Talk:M-theory/Archive 1

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This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page.

This talk page is quite old. I have partially sorted out the somewhat garbled history and re-ordered some of the undated entries. Please add new material to the bottom of the page. --Blainster 00:07, 2 November 2005 (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

11-D M-theory is non-chiral, because it is odd-dimensional. However, it is possible to intruce chirality in compactifications down to lower dimensions, so this is not a problem. -ps

I am not a physicist or mathematician, but I just finished watching a special on strings via pbs broadcast here in the US that distinctly said 12 dimensions.....just a note, not an arguement.

Hi, I think I can clear this up. M-theory lives in an eleven-dimensional spacetime (ten spatial dimensions, one time). This is sometimes written "10+1 dimensions" to avoid just this kind of confusion. Superstring theories all live in 9+1 dimensions, and the bosonic string lives in 25+1. There are also proposals for another "unifying theory" called F-theory that lives in 11+1 dimensions, with one more spatial dimension than M-theory. Wesino 10:11, 6 December 2006 (UTC)

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

Additions requested

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. -- 29 May, 2002

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.

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)

When I first read the merge proposal I was skeptical. But after looking at the two articles I think it's an excellent idea. Almost the entire M-theory article is taken up by "Basics" and a section on what the "M" stands for. In other words, the current article is a simplified account of M-theory. It takes more knowledge (mostly of vocabulary) to be able to read the M-theory article, but the reader learns less. The content of the present article is just more jargony than the "simplified" account but the content is pretty much the same. Wesino 10:30, 6 December 2006 (UTC)

Rewrite attempt aborted

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 and make it better, they're more than welcome to it.

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. 20 June 2005

See an answer here

the orbits of the planets about tne sun are unstable (at least as observable from our own planetary system, there is currently no way of observing the orbits of others) and they are tending to spiral inward... that is to say our planet is falling toward the sun in an observable manner, as are all of the orbiting planets, planetoids, asteroids, moon, etc... do you honestly think that if a human being was able to clearly observe an atom for an unlimited amount of time, in a perfect manner, they would find something different? it will take longer than the life of the universe (as can be predicted by thermodynamics), but guess what, earth will fall into the sun... why are atoms any different? seems to me, and grant this is a completely unsupported view, but fractals and thier repeating patterns from as far out as you can go to as far in as you can zoom, could go a long way toward explaining the universe....

New Article version

Saw this entry and thought it needed rewriting. The exposition is incoherent. I'm trying to clean up the exposition by incorporating some aspects of the "M-theory simplified" article. --User:Ajt, 10/28/05

Corrected some errors and some miscorrections. In particular, please leave intact the fine distinction about Witten proposing the EXISTENCE of M-theory. He didn't actually propose M-theory, as the theory has not been fully defined. Likewise, M-theory itself does not explain the string dualities: the theory is not yet thoroughly developed enough to support this sort of proof. However, such a theory, if it does exist and could be fully defined would (presumably) explain the known string dualities. I wrote the introduction to gloss over this point. It's unfortunately easy to change the language, and in doing so, introduce technically incorrect statements. --User:Ajt, 11/1/05

The words "proposed the existence of", do not suggest that the theory is merely not completed, rather they say that the theory has being apart from it's creation by a human being. This is not the way science understands the concept of theory. Theories are created, not discovered. The relationships or facts which support a theory are discovered by experiment. A scientific theory such as the theory of gravity is a human conceived model for the way we understand reality. Theories provide a structure for understanding the established facts of existence; they do not in themselves constitute that existence. See article: theory. --Blainster 19:13, 2 November 2005 (UTC)

I'm using "theory" as it's typically used among my colleagues in mathematical physics. In particular, the term "M-theory" refers to a specific mathematical model. I apologize if you found this confusing and have corrected the article.

I'd caution you, by the way, that the terminology in the wikipedia theory article does not conform to the terminology commonly used by working physicists. In particular, most of us would read the sentence "Witten proposed M-theory" as giving Witten credit for creating the model itself. --User:Ajt Nov 2 2005

Wikipedia is written for the general educated public, and should not conform to the ways of specialists in any one field. It is up to specialists who contribute to it to use either non-specialist language, or to define special terminology they use. Hyperlinking provides an easy way to do this. (WP should read more like Scientific American than the Journal of Mathematical Physics). That said, my misunderstanding of what you wrote was not due to technical jargon, but because the phrase you used previously suggested the meaning I explained in my previous post.

The article makes clear further on, that Witten's proposal was that the physics community should work towards uniting the various string theories into a single model, and that he did not propose a particular expression of it. That is what the introduction should say. The article could state in the opening paragraph that Witten provided a name for a yet-to-be formulated theory. It can be surprisingly difficult for advanced researchers to switch gears into language that general readers can follow, and I think you explained things well in the body of the article. --Blainster 11:07, 3 November 2005 (UTC)

Inaccuracies / mistakes

In "The Theory": "So when one studies string theory at low energies, it becomes difficult to see that strings are extended objects—they become effectively one-dimensional (points)."

One-dimensional objects are lines - they can be measured in one dimension, like a string. Points have zero dimensions - they can't be measured. I believe this sentence was supposed to say that they become effectively zero-dimensional, but since I'm a little out of my league I'll let someone else correct the mistake. --nunocordeiro 20:38, 6 December 2005 (UTC)

Good point! --Blainster 22:14, 6 December 2005 (UTC)

suprised

I am suprised at how there a longer passage for the possibility of what the "M" stands for than the background of the theory! The background did not have any metion of Witten, which there should be. After all, M theory was the byproduct of the second superstring revolution. M-theory should deserve better than this. The pointer outer 03:11, 19 January 2006 (UTC)

Well that's probably because 'what the "M" does or doesn't stand for' is all most people can comprehend about the theory ;) This article is in poor shape and should probably be merged with its "layman's fork" M-theory (simplified). -- Fropuff 03:45, 19 January 2006 (UTC)

Why is there a hoax template at the top of the article?

Notwithstanding the legitimate scientific controversy of M-theory and/or string theory, is there any evidence that some poser was deliberately inserting plausible garbage in the article? if not, the hoax template should be removed. r b-j 03:06, 12 February 2006 (UTC)

Branes and Matrixes

The branes may be the fisical manifestation of the shapes allowed by the law and the four forms of energy allowed by the order: fabric (relativistic), fluid (quantic), light (photons) and spirit (thought-form). Mass probably is the knotting of the underlying branes.

It is interesting to remember that tachyons are entities of imaginary mass different from zero that may travel at speeds greater than the light. Certainly life forms are entities with real and imaginary mass (or energy, it's the same). They travel at under-light speeds in the real world and may achieve super-light speeds in the other dimensions of lighter matter.

It may be that these "enveloped" dimensions include the integral and fractal parallel dimensions of the astral, the subjacent divinely omniscient quantic computation and the gravitational time webnet and other sets of multiverse.

Knowing these concepts of dimensions, one may quickly percieve time as imaginary and translate this in the natural Rhythm of the underlying branes. Count time and discover the natural oscillation of the local brane. Then time becomes imaginary, existing in a transform of the reality.

These comments go there or here?

Definition of "M" in "M-Theory"

Yes, it's debated. I know that. The problem is that the M-Theory Article (this one) differs from the String Theory's explanation. Quoted from the first guess on the "Naming Conventions..." part says:
When Witten named M-theory, he did not specify what the "M" stood for, presumably because he did not feel he had the right to name a theory which he had not been able to fully describe. According to Witten himself, "'M' stands for 'magic,' 'mystery' or 'membrane,' depending on your taste." Also suggested, has been 'matrix' (see below) and 'mother of all theories'.

The String Theory article has this to say about Witten believes the "M" stands for:
According to Witten himself, as quoted in the PBS documentary based on Brian Greene's The Elegant Universe, the "M" in M-theory stands for "magic, mystery, or matrix according to taste."

And the M-theory (simplified) version has the same thing as the String Theory article. Should I just assume that whoever wrote this article wasn't thinking?

Yeah, they conflict. My question is: which one is correct? Xgamer4 02:26, 8 April 2006 (UTC)

The normal practice would be to use whichever one has a good reference - David Gerard 18:44, 4 May 2006 (UTC)

Copyedit, please check

Some of the grammar struck me as clumsy and it was peppered with typos. As such, I did a copyedit for clarity. Since I know nothing about the theory itself, could someone please check I haven't inadvertently made it inaccurate? - David Gerard 18:44, 4 May 2006 (UTC)

What ???

I've looked through the article, and still have no idea what M-theory IS. If someone reads the first few paragraphs, they should have some idea how this idea ties in with what they already know. Otherwise it's "for members of the club only" and isn't encyclopedic.
And I majored in the physical sciences. This page has to be gobbledy-gook to laymen. Which is fine if that's what M-theory is. Otherwise someone who can write for intelligent laymen needs to step up to the plate.

Difference Between String & M - Theory

         For quite a few years a debate raged -

Was string theory based in 10 or 11 dimensions? The 10 - dimensional viewpoint was later worked out and disproven, and when one turned to the 11 - dimensional viewpoint, two things happened :

         1. The strings merged, forming a single membrane constituting the known universe.
         2. The five string theories were found to only be

different manifestations of one theory, which later became M- Theory.

Wow

I have nothing of substance to add. I just wanted to give enormous kudos to the authors of this article. In spite of knowing nothing about string theory and very little about physics, I was able to understand every word. The contrast with our articles on advanced math is enormous. It's enough to restore one's faith in Wikipedia, if it needed restoring! Thanks!

Information

There is A LOT of vital information within M-Theory that is not being presented in this article. Furthermore, the article has a confusing format, and at one point even talks about the unification of electromagnetism (??).

Ora, Labora Gagueci 20:34, 31 July 2006 (UTC)

NAturally the subject is very big ,complicated, technical and quite new. I dont't think full mathemtaicl forumalization is needed, not now at least.

The unification of EM has everything to do both historically and physicall with M-theory unification of different sting theories. --Procrastinating@^talk2me 10:44, 5 August 2006 (UTC)

Sub Sections

I think these would do:

Introduction (done)

Overview of Unification (some of this has already been done)

M-Theory and Extra Dimensions (needs work)

M-Theory and Membranes (needs work)

Cyclic Cosmology (Brief)

Gagueci 19:37, 1 August 2006 (UTC)

please help those are watching this article to do just that, by reverting your HUGE edit and using 5 different edits including summaries, so we can help make this article better. thnak you. --Procrastinating@^talk2me 10:45, 5 August 2006 (UTC)

Supersymmetry

There should be some inclusion of the concept of supersymmetry. Supersymmetry is a major compenent of M-Theory and explains sparticles, dark matter, etc. Even though this excluded the article is pretty good at introducing M-Theory.

Well...most of these sare of still spculative nature, even the whole the theory is dubbed by some to be unscientific...the dark matter supersymetry subject can and should be added with great caution...there are still some contradictions in this theory..--Procrastinating@^talk2me 10:47, 5 August 2006 (UTC)

This article is a joke

It's hard to tell where one error ends and another begins. 1. The discussion of "Spiritual speculations and analogies" has NO place in this article. 2. Many concepts are left unexplained, described only in vague terms or actually incorrect. 3. The analogy with electromagnetism in the opening paragraph is very poor.

The article is beyond repair. Recommendation: Delete it. Let "M-theory (simplified)" stand in its place.

Albertod4 18:52, 30 September 2006 (UTC)

Scientific Spirituality

I was please to find a discussion on the spiritual implications of M-theory in this article, only to have them disappear seconds later. The opinion expressed by Albertod4 in comment 22 implies that there should be separation of science and spirituality, an inherently flawed sentiment in my view of things. The radical changes in perspective which M-theory and Superstring theory have brought us should have spiritual implications for humanity. It was once believed that God lived literally above us in the the sky and that the Devil took residence in the earth beneath our feet. There are many educated people who follow the Christian faith. Few still believe these things about God and the Devil (at least so literally) and it is due to advances in scientific knowledge and the changes in perspective these advances bring. Any time discussion or the expression of insight is limited humanity's ability to progress becomes limited. Please at least make that section it's own cross referenced article.

Ally Lorton '01 Reed College

I agree.--Procrastinating@^talk2me 22: 43, 6 November 2006 (UTC)

Well, the deletion has been reverted, along with my re-write of the big bang section, which again reads really badly now.

It's extremely sad that `spiritual speculations' are now considered a relevant part of an encylopaedic entry about a

mathematical/scientific theory. Even putting that aside, the actual content of the section shows utter ignorance of the

ideas of extra-dimensional physics. Students or other interested beginners derive no help at all from such nonsense.

Shambolic Entity 03:57, 9 November 2006 (UTC)

I am a student of physics, and I find this interesting. if you feel in undershoots the level neede, please feel free to add information.--Procrastinating@^talk2me 15:39, 11 November 2006 (UTC)

The inclusion of the metaphysical gobbledogook in the section Scientific spirituality has no more right to a place in this article than a section on numerology has a right to space in an article on number theory or a section on astrology has a right to a place in an article on astronomy. There is a clear distinction between scientific subjects (which are based on experiments, models, well-defined theories, mathematics and logic) and wooly superstitions (which are based on the unsubstantiated pronouncements of mystics). It is not a matter of objecting to such beliefs, it is merely that such beliefs do not form part of science. I propose that if enough people think the ideas in the section justify inclusion in Wikipedia at all, that they be moved to a non-science article. Elroch 15:27, 12 November 2006 (UTC)

Agree with Elroch. This material needs to be deleted or moved to another article. It has no bearing on M-theory. It is also unreferenced. -- Fropuff 01:21, 13 November 2006 (UTC)

There is absolutely no reason to have spirituality in this article. There is no info in the spirituality section that has ANYTHING to do with M-Theory, and nothing in that section is referenced. I erased it. Nly8nchz 01:12, 14 November 2006 (UTC)

I do not agree. When Stephen Hawkings, who is an agnostic as I understand it, speaks of the Cosmos and esoteric theories he often (nevertheless) refers to God. Other cosmologists also do. It is an odd thing but science seems to be investigating and encroaching slowly on "spiritual" things. Certainly this is happening faster than spiritual people are embracing science! Cosmology is one is one of the areas where science starts to touch onto metaphysics and I think it is ok to keep that stuff in. Particularly given the original purpose of wikipedia -- to be an organized collection of information. Since others have put it in previously and had positive things to say, I do not think it should be deleted without a discussion.--Blue Tie 03:21, 14 November 2006 (UTC)

But what does any of that material have to do with M-theory? You could just as well stick it in an article on general relativity or an article on magnets. -- Fropuff 03:29, 14 November 2006 (UTC)

These specific contributions dealt with spiritual significance of visualized strings of unusual characteristics. This is how it relates to M-theory and branes or n-dimension strings. --Blue Tie 03:37, 14 November 2006 (UTC)

Numberology shoudl not be included in number theory, because it does not have causual connection. The many world interpretation of quantum theory have Many spritualistic views that uses that interpretation of ampirical results as their rational. M-theory's many world's as viewed my the spiritualist may act an yet another rational of the same view. The view it self may be excluded or at least be very quintesential, yet the connection should be in the article. --Procrastinating@^talk2me 13:17, 14 November 2006 (UTC)

This is all just nonsense. The sprituality section has no place in this article. The philosophizing of Shamans, Yogis and Monks has had no part in the development of M-Theory, and has no bearing on the theory. Religious people have the right to look at scientific theories however they want, but please don't put their uninformed views in an encyclopaedic artile on M-Theory. We might as well put my 10-year-old brother's views on M-Theory into this article - they're more scientifically informed anyways.
If anyone would like to make an argument that the spirituality section does anything more than present the views of nonscientists who have no real idea what M-Theory is (they have only a vague idea that it includes extra dimensions), that argument will be considered. However, as things stand, the only argument for this section's continued existence has been that these people's unscientific views should be "represented." If that is the only argument, the section should be deleted forthwith. --Thucydides411 21:47, 2 December 2006 (UTC)

That's where you wrong. First, you are repeating the arguments already put forth and disregarding the discussion here. That is disrespectful.

Second, your very point does the same dis-empathic act again by stating that those view (albeit non-scientific) are not worthy of inclusion. This is a major issue for many people, and for this reason alone a section should exist. this is NOT britanica's 1911 snobish edition. Just look at the page's history to see how many people actualyl added anything to the article.--Procrastinating@^talk2me 22:26, 2 December 2006 (UTC)

I would appreciate it if you would answer the question I posed, which you can read in my second paragraph above. How can you seriously claim that anyone's view is fit to be represented in this article? If it is, I'll go right ahead and add my personal view, which is that the Olympian gods reside in the extra dimensions; in the eleventh dimension, of course, sits Zeus, and in the tenth his wife, Hera, sits by his side. I hope nobody is so snobbish as to prevent me from adding my views to this article. --Thucydides411 23:11, 2 December 2006 (UTC)

Just to weigh in here, it is true that in some of his popular books and lectures Steven Hawking (who may not appreciate the extra "s" in his last name) has mentioned God and so on. But he hasn't in any papers in a scientific journal or in his textbook on GR. And he hasn't proposed any models based on God or really anything other than mathematics and science. You have to draw a line between S.H. as a scientist, doing science, and S.H. as a person, speculating on the mysterious facts of life as we all know them.

In general, it seems that a lot of the Wikipedia science articles (especially cosmology ones) suffer from a kind of obligatory last section on mystical connections or spiritual interpretations or whatever. I think that, for scientific theory X, having a page "Spiritual Dimensions of X" is fine, and even linking to it from the page on X is ok. But the stuff doesn't belong on the page talking about the scientific theory itself. It isn't science. That doesn't mean it isn't true, or "worthwhile," but just that it isn't science.

A lot of people feel strongly that there is some kind of convergence between physics and religion (or mysticism, or spirituality). But it isn't happening, and can't happen. As others have pointed out, they are different modes of thought. It could be that one or the other is "true," but if it turns out that religion/spirituality/mysticism is, that doesn't make it science, and if it turns out to be science, that doesn't make it religion/spirituality/mysticism.

I think even the strongest objectors to the inclusion of the religion/spirituality/mysticism comments on this page are in favor of merging them to another page. Perhaps those who feel strongly about the value of these speculations could comment on this proposal? Wesino 01:29, 6 December 2006 (UTC)

The problem with merging these spiritual interpretations of M-Theory to another page is that one would have a hard time deciding which to mention and which to leave out. One really has no criteria, because each is equally contrived. Say we were to include the Samskara interpretation but leave out the Zeus interpretation, what possible justification could we give? Neither really has any relevance to M-Theory, and both are attempts to find evidence for a certain religion where no evidence exists. The article fares best when it deals only with the theoretical underpinnings of M-Theory, its history and scientific implications. --Thucydides411 09:09, 7 December 2006 (UTC)

When this section grow to a suifficient size we can excommunicate it from the flok of righteous physicists. --Procrastinating@^talk2me 16:30, 7 December 2006 (UTC)

Building spaces from circles?

I'm dubious regarding the sentence that says that you can "build any space from gluing together circles in various ways" in the Basics section. It's almost certainly false, but it's hard to judge this because it's not clear what "gluing" is. Certainly you can build many spaces from circles, depending on what you mean by "gluing." But all? I think not. Wesino 14:59, 26 November 2006 (UTC)

please be more specific as to what do you mean. The definition of space is what is described here, not it's content. --Procrastinating@^talk2me 22:29, 2 December 2006 (UTC)

I can't be more specific because the article isn't. But I'm not talking about the content of a space, I'm talking about the space itself. Probably what this article is referring to is a topological space such as a manifold (though this is not clear), and possibly "gluing" is supposed to be a direct product or some other operation (also not made clear). But with pretty much any choice of "gluing" operation I think the claim is false -- though a reference to the contrary would be interesting.

What certainly is true is that IIB on a torus Tⁿ (direct product of n circles) is equivalent by T-duality to IIA on a different torus (provided we do an odd number of T-dualizations).

Since I'm pretty sure the assertion that "all spaces can be made from circles" is false, I'm hoping the author of the passage could weigh in with what they had in mind -- otherwise I think it needs to be modified. As it is, it vastly overstates the case. Wesino 01:11, 6 December 2006 (UTC)

Massive factual inaccuracies

I've looked through the article a few times, and I'm getting increasingly disturbed by the fact that it's rife with factual errors and false statements, which are obscured by jargon which gives them a kind of false appearance of truth.

A few samples,

The business about building any space from circles (spoken about elsewhere on the talk page). A ref would be nice here, but I'm not sure you could find a professional mathematician who would make that statement. If you can, reference a textbook or journal article where they do.

The heterotic SO(32) and heterotic E8×E8 string theories also reduce to Type IIA and Type IIB supergravity in the low-energy limit. No, they don't. They reduce to N=1 supergravity coupled to a super-Yang-Mills gauge theory. IIA/B are N=2 supergravities without gauge fields. This is made clear in any reasonable textbook on string theory -- such as Polchinski's String Theory, or Superstring Theory by Green, Schwarz, and Witten.

dimensional reduction [of M-theory] to a line segment yields the heterotic SO(32) string theory. Dimensional reduction on a line segment (known technically as a S¹/Z₂ orbifold) yields the E₈ x E₈ heterotic theory in ten dimensions, not the SO(32) one. A reference would be the Polchinski's textbook, or "Eleven Dimensional Supergravity on a Manifold with Boundary," by Petr Horava and Edward Witten (which can be found by searching the arXiv [1]) or even the figure in the M-theory (simplified) article (!!).

The beginning of the "M-Theory and Membranes" section, the article suggests that the low-energy effective supergravity equations are "too weak" to reveal p-branes. But they do! The p-branes were discovered as black hole-type solutions to these supergravities. Polchinski's insight was that these black hole solutions corresponded to an extended object in string theory -- the D-brane. Again, this should be in Polchinski's book.

This is in addition to a whole lot of garbled explanations of things, which many others on this talk page have noted.

What worries me much more seriously though is that some of the statements made in the article don't sound garbled and have the appearance of truth, but are wrong.

Elsewhere on this page, there is a discussion going on regarding a merge proposal with M-theory (simplified). I've noted that I'm in favor of the merge, but given these factual issues I'm not so sure what the content of this article has to contribute to the M-theory (simplified) one. To the extent that M-theory (simplified) touches on these issues, it actually gets them right -- for example, regarding my third point above, the diagram at the top of the M-theory (simplified) article actually has the right relationship. I think the 'what M stands for' section is more extensive in this article than the other one, so it could be moved over without too much trouble. A lot of the factual information is either duplicated or wrong, so should be checked carefully (citing sources) before being merged over.

...but a more efficient use of time would probably be to nuke a lot of the content in this page and replace it with a stub (with technical references left intact for the interested reader), or a redirect to the simplified page. Wesino 11:18, 6 December 2006 (UTC)

I opt you gradually upgrade this page, trim out any factual inaccurcies and replace them with cited and well worded truths. Be Bold. thank you. Procrastinating@^talk2me 16:44, 6 December 2006 (UTC)

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