Talk:String field theory

Revision in less complicated Language

It's probably a good idea to rewrite this article as it's totally difficult to parse by the ordinary person, preferably in plainer English. It's a nightmare of links to figure out what half of these terms, equations and ideas even mean for the ordinary person. — Preceding unsigned comment added by 24.57.107.62 (talk) 23:38, 15 August 2011 (UTC)

Michio Kaku

After a second person added Kaku as the "inventor of string field theory" (apparently he is listed as such in a popular science book), I did a little reference hunting and added his work with Kikkawa to the light-cone string quantization section. They appear to be the first to give an explicit second-quantization of the formalism Mandelstam introduced.

Iellwood (talk) 10:36, 17 February 2010 (UTC)

I removed a sentence from the introduction which gave Michio Kaku as co-inventor of string field theory. I don't believe this to be either a fair assessment of his role in string field theory or appropriate for the introduction. A discussion of his work on gluing open/closed strings together, which was cited a fair amount in the early days, would be reasonable. I am not completely clear how this work influenced the field so I leave it to someone else. Iellwood (talk) 19:00, 14 September 2009 (UTC)

Explanation of rewrite

The original string field theory page was very poor and in serious need of a complete rewrite. It stated many false things about string field theory from its opening sentence, "string field theory is a proposal to define string theory in such a way that the background independence is respected", which was completely untrue, to its strange attempt to write down the cubic open string field theory action without ghosts.

As one can tell from reading the article, the term string field theory is used in many contexts in string theory. Theories in the spirit of Witten's cubic theory are certainly the canonical examples, but I felt it necessary to include a section on light-cone string field theory as well even though this can also be thought of as just ordinary string perturbation theory in light-cone gauge. Some physicists, will occasionally refer to an effective action for the massless and tachyonic fields as a string field theory, but I have avoided this usage as I find it confusing. Personally, I would prefer to use the phrase string field theory only for theories in which there is some notion of a string field, but this is too narrow for the common usage.

Future work:

1. The section on closed string field theory is currently very brief. This is partially due to my ignorance of the subject.
2. There is no section on open-closed string field theories.
3. There is no discussion of the covariantized light-cone theories. These theories have not been studied recently because of the many extra gauge degrees of freedom they have (whose interpretation remains unclear). One of the authors of HIKKO would be probably be required to say anything sensible about these theories. Nonetheless, they are an important stepping stone from the free covariant theories of Siegel to Witten's theory and I believe they represent the first examples of the non-linear BRST symmetry that has been so important in later theories.
4. There is currently no section on Witten's background independent open string field theory. The main reason for this is that the a) action is not considered a string field theory by many physicists as it is not well-defined beyond the massless level (it does, however yield an effective action for the massless and tachyonic fields which has had applications), and b) it uses some high-powered BV-formalism which I don't care to introduce.
5. There is no discussion of the relationship between open string field theory and standard conformal field theory techniques. This is mostly due to my desire to keep the article short and not introduce too much extra math. Additionally, results on gluing worldsheets and the importance of producing a single cover of moduli space seem far too technical, though they are the underpinnings of the whole subject.
6. The equations are not uniformly large or small. This appears to be a problem with Wikipedia and is not special to this article. Nonetheless, it's very annoying. I have employed the hack of including \left. \right. in the LateX to force some of the equations to be large.
7. I have no idea if the references are in Wikipedia format. They could also be hyperlinked to the arXiv/spires, but currently, are not. There were also a number of places where I wished to cite the same reference in multiple places, but I am not aware of how to do this.

Iellwood (talk) 01:13, 30 October 2008 (UTC)

Michio Kaku - Parallel Worlds

In response to the removal of Michio Kaku's name as the co-founder of string field theory, In his book entitled Parallel Worlds, he states the following ...

"In 1974 I decided to tackle this problem. With my colleague Keiji Kikkawa of Osaka University I successfully extracted the field theory of strings. In an equation barely half an inch and a half long, we could summarize all the information contained within string theory. Once the field theory of strings was formulated, I had to convince the larger physics community of its power and beauty. I attended a conference in theoretical physics at the Aspen Centre in Colorado that summer and gave a seminar to a small but select group of physicists. I was quite nervous: in the audience were two nobel laureates, Murray Gell-Mann and Richard Feyman."

Joseph leen (talk) 00:56, 16 February 2010 (UTC)