Talk:M-theory
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April 27, 2004
Was bored, rewrote the whole thing. Unfortunately, I have a bad feeling the thing's completely incomprehensible now. Still, the simplified page is out there. It probably needs a lot of linking now. Feel free to change it back if it's hopelessly obscure.
April 27, a bit later at night... Ugh. Changed it back. It needed too much work to be comprehensible, I think. If anyone else wants to grab from it (http://en.wikipedia.org/w/wiki.phtml?title=M-theory&oldid=3357041) and make it better, they're more than welcome to it.
Note: add a mention to Vafa's F-theory with 12 spacetime dimensions (2 time, 10 space).
Note 2: explain T-duality (between R and 1/R) and how it relates to energy; that there are two distinct measures for energy which give rise to different measures for dimensional size.
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Please merge
This article is still poorly written (see my comments below); however, the article at M-theory (simplified explanation) is actually good. I suggest that this "simplified explanation" replace the current article. What little information is present in the current article and not in the other article could possibly be merged in. Stuff like the "Strominger and Vafa D-brane quantum microstates" Star Trek technobabble could possibly be merged or, even better, made nice like in the "simplified" article (really, not much simplified, just clearer.)
If it stays as is, I might have a "moment of lucidity" and move the current article to "M-theory (obfuscated)" and move the simplified one to the current article. Loisel 04:31, 18 Apr 2004 (UTC)
11d vs 12d
On the article it talks about 11-dimensional spacetime. Shouldn't this be a 12-dimensional spacetime with an eleven dimensional space? I don't know very much about M-theory, but I'm pretty sure that in string theory and Kaluza-Klein models in general, you need an even dimensional spacetime in order to allow left-handed and right-handed spins.
Read this article. http://www.2think.org/t000104284.shtml . I'm not certain this helps. Will review my notes again. Remember I don't fully understand this, and to explain it is worse ! BF
Hmm, that says 11-D spacetime, and some further searching confirms it. How very odd that that permits chiral asymmetry, but maybe some property of the 'branes allows it. Hmm. Sorry for the unwarranted questioning, and feel free to delete this conversation.
There's no simple answer since the superstring theories are constructed on top of the bosonic string theory, which is 26 dimensional. So for all I know, chirality is related to dimensionality. I am curious where you got the idea though. -- ark
yet to produce testable predictions
"yet to produce testable predictions" can only come from a qualified physicist who is working in the field.. sorry" Boggle. WTF does that mean? Are you pulling rank? -- GWO
Of course not. I am explaining that whoever added that part must be researching M-theory, unless they are quoting someone who is. once again, that deletion was made because the THEORY has already been scrutinized by fellows of Witten, and stands. Someone chooses to assume or fantasize they are part of the M-theory group of physicists, outside wiki. That tiny addition to the main page was unsubstantiated presumption on someone's part. Moreover, I have read some recent journal abstracts(some Japanese scientists) which use M-theory to expand into new areas of superstring, meaning it works.
I found a site or paper (don't have it at hand) which had that section of the page (now moved/deleted) almost word for word. So I believe the person who wrote it was quoting a physicist, and not presuming to be a physicist. -- ark
String theory is different.
String theory is different. Some people complain that it does not predict - but it in fact predicts a lot. To include gravity consistently to a quantum theory, we were forced to go to 10 dimensions, to discover supersymmetry, to allow topology change etc. Some people criticize string theory that it predicts nothing new, some people complain the string theory involves/predicts too much new stuff (excited strings, higher dimensions, SUSY etc.). Some critics happily belong to both categories and they do not realize how inconsistent their position is... ;-) (http://www.lns.cornell.edu/spr/2001-06/msg0033389.html)
- Nice job cleaning up the article I originally wrote. The LD Learning Lab at Caltech does help a lot! I noticed some formulas painstakingly added with symbol fonts were removed by someone. This is very annoying to see on a science page. Not sure if wiki supports pdf yet, so restore the formulas, or I will. BF 22:55 Dec 12, 2002 (UTC)
Not well written
I'm a mathematician and I've written a number of articles about analysis, and sometimes people complain that my articles are too specialized and don't make any sense. (For instance, see Lebesgue integration or Riemann surface.) However, I'm almost certain you guys are doing a poorer job than I am. There are a zillion and a half technical terms that aren't defined at all. In fact, almost every word of every sentence is some undefined techincal term. Here's a specific example:
The T duality infers the existence of open strings with positions fixed in the dimensions that are T-transformed.
T duality? T transform? What does it mean to have open strings with positions fixed in whatever dimensions?
Do you mean open as in f:[0,1]->X with f(0) \ne f(1) or as in f:(0,1)->X? Articles such as Riemann integral are long, not because the topic is complex, but because a more terse discussion missing numerous definitions is inappropriate, especially for an encyclopedia.
I think a lot could be done to disambiguate, clarify and otherwise make this very interesting article even better. Loisel 00:06 Jan 30, 2003 (UTC)
- I agree absolutely. Sentences like The theory requires mathematical tools which have yet to be invented in order to be fully understood make me instantly assume that the following paragraphs are not going to be too enlightening. If nobody understands the theory because we don't have the mathematical tools - well, what kind of theory is that? Chas zzz brown 03:40 Feb 1, 2003 (UTC)
- Right, that sentence is not particularly good. Some fields of physics haven't been completely axiomatized yet, and sometimes many mathematical details are unproven (I believe this was the case for much of Witten's work, which was otherwise excellent and warranted a Fields medal.) So I would understand if some of the theory hasn't been worked out to a mathematician's satisfaction. However, with the article as it is now, much more profound changes are needed than an axiomatization. Right now, the article is unreadable to non-experts and probably useless to experts.
Extra Dimentions.
I read with interest the theory that extra spatial dimentions exist. However, this view is at variance with one expressed by Professor Stephen Hawking, who remarks that " if there were more than three spatial dimentions, the orbits of planets around the sun or electrons around a nucleus would be unstable and they would tend to spiral inward."
Derek R Crawford.
- See an answer here (http://en.wikipedia.org/wiki/Talk:Why_10_dimensions#Extra_Dimentions.)