Editing Physics (section)

=== 20th century ===
{{see also|History of special relativity|History of quantum mechanics}}
{{further|History of physics#20th century: birth of modern physics}}
[[File:Max Planck Nobel 1918.jpg|thumb|left|[[Max Planck]] (1858–1947), proposed [[quantum|quanta]] to explain the [[blackbody spectrum]],<ref>{{cite web |url=https://www.esa.int/Science_Exploration/Space_Science/Planck/Max_Planck_Originator_of_quantum_theory |title=Max Planck: Originator of quantum theory |date=2012-08-12 |quote="He renounced previous physics and introduced the concept of ‘quanta’ of energy."|work=esa.int |access-date=2025-03-04}}</ref> originating [[quantum mechanics|quantum theory]].<ref>{{Cite web|url=https://www.esa.int/Science_Exploration/Space_Science/Planck/Max_Planck_Originator_of_quantum_theory|title=Max Planck: Originator of quantum theory|website=www.esa.int}}</ref><ref>{{Cite web|url=https://www.britannica.com/biography/Max-Planck|title=Max Planck &#124; Biography, Discoveries, & Quantum Theory &#124; Britannica|date=19 April 2025|website=www.britannica.com}}</ref>]]
[[File:Einstein1921 by F Schmutzer 2.jpg|thumb|right|[[Albert Einstein]] (1879–1955), discovered the [[photoelectric effect]] and [[theory of relativity]].]]
[[Modern physics]] began in the early 20th century with the work of [[Max Planck]] in quantum theory and [[Albert Einstein]]'s theory of relativity. Both of these theories came about due to inaccuracies in classical mechanics in certain situations. [[Classical mechanics]] predicted that the [[speed of light]] depends on the motion of the observer, which could not be resolved with the constant speed predicted by [[Maxwell's equations]] of electromagnetism. This discrepancy was corrected by Einstein's theory of [[special relativity]], which replaced classical mechanics for fast-moving bodies and allowed for a constant speed of light.<ref name="oconnorrobertson1996-relativity">{{harvnb |O'Connor|Robertson|1996a}}</ref> [[Black-body radiation]] provided another problem for classical physics, which was corrected when Planck proposed that the excitation of material oscillators is possible only in discrete steps proportional to their frequency. This, along with the [[photoelectric effect]] and a complete theory predicting discrete [[energy levels]] of [[Atomic orbital|electron orbitals]], led to the theory of quantum mechanics improving on classical physics at very small scales.<ref name="oconnorrobertson1996-quantum">{{harvnb |O'Connor|Robertson|1996b}}</ref>

Quantum mechanics would come to be pioneered by [[Werner Heisenberg]], [[Erwin Schrödinger]] and [[Paul Dirac]].<ref name="oconnorrobertson1996-quantum"/> From this early work, and work in related fields, the [[Standard Model of particle physics]] was derived.<ref name="donut2001">{{cite web |website=[[DONUT]] |title=The Standard Model |publisher=[[Fermilab]] |date=29 June 2001 |url=http://www-donut.fnal.gov/web_pages/standardmodelpg/TheStandardModel.html |access-date=1 April 2014 |archive-date=31 May 2014 |archive-url=https://web.archive.org/web/20140531012204/http://www-donut.fnal.gov/web_pages/standardmodelpg/TheStandardModel.html |url-status=live }}</ref> Following the discovery of a particle with properties consistent with the [[Higgs boson]] at [[CERN]] in 2012,<ref name="cho2012">{{harvnb |Cho|2012}}</ref> all [[fundamental particles]] predicted by the standard model, and no others, appear to exist; however, [[physics beyond the Standard Model]], with theories such as [[supersymmetry]], is an active area of research.<ref>{{cite magazine |last=Womersley |first=J. |url=http://www.symmetrymagazine.org/sites/default/files/legacy/pdfs/200502/beyond_the_standard_model.pdf |date=February 2005 |title=Beyond the Standard Model |magazine= Symmetry |volume=2 |issue=1 |pages=22–25 |archive-url=https://web.archive.org/web/20150924114111/http://www.symmetrymagazine.org/sites/default/files/legacy/pdfs/200502/beyond_the_standard_model.pdf |archive-date=24 September 2015 |url-status=live}}</ref> Areas of mathematics in general are important to this field, such as the study of [[probability amplitude|probabilities]] and [[Group theory#Physics|groups]].