experimental physics Experimental physics is the category of disciplines and sub-disciplines in the field of physics that are concerned with the observation of physical phenomena and experiments. Methods vary from discipline to discipline, from simple experiments and ...

, a test theory tells experimenters how to perform particular comparisons between specific theories or classes of theory. Without a good reference test theory, these

experiment An experiment is a procedure carried out to support or refute a hypothesis, or determine the efficacy or likelihood of something previously untried. Experiments provide insight into Causality, cause-and-effect by demonstrating what outcome oc ...

s can be difficult to construct. Different theories often define relationships and parameters in different, often incompatible, ways. Sometimes, physical theories and models that nominally produce significantly diverging predictions can be found to produce very similar, even identical, predictions, once

definition A definition is a statement of the meaning of a term (a word, phrase, or other set of symbols). Definitions can be classified into two large categories: intensional definitions (which try to give the sense of a term), and extensional definitio ...

al differences are taken into account. A good test theory should identify potential sources of definitional

bias Bias is a disproportionate weight ''in favor of'' or ''against'' an idea or thing, usually in a way that is closed-minded, prejudicial, or unfair. Biases can be innate or learned. People may develop biases for or against an individual, a group, ...

in the way that experiments are constructed. It should also be able to deal with a wide range of possible objections to experimental tests based upon it. Discovery that a test theory has serious omissions can undermine the

validity Validity or Valid may refer to: Science/mathematics/statistics: * Validity (logic), a property of a logical argument * Scientific: ** Internal validity, the validity of causal inferences within scientific studies, usually based on experiments ** ...

of experimental work that is designed according to that theory.

Examples

Parameterized post-Newtonian formalism In physics, precisely in the study of the theory of general relativity and many alternatives to it, the post-Newtonian formalism is a calculational tool that expresses Einstein's (nonlinear) equations of gravity in terms of the lowest-order devi ...

is used to compare theories of gravity.

Test theories of special relativity Test theories of special relativity give a mathematical framework for analyzing results of experiments to verify special relativity. An experiment to test the theory of relativity cannot assume the theory is true, and therefore needs some other fr ...

are useful when designing experiments to look for possible violations of Poincare symmetry. Physics experiments {{Physics-stub