Talk:Quantum electrodynamics

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Needs expansion, as detailed below. Tompw

Page on the Nobel Prize official site http://www.nobel.se/physics/laureates/1965/feynman-bio.html shows this as the 1965 Prize in Physics

I didn't initiate the attention notice, but the guidelines state that it is alright to put the notice on the talk page. Interested parties will note that the category will alphabetize this entry correctly. Ancheta Wis 22:38, 31 Dec 2004 (UTC)

Contents

[edit] Expansion request

Please help improve this article or section by expanding it.
Further information might be found on the talk page or at requests for expansion.

A lot of information on the history of this theory should be pulled in here. See e.g. Quantum_mechanics#History. -- Beland 05:50, 14 August 2005 (UTC)

[edit] From PNA/Physics

  • Quantum electrodynamics - I fixed the broken LaTex formula to conform to the author's apparent intent. I'm not sure if the "D" in the sentence following the formula should also be slashed. Could someone who knows QED double-check this please? --Ortonmc 23:22, 13 Sep 2003 (UTC)
cleaned up some Latex, but it still needs a lot of work lethe
I moved this from the "mathematics" section. Paul August ☎ 18:33, Jun 5, 2005 (UTC)

</math>

[edit] Persistent... idontknowhattocallit

The same anon that's been going around vandalizing other theoretical phyisics related articles, has apparently settled on this page, and while I wouldn't call its edits outright vadalism, I would say that its past history makes me doubt its seriousness, seems more like it's picked an article where vandalism wouldn't be very likely to be noticed, and stuck with it

My opinion is that you should look up the information in the citation before accusing the person of vandalism. Edit: ...though it seems that the user has not made a strict citation or reference, making a check quite difficult to do. I'll see what I can dredge up. In the meantime, let's not treat something as vandalism until we see genuine reasons to do so. Lucidish 01:42, 5 January 2006 (UTC)
The citation for the Feynman quote that's floating around is James Gleick's "Genius: The life and science of Richard Feynman", p348. Lucidish

The editor was a notrious POV-pusher, Licorne. I have re-removed the quote, because as it stands it sounds like Feynman repudiated QED in his later life, which is, as best I know, not true. –Joke 16:43, 14 March 2006 (UTC)

He didn't repudiate it, but even in his Nobel acceptance speech he called the theory he'd won the prize for a bit of a cheat or something to that effect. This quote doesn't seem to be inappropriate to me, I'm going to reinsert it, but with a small amount of explanation.WolfKeeper 17:21, 14 March 2006 (UTC)

Fair enough. I'm happy with your version. –Joke 17:28, 14 March 2006 (UTC)

[edit] Every Possible Path?

From article "In fact, according to QED, it takes EVERY possible path between the start and end points."

I think that the claim that it takes EVERY possible path is Feynman's Many World's interpretation of quantum mechanics and not a necessary component of QED.

IRC Feynman claimed only the consistent histories interpretation of quantum mechanics which is a stronger claim than many worlds, since it makes no claim for non observable universes, only those that reconnect back with ours.WolfKeeper 13:07, 23 February 2006 (UTC)

However, in order to do some of the calculations in QED, which, according to the book "QED" cited on the page, can be done by drawing pictures on a 2d access of space and time, Feynman diagrams. Now in order to do the calculations you need to know every possible path it can take before you compute the probability of it taking a certain path (which is the experimental evidence of QED), but that is not the same as it taking every possible path.--MobyDikc 23:43, 8 February 2006 (UTC)

Yeah, it is, due to destructive/constructive interference. If the particle didn't go every which way you wouldn't get interference like that.WolfKeeper 13:07, 23 February 2006 (UTC)

[edit] We Need a Picture of the Basic Vertex!

One of the simple beauties of QED is that the trilinear term in the Lagrangian corresponds to a vertex in a Feynman diagram where an electron absorbs a photon (or emits one, or etcetera depending on how one views the vertex). This should be explained, and there should be a nice picture of this basic vertex. Right now only some fancier Feynman diagrams are shown... the simplicity of the theory is not being explained!

I would improve this article right now but I'm busy preparing a talk and I just wanted a picture of this vertex...

John Baez 10:32, 23 February 2006 (UTC)

John, it is very good to see someone of your calibre take a close interest in this important article on the "jewel of physics." Although I am no physicist (but do own a copy of Feynman 1985), forgive me for making the following possibly rash and uninformed remarks:
  • Someone please do a yeoman's job of communicating the essential "simplicity" of QED.
  • A subject this rich and this important deserves a longer entry, period.
  • Beautiful physics (GR, Maxwell's EMF, Boltzmann) often culminates in beautiful equations, especially when these are cast in Planck units. Why does no beautiful equation command pride of place in expositions of QED?
  • Wikipedia should include a killer intro to Feynman diagrams, a splendid instance of science done by semiotic means.
  • The last word re renormalization has yet to be written. One day the physics and math will reach a state that Feynman would applaud.202.36.179.65 19:33, 25 March 2006 (UTC)

[edit] Feynman diagrams

There are some nice illustrations of Feynman digrams with loops but no accompanying explanatory text. Could someone please remedy this ommission?

[edit] "See Also" list

The "See also" list is very long; in my opinion there is a lot there that isn't directly relevant to quantum electrodynamics. E.g.: Basics of quantum mechanics, Photon dynamics in the double-slit experiment, Schrödinger equation, and Theoretical and experimental justification for the Schrödinger equation. Paring down this list might help focus people on the more relevant items. (I'm not confident enough to be bold here.) HEL 02:30, 8 October 2006 (UTC)

I agree, as well with the pages on Standard Model, Positronium, and Photon polarization. Watchayakan 05:14, 14 November 2006 (UTC)

[edit] Accuracy

Predictions of QED agree with experiments to an extremely high degree of accuracy: currently about 10−12 (and limited by experimental errors)

What does this 10−12 mean exactly? Significance? This seems unclear to me. --Jaapkroe 11:40, 28 October 2006 (UTC)


This means "Theory and experiment agree with each other to within one part in a million million." This is a completely standard scientific terminology, but a translation into words might be nice for a broader audience.

My complaint with this statement is with the "and limited by experimental errors". In QED most of the experiments are performed in particle accelerators which pin down particle-particle interactions to a very high level. In MANY cases the experiments are far more accurate that the QED predictions because to get better and better predictions, more and more higher order possible interaction pathways have to be considered. Eventually you just give up because your computer isn't big enough to work them all out. You just say "I've got the most imporatnt ones and I'll just ignore all the rest".

So I'd very much like the slur on experimental physicists removed. Please.

131.111.8.96 16:31, 6 November 2006 (UTC) Will (an experimental physicist)

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