Theoretical physics is a branch of the field of physics which is dedicated to coming up with mathematical explanations for natural events. Many disciplines within physics fall under the umbrella of theoretical physics because they involve the design of formulas which may not be able to be empirically tested. Researchers in this field are pondering some very complex problems and questions, such as how the universe developed.
Physics is an intriguing branch of the sciences because it often involves the development of theories which cannot be tested with an experimental model, violating one of the fundamental precepts of empirical science. Scientific researchers usually want to develop a theory, design an experiment which will test that theory, perform the experiment, and publish results. In theoretical physics, researchers develop theories, but they are unable to test them. This separates theoretical physics from experimental physics, in which researchers design and perform experiments to explore their theories.
Since theoretical physics cannot be supported with the use of experiments, researchers rely on other tools to determine whether or not their theories are accurate. The theory should be able to accurately predict or explain physical phenomena, for example, and it should be supported by known observations. Ideally, the theory should also be clean and neat, with some theoretical physics subscribing to the idea of Occam's Razor, believing that the simplest explanation is the best one. Theories should also withstand vigorous discussion and debate, with theoretical physicists constantly exchanging ideas and criticism to improve their field of the sciences.
Some theories in this field have been widely accepted and they are routinely taught in classrooms, used in physics research, and applied in industries all over the world. Ongoing research on these theories continues as scientists want to fully explore all aspects of theoretic physics. Other theories have been proposed, and seem plausible, but have not been fully supported, or require more research, and the newest theories are considered “fringe theories” which require much more exploration, discussion, and observation.
Sir Isaac Newton is widely regarded as a pioneer in the field of theoretical physics, as is Albert Einstein. Both physicists distinguished themselves by making logical leaps which sometimes defied known information or observations and required a highly theoretical view of the world. Newton's work even involved a substantial expansion of the mathematical language of calculus so that he could express his theories. Theoretical physicists also famously engage in thought experiments, in which they explore their ideas in their minds, without the use of a lab.