physical phenomena, but they must do it elegantly and concisely, with a degree of economy. This idea is known as Occam’s Razor or the Law of Parsimony, whose defining principle demands that the simplest explanation is the truest and preferred. That is, when presented with competing hypothesis of the same prediction, we select the solution with the fewest assumptions. After all, at the heart of science we are seeking the simplest explanations for the way things are.