Talk:String theory

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This article covers material that is considered less important in mathematics than it is physics, hence the difference in importance ratings. Tompw 12:03, 5 October 2006 (UTC)
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Archives

2001 – April 2006 January 2006 – October 2006

Contents 1 A speculation on the 10 dimensions 2 References and Popper 3 Verifiability 4 "want to"? 5 Huh? 6 Introduction... 7 Analogy with Guitar Strings 8 Eclipse 9 String Theory vs. Superstring Theory 10 Directly Testable Alternative to String Theory 11 Overview not up to standard 12 Clarification 13 Thanks for that 14 Quantum strings ? 15 String theory stub 16 New article on String duality ? 17 Too much repetitive info. ? 18 Mirman 19 Asians? 20 Where are 'the same set of equations' ? 21 Supersymmetry and String Theory 22 Removed dead link

[edit] A speculation on the 10 dimensions

I think this new section should be removed. As the title already indicates, and the text clearly shows: This violates WP:NOR. Does anybody have any attribution of this text to a WP:RS? Awolf002 14:47, 5 November 2006 (UTC)

Agreed. Joshua Davis 19:46, 5 November 2006 (UTC)

[edit] References and Popper

I agree with the GA review committee that this article could use more inline references. It's handy when you come across a bold statement, and your immediate question is, "says who?" For instance, the idea that anthropic explanations are not considered scientific in the Popperian sense. First of all, this passage should explain what "the Popperian sense" is, in a few words, and then give a citation to support that claim. The notion that a few general sources support any unreferenced statements is rather dangerous, as anyone can add any claims to the article at any time. It's also inconvenient to check those claims. For example, if there are several books referenced, one might need to read through the entirety of all of them to find the source for a claim, which may or may not even be supported by any of the references. Connecting statements with specific sources and if applicable, specific page or chapter numbers would be of immense help to fact-checkers and students. -- Beland 01:31, 10 November 2006 (UTC)

I hardly think you need a citation when you say as in the final paragraph that the explanation is unscientific in the Popperian sense. Perhaps a rephrasing to say that it is difficult to consider the explanation as scientific in a Properian sense as that it a statement pointing out the currently unfalsifiable nature of the universes as vacua. It could also represent a biased statement but are we forgoing all interpration and common sense as well.??? --66.194.118.10 22:10, 14 January 2007 (UTC)DAYork

We should be forgoing original research, which an absence of citations tends to indicate. The claim that string theory is unfalsifiable is disputed among physicists and philosophers of science, and thus isn't NPOV. Certainly if string theory predicts electromagnetism, then it is falsifiable, since it would be false if there were no electromagnetism. And that's just one of many predictions (logical entailments) of string theory. -- Jibal 06:57, 6 March 2007 (UTC)

[edit] Verifiability

I think the phrase in the text, "No version of string theory has yet made an experimentally verifiable prediction that differs from those made by other theories." is misleading. An anonymous editor recently tried to remedy this by pointing out that there are, in fact, falisfied string theories, but his/her edit was reversed. I think that this editor made a good point; if one looks at a particular string theory, one can often see why it is not true(for instance, heterotic SO(32) in d=10 Minkowski space). So any given background is falsifiable in this sense. But I have another point; it is simply not true that string theory is indistinguishable from field theory in principle. String scattering amplitudes generically have amuch different behavior than field theories at energies above the Planck scale(see e.g. Polchinski's book). This, of course, has not been able to be tested yet(or maybe ever) but is a prediction which differs from field theory. Also, superstring theory predicts ten spacetime dimensions; this is also not predicted by other theories. So I think we should change "verifiable" to "verified" in the text I quoted. I'll make this change if I don't get any objections. Joshua Davis 04:38, 20 November 2006 (UTC)

String theory has been tested and found wrong since it requires some weird number of dimensions while it is known that physics would be impossible in any dimension but 3+1. See Our Almost Impossible Universe: Why the laws of nature make the existence of humans extraordinarily unlikely, R. Mirman, for the proof. Someone keeps removing this, trying to hide the failure of string theory, preventing others from learning of that. What can be done? It shows contempt for other people. R. Mirman 19:16, 9 February 2007 (UTC)

Wikipedia has a policy of not allowing people to present original research in the encyclopedia. Please see WP:OR for more details. --Dante Alighieri | Talk 23:56, 9 February 2007 (UTC)

[edit] "want to"?

From "Basic Properties": "Like springs, the strings want to contract to minimize their potential energy" Talk about anthropomorphism! "tend to"? "will, if unconstrained,"? "tend towards a state of minimal potential energy by contracting"? --Hugh7 09:31, 13 December 2006 (UTC)

[edit] Huh?

"Studies of string theory have revealed that it must never be known by Pete and also predicts not just strings, but also higher-dimensional objects..."

Who/what the heck is pete?

A bit of minor vandalism. In that case, it was removed two minutes after it was placed, but it would seem you saw the vandalized version. --TeaDrinker 05:23, 28 December 2006 (UTC)

[edit] Introduction...

I don't quite follow where it begins "String theory is like a big tree, being purple and like a kitty Cat with a ball of yarn, and everyone knows there is nothing cuter..." - could someone enlighten me? Is it saying that string theory is ridiculous, or demonstrating all the possibilities of multiple worlds, or what? If so, it is badly worded... Just my contribution. Parky 23:23, 5 January 2007 (UTC)

[edit] Analogy with Guitar Strings

I am certainly no expert on string theory, but i play guitar and suspect that a guitar string can only really produce different notes by shortening the string, not by vibrating at different frequencies (wouldnt that just make it softer or louder??). Is the analogy between a guitar string and the particle-string accurate, made on the third line of the first section?24.235.120.106 18:29, 8 January 2007 (UTC)James

By lengthening and shortening the guitar string you are in fact making it vibrate at frequencies. Intensity in determined by the amplitude of tha wave, not the frequency. Therefore the analogy used is still valid, it is just slightly misleading if you are unfamiliar with either sting-instrument theory, or wave terminalogy.

The "different" notes are harmonics. On a real-world guitar I don't think that there's any way to strum a guitar so that you play a harmonic without playing the fundamental note, but in principle the guitar string can vibrate at any of its harmonics, not just the fundamental. Geoffrey.landis 19:45, 18 January 2007 (UTC)

---

By stretching the string aren't you increasing the frequency?

To James: audio frequency determines pitch (and rapid frequency changes make complex sounds).

To Geoffrey: each note on a guitar is composed of a series of harmonics, one of which is dominant (the lowest); but it is possible on a guitar to isolate specific harmonics by plucking the string muted in particular places along the string (muting directly above the fifth half-step, or fret, produces a harmonic note two octaves above the base note; muting at the seventh half-step produces a harmonic note one octave and seven half-steps above the base note; the twelfth half-step produces a harmonic note one octave above the base note; there are quite a lot of other harmonics that can be isolated in this manner along the string).User:Eyelidlessness

[edit] Eclipse

I deleted this line: "(Of course, the existence of such a simple test of general relativity rested on the historical accident that the moon and the sun have the same angular size as seen from Earth, allowing total solar eclipses to occur.)"

Primarily, it is incorrect. The feature of an eclipse required for the testing of the bending of light is that the moon's angular diameter be GREATER THAN or equal to the angular diameter of the sun. It's not required that the moon and sun have the same apparent angular diameter, only that the sky get dark enough when the sun is up that the stars can be observed. Second, since we can do this measurement with radio telescopes even without a total eclipse, the "historical accident" only affected the timing, allowing the confirmation of GR to be done without waiting for radio telescopes to be developed.

This could be clarified by adding explanations, but why should it be? The point has nothing to do with string theory. The article has a link to the solar eclipse page, to allow those interested in it to find that proper information. Geoffrey.landis 19:41, 18 January 2007 (UTC)

[edit] String Theory vs. Superstring Theory

I think it is important to differentiate between standard String Theory and Superstring Theory. I added "This phrase is often used as shorthand for Superstring Theory," but most of the article is discussing Superstring Theory so perhaps the content related to Superstring Theory should be moved to the Superstring article.—The preceding unsigned comment was added by 70.63.79.219 (talk • contribs) 13:54, 28 January 2007.

I thought they were the same thing.Wikidudeman ^(talk) 04:06, 5 February 2007 (UTC)

[edit] Directly Testable Alternative to String Theory

After reading an article in Scientific American's website on The Geometer of Particle Physics which refers to the work of mathematician Alain Connes [1] on noncommutative geometry and renormalization, it appears that a directly testable method is available as an alternative to String Theory. The article referenced is at [2]. When the Large Hadron Collider boots this year it will give Connes data to to extend his work to smaller scales.

The point of making this comment is that testable alternative to Sting Theory should at least be presented under an Alternatives to String Theory section, and particularly, Connes work should be referenced and his webpage at Wikipedia elaborated on in light of this promising body of work. --4.156.144.246 18:46, 6 February 2007 (UTC) --4.156.144.246 18:48, 6 February 2007 (UTC)

[edit] Overview not up to standard

The overview doesn't cite sources very well, and there are far too many rhetorical questions asked. --24cell 07:48, 7 February 2007 (UTC)

[edit] Clarification

I need some clarification here. In the last part of the intro., it says,

Studies of string theory have revealed that it predicts not just strings, but also higher-dimensional objects (branes).

Doesn't string theory assume the existence of objects called strings rather than predict them ? Same for branes ? Could someone knowledgeable about these matters clarify this ? Thanks. MP (talk) 16:34, 7 February 2007 (UTC)

Scientific theories make or entail claims about the world -- such claims are predictions, not assumptions. Suppose that I have a frog theory that posits that there is a frog at the bottom of every well, even those we aren't able to descend. A prediction of this theory is that one will hear croaking coming out of any well. Eventually, if we develop the technology to descend down to the bottom of every well, the theory predicts that we will actually find frogs at the bottom of each of them. At no point is the existence of frogs an assumption of the theory. -- Jibal 07:20, 6 March 2007 (UTC)

Branes are a prediction of string theory, not an assumption. They arise in many ways. 1) If we postulate (assume) strings that have ends, a mathematical transformation called T-duality brings about an equivalent theory with dynamical branes in it. 2) Some string theories have excitations that are a bit like electromagnetism, called Ramond-Ramond fields, which need to be sourced by extended objects, the branes. There are many, many other ways that branes pop-up.PhysPhD 02:39, 29 March 2007 (UTC)

[edit] Thanks for that

"String theory is a model of fundamental physics whose building blocks are one-dimensional extended objects called strings, rather than the zero-dimensional point particles that form the basis for the Standard Model of particle physics."

What? —The preceding unsigned comment was added by 84.66.228.157 (talk • contribs) on 04:35, 30 March 2007.

[edit] Quantum strings ?

Is a 'quantum string' the same as a 'string' (a string in the sense of string theory) ? I think they are the same, but I need some experts to verify this. The article mentions quantum strings, but I don't think it's made clear that these are the same (if they actually are) ? I await clarification. MP (talk) 17:23, 7 February 2007 (UTC)

One can study classical (ie, non-quantum) string theory, and this is generally done as you're learning string theory. It's (currently) more of a pedagogical tool and toy model, so almost always when people refer to string theory they are referring to the quantum version. If you want to emphasize aspects of the string that are quantum or non-quantum, you prepend quantum or classical. That is, the fact that a given string vibrates at a given set of frequencies (harmonics) is a classical property (witness a guitar string), but the fact that a string vibrates only at certain amplitudes is a quantum property. I should note that many classical properties are inherited by the quantum string -- so a quantum string has both quantized frequencies and quantized amplitudes. 69.143.82.37 17:07, 7 March 2007 (UTC)

[edit] String theory stub

I'd like to create a string theory stub. My proposal can be viewed here. MP (talk) 20:11, 8 February 2007 (UTC)

The string theory stub has now been created. You can find it here: Template:String-theory-stub. MP (talk) 20:48, 12 February 2007 (UTC)

[edit] New article on String duality ?

The subsection on duality is very long. How about we create a new article called String duality to include the bulk of the material in the present subsection and include a main article link to this proposed new article ? Comments appreciated. MP (talk) 19:49, 9 February 2007 (UTC)

I think that would be appropriate given the size and importance of the material. -- Fropuff 19:57, 9 February 2007 (UTC)

Done. I have 'created' string duality in the sense that I just copy and pasted the present article's material there and have not removed the material from here. I am not confident of removing the material here and rehashing it into a more concise form, as I don't know enough about the topic. I'll leave that for more knowledgeable editors to deal with. MP (talk) 20:21, 9 February 2007 (UTC)

[edit] Too much repetitive info. ?

Is there too much repetition in the article, for example, in the intro. and the overview ? MP (talk) 19:00, 10 February 2007 (UTC)

[edit] Mirman

Removing information is vandalism R. Mirman 16:16, 11 February 2007 (UTC)

You are mistaken, on this matter and others; removing information is not WP:Vandalism. -- Jibal 07:27, 6 March 2007 (UTC)

You've been informed about WP:OR. If you do not begin to comply with Wikipedia process and community standards, you will end up blocked. --Dante Alighieri | Talk 20:09, 11 February 2007 (UTC)

Do not remove correct material! Or is the material required to be wrong? The material proving that space must have dimension 3+1 added to the article is not original research. It has appeared in papers and in two books, going back more than two decades. References are given in the added material, and these have further references. Look at the books instead of jumping to the conclusion that they are original. It shows contempt for others to force them to believe in material that is known wrong, and waste their time doing work that cannot lead anywhere. What right do you have to do that to them? It also undermines the credibility of Wikipedia if it carries only material known to be wrong. Why is the material continually removed? This is highly improper. R. Mirman 13:40, 11 February 2007 (UTC) (moving comment that was placed INSIDE the template at the head of the page for some reason --Dante Alighieri | Talk 15:50, 12 February 2007 (UTC))

Your book (I see it's sold on Amazon) is self-published at vanity press publisher iUniverse. I am unable to find any reviews of your book in Physics journals, nor any papers that you've submitted to peer-reviewed journals. The mere fact that your ideas have been printed is not sufficient... ANYONE can publish ANYTHING. If you can provide references that show your articles have been peer-reviewed or supply reviews of your book(s) by reputable academics, then (AND ONLY THEN) they can be used as sources for the article. --Dante Alighieri | Talk 17:23, 12 February 2007 (UTC)

Given your stance on peer-reviewing[3], I shall assume that you do not plan on offering any journal articles. However, at that same link there are 3 reviews from (presumably) your peers who don't seem much impressed by your post. --Dante Alighieri | Talk 17:31, 12 February 2007 (UTC)

[edit] Asians?

What does the first line have to do with anything, is that just vandalsim?

I'm unsure what it is that you saw, as there is nothing in the first line about Asians... nor has there been at any time in the recent history. --Dante Alighieri | Talk 23:48, 12 February 2007 (UTC)

The last version of the 'asian info' in the first line is here. MP (talk) 16:13, 13 February 2007 (UTC)

I stand corrected. I didn't see that diff when I was looking before. Sorry. :) And yes, that was "just" vandalism. --Dante Alighieri | Talk 22:40, 13 February 2007 (UTC)

[edit] Where are 'the same set of equations' ?

The end of the first paragraph mentions the 'same set of equations'. Perhaps the link could be sharpened (which is presently very vague for the topic in question) to the actual equations that supposedly unify the 4 forces. Admittedly, this is asking for a lot, but someone out there must know what these equations are. Experts, we need your help !!! MP (talk) 19:34, 17 February 2007 (UTC)

[edit] Supersymmetry and String Theory

The article states:

Investigating how a string theory may include fermions in its spectrum led to the invention of supersymmetry, a mathematical relation between bosons and fermions.

Supersymmetry was invented/discovered by Wess and Zumino in context unrelated to string theory. See the article on Supersymmetry for further references. 69.143.82.37 17:17, 7 March 2007 (UTC)

[edit] Removed dead link

I have just removed this dead link from the article: Has string theory tied up better ideas in physics?, Northwest Florida Daily News, 6/23/2006. If someone can find the correct link (if it still exists in some form, then it's still here in the talk page. MP (talk) 20:13, 7 March 2007 (UTC)