Editing Physics (section)

===Theory and experiment===
{{Main|Theoretical physics|Experimental physics}}
[[File:Bruce McCandless II during EVA in 1984.jpg|thumb|right|The [[astronaut]] and Earth are both in [[free fall]]. (Pictured: Astronaut Bruce McCandless.) ]]
[[File:Lightning in Arlington.jpg|thumb|right|[[Lightning]] is an [[electric current]].]]

Theorists seek to develop [[mathematical model]]s that both agree with existing experiments and successfully predict future experimental results, while [[Experimentalism|experimentalists]] devise and perform experiments to test theoretical predictions and explore new phenomena. Although [[theory]] and experiment are developed separately, they strongly affect and depend upon each other. Progress in physics frequently comes about when experimental results defy explanation by existing theories, prompting intense focus on applicable modelling, and when new theories generate experimentally testable [[prediction]]s, which inspire the development of new experiments (and often related equipment).<ref>{{cite web |date=June 2015 |title=Has theoretical physics moved too far away from experiments? Is the field entering a crisis and, if so, what should we do about it? |url=https://www.perimeterinstitute.ca/research/conferences/convergence/roundtable-discussion-questions/has-theoretical-physics-moved-too |publisher=[[Perimeter Institute for Theoretical Physics]] |archive-url=https://web.archive.org/web/20160421064320/http://www.perimeterinstitute.ca/research/conferences/convergence/roundtable-discussion-questions/has-theoretical-physics-moved-too |archive-date=21 April 2016 }}</ref>

[[Physicist]]s who work at the interplay of theory and experiment are called [[Phenomenology (particle physics)|phenomenologists]], who study complex phenomena observed in experiment and work to relate them to a [[Theory of everything|fundamental theory]].<ref>{{cite web |title=Phenomenology |url=https://www.mpp.mpg.de/english/research/theory/phenomenologie/index.html |publisher=[[Max Planck Institute for Physics]] |access-date=22 October 2016 |archive-url=https://web.archive.org/web/20160307105406/https://www.mpp.mpg.de/english/research/theory/phenomenologie/index.html |archive-date=7 March 2016 }}</ref>

Theoretical physics has historically taken inspiration from philosophy; electromagnetism was unified this way.{{efn|See, for example, the influence of [[Immanuel Kant|Kant]] and [[Johann Wilhelm Ritter|Ritter]] on [[Hans Christian Ørsted|Ørsted]].}} Beyond the known universe, the field of theoretical physics also deals with hypothetical issues,{{efn|Concepts which are denoted ''hypothetical'' can change with time. For example, the [[atom]] of nineteenth-century physics was denigrated by some, including [[Ernst Mach]]'s critique of [[Ludwig Boltzmann]]'s formulation of [[statistical mechanics]]. By the end of World War II, the atom was no longer deemed hypothetical.}} such as [[Many-worlds interpretation|parallel universes]], a [[multiverse]], and [[higher dimension]]s. Theorists invoke these ideas in hopes of solving particular problems with existing theories; they then explore the consequences of these ideas and work toward making testable predictions.

Experimental physics expands, and is expanded by, engineering and technology. Experimental physicists who are involved in [[basic research]] design and perform experiments with equipment such as particle accelerators and [[laser]]s, whereas those involved in [[applied research]] often work in industry, developing technologies such as [[magnetic resonance imaging]] (MRI) and [[transistor]]s. [[Richard Feynman|Feynman]] has noted that experimentalists may seek areas that have not been explored well by theorists.<ref name="feynman1965p157-experiment">{{harvnb|Feynman|1965|p=157}} "In fact experimenters have a certain individual character. They ... very often do their experiments in a region in which people know the theorist has not made any guesses."</ref>