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Given all of the noise being generated about evolution being "only a theory" and the responses to this that "a theory in science is as close to fact as you get," should not "String Theory," when used in Physics (as opposed to pure mathematics), be properly called "String Hypothesis" or "String Hypotheses?" Physics certainly has not verified strings in nature to anything close to the extent that biology has verified evolution. -- DvTHex 04:24, 21 January 2006 (UTC)
Here is a news report that might have some information worthy of this atricle. —The preceding unsigned comment was added by 24.42.118.244 ( talk • contribs) 16:14, 28 January 2006 (UTC)
I don't think the string has so much dimensions but capabilities. The string would need to built of a super partical that operates in all dimensions. A Dimension is a concept. strings are built of super particals. the universe is a Haze of identical particals. how can I explain. . . like cells in the body. All cells are basically the same but choose to take on different functions to support a fully functioning body. All particals in the universe are ultimately the same they take turns in managing energy and motion in different dimensions. Thats why strings vibrate in so many ways. Its like a shimmer across the strings surface as each superpartical rotates work. like an octopus skin changing color.
Is that correct??. . the partical would be immensily complex yet not complex at all. it has no begining or end it is a cirlce. . a 10 11 26 or whatever dimensioned circle. the number of capabilities depend on the number of dimensions.
How many different properties of the universe are need in order to have the universe sustain itsself. Is it actually sustaining its own operation. . How long in relation to what exists beyond the universe is a second. What exactly is the universe?? Why does it move in way it does. What makes a string??? Find out what makes a string and you have found the first piece of the puzzle. What is a super partical how are they woven into a string. —The preceding unsigned comment was added by 194.237.142.11 ( talk • contribs) 16:07, 2 February 2006 (UTC)
What you have described have nothing to do with string theory. Dan Gluck 19:14, 14 September 2006 (UTC)
Some IP has been deleting things from the tallk page. Cf. this edit and these edits. I didn't check back further. The IPs check out as in Ontario, Canada. Probably nothing to worry about, but worth keeping an eye out for. – Joke 22:52, 13 March 2006 (UTC)
To say that string theory is not testable is incorrect. String theory can be tested by picking up an ball and observing it leave your hand and hit the ground. This is called gravity. String theory predicts gravity. Gravity has been a confirmed prediction of string theory. I will soon remove all statements from the article that claims that string theory is not falsifiable, because it is not true. Atraxani 04:36, 19 March 2006 (UTC)
The two tests I know of is discover supersymmetry and detect the graviton. Neither one would actually test all of string theory. I do not think all of string theory is testable. Read the interviews on http://www.pbs.org/wgbh/nova/elegant/ . What experiment or observation will tell us that strings are the building blocks of matter? Timothy Clemans 02:49, 20 March 2006 (UTC)
The 7th paragraph starts with "Roughly between 1984 and 1986, physicists. . ." The last sentence of this paragraph has errors. Originally, I isolated a couple, but it is better to replace it than to try and fix it.
could be replaced by
To say "and everything else," is a terrible thing to have in any essay or definition. If there is a long list of items correted, then a brief list of those items would be applicable, otherwise it is ambiguous dogma.
The formula explaining why there are 26 dimensions is meaningless without explaining what the simbols (such as \rho) stand for. Since there is a reference cited anyway, I am deleting the formula. Shokopuma 20:08, 1 May 2006 (UTC)
String theory as a whole has not yet made falsifiable predictions that would allow it to be experimentally tested . . .
Since string theory may not be tested in the foreseeable future, some scientists have asked if it even deserves to be called a scientific theory: it is not yet falsifiable in the sense of Popper.
These statements are incorrect, as User:Atraxani seems to have tried to have point out above. String theory is conceivably falsifiable. If tomorrow gravity stopped working, string theory would be falsified.
The reason it's criticized (whether or not the critics explicitly recognize this) is because it does not yet make predictions—that is, it says nothing about things that we don't know yet but will probably know soon. It has little if any predictive power; it has only descriptive power. The descriptive power it has is sufficient to make it falsifiable, but only in such a way that if it's falsified, more accepted theories of physics will also have to be falsified. Correct or incorrect? — Simetrical ( talk • contribs) 23:48, 1 June 2006 (UTC)
The point is that it doesn't say anything new which is falsifiable. In fact, it is not even clear if it says anything at all, because even gravity doesn't exist in some versions of it. Anyway, when people say it is not yet falsifiable, they mean that the theory have so many variations, part of which have no been solved yet, so one cannot perform an experiment which falsify this theory, assuming that it does not flasify the physics we already know. Shokopuma 20:24, 4 June 2006 (UTC)
Has anyone read Bohm and his theory of Thought Processes impeding our understanding of things? Could it be possible that the falsifiable criteria for String Theory is the thing which stops us from really facing up to its implications? Maybe its lack of predictability is the whole point and its the tests that we impose upon it which are causing us to not properly understand it? ThePeg 17.30 11.06.06
Quick question regarding Quarks
So, Quarks are made up strings, right? Is there an intermediate/yet-to-be-discovered sub-sub-atomic particle which is between quarks and strings? Am I looking at this the wrong way? Thanks!
-- 72.90.177.220 02:54, 8 June 2006 (UTC)
Yes, it is possible that quarks are composties of some sub-quark particles. However, if we assume quarks (and electrons, etc) are point-like (rather than composite) on distances scales much, much shorter than we can test directly (and if we also assume the three coupling constants of the Standard Model are unified at a certain "Grand Unified", very short distance scale) then we can rather amazingly explain the values of those constants that we observe. If instead, quarks were composites, this argument would break down, and it would instead be a bizzare coincidence that these predictions match what is observed. So probably not.—The preceding unsigned comment was added by 24.7.93.102 ( talk • contribs) .
Vis-à-vis bosonic string theory, the article says the following:
I'm not a specialist, so I can only guess that this refers to the existence of a tachyon in the bosonic string spectrum and the fact that D-branes in bosonic string theory are unstable. . . but Dirichlet branes are not spacetime. Did something get garbled or oversimplified here? Anville 20:00, 8 June 2006 (UTC)
The bosonic string has two tachyons: the open string tachyon, whose condensation (according to Sen's conjecture)creates D-branes and thus lower the number of spacetime dimensions in which the open string "lives"; its further condensation lowers even more this number, as 24-branes become 23-branes, then 22-branes, and so on until there are no open string any more. Another is the bosonic string tachyon, and this it is unknown how this one decays, but some believe its decay is related to lowering the number of dimensions in which the closed string lives, which is just the number of dimensions of spacetime (remember that spacetime coordinates are just degrees of freedom of the bosonic string). Dan Gluck 18:40, 11 June 2006 (UTC)
Someone deleted my previous corrections to the table in the "basic properties" section, I wrote them once again. The tachyon in bosonic string is an instability, as in any field theory. the nature of this instability is discussed in the previous section. In type II string theory there are no open strings only perturbatively. However it is well known that these theories do include open strings, attached to D-branes. For references, see Polchinsky's book ("string theory"), volume 2, chapter 13. Dan Gluck 18:53, 11 June 2006 (UTC)
it is so B.S., it's not even wrong. see http://www.nwfdailynews.com/articleArchive/jun2006/notevenwrong.php
I don't think we can exactly write "most people the anonymous editor has spoken to think string theory is 100% total B.S." But, seriously, I have tried to expand on the criticisms in my recent edits (it does, in fact, have a criticisms section called, aptly enough, "problems"), and overall they make up a greater fraction of the article. Perhaps someone who reads Woit's book can add something. – Joke 03:39, 28 June 2006 (UTC)
"Pope Benedict XVI also appointed Witten as a member of the Pontifical Academy of Sciences (2006)." Not surprised on my part. I stand to the fact that you are either a scientist at heart or a cult member/leader. —The preceding unsigned comment was added by Slicky ( talk • contribs) .
There are no strong leads other than string theory. String theory is acknowledged by many top physicists, such as the praised Witten. Where do we go, if not string theory? There is a small minority that opposes the theory and these are either the pessimists or people who have a theory of their own that is better. Sr13 08:44, 26 September 2006 (UTC)
I tried to shorten this article up and clarify it. This involved moving the section on cosmic strings to the cosmic string page – the debunking of CSL-1 has somewhat damped interest in this topic – and moving the "aspects of quantum field theory section" to its own page, Relationship between string theory and quantum field theory, because I have a hard time seeing how this fit into the main thread of the page (and, quite frankly, I don't agree that many of the topics mentioned are more natural in string theory, and I think it would be hard to find a significant number of string theorists who argue that they are). This page still has problems with the uneven technical level and chatty phrasing. – Joke 03:36, 28 June 2006 (UTC)
I removed two incorrect statements in the "Problems" section. 1) It said that d-branes have no quantum description. Just not true. They have a perturbative quantum description in the DBI/Super Yang Mills Theory. They have non-perturbative quantum desciptions by various dualities, and as realizations as solitons living on other branes. ADS/CFT gives complete, non-perturbative, quantum desc. of all of Type IIB (in ADS), including all of its brane objects.
2) It said the Landscape contradicts the old idea that string theory has no adjustable parameters. Again, just not true. The idea has always been that string theory has no adjustable parameters *as a theory*, but many adjustable parameters describing its solutions, including its vacua. For example, the coupling constant of string theory is understood not as some external parameter (as in most quantum field theories) but as the value of the dilaton, a dynamical field in the theory. The Landscape actually represents a dramatic reduction in these parameters: rather than an infinite continuum, these parameters can take on only finitely many values in the Landscape. But these parameters are still just describing which solution/vacuum of string theory one is living in. – a PhD,7/15/06
1 – I agree about dualities. As for perturbative description in DBI/SYM, it was my understanding that this doesn't work, per the 1989 paper of de Wit, Lüscher and Nicolai "The supermembrane is unstable." I wasn't aware that these problems had gone away.
2 – I agree, it doesn't contradict it and I never suggested it did. But, if you remember, in the mid '90s it was popular to suggest, particularly in popular lectures, that there were only five versions of string theory and that once we found out which one we lived in, the problem was substantially solved modulo choosing a Calabi-yau. Then things got a little simpler with dualities and somewhat more complex with M-theory. With the advent of the discretuum, people have stopped talking this way and in retrospect it has come to seem naïve. Nonetheless, I don't object to removing this sentence. – Joke 16:53, 16 July 2006 (UTC)
1) If I recall, the instability you mention was in a specific quantization of a 2-brane, related to matrix theory. I think that instability is now understood to reflect the fact that this description is non-perturbative, describing not just one brane, but any possible mulit-brane configuration. See review of Matrix theory by Washington Taylor. But as for DBI/SYM, this isn't contraversial as a perturbative, quantum description of fluctuations of branes. (Holography has a great deal to do with the fact that this perturbative description is actually much, much better than you'd think).
2) The landscape is still basically the question of choosing that Calabi-Yau. We relax the Calabi-Yau conditions, turning on fluxes wrapping the various cycles. (These hadn't been studied until recently because it is hard to solve). The fluxes back-react, so they aren't CY anymore. But the landscape is just basically the set of these solutions, charactarized by the (quantized!) fluxes wrapping the cycles.
Hope this is helpful.– a PhD,7/16/06
I removed this text:
This is not a solid test of string theory. It is the result of a fanciful press release. Apparently it is quite popular these days to claim that your experiment can test string theory. – Joke 18:13, 12 July 2006 (UTC)
The history of the string theory is false and based on rumors. The finding of the strong force wasent by a accident ina 200 year old book. thats all a lie and theoretical physicers are sad/pissed because of that rumor. I suggest we change it to be accurate or move that part to a rumor section im going to quote his own words.
By Gabriele Veneziano
i acationaly see writing in books that this model was invented by chance or was found in a math book. makes me feel pretty bad
Do not add rumors, and histories to history parts wich is supposed to hbe true.
--zelos 12:34, 15 July 2006 (UTC)
So, tempted by the Borgesian pleasure of leafing through a cherished textbook's pages, I looked up the Veneziano amplitude in Zwiebach's A First Course in String Theory. The in-depth discussion can be found in chapter 22, starting on page 513. Equation 22.109, which gives the Veneziano amplitude itself, reads as follows:
where the pi denote the momenta of the four interacting particles, is the slope parameter, g0 is the open string coupling and is a coordinate of a world-sheet puncture (arbitrary but confined to the interval between 0 and 1). That's quite a mouthful, but the reader can easily compare it to the expression found at beta function,
Neglect the constant out in front and replace with t, and the resemblance becomes clear. (On the following pages, Zwiebach rewrites the Veneziano amplitude in terms of gamma functions to investigate its poles, of which it has an infinite number.) The statement in the current version of the article is accurate, if not the most illuminating thing I've ever read; the confusion here is fundamentally misguided. After all, we use integral calculus all over the place, and that is hundreds of years old — thousands, if you count Archimedes. The old sentence was about as silly as saying that Veneziano used "algebraic techniques which date back to al-Khwarizmi" — just the sort of silly breathlessness one gets from n-times-digested pop science. The new phrasing is verifiable, more concise and even a little educational, if you already know a bit of math.
Let me amplify: it does no dishonor to Veneziano to say that he used old mathematical tools to do something new and interesting. Does it dishonor you to say, correctly, that the words you speak have existed in your language for hundreds of years, and had ancestors in other languages before that? Anville 15:32, 16 July 2006 (UTC)
Added some stuff and: Corrected some flase statements: - that the length of a string is a planck length.
Deleted the statement in the remark that "Some string theorists think that this phenomenon prevents the singularities of classical general relativity from forming.". There are many thoughts about how this may happen and this remark is not the place to mention them, nor to mention only one of them.
Deleted the remark that "much progress has been made in the direction" and the ref in the sentence: " It is not yet known whether string theory will be able to describe a universe with the precise collection of forces and particles that is observed, nor how much freedom to choose those details that the theory will allow, but much progress has been made in this direction.[3]" because this is not yet a well accepted view or work. It may appear somewhere in the article, not in the overview. —Preceding unsigned comment added by Dan Gluck ( talk • contribs) Dan Gluck 19:47, 18 July 2006 (UTC)
Although I have not read the entire article, I have one question. Are superstrings replacing quarks, or are they simply the sub-constituents of quarks? Also, does it state in this article that the precise energy content of a superstring is proportional to its (representative) particles' mass? (Given that the frequency of the open [non-graviton] superstring represents the particle type, and energy amplitude is proportional to the particle mass. Of course the energy properties of the superstring depend on its location on the Calibi-Yau shape, manifold if you like) Is this true? -- Dark Observer
"Are superstrings replacing quarks, or are they simply the sub-constituents of quarks?"
I believe the latter of your statement is correct. 67.68.54.24 16:09, 10 September 2006 (UTC)
It would be fair to say that strings are replacing quarks, in the sense that if you take a quark (or an electron) and zoom-in, you are probably expected to see that it is actually a string (or some other extended object of string theory).
The energy of the string is equal to the energy of the particle, and it receives contributions from both the string velocity and the string oscillations, just like the energy of the particle receives contributions from both its velocity (kinetic energy) and its rest mass. Therefore the string oscillations are responsible to the rest mass (the energy of the string oscillations = the rest mass of the particle). Remember the string and the particle are just two different ways to look at the same thing (the particle is the convinient way to use for low energies / large length scales, and the string should be used for high energies / small length scales). Dan Gluck 19:08, 14 September 2006 (UTC)
Hello, When I try to edit the "Footnotes" or "References and further reading" I don't get the text displayed in the article webpage, but instead get this:
===Footnotes=== <references />
All I'd like to do is correct the spelling of "charateristics" to "characteristics" in footnote 3. Maybe I'm just experiencing a little bug. Can somebody else have a try? Thanks, Daniel.
I reverted a series of edits made by 198.240.130.75, being uncertain as to their veracity and usefulness. If there are any experts in String Theory around, maybe they can examine these edits more closely and decide what to do. Yandman 14:59, 11 September 2006 (UTC)
I am a professional string theorist (post-doc at UCLA) and I have to say that there are incorrect statements in the second to last paragraph of the section "Problems and Controversy". The statement that supersymmetry is required to get rid of tachyons and produce fermions is false, although a common misperception. For example, see pages 58-59 of volume 2 of Polchinski's textbook(this is already in the references). You will find a description of a heterotic string construction that has no spacetime supersymmetry, but also is free of tachyons and has fermions in the spacetime spectrum. The confusion might arise because supersymmetry is required to exist on the string world sheet. But this is just a part of the mathematical construction and does not lead to an observable supersymmetry in proper spacetime.
Even were the claim that string theory needs supersymmetry true, the statements made about supersymmetry are pretty dubious. It is a nice pithy statement that supersymmetry is the square root of spatial translations, but the reality is slightly more subtle(the author should learn about local supersymmetry or "supergravity"). It is fair to say that time-dependent spaces aren't supersymmetric, but the statement about black holes is not quite related to that. Supersymmetry is defined as a certain mathematical condition (the existence of globally defined Killing spinors) and the black holes in question do satisfy this property. One might put in the statement that "string theory has only successfully described supersymmetric black holes and that such objects are, as of now, merely suggestive mathematical abstractions". But any criticism along these lines should be a sharp, and correct statement.
If one really wants to intertwine the viability of string theory with supersymmetry, one has to be fair. The best way to put it is that "string theory doesn't require supersymmetry but strongly suggests it". If no supersymetry is found in nature(say at the Large Hadron Collider at CERN), then this puts a serious damper on string theory but does not logically kill it. Conversely, the discovery of supersymmetry will not prove string theory but will give it a big boost.
I'm not taking it upon myself, but my suggestion for edit is to delete (or perhaps rewrite) from that paragraph everything from "On a more technical level," onwards. The earlier part of the paragraph and the next paragraph are fine. -- Joshua Davis 11 September 2006
I generally agree with Joshua's comments, but remember that when people say there is only 1 string theory, they refer to the supersymmetric models linked by several dualities. It will be probably true to say that if there is no supersymmetry then this version of string theory is dead. The non-supersymmetric versions are expected to receive very large corrections, and these may render them unstable, and I think this is why they are usually being ignored. In any case, even if supersymmetry is not detected in the next accelerator (or the one next to it), it can still be that it simply exists in higher energies, so supersymmetry as such may never be proven not to exist (of course it creates other problems but this has nothing to do with the current discussion). I think 198.240.130.75's comment about gravity/gauge duality is not precise since there is much evidence for this duality (at least in certain limits). Dan Gluck 11:44, 14 September 2006 (UTC)
A black hole singularity is an infinitesimally small, two dimensional ring that spins at the speed of light and its surface wiggles with quantum foam. Wouldn’t this pretty much describe a closed string as well? Especially since closed strings describe fermions and the shorter the wavelength at which they oscillate, the greater the mass of the particle of matter they represent. Wouldn’t this prove that strings do exist?
Please don't knock on Brian Greene, I have read his book back to front, and it has personally turned me onto hypothetical physics, and I'm none for the worse.
String theory is a model, or a mathematical model, not a conceptual model.
It is unkown whether string theory is mathematically sound. In fact string theory is not fully defined non-perturbatively, so it cannot be mathematically sound, it is not even mathematically defined. Moreover, even algebra isn't "mathematically sound" in the sense that one cannot prove that it does not lead to a contradiction (Goedel's theorems).
String theory has not been experimentally tested at all, hence I deleted "with repeatable results".
Deleted a completely unrelated / false part in the end of "T-duality" subsection. Dan Gluck 10:23, 14 September 2006 (UTC)
Another change: it is not exactly true that string theory needs 11 dimensions. It certainly needs 10 dimensions, and a 10-dimensional type IIA theory can also be seen as 11-dimensional. The 11 dimensional supergravity approximation is good if the coupling of the 10-dimensional type IIA theory is large, so in a sense the theory is 11-dimensional only if the 10-dimensional type IIA description has a large coupling. For other cases, the 10-dimensional description is good even at large coupling (in type IIB, for example). It is true that it is thought that the underlying theory is "M-theory" which is defined (when it is known how to define it) in 11d. In all, the question whether there are 10 or 11 dimensions is a matter of definition or taste. Regarding 4 dimensions, it is not unique to humans that we perceive only 4 dimensions. It is also a physical experimental result, at least for energies lower than 1 TeV (i.e. for energies probed so far). Dan Gluck 10:27, 14 September 2006 (UTC)
This article states a number of times that string theory requires the dimension of spacetime to be 10 or 11. However, this is not strictly true. The actual condition is a bit technical; the (super-)Weyl anomaly on the string worldsheet must vanish. For the bosonic string, this is most easily done for 26 flat spacetime dimensions; for the superstring the simplest result is ten flat spacetime dimensions. But there are other possibilities. The most commonly studied are probably the two-dimensional strings, or more generally non-critical strings. There are others however. For a reference that I'm not making this up, you can see Polchinski vol. 1, section 9.9. Incidentally, the two-dimensional string theories are generally more well-defined than their higher-dimensional cousins, since they sometimes have non-perturbative definitions in the form of matrix quantum mechanics.
I'm not advocating that we go into all of this in this article(although I've been thinking about starting a technical article on d=2 strings). However, I think that the statements that string theory must have a certain dimensionality should be scaled back. Maybe we should use phrases like "The string theories most often studied have ten dimensions" or "The string theories which are considered most phenomenologically viable are in ten dimensions" or more precisely, "the string theories known to have supersymmetric vacua are defined in ten dimensions". These have the benefit of being correct without having to introduce a bunch of new material. On the other hand, this material might be of interest and worth introducing, perhaps in a separate article. Joshua Davis
So I went ahead and changed the opening paragraph a little to reflect the point about how ten dimensions isn't strictly needed but yet basically what's called. Also added a link to non-critical string in the footnote. – Josh
OK Jushua it seems fine (in fact I have already pointed that out in footnote no. 4, though I agree it's not easy to get there). However be careful about these things. You may also say that it is not correct that string theory "predicts" gravity, since there are versions without gravity. In fact for almost every statement you can make, there is some version of string theory for which it is not correct. I think it is usually enough to write "in string theory..." even though the statement is correct only for the superstring theory which is usually studied, and put the reservations in notes or footnotes, for those who will read it all to the end. Dan Gluck 13:14, 16 September 2006 (UTC)
Just wanted to let you guys know that I've been trying to spruce up the non-critical string article. Any help would be appreciated. Joshua Davis 03:08, 28 September 2006 (UTC)
I want to raise an objection regarding the statement "String is a model". I would prefer "String is a (conceptual, mathematical) framework" instead. My reasoning is that models are directly testable; they say "this physical quantity should be this". A framework is the set of mathematical tools and physical concepts with which one constructs models. That is, a framework is not really testable, rather a model constructed in a given framework is testable. So I could propose the framework "quantum field theory", but you can't test it; there are no specific predictions. To test it, I need to posit a particular model that obeys the rules of QFT; say quantum electrodynamics. Then I can calculate a cross-section, go to lab, and check it. If I hadn't specified the Lagrangian of QED then I wouldn't be able to calculate anything specific.
In this vein, I would say perturbative string theory, as it currently stands, is a framework. I can specify a particular model, say Type IIB string theory in 10 flat spacetime dimensions. This model is falsifiable; I don't even really have to do an experiment to see that we do not live in ten flat dimensions. But I can make another model, where I compactify 6 dimensions on a Calabi-Yau. This has too much supersymmetry in the effective d=4 description so its false. Now I look at another model, with Ramond-Ramond fluxes in the Calabi-Yau; that's starting look more like our universe but maybe has the wrong gauge group. So I work up another model. This doesn't seem very different than what historically occurred in the construction of the Standard Model of particle physics.
I will be the first to point out that string theory is more subtle than this. Many of the models in this sense are related by various dualities. And there is a conceptual aspect that these models are thought to be different states in a more grandiose model like M-theory. I don't know the answer but there is a similar ambiguity in quantum field theory. Even in QFT one has to specify boundary conditions to the path integral. It might be that one has to specify the background spacetime solution in which strings interact.
I think this is a fair viewpoint to try to include in the article in some way. I think it more accurately captures the state of string theory as a science and puts the criticisms of it in better perspective. Joshua Davis 21:33, 23 September 2006 (UTC)
Note: This article has a small number of in-line citations for an article of its size and currently would not pass criteria 2b.
Members of the
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00:54, 26 September 2006 (UTC)
There is more discussion of this at Wikipedia talk:WikiProject Physics. The people at GA did not bother to get the opinion of science editors when they came up with this idea. Nor did they bother to decide on what number of inline references was too few to qualify. -- ScienceApologist 20:42, 26 September 2006 (UTC)
I have made a request regarding this issue here. -- ScienceApologist 21:01, 26 September 2006 (UTC)
I am an engineering student at Iowa State University, and I am doing a project for my technical writing class involving Wikipedia. I chose to write an article on the string theory, and when i posted my article it was incorporated into this one. My hope in writing the article was to provide a more "general" description of the string theory. I was hoping to add a section this article that presents the string theory to those who are not familiar with physics and the topic. Would this be a worth-while thing to add? As a new Wikipedia user, any suggestions would be appreciated! Thanks. Mkroh 01:10, 28 September 2006 (UTC)
Removed an entry in "See also" section
I removed a bullet titled 'Dance of Shiva' in the "See also" section. Don't understand why this is relevant to string theory. KrishSundaresan 21:37, 29 September 2006 (UTC)KrishSundaresan
I added a section titled "Motivation." I intend to add to it and continue to edit it, but I just wanted to start it and see what kind of feedback I would get from those more experienced with this article than myself, or see what others would have to add. Mkroh 22:38, 6 October 2006 (UTC)
I've formated the Archive Box into something easier to access opposed to an unformated link. Wikidudeman 22:42, 30 September 2006 (UTC)
Just adding this section title won't help us much. What are you disputing? Awolf002 17:27, 14 October 2006 (UTC) Obviousness;look at this page and the entry.First sentence of entry is misleading, as to distinctions between mathematical and physics theories, and ignores recent discoveries that indicate spin factors of particles are being proven.This is an elementary particle(3D) not a zero dimensional theoretical mathematical model or the point particle, and yet the string is taken beyond such limitations in this sentence and granted 3D status.Bias.This is not to argue string concepts, rather the way they are presented in a favorable light out of context, and ignoring multiple other approaches to a unified theory.The comparisons are the starting foundation of the article.
Added the following sentence to the introduction: The goal is to be able to describe the four forces (strong, gravitational, electromagnetic, and weak) with the same set of equations. Mkroh 00:18, 18 October 2006 (UTC)
Is there any information on things that have been proposed as dimensions 5 through 10? I wondered if the five senses could be considered part of those missing dimensions. Does that make any sense? Titan4mmb 03:41, 22 October 2006 (UTC)
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)
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
FWIW, the "unscientific in the Popperian sense" you're referring to is I think more appropriately "unscientific in the Positivistic sense", a school of thought Popper was often thought to belong to because he wrote about it so much, but was mainly opposed to.
76.178.143.51 (
talk)
06:28, 29 February 2008 (UTC)
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, falsified 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)
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)
"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?
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)
Can someone post something on this website that explains string theory in a way so that you don't have to be a quantum mechanic to understand?
go to simple.wikipedia.org, that has a good description for us non-quantum mechanics —Preceding
unsigned comment added by
76.124.50.59 (
talk)
01:25, 18 March 2009 (UTC)
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 that 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 terminology.
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
I think that the whole reason why this topic was created was to answer the question: does the frequency of a superstring determine the type of particle (as defined by that particles rest-mass and spin-charge) and the amplitude of the string defines the scalar magnitude of the particles vector (speed)?
Actually, both the frequency and the amplitude determine the particle type.
PhysPhD
17:37, 25 April 2007 (UTC)
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)
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.
No, that is not needed. There is currently almost no research on the bosonic string theory, since it is not consistent (it is unstable). Moreover, it is now thought to be related to superstring. So there is no such subject as "bosonic string theory" separately from "superstring theory", and the latter is known as simply "string theory". Dan Gluck 20:43, 9 April 2007 (UTC)
After reading an article in Scientific American's website on The Geometer of Particle Physics which refers to the work of mathematician Alain Connes [2] 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 [3]. 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)
This should appear in quantum gravity article, since it is not related to string theory. The current article should only have a link to that one. Dan Gluck 21:33, 9 April 2007 (UTC)
The overview doesn't cite sources very well, and there are far too many rhetorical questions asked. -- 24cell 07:48, 7 February 2007 (UTC)
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)
"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.
In the standard model, the particles are points. In string theory, they are little lines. Dan Gluck 21:34, 9 April 2007 (UTC)
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)
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)
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)
Is there too much repetition in the article, for example, in the intro. and the overview ? MP (talk) 19:00, 10 February 2007 (UTC)
Removing information is vandalism R. Mirman 16:16, 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))
What does the first line have to do with anything, is that just vandalism?
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)
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)
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)
I don't think the section on extra dimensions is correct, and, at a minimum, there certainly there isn't a citation around the relevant passages.
There are:
One intriguing feature of string theory is that it predicts the possible number of dimensions in the universe. . . .
Unlike general relativity, string theory allows one to compute the number of spacetime dimensions from first principles.
I don't think that's right at all. Extra dimensions are assumptions of string theory, and the number of dimensions were selected to conform the theory to the observed behavior of particles. That isn't a "prediction," and the number of dimensions is not being "computed" from "first principles," dimensions are being added to make the theory work with experimental results.
And isn't there still some question about whether the ten-dimensional theories are really eleven dimensional ones? 208.226.153.24 18:11, 5 April 2007 (UTC)
Respectfully, it seems to me that you've entirely missed the point, and that in fact you are in error. The claim in the article is that the number of dimensions is "predicted" and that the number of dimensions is "computed" from principles. But that isn't what you're description says. Your description says that you picked a set of dimensions in order to make the math work out, and in fact you're not even sure about what number of dimensions you've picked. That isn't a "prediction" its an "assumption" of the theor(ies). Respectfully again, this isn't a disagreement about physics, its a disagreement about the English language. 207.237.10.120 03:51, 10 April 2007 (UTC)
I changed a paragraph the introduction to reflect the ongoing debate on the predictability of string theory.
I created in the introduction a paragraph about string theory as a possible theory for the strong interactions (thorough gauge-gravity duality), because although the math is identical, it is a theory of totally different phenomena than quantum gravity.
There was a link in the introduction about AdS-CFT RHIC-related stuff. This was a non-scientific media report, and the link was in the wrong context - suggesting that success in predicting stuff at RHIC is related to string theory as a theory of quantum gravity. I changed the link to few links to the related scientific papers and placed it in a paragraph of a correct context - the new paragraph in the introduction about gauge-gravity duality.
In the "problems and controversy" section, I added a paragraph about the "string wars" - the 2 new books by Woit and Smolin and the discussion that followed. I incorporated into this paragraph the quote by Smolin which has previously been put out of any context, and added the infamous "only game in town" answer for balance - perhaps both quotes should be omitted? —The preceding unsigned comment was added by Dan Gluck ( talk • contribs) 18:52, 9 April 2007 (UTC).
"There are different versions of string theory, depending on factors such as what type of string is being used (open or closed)" I deleted this since no theory of purely open strings or purely closed string is thought to be consistent. The former is surely not unitary because closed strings appear in loops, and the latter is probably impossible because one must probably incorporate D-branes as non-perturbative effects, showing up at the loop expanion for high genus (see Polchinski chapter 9). Dan Gluck 19:48, 9 April 2007 (UTC)
String theory is an interesting way of combining quantum mechanics and Einsteinian relativity. However string theory, in my opinion, hasn't given any major predictions about the universe and the way it functions. Does string theory actually tell us anything about the universe that we didn't already know? Wikiisawesome 11:41, 11 April 2007 (UTC)
No. At least not yet, and in many people's opinion not in the foreseeable future. I tried to reflect it in the last edit. Dan Gluck 19:21, 12 April 2007 (UTC)
The article should better reflect that there are still many fundamental problems with the string theory and its successors (M-theory etc.). I mention just three problems which a good Theory of Everything (TOE) should solve:
1. A good TOE should be able to formulate its own principles and fundamental equations. Moreover, these principles and equations should clarify and simplify our picture of the physical world and allow some testable predictions. As far as I know, nothing like that is still available for the string theory (M-theory), in contrast to its rather long development and far-reaching claims.
2. A good TOE should allow calculations of all interaction constants and particle parameters from its fundamental principles. It was actually one of the original Einstein's goals - to give some purely geometrical or mathematical origin to fundamental physical constants (see e.g.: J. D. Barrow: The Constants of Nature. J. Cape, London, 2002, esp. Ch. 3.). No variant of string theory is able to calculate these parameters from some first principles.
3. If the TOE is formulated in some space of higher dimension (11, etc.), as expected, there should be also a unique and justified principle of compactification - e.g., a principle how to project the structures from the 11-dim world to our tangible 4-dim world. In its contemporary status, (super)string theory is very fuzzy and ambiguous concerning the compactification.
Many physicists of unquestioned competence think that the very word "theory" is rather premature in connection with the (super)string model of physics. Einstein himself probably would not be very happy with its present form and claims. --
ArepoEn
08:36, 18 July 2007 (UTC)
From the Problems section: "Philosophically, string theory cannot be truly fundamental in its present formulation because it is background-dependent: each string theory is built on a fixed spacetime background." This is opinion, not a neutral fact. My opinion differs: Background independence is an aesthetic criterion. Possibly nature is background independent, but it's possible nature does not treat all backgrounds the same, preferring AdS, say. Either way, the "cannot" assertion needs to be modified. I'll give it a shot. PhysPhD 03:38, 13 April 2007 (UTC)
Is it worth creating a second page with a more technical intro to string theory, more like a lot of math pages that aren't affraid of including equations? If people think this is a good idea, someone who knows how could create the page and I could start filling it in... PhysPhD 04:27, 13 April 2007 (UTC)
I deleted the section on "integrated functionality" again. Nothing in that section has anything to do with string theory. What is described in that section can either happen in standard quantum field theory, or is just incorrect. It reads like the author's source is a science fiction tv episode. PhysPhD 18:20, 17 April 2007 (UTC)
I don't mean to sound haughty, but I am a "scientist specializing in string theory", and even though this may have been here a long time, it doesn't mean it's right. It is common knowledge in physics that various processes can turn one kind of particle into another. This much is true, but it just has nothing to do with string theory. Worse, the whole paragraph is full of mumbo-jumbo, to the point that it could have been written as intentional vandalism. "The energy consumed by this process is inversely proportional to the energy produced by the cancellation of matter and antimatter." This sentence has no discernible scrap of truth, whatsoever. PhysPhD 21:26, 19 April 2007 (UTC)
New, interesting, preprints are popping up every day on arXiv and are discussed on the relevant blogs. But this here aims at being an encyclopedic article, doucumenting established knowledge. So can we pls wait adding new stuff until it has evolved to a review article written by a respected author, or something similar? -- Pjacobi 12:16, 21 April 2007 (UTC)
Hey everyone. If you like being confused by this stuff, go to
www.tenthdimension.com
and watch the video, "Imagining the Ten Dimensions" under the "Navigation" bar.
It's really cool and kinda confusing, but cool and fun to watch. —The preceding unsigned comment was added by Tidman5 ( talk • contribs) 17:46, 24 April 2007 (UTC).
This seems like major news which should be reported within the article:
See these websites [5]
how can string theory be proven? I've never actally seen it work...
I just - somewhat bluntly - reverted an edit that painted a very rosy picture of the prospects of experimental verification of string theory, claiming the optimism to better reflect the "expert" consensus. The consensus among basically every other string theorist I know (including one of the people behind the work at Princeton alluded to above) is that it is very unlikely we would have confirmation of s.t. as a theory of gravity any time soon. There are some scenarios where it could amazingly appear at the LHC, but this is just what people talk about to get grant money. People who believe in string theory (such as myself) just don't expect to see it there. The problem is that the Planck scale, where quantum gravitational effects are believed to become significant, is like 15 orders of magnitude higher than the energies produced at cern. Some phenomenological theories (eg ADD) would move the scale way down, but most think it would take a stroke of blind luck if these theories are realized. Assuming the Planck scale is where most people think it is, no theory of quantum gravity (not string theory, not Smolin's loop quantum gravity...) is going to be tested at the LHC. PhysPhD 06:13, 27 May 2007 (UTC)
This sentence contains an alleged direct quote that appears in a publisher's blurb as if it is a paraphrase (that is, not in quotes):
A quote from Smolin may be good here, but unless the above can be verified as his actual words, someone needs to find another one. I've removed the sentence.
This quote was removed from the article:
A quick Google search will reveal that this is from the Publishers Weekly review of The Trouble With Physics: The Rise of String Theory, the Fall of a Science, and What Comes Next by the named author. I have no particular opinion about whether the quote, properly cited, should return to the article.
CRGreathouse ( t | c) 12:28, 7 June 2007 (UTC)
The following invisible remark has been added to gauge-gravity duality section: <!-- This section is linked from [[String theory]] --> What is the meaning of this? Dan Gluck 17:28, 26 June 2007 (UTC)
I have deleted a link to an animation taken from the pseudoscientific "the tenth dimension" book and website, which has nothing to do with string theory's interpretation of this concept. Dan Gluck 14:29, 4 July 2007 (UTC)
I added a Preface right before the Overview section...
I think it's important for the readers to know that an article could be endless if it highlighted all the possibilities that string theory says could happen, and that the information presented is going to highlight one of the many "versions" of String Theory.
Feel free to edit the preface, but after hearing many documentaries on it (many of which conflicted with each other) it's good to know that the information you read isn't always the ONLY way string theory could work. --
Huper Phuff
talk
21:45, 12 July 2007 (UTC)
There was a sentence that I have deleted which stated that String Theory was at this point, a mere philosophy since it has not made any falsifiable prediction. This is an extreme POV since String Theory is not just some random philosophical speculation but a mathematically consisitent model that has compelling features to be considered as a contender for the Theory of Everything —Preceding unsigned comment added by 220.227.207.36 ( talk)
I noticed that a previous edit in which I said string theory was not a tightly constrained theory was removed without editorial comment in discussion. I'll assume for the moment that it was done in good faith. But I would like to know what the reason for that removal was.
My understanding of string theory shows that it has not even been proven to be a finite theory. Rather it was assumed to be finite until Dr Smollin showed that it was never proven. Furthermore, until Witten introduced the idea of a membrane it was really 5 different theories. But even though the membrane idea is only a "concievable" link between the five theories it is not in anyway proven or even well defined.
So unless someone can explain how this isn't an important issue and that it doesn't belong in the category of an "unconstrained" theory I will put my previous comment back in. Does anyone want to refute this? I think it may be just as important an issue as string theory not making any predictions that can be validated at conceivable energy levels. For instance, if you just adjust the parameters, which you can do because its so loosely defined, you can make it match whatever you want - albeit with negative sideeffect that don't actually show up in observed reality. —Preceding unsigned comment added by 75.7.37.102 ( talk)
—Preceding unsigned comment added by 75.7.37.102 ( talk)
—Preceding unsigned comment added by 75.7.37.102 ( talk)
The introduction said "a sensible quantum theory of gravity emerge". "Sensible" is not well defined and I changed it to "consistent". However, it is not known - though there are signs in favour - that string theory is consistent (certainly it is not obvious that it is "sensible"). Therefore I wrote "a consistent quantum theory of gravity seem to emerge". Perhaps it should better be "a quantum theory of gravity, hopefully consistent, emerges" ? Dan Gluck 20:17, 31 July 2007 (UTC)
I just undid an edit that went way too far in weakening this claim about string theory. I think the edit was correctly motivated by the existence of non-critical string theories with different dimensionalities. However, its claim that only "exactly flat" solutions have constrained dimension is incorrect. For example, in the standard 5 superstring theories, all metrics that obey Einstein's equations and have perturbative curvature would be constrained to be 10-dimensional, right? In all cases that I know, string theory succeeds at the highly non-trivial task of constraining the dimension of space-time according to the local field content of the (space-time) theory. PhysPhD 20:04, 21 September 2007 (UTC)
(First, 76.205.212.31 please try to conform to the format/signing conventions, including the four-tilde signature. Thanks.) To reiterate what I said above, the problem with your edit is that it takes away the completely valid success of string theories in relating matter content to dimensionality. For a given local field content, consistency predicts the dimensionality. It is great to emphasize that there is a lot of (beautiful) complexity to this story, such as Simeon's dimensional transitions. And yes, the linear dilaton is just a non-critical case that we happen to be able to solve, not the whole picture. But we owe it to string theory to emphasize this very non-trivial relationship between field-content and dimensionality. PhysPhD 20:57, 22 September 2007 (UTC)
Why did you delete the nice analogy "just as a guitar string can produce different notes"? I returned it. Dan Gluck 09:03, 24 September 2007 (UTC)
I really appreciate the guitar analogy as well, it really tied the theory into my head (no pun intended though funny after realizing). As a non-math person (sorry i'm a silly visual artist with wide interests) it is important for the article to try to reach a little bit beyond the math. Something i would personally like to see on it, would be a link to maybe fundamentals of math for physics (probably beyond the scope, but just as a reference point from this article to one). thanks, keep up the good work on weeding out the nonsensible arguements for those of us not as well informed on the technical aspects of this subject.
Joe iguana
00:28, 12 November 2007 (UTC)
I've ported a diagram presenting the level of strings in comparison to other entities (molecules, subatomic particles) from the French Wikipedia. The caption has been directly translated from French. —Preceding unsigned comment added by 203.28.13.57 ( talk) 03:08, 20 November 2007 (UTC)
Early in the article is the following:
For a scientific theory to be valid it must be verified empirically, i.e. through experiment or observation. Few avenues for such contact with experiment have been claimed.[1] With the construction of the Large Hadron Collider in CERN some scientists hope to produce relevant data, though it is widely believed that any theory of quantum gravity would require much higher energies to probe directly. Moreover, string theory as it is currently understood has a huge number of equally possible solutions.[2] Thus it has been claimed by some scientists that string theory may not be falsifiable and may have no predictive power.[3][4][5][6]
First of all, verification (as mentioned near the top) and falsifiability (mentioned near the bottom) are not the same thing; although the passage above does not state that the two are the same, the implication is strong. Verification has long been recognized (at least since the time of philosopher David Hume who wrote on the subject) to be logically impossible as a result of the so-called "logical problem of induction". Any verification of a universal statement (as most scientific theories aim to make universal statements) relying on a finite number of observations (this process in the field of logic is referred to as induction) runs into this problem (it is logically fallacious to make universal statements based on a finite number of observations). If all scientific theories must be verified then we would have no scientific theories, as all would fall to the problem of induction.
It was due to this gaping hole in most scientists' understanding of and statements about their own practice that the philosopher Karl Popper proposed his theory of falsificationism in the 1930s and later, as Popper realized that science must be saved from itself in way; if science indeed operated by induction then it could not logically claim any higher level of knowledge than any other arbitrary set of statements that merely were consistent with observations. In any case, induction was illogical, and scientists had to be saved from any taint of illogical reasoning. Popper and his works were hugely influential (especially among scientists themselves when they became increasingly acquainted with his work and his glorification of science and scientists) and falsificationism to this day remains about the extent of what most scientists are familiar with with respect to philosophy of science.
Although compelling, Popper's falsificationism runs into one very large problem when one examines scientific practice; scientists often do not actually behave this way. This has been called the "is-ought" problem. Popper's description of science as a process by which scientists make statements and vigorously attempt by experiment to falsify them is a compelling myth. While it maintains science as logical, and to an extent serves to distinguish it categorically from other fields of human endeavour (or statement making), later philosophers of science have shown that while Popper might well have compellingly shown what scientists "ought" to do, he has failed to show that falsification "is" what scientists actually do. Indeed many authors have shown over the years that scientists will hold on to theories in spite of their logical status as "unfalsifiable" (it can be argued that evolution, insofar as it makes NO predictions about what creatures will look like in the future, is unfalsifiable), and that they often in their work make no effort to falsify their theories, and that often scientists actually DO use induction and verificationism in the course of their work, or rely on statistical arguments which by their very nature are not universal in nature and would count as unscientific in the Popperian philosophy. It has also been argued that scientific facts are whatever the group of people accepted as "scientists" say. All of these approaches have been considered in the history and philosophy of science.
The collision (sorry ... couldn't resist the pun) of two major theories-the standard model, and string theory-that is about to occur at the LHC should be very instructive to the community that studies history and philosophy of science. What will people see? How will they interpret the results? Who will (and who will not!) get access to this very special piece of equipment? How will the argument unfold from there?
Nevertheless, I propose that these types of philosophical arguments about string theory (verification, falsifiability) should be dropped (or at least separated), as they really have no bearing on the theory itself (they are simply non NPOV bickering between the camps), and to lead off the article about string theory with these philosophical arguments is inappropriate, misleading, and shows bias. My experience is that scientists will often trot out "Ockham's Razor" or "verifiability" or the "scientific method" or indeed Karl Popper when it is convenient and they wish to attack a view they don't believe in (those who are clinging to the Standard Model in this case in the face of string theory). It could be equally argued that clinging to the belief in the somewhat arbitrary ancillary hypothesis of the Higgs Field and the Higgs Boson is unscientific, since, as Karl Popper says, the addition of ancillary hypotheses to a theory in order to protect it from falsification is unscientific. Philosophy of science is its own subject, and should be written about as such. Major conflicts in theories are often the most interesting places to be (I think it was the philosopher of science Imre Lakatos that said you can always tell which scientists have the most in common ... they are the ones that are arguing the most between themselves!), but these articles in Wikipedia are supposed to define and explain the topic, NOT the conflict between views.
In any case, as an encyclopedic type resource, I think Wikipedia contributors should refrain from making these kinds of judgmental edits that do not serve to make clear WHAT the theory is. UNLESS one is actually writing an article about the debate itself between opposing views (in the case of String Theory vs. The Standard Model this would be a very interesting article indeed), one should refrain from engaging in debate WITHIN an article that is simply supposed to discuss a view, or theory, or whatever. The debate is and should be kept a separate topic until overall consensus is reached. For now there is no consensus, and a resource such as Wikipedia should serve as an encyclopedic resource to help people understand, not as a forum for bickering between people with conflicting views on a rather esoteric subject that is nevertheless of great importance to our understanding of the world. Keep the articles helpful to people who just want the "WHAT IS THAT?" explanation.
J.A.Ireland, BA (IHPST) ( talk) 22:53, 18 January 2008 (UTC)
In fact, Kaluza and Klein's early work demonstrated that general relativity with five large dimensions and one small dimension actually predicts the existence of electromagnetism.
Five large and one small, or five total (four large and one small)? 72.75.125.22 ( talk) 02:21, 25 January 2008 (UTC)
Why is this article tagged? This article does NOT have too much jargon. I think that it was tagged by someone who didn't want to take time to read the whole article thoroughly. I am in the 7th grade, and I don't understand physics, but I understood THIS article enough to write a paper on the string theory! If you need an article that uses simple words and concepts, then use Simple English.-- Princess Janay ( talk) 17:58, 27 February 2008 (UTC)
I think thats a pretty harsh reaction. Careful you don't hurt yourself dismounting your high horse, or do you just stay up there all the time. To be honest, if you didn't already know something about theoretical physics, you'd find most of the stuff in this article impenetrable. It does jump into very esoteric territory early on. Where is this template:theory of everything that people can read through first so they at least have some clue of what's going on? I think that would be very helpful.
60.228.249.60 (
talk)
13:33, 8 February 2009 (UTC)
I couldn't see any section in the article discussion the relationship between the String Theory and the Unified Field Theory. Should we include such a section into the article?
-- Mhsb ( talk) 22:01, 28 February 2008 (UTC)
In the Principia Newton defined time and space for physics:
I. Absolute, true, and mathematical time, of itself, and from its own nature, flows equably without relation to anything external, and by another name is called duration:
relative, apparent, and common time, is some sensible and external (whether accurate or unequable) measure of duration by the means of motion, which is commonly used instead of true time; such as an hour, a day, a month, a year.
II. Absolute space, in its own nature, without relation to anything external, remains always similar and immovable.
Relative space is some movable dimension or measure of the absolute spaces; which our senses determine by its position to bodies; and which is commonly taken for immovable space; such is the dimension of a subterraneous, an aerial, or celestial space, determined by its position in respect of the earth.
We all know that Einstein had something to say on this topic.
He writes in Relativity Chapter 9:
Now before the advent of the theory of relativity it had always tacitly been assumed in physics that the statement of time had an absolute significance, i.e. that it is independent of the state of motion of the body of reference. But we have just seen that this assumption is incompatible with the most natural definition of simultaneity; if we discard this assumption, then the conflict between the law of the propagation of light in vacuo and the principle of relativity (developed in Section VII) disappears."
The reason for the assumption could be Newton's description of absolute time being mathematical rather than relative time.
In Chapter 8, Einstein gives his working definition for time:
Under these conditions we understand by the 'time' of an event the reading (position of the hands) of that one of these clocks which is in the immediate vicinity (in space) of the event
Einstein is defining time in terms of the moving hands of a clock, which is nearly identical to how Newton defined relative time:
Relative, apparent, and common time, is some sensible and external (whether accurate or unequable) measure of duration by the means of motion, which is commonly used instead of true time; such as an hour, a day, a month, a year.
While I often hear some claim "Einstein has shown that time is relative", really, all that he has shown is that our present mathematics represent relative time, contrary to Newton's definition.
In fact, Einstein had made this point to Heisenberg, I think demonstrating how easily this subtle point is missed:
"But you don't seriously believe," Einstein protested, "that none but observable magnitudes must go into a physical theory?"
"Isn't that precisely what you have done with relativity?" I asked in some surprise. "After all, you did stress the fact that it is impermissible to speak of absolute time, simply because absolute time cannot be observed; that only clock readings, be it in the moving reference system or the system at rest, are relevant to the determination of time."
"Possibly I did use this kind of reasoning," Einstein admitted, "but it is nonsense all the same. Perhaps I could put it more diplomatically by saying that it may be heuristically useful to keep in mind what one has actually observed. But on principle, it is quite wrong to try founding a theory on observable magnitudes alone. In reality, the very opposite happens. It is the theory which decides what we can observe."
(In 'Physics and Beyond - Encounters and Conversations', Harper Torchbooks, 1972, p. 63.)
To summarize all that: in the eyes of both Newton and Einstein, while absolute space and time are "somewhere out there"; it is relative space and time that we measure..
Emphasis: RELATIVE SPACE AND TIME ARE MEASURED.
Now.
String theory.
There are visible dimensions of space and time, and there are hidden dimensions.
These hidden dimensions, cannot be measured.
Is there an opinion in the field regarding whether or not these extra dimensions are a "new" type of relative space?
Or is it absolute space? MobyDikc ( talk) 06:34, 29 February 2008 (UTC)
I am not an expert on string theory by any means, but i have a basic understanding, whist on the Primordial black holes wikipage i noted that it mentioned some work on trying to find black holes that are predicted by string theory which would be the "could be the first indirect evidence for primordial black holes and string theory.". Interested i came to the string theory wikipage to find out about any more projects aiming to do similar things but could not find any. A section dealing with these kind of experiments/projects/whatever that attempt to do this (even if its just links to other wikipages) could be quite useful and improve the article somewhat. gord ( talk) 01:07, 21 March 2008 (UTC)
In the first line of 'Overveiw' it says: "Matter is composed of atoms, which in turn are made from quarks and electrons." Atoms are not made of quarks and electrons. this should say: "Matter is composed of atoms, which in turn are made of protons, neutrons, and electrons." Going on to state that protons and neutrons are made of quarks, leptons, and gluons should also be considered, but i don't think it's necessary. Oh no! I've messed up the discussion page. I'm sorry. I deleted the last post and replaced it with mine.
Minduser
01:22, 18 April 2008 (UTC)
The recent work to expand the history section is for the most part really good, but I worry about its uncited attribution of so much work to various individuals. I removed a claim that Ramond made "the first formulation of a supersymmetry outside the Soviet Union" in 1970. This contradicts my understanding, and the supersymmetry page, which says that Wess and Zumino invented SUSY (outside the USSR), but I don't know for sure. In general, we need to be very careful in writing history that we are fair to all who participated in it. PhysPhD ( talk) 14:39, 22 April 2008 (UTC)
It's probably impossible to draw a clear line in this type of thing; In science, so many contribute incremental refinements, and who is to say which one step was key? I think erring on the side of mentioning more people is best, giving credit to all of the above. PhysPhD ( talk) 20:01, 22 April 2008 (UTC)
Use of "SUSY": The main article has a section heading "SUSY", but no mention is made of SUSY in the section, or indeed anywhere else in the article. This is meaningless to the amateur reader. Fredsie ( talk) 17:14, 24 January 2009 (UTC)
While string perturbation theory suggested that spacetime was ten dimensional, string theory is just a limit of a non-perturbative theory which is fully eleven dimensional, and is only string-like when one of the dimensions is curled up. To say that string space-time is ten dimensional is so totally eighties. Likebox ( talk) 01:02, 2 May 2008 (UTC)
You guys can remove this post if you like - it's not about editing, afterall. Just want to say that I'm also an artist with a wide field of interests, and this is one of the better articles I've read on any topic in WP. I suggested in "quantum gravity" that this could be a model for a deep article that's still readable. Good Job!!!
I edited the section on compact dimensions to mention structure. The article said the compact dimensions must have holonomy of SU(3) or G2. This is wrong. They must have SU(3) or G2 structure which is basically including torsion. SU(3) holonomy assumes no torsion because it assumes the background NS-NS 3-form flux H3 is turned off. While this is true in the simplest cases, flux compactification is specifically making use of the non-zero H3 flux (along with things like the RR F terms and fluxs created by T duality from H3). Papers often assume SU(3) holonomy despite turning on H3, but again, it's an approximation. Considerable work is being done in the area of full SU(3) structure. See publications by Palti and de Carlos for the differential geometry approach and work by Wecht, Ihl and Shelton in terms of fluxs being turned on and their effect on orientifold model. While I'm not as up to speed for M theory models (non-geometric fluxs in IIB is my thing), a quick look through the thesis of Palti mentions G structure again, which is the M theory version of SU(3) structure. Hence I think it's important not to say "must have holonomy" and to mention the difference. If specific citations are needed, I can provide them AlphaNumeric ( talk) 19:52, 20 June 2008 (UTC)
Please comment on the new image on the progression from macroscopic objects to strings. Dhatfield ( talk) 12:13, 27 June 2008 (UTC)
I noticed a few missing features after reading the Wikipedia article and watching the 3h instructional video, "The Elegant Universe" (see External Links on the article page), and am wondering about the following:
Musicnotz ( talk) 17:20, 29 July 2008 (UTC)
The usage of "p-brane" and "D-brane" without stating that they are black holes in the classical limit makes them seem more mysterious than they are. They are not just surfaces, like topological domain walls in a field theory, they are gravitational objects. The metric for a p-brane is a higher dimensional charged black hole solution extended in the world-volume dimension, and sometimes with a long-ranged scalar field contribution. They are higher dimensional extremal charged black holes, and I believe they were originally defined this way in the supergravity literature (I didn't read the original p-brane papers--- someone who has please correct me).
D-branes are superficially different--- they are endpoints for strings--- but it was Polchinski's great insight that the D-brane should be identified with the p-brane at weak string coupling. In other words, the D-brane is just a p-brane, or what's left of it in limits where strings become perturbative. Unfortunately there is conflicting terminology. Some people call any extended object a "brane", using it as short for membrane, not restricting the usage to those objects which are an extended black hole solution in the classical limit. As far as I know, this is not the terminology that has become standard. If it's not a black hole, just an extended defect, most people (as far as I know) still call it a "domain sheet" or "domain wall" or "topological defect" or whatnot.
Howver in the literature on Randall Sundrum style models, the two concepts of "brane" and "sheet" are blurred. I believe that the reason is that the Randall Sundrum models are sometimes very phenomenological, and don't have to be completely precise about what the branes exactly are as fundamental string theory constructs. So the Randall Sundrum "branes" are not always branes. But I think that this article should stick to the terminology used here, because I think it makes things clearer. Just my 2c. Likebox ( talk) 21:30, 2 September 2008 (UTC)
To avoid saying clearly, point blank, that D-branes are quantum versions of charged black holes makes it difficult for people to appreciate the logical coherence of string theory, and leads them to think that it is just guesswork. This is unfortunate, because it makes many people view the whole field with much more skepticism than it deserves. The string theory identification of matter and black-hole, resulting in a precise holographic description of both, is, in my opinion, the greatest achievement of science. But for some reason, people always tiptoe around saying this clearly. I tried to fix that here, but the weasel-words return.
For example--- D-branes are "extended objects which source a differential form vector potential" sounds much more mysterious than "D-branes are extended quantum-mechanical charged black holes". "D-branes are identified with black-hole like p-branes through AdS/CFT correspondence" sounds much more daunting than "when a bunch of D-branes are stacked up one on top of the other, they become classical charged black hole sheets, while the behavior of nearby objects is still described by a theory of the oscillations of the surface". Which is nearly the same statement.
To be fair, there are a few differences between the mental image conjured up by the words "black hole" and the mental image of D-branes. Black holes are classical, and the D-brane is quantum. Black holes are usually imagined to be neutral and thermal, while D-branes are extremal-charged and so non-thermal. Black holes are usually imagined as spherical in four dimensions, while branes are extended in higher dimensions. But that's the end of the list of differences. So to say "A D-brane is like a black hole" is too careful--- it's like saying "an electron in field theory resembles a negative point charge" or "an atom is similar to an electron orbiting a nucleus". We don't say those things anymore, we say "an electron is a point charge" and "and atom is an electron orbiting a nucleus", because the fact that they are quantum mechanical, so that the classical description is not completely correct, goes without saying. As far as authorities go, Witten said it in 1996, before AdS/CFT, and he's the most authoritative authority there is. Likebox ( talk) 22:46, 7 September 2008 (UTC)
M-theory has a simplified version. Why can't we have one for string theory? It would help quite a few people understand the concept better, which many would like.
Thank you for considering the idea.
Lu na ke et 13:55, 18 October 2008 (UTC)
I remember vaguely that Einstein at one point introduced a non-symmetric metric tensor for unification purposes. This is vaguely reminiscent of the way that you get a two form in string theory, it enters like an antisymmetric part of the metric tensor. Since this two form is fundamental--- it is the field of the charge carried by the string--- I thought it might be nice to make the connection, even though I think it is nearly certain that there was no historical connection between these two ideas.
On the other hand, I haven't read Einstein's unified field theory papers (very few people have) and I am not sure if the antisymmetric tensor he played around with is at all similar to the 2-form field. I was hoping somebody would know. Likebox ( talk) 19:46, 9 November 2008 (UTC)
The first line of the table under the String_theory#Dualities section says: "Only bosons, no fermions, meaning only forces, no matter, with both open and closed strings; major flaw: a particle with imaginary mass, called the tachyon, representing an instability in the theory."
So does the tachyon have an imaginary number value for mass under string theory, or is it some other interpretation of the word "imaginary"? I don't know enough about the subject, so I'll leave this change to somebody else. FFLaguna ( talk) 06:43, 14 December 2008 (UTC)
if the string frecuency is the diffrent between subatomic particle so in theory there is an infinet kinds of subatomic particles am i right?-- אזרח תמים ( talk) 11:22, 28 December 2008 (UTC)