Talk:Renormalization

This page should actually explain renormalization (as, say, in QED) rather than redirecting to "renormalization group".

Done! --Matt McIrvin 22:29, 9 Oct 2004 (UTC)

Some more math and pictures now. I don't think I want to get into the details of regularization techniques and such, as more on loop calculation methods would probably obscure the central ideas rather than illuminating them (there may even be too many equations already, but I wanted to at least sketch the outlines of an example). So I'm probably done with major additions, and I think it's getting pretty encyclopedic. --Matt McIrvin 03:49, 17 Oct 2004 (UTC)

Listed as a featured article candidate (http://en.wikipedia.org/wiki/Wikipedia:Featured_article_candidates#Renormalization), but not doing very well for now. People are posting excellent constructive criticisms of the article over there, though, and any help with addressing them is appreciated. I think it's written on a slightly more popular level than most Wikipedia articles on quantum field theory, but it has a long way to go; the most mathematical parts maybe need to be moved somewhere else. --Matt McIrvin 20:01, 17 Oct 2004 (UTC)

Failed FAC nomination

Self-nom. This is a subject about which much more could be written, but perhaps not within the scope of a single encyclopedia article. Though the material is fairly arcane, I've tried to strike a balance between concreteness and clarification for nonspecialists. - Matt McIrvin 15:12, 17 Oct 2004 (UTC)

• Object IMHO, a featured article should be easily understandable by someone who knows a little about a subject, but who has some (but not a lot) of willingness to learn. I hope this article can be rewritten to achieve this. (After all, Albert Einstein's General Theory of Relativity was a popular book explaining a complicated technical idea to laymen willing to put a small amount of work into it.)

More specifically, but not exhaustively:

In the lead section: what are 'field effects'?; The article states 'Renormalization arose in quantum electrodynamics as a means of making sense of the infinite results of various calculations and extracting finite answers to properly posed physical questions.' What infinite results, what calculations, what sort of physical questions?

Can't understand the diagrams.

Prehistory: What are point particles? What's a back reaction? What is a particle's field? Can 'inertial mass' be explained here - there are links to 'inertia' and 'mass' but not 'inertial mass'. What's a singularity? Did the 'Attempts to deal with the back-reaction' predict bizarre behaviour that was not observed, or not explain bizarre behaviour that was observed?

Divergences in quantum electrodynamics: What are 'divergent integrals'? What is the importance of 'calculations involving Feynman diagrams'?

A loop divergence: There's no way a layman can understand this! Einstein was kind with his maths (from memory, I think he put much of the details of Lagrangians in appendices a casual reader didn't have to look at. Perhaps it would be better to describe the effect of the formulae here and provide a link to a technical page for those interested (and capable of understanding it).

I'm lost by now, so I've given up reading the article. Personally, I think articles that deal with complex scientific ideas for the layman are as important as they are difficult to write. I hope it is possible to rewrite it so anyone can understand it, but until that happens, I vote object to it being a featured article. jguk 18:08, 17 Oct 2004 (UTC)

Fair enough; part of the problem is that we need comprehensible articles explaining all of the rest of physics that provides background for this; I'm afraid that doing it in the renormalization article would turn it into a complete tutorial on calculus, quantum mechanics, particle physics, and classical and quantum field theory. Maybe we're simply not ready to turn something at this level of specialization into a featured article. --Matt McIrvin 18:51, 17 Oct 2004 (UTC)

No so. For example if you start by explaining what field effects are particularly what a field is in the context of QED (QED being a subset of quantum physics - and quantum physics being readily explainable on a rudimentary level. This can be made to be a very interesting article if it is worked on compassionately and with a view of educating someone with a non science degree background. Do not be discouraged and do not discount the added dimension of understanding provided to yourself when you are forced to explain such complexity to a novice. It is a rewarding challenge! prometheus1

I don't think it's impossible to have a featured article out of this subject. I'm sure I've seen elsewhere pages for laymen, with links to more comprehensive pages for those more scientifically minded. Many pages in the non-scientific world, eg cricket are written for everyone, but have lots of links to more specific areas that only cricket-lovers are going to read. I can't see why a scientific subject can't do the same. jguk 19:43, 17 Oct 2004 (UTC)

Weak oppose for now. Too complex. One thing that might help is if the diags were better labelled: at the moment they are very cryptic. When the text is dense, one tends to skip towards the piccies, in which case they need to be fairly self contained. OTOH the stuff about scale-dependence of forces I found very good, thats the closest I've ever come to understanding it -- William M. Connolley 19:32, 17 Oct 2004 (UTC).

• Support with better explanation of diagrams. Are they Feynman diagrams? Label them as such if so. —siroχo 05:12, Oct 19, 2004 (UTC)
• Neutral, I want to remind people that the objection that laymen will not understand it only because the subject is too complex is invalid, because it is not an objection that can be dealt with. Andries 16:36, 21 Oct 2004 (UTC)
  • It can be dealt with. See Einstein's General Theory of Relativity and Hawking's A Brief History of Time for two examples of making a complex subject understandable for a layman. jguk 19:09, 21 Oct 2004 (UTC)
  • That is incorrect. Just because an objection is difficult to deal with, does not make it invalid. It is certainly possible to do to some extent. - Taxman 19:24, Oct 21, 2004 (UTC)
    • On second thought, I think you are right that the article can be made more accessible to lay men. Andries 10:05, 24 Oct 2004 (UTC)
• Object. The article is certainly better than most tries I've seen so far too explain the subject, but it is too high level and implicitely assumes quite some familiarity of the reader with physics, especially terminology. I'd judge it higher undergraduate physics level. While it is fine to get into detail, for the benefit of specialists, one should cover the key point before in a language accesible to the layman. Material for this is present, but there is quite some work to be done. Simon A. 21:05, 22 Oct 2004 (UTC)

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I'd just like to say that Matt McIrvin did a terrific job with this article. It's the best non-technical (or at least semi-technical) explanation of renormalization I've read, though, like some of the posters above, I'm dubious about whether it's ultimately possible to make this subject completely understandable for laymen (whatever "understanding" means...) Great attempt though!

The only quibble I have is that the article doesn't mention Hans Bethe's classic "back-of-the-envelope" calculation of the Lamb shift. This was the paper that first showed how the infinities in a perturbation expansion can be dealt with, by dumping the divergent terms into a "dressed electron mass". Even though Bethe's method was primitive and incomplete, and doesn't click with modern methods (i.e. Feynman diagrams), it cuts right to the idea of what renormalization means. -- CYD