Physics:Quantum electrodynamics - Revision history

WikiHarold: Remove imported red links from Quantum page

2026-05-23T23:47:15Z

Remove imported red links from Quantum page

← Older revision		Revision as of 23:47, 23 May 2026
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	==History==		==History==
	~~{{Main\|Physics:History of quantum mechanics\|Physics:History of quantum field theory}}~~
	[[File:Dirac 3.jpg\|upright\|thumb\|right\|Paul Dirac]]		[[File:Dirac 3.jpg\|upright\|thumb\|right\|Paul Dirac]]

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	===Mass renormalization===		===Mass renormalization===
	~~{{Main\|Physics:Self-energy}}~~

	[[File:Electron self energy loop.svg\|thumb\|right\|200px\|Electron self-energy loop]]		[[File:Electron self energy loop.svg\|thumb\|right\|200px\|Electron self-energy loop]]
	A problem arose historically which held up progress for twenty years: although we start with the assumption of three basic "simple" actions, the rules of the game say that if we want to calculate the probability amplitude for an electron to get from ''A'' to ''B'', we must take into account ''all'' the possible ways: all possible Feynman diagrams with those endpoints. Thus there will be a way in which the electron travels to ''C'', emits a photon there and then absorbs it again at ''D'' before moving on to ''B''. Or it could do this kind of thing twice, or more. In short, we have a fractal-like situation in which if we look closely at a line, it breaks up into a collection of "simple" lines, each of which, if looked at closely, are in turn composed of "simple" lines, and so on ''ad infinitum''. This is a challenging situation to handle. If adding that detail only altered things slightly, then it would not have been too bad, but disaster struck when it was found that the simple correction mentioned above led to ''infinite'' probability amplitudes. In time this problem was "fixed" by the technique of renormalization. However, Feynman himself remained unhappy about it, calling it a "dippy process",<ref name=feynbook/>{{rp\|128}} and Dirac also criticized this procedure as "in mathematics one does not get rid of infinities when it does not please you".<ref name=":1" />		A problem arose historically which held up progress for twenty years: although we start with the assumption of three basic "simple" actions, the rules of the game say that if we want to calculate the probability amplitude for an electron to get from ''A'' to ''B'', we must take into account ''all'' the possible ways: all possible Feynman diagrams with those endpoints. Thus there will be a way in which the electron travels to ''C'', emits a photon there and then absorbs it again at ''D'' before moving on to ''B''. Or it could do this kind of thing twice, or more. In short, we have a fractal-like situation in which if we look closely at a line, it breaks up into a collection of "simple" lines, each of which, if looked at closely, are in turn composed of "simple" lines, and so on ''ad infinitum''. This is a challenging situation to handle. If adding that detail only altered things slightly, then it would not have been too bad, but disaster struck when it was found that the simple correction mentioned above led to ''infinite'' probability amplitudes. In time this problem was "fixed" by the technique of renormalization. However, Feynman himself remained unhappy about it, calling it a "dippy process",<ref name=feynbook/>{{rp\|128}} and Dirac also criticized this procedure as "in mathematics one does not get rid of infinities when it does not please you".<ref name=":1" />
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	{{Clear}}		{{Clear}}
	~~{{QED}}~~
	{{Standard model of physics}}		{{Standard model of physics}}
	{{Branches of physics}}		{{Branches of physics}}

	~~[[Category:Quantum electrodynamics\| ]]~~
	~~[[Category:Quantum electronics]]~~
	~~[[Category:Quantum field theory]]~~

	{{Sourceattribution\|Quantum electrodynamics}}		{{Sourceattribution\|Quantum electrodynamics}}

WikiHarold: Clean Quantum page image and red links

2026-05-23T23:34:10Z

Clean Quantum page image and red links

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WikiHarold: Use Quantum See also index module

2026-05-23T22:21:36Z

Use Quantum See also index module

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 This theory can be extended, at least as a classical field theory, to curved spacetime. This arises similarly to the flat spacetime case, from coupling a free electromagnetic theory to a free fermion theory and including an interaction which promotes the partial derivative in the fermion theory to a gauge-covariant derivative.
-==See also==
+== See also ==
-{{Div col|colwidth=20em|small=yes}}
+{{#invoke:PhysicsQC|tocHeadingAndList|Physics:Quantum basics/See also}}
 ==References==
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 {{Standard model of physics}}
 {{Branches of physics}}
 [[Category:Quantum electrodynamics| ]]

Maintenance script: Point hydrogen atom link to Quantum Collection page

2026-05-23T10:40:43Z

Point hydrogen atom link to Quantum Collection page

← Older revision		Revision as of 10:40, 23 May 2026
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	[[File:Hans Bethe.jpg\|upright\|thumb\|Hans Bethe ]]		[[File:Hans Bethe.jpg\|upright\|thumb\|Hans Bethe ]]
	Difficulties with the theory increased through the end of the 1940s. Improvements in [[Physics:Microwave\|microwave]] technology made it possible to take more precise measurements of the shift of the levels of a [[Physics:~~Hydrogen atom~~\|hydrogen atom]],<ref name=lamb>		Difficulties with the theory increased through the end of the 1940s. Improvements in [[Physics:Microwave\|microwave]] technology made it possible to take more precise measurements of the shift of the levels of a [[Physics:Quantum atoms/hydrogen\|hydrogen atom]],<ref name=lamb>
	{{cite journal		{{cite journal
	\| year=1947		\| year=1947

Harold: Add missing image fallback to Quantum header

2026-05-17T22:33:03Z

Add missing image fallback to Quantum header

← Older revision		Revision as of 22:33, 17 May 2026
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	<div style="width:300px;">		<div style="width:300px;">
	~~<!--~~ No ~~lead~~ image available ~~in existing page~~. ~~-->~~		[[File:File not found.png\|thumb\|280px\|No image available.]]
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Harold: Restore Quantum article header template

2026-05-17T21:52:08Z

Restore Quantum article header template

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 {{Short description|Quantum field theory of electromagnetism}}
 {{Quantum field theory}}
 In [[Physics:Particle physics|particle physics]], '''quantum electrodynamics''' ('''QED''') is the relativistic [[Physics:Quantum field theory|quantum field theory]] of [[Physics:Electrodynamics|electrodynamics]].<ref name="feynman1" /><ref name="feynbook" /><ref name=":0" /> In essence, it describes how [[Physics:Light|light]] and [[Physics:Matter|matter]] interact and is the first theory where full agreement between [[Physics:Quantum mechanics|quantum mechanics]] and [[Physics:Special relativity|special relativity]] is achieved.<ref name="feynbook" /> QED mathematically describes all [[Philosophy:Phenomenon|phenomena]] involving [[Physics:Electric charge|electrically charged]] particles interacting by means of exchange of [[Physics:Photon|photon]]s and represents the [[Physics:Quantum mechanics|quantum]] counterpart of [[Physics:Classical electromagnetism|classical electromagnetism]] giving a complete account of matter and light interaction.<ref name="feynbook" /><ref name=":0">{{Cite journal |last=Feynman |first=R. P. |date=1950 |title=Mathematical Formulation of the Quantum Theory of Electromagnetic Interaction |journal=Physical Review |volume=80 |issue=3 |pages=440–457 |doi=10.1103/PhysRev.80.440|bibcode=1950PhRv...80..440F |url=https://authors.library.caltech.edu/3528/ }}</ref>
 In technical terms, QED can be described as a very accurate way to calculate the probability of the position and movement of particles, even those massless such as photons, and the quantity depending on position (field) of those particles, and described light and matter beyond the wave-particle duality proposed by Einstein in 1905. [[Biography:Richard Feynman|Richard Feynman]] called it "the jewel of physics" for its [[Physics:Precision tests of QED|extremely accurate predictions]] of quantities like the anomalous magnetic moment of the electron and the [[Physics:Lamb shift|Lamb shift]] of the [[Physics:Energy level|energy level]]s of [[Chemistry:Hydrogen|hydrogen]].<ref name=feynbook>{{cite book |last=Feynman |first=Richard |year=1985 |isbn=978-0-691-12575-6 |title=QED: The Strange Theory of Light and Matter |publisher=Princeton University Press}}</ref>{{rp|Ch1}} It is the most precise and stringently tested theory in physics.<ref>{{Cite book |last=Venkataraman |first=Ganeshan |title=Quantum Revolution II — QED: The Jewel of Physics |year=1994 |isbn=978-8173710032 |language=en |author-link=Ganeshan Venkataraman}}</ref><ref>{{Cite web |date=2023-10-05 |title=Testing the limits of the standard model of particle physics with a heavy, highly charged ion |url=https://www.nature.com/articles/d41586-023-02620-7 |access-date=2023-10-23 |website=Nature}}</ref>
 ==History==

imported>WikiHarold: link

2024-02-08T05:46:43Z

link

← Older revision	Revision as of 05:46, 8 February 2024
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imported>WikiHarold: link

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