Talk:String theory/Archive 1

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

Archive 1

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Miscellaneous comments

The units in this sentence are incorrect for tension: (should be Force = mass x acceleration)

"The basic idea is that the fundamental constituents of reality are strings of the Planck length (about 10-33 cm) which vibrate at resonant frequencies. The tension of a string (10^39 tons) is about 1041 times of the tension of an average piano string (75 kg)."

You are technically correct. This sentence was written for a lay audience that is doesn't deal regularly with Newtons. Assuming the tons are short tons, the correct numbers should be 8.9*10^42 Newtons and 735 Newtons, respectively. I've made the change on the page.

It seems likely that observable phenomena will be emergent ones from the complex interactions of strings in any real-world scenario. Presumably string theorists are using chaos theory and computer simulation to deduce these emergent phenomena? I can't imagine that anyone expects to find a nice analytical solution that manifests itself in the observable universe when, at quantum scales, virtually every observable thing is an incredibly complex system.

Has anyone explored the relationship between string theory and the Transactional Interpretation of quantum mechanics? Both involve the representation of particles as standing waves in n-space (although I agree that the TI much simpler). The TI states that it is the interference of advance & retarded waves that creates these standing waves. This seems to elegantly resolve every quantum paradox, while at the same time making use of a previously disregarded solution to Maxwell's equations. Does string theory still disregard waves that propagate backwards in time...?

The article says '..measure distance between two points.. rotate that observer'- are we talking about rotating the observer about its own central axis, or rotating it about some third axis? This is confusing 24.176.6.165 07:23, 29 Dec 2004 (UTC)

As is written twenty different times on this page, the article says that in string theory, space has either 10, 11 or 26 dimensions. First, this has been corrected to say spaceTIME since it was wrong before. Second, I'm pretty sure the 26 dimensions is wrong too.

http://superstringtheory.com/basics/basic5a.html says:

That sounds crazy -- because bosonic strings live in 26 dimensions but supersymmetric string theories live in 10 dimensions. But the extra 16 dimensions of the bosonic side of the theory aren't really spacetime dimensions. Heterotic string theories are supersymmetric string theories living in ten spacetime dimensions.

I believe that the quote you've given comes specifically from a discussion of "heterotic" string theories. They are called "heterotic" because left-moving and right-moving excitations (think of them as waves moving around the closed string) look very different. The left-movers look like excitations of the bosonic string and the right-movers look like excitations of the supersymmetric string. That's the context of the statement you quoted above. (For the record, the comment about 11 dimensions refers to M-theory.) -- Steuard 02:21, 26 Mar 2004 (UTC)

Third, there's no mention of F-theory invented by Vafa which has 12 spacetime dimensions (2 time, 9 space).

Fourth, I'd like the article to explain the difference between bosonic string theory and superstring theories.

Fifth, it might be useful to explain T-duality (between R and 1/R) and how it relates to energy; that there are two distinct measures for energy which give rise to different measures for dimensional size.

article says string theory permits space to have

either 10, 11, or 26 dimensions

i thought it only allowed 10 or 26, not 11. comments from any real physicists here? -- SJK

Dug up my notes on M-Theory. If you want to help me finish please do. ~BF

BF: I honestly don't know that much about M-theory. I read a book on string theory a few years back, but it was the popular science sort of book that skips most of the technical details. M-theory it didn't even mention -- SJK

It so new ( 5 yrs or so) that I enjoy it ! Don't ask me to explain it though. It has been stated by the cutting edge Theoretic Physicists, that M-theory finally solves Einstein's problem with general relativity, the black holes' issue and a few other unsolvable physics questions. What I like about it, is Witten himself said at a lecture, " This is 21st century knowledge that somehow dropped into the 20th century." Very new age for physics !

OK, now as we all know, encyclopedias are supposed to explain difficult concepts. So, here in this article we are exposed, straight-facedly and without any explanation at all, the notion of 10, 11, or 26 (spatial?) dimensions. What on Earth does this mean? I'm just a stupid philosopher, see. I'm sure I've seen explanations before, but I'm also sure I didn't understand one bit of them and therefore promptly forgot whatever I read or was told. Now, based on touch and sight I think I have a pretty clear notion of what three spatial dimensions amounts to; it also seems to me that this pretty much exhausts my understanding of what "spatial dimension" means. I'm perfectly willing to believe that physicists know all sorts of stuff about dimensions that I don't know, and perhaps never will know. But at least the article should make some attempt to explain what the hail "dimension" means if it can, possibly, mean something that can be numbered more than four! So, go ahead--explain it, or try! --LMS, being deliberately provokative :-)

I think the article already handles this - it says the other dimensions are subatomic in size, and so can't be observed normally.

But what does it mean to call a dimension "subatomic in size"? That's kind of like calling length, width, breadth, or duration "subatomic in size." I am still not enlightened. I'm sorry, I don't mean to be raising objections. I'm just saying that you're going to have to say a lot more in order to make the very notion of fifth+ dimensions clear. (Why are they called "dimensions," whatever these theoretical entities are?) --LMS

LMS: Let me explain it for you. We have three normal spatial dimensions, x, y and z. Now the radius of the universe along the x, y and z dimensions is going to be big -- billions of light years -- e.g. it might be that the universe is twenty billion light years tall and thirty billion light years wide and forty billion light years deep. By contrast, the other spatial dimensions beyond the normal three, are very tiny -- nanometres, picometres across. Does that make any sense to you?

No, none whatsoever.

As to the concept of a dimension, we all know what it is like to have one dimension (a line), two (a plane) and three (percievable space). Our minds really can't understand what more than three dimensions are like -- sure, we can manipulate the maths, we can do the reasoning -- but we can never intuitively understand what we are doing, in the same sense that we can for the normal spatial dimensions. -- SJK

Have you added the above to an article, SJK, or do you think it's not clear enough for that? --LMS

I think that the concept of a dimension having any *size* at all is quite confusing - dimensions are supposed to be the infinite canvas on to which things with size are placed. I think that extra-dimensions can be handled intuitively, it is just that this intuition has to be learnt. Modern physicists will tell you that they can kind of see what extra dimensions are like, albeit without fully understanding them. The book 'Flatworld' deals with this - a 2D thing realising that their are other dimensions. --Na

Precisely: "the concept of a dimension having any *size* at all is quite confusing."

It's not confusing at all so long as you realise it is a closed space (at least along the additional dimensions predicted by string theory) -- just like the surface of a sphere is two dimensional, and each of those dimensions can be said to have a size (the maximum distance you must travel along that dimension before you run into the same point again.) (Also, IIRC its called Flatland, not Flatworld.) -- SJK

If they have a definite size does that mean they have a definite position - are there millions of dimensions floating around inside the big 3D universe, or am I becoming more confused... --Na

No, there are only 10 (or 11, or 26, or whatever) dimensions; our three dimensions are a 3D slice out of the 10-or-whatever-D space. A dimension can't have a position: Height doesn't have a position, nor does length nor width. They are axes along which position is measured. So accurately, we really shouldn't say the dimension is subatomic -- we should say that the universe is subatomic measured along that dimension -- SJK

OK, OK, so let's start working on an article about this. :-) --LMS

I think there are two ways to think of dimensional size: 1. The baloon system described in the article. Since the size is how far you must go before bumping into yourself, think of a very very tall bug standing on a very very tiny baloon. It would not notice the balloon; it would think it is just standing on a point. 2. Point 1 raises a problem, as stated in a previous post: is there something outside the dimensions? My personal answer is "yes", but in a different way, and a way probably scientifically unfounded, so I'll say "no" and explain it this way: the dimension is, indeed, infinite. The thing is, if you stand at a point, you will see that one "dimensional size" away is an exact copy of everything at that point. In three dimensions, the "dimensional size" is so huge that we don't see the copy. But when the size is subatomic, everything is jammed up against exact copies. If you touch the copy in front of you, every copy touches every copy in front of it; the one behind you touches you. It is like the hall of mirrors. The reason we can't perceive these other dimensions is evolution; as explained in Michio Kaku's book Hyperspace (which I really recommend; it has great explanations) sabertoothed tigers do not jump out of the fifth dimension. Therefore, natural selection will not care about whether a species can see the fifth dimension. It might even be detrimental; it would use up valuable brain space.

Well, this isn't too bad -- we haven't even gotten into the math, after all, and that's the truly hard part. But staying on a conceptual level for now: a dimension is a degree of freedom in which an event may occur. Dimensions are orthogonal to one another, and may be visualized like the coordinate axes on a graph. In other words, a universe in which any event can be located with n numbers is called an n-dimensional spacetime. Our universe appears at a first glance to be 4-dimensional: three spacial dimensions and one time dimension. But this may not necessarily be the actual case.

To illustrate, I will paraphrase an example from The Elegant Universe: picture a simple universe with one space and one time dimension. It is named Lineland and is inhabited by one-dimensional Linepeople. As far as they can tell, their universe has only two dimensions in all. Later on, it is discovered that the supposed "line" universe is actually a thin tube, a two-dimensional surface with the 'new' dimension curled up into a circle so small that even the width of a Line-atom is many times greater than the circumference. Observing this extra dimension directly is therefore nearly impossible, but the rather subtle effects of its existance may be observed. Lineland, then, is basically a lower-dimensional picture of our own universe. There are all sorts of extra dimensions down there, but they're so damn small that we can't tell. -- Xaonon

Let me have a crack at what I got out of the "dimensions have a size" thing to see if a) I'm following it, and b) my explanation is then helpful to the layman.

The issue here is "how big is the universe in the given dimension". Obviously everything *in* the universe has to be smaller than the universe is in each of its spatial dimensions. So the universe is 13 billion light years across in the the x, y, and z spatial dimensions and microscopic in all others. All objects in the universe then have to be smaller than that. My desk, at about two feet by five feet by three feet fits within the universe in x, y, and z, and is mini-microsized in all the other dimensions, in order to fit as well.

So we don't see the other dimensions because the measurements of *everything* are too small to impact us in any way. This is why (getting back to the initial confusing statement) "the dimensions are subatomic in size" -- the entire universe is that small in those dimensions, so so is everything else.

Is that summation right? And if so, does it help? -- Paul Drye

Yep, great summation.

Yeah, thats basically it.

Except for the complications like that objects can wrap around the small dimensions. Just because a dimension has a radius R doesn't mean that an object is restricted to having length R in that dimension.

The way I deal with thinking about extra dimensions is not to think about extra dimensions and just think of them as numbers in an equation. After looking at how the numbers interact, you start seeing patterns and developing an initution about how things work, but it's less confusing to start off by *not* even trying to visualize the extra dimensions.

The universe works in a certain way that we are used to. The point is that there is no mathematical reason why it has to work the way that we are used to. You draw a circle, measure the area inside and it's pi r ^2. There is no mathematical reason why that *must* be the area. It just works out that way.

Well, I read that string theory permits space to have 10 or 26 (but 16 collapsed into very small piece, so it gives also 10) dimensions. --swPawel

Just my two cents, but I have heard that there are about 5 similar but competing versions of String theory. Incidentally, it was also noted that the extra dimensions are indeed spacial.--Anon

That's good enough for me to justify the split. --maveric149

They're not similar, they're identical. It just wasn't realized they were the same till the 1990s. And by "identical theories", I mean identical laws of physics; it doesn't matter how you write it down.

I made the split to be able to talk about bosonic string theory and to make sure people knew there might be a name confusion. It's not a problem with physicists but ... anyways, I just don't like the ambiguity. Besides, this way people will know what the super means in superstrings.

Shouldn't the title be string field theory? Or am I mistaken for something else? -- Taku

Google would suggest not - 211,000 hits for "string theory" and 5,860 for "string field theory". I've never heard it called string field theory. Angela 20:03, Oct 18, 2003 (UTC)

String field theory is an alternative formalism for string theory. It's ultimately the same thing. Mporter Jan 29, 2004 (AEST)

I have a question concerning this theory. The idea of 10, 11 or 26 dimensions, or evens strings themselves, doesn't seem very elegant. So, can we say there are no strings or 11 etc. dimensions, but it is our only way to describe the world as it is? (Because the mind is unable to understand it in another way than "string" or "dimension"?) E.g. there are no Calabi-Yau-Spaces, but we can describe the thing that is as if there where Calabi-Yau-Spaces? So: reality stays beautiful, because it is our mind that is not capable enough to think of a real elegant theory. I like this more than saying "there are 11 dimensions". Hhc2 14:19, 21 Oct 2003 (UTC)

On the one hand, one way of doing physics is not to bother asking wether Nature really behaves the way your model says as long as it gives the right answer to experiments. This is mainly due to Quantum Mechanics where people stopped asking wether particles really travelled along two different paths at the same time as long as the probabilities they got where the good ones. Your position is thus perfectly acceptable form this point of view. But on the other hand you should accept the idea that Nature is not reducible to what our senses tell us. For example can you find an absolute reason why spacetime should be 4 dimensional ? All you can say is that at your (low-energy) scale, Nature seems to be 4 dimensional, right. But you cannot infer the answer, say, just after the Big Bang. There's no reason why the dimensionality of spacetime should be an absolute concept. So you can distinguish between Nature and our different representations of it but Nature still could change considerably with the scale. Stating the contrary would be a bit anthropocentristic :) LeYaYa 8 Feb 2004

I am glad that - after some months - somebody has answered my question! I would like to point out that my intention was not to reduce nature / the reality to a level that I can understand it. That indeed would be anthropocentric. I wanted to express the regrettable status of my mind, which ist not able to think at the same time in 11 dimensions and call it beautiful or elegant.

Reading the popular articles on string theory, I have the impression that they talk about strings as existing objects, that the average reader must come to the conclusion that the universe consists of some sort of very small spaghetti, only to small to see them. hhc2 6. march 04

Fixed article a bit

I don't have the time nor the energy to write a long essay, but I fixed a lot misconceptions and ouright errors in the original page.

A link or quick defininition for the term "perturbative" in this context would be helpful for the layman.

Although the general structure of this article is quite good, I think we should word it more carefully. All the arguments given are mathematical (and valid), but in physics it is important to tie them in with experiments. Or at least clearly show their "speculative character." Here, it sounds like string theory is already a given fact... Awolf002 01:26, 6 Apr 2004 (UTC)

I like that added "hint" about missing tests. Much better now Steuard, right? Awolf002 19:04, 8 Apr 2004 (UTC)

Two questions and clarifications

I'm new at this, and a little confused, but intrigued. The article says, "string theories are able to avoid problems associated with the presence of pointlike particles in a physical theory. Detailed study of string theories has revealed that they contain not just strings but other objects, variously including points, membranes, and higher-dimensional objects."

Can anyone explain to me what sort of problems string theories are able to avoid?

Also, how is it possible that each string "contains" other objects? I thought the whole point of a string theory is that the strings are the smallest, indivisible building blocks (as opposed to conventional physical models, which hold that the smallest building blocks are three-dimensional)?

I'd love to understand this better.

--Seneca644 03:56, 6 Jul 2004 (UTC)

One of the most obvious (to physicists) problems has to do with the infinities that show up when you try to describe a point charge. With a finite amount of electric charge concentrated at a single infinitely small point, the electric field at that point is infinitely large. If the same charge is instead distributed continuously along a string, no infinitely small point along the string has a non-zero charge, so the problem goes away. (The actual calculations used in string theory are rarely this straightforward, but I think the principle is pretty much the same.)

As for your second question, that's just an unclear phrase in the article (embarassingly, I think I wrote it). The strings don't contain other objects, the theories do. I've just changed the word "contain" to "describe", which should make the meaning much clearer.--Steuard 22:21, Jul 9, 2004 (UTC)

I don't know about other people's hoses, but my garden hose has 3 dimensions, one more than this article seems to indicate. Is it some kind of gateway to another universe perhaps? Is it leaking into another brane like gravitons supposedly do? Infradig (andrew) 04:46, 1 Sep 2004 (UTC)

Image

Is anyone able either to obtain royalty-free string images like those cool ones on that nova documentary, or render something? That'd add to the article. [maestro] 04:47, 4 Dec 2004 (UTC)

"String theory, as with any current theory of quantum gravity, is unverifiable, and therefore it is also unfalsifiable."

GAHHH!!! I just had a two hour argument with my agnostic friend (I am an atheist) about this.

Just because an idea is created does not make it unfalsifiable! Theists always use this argument and it is flawed. It is the exact point of the Invisible Pink Unicorn--that becuase it is created, you can not disprove it, even though we all know she is a falsehood (blessed be her holy hooves). It's because the moment an idea is created, and you vehemently defend it, people say it can not be disproven.

By this token, Gimli exists, because I say so, and therefore, it is unfalsifiable.

Lockeownzj00 20:13, 5 Feb 2005 (UTC)

I think you misunderstand something here. Unfalsifiability is bad, from a philosophical viewpoint, for the reasons you stated above. Of course, an Invisible Pink Unicorn cannot exist, because invisibility precludes colour. *shakes head* BovineBeast

By Rob: JUST because the grasp of the human mind cannot process a consept and theory so complicated, doesn't make it untrue!, But what we perceve is what we belive.

What is wrong with the above statement is that it is the wrong way around. It should say "string theory is unfalsifiable and therefore unverifiable". The point being that modern scientific method requires experimental tests that can disprove a theory - as Einstein put it "no number of experiments can prove me right, but one could prove me wrong".

If only Einstein could be alive today to see the experimentation and technology that was only a dream in 1930, mind you the backs of old envelopes are still the same size!

Superstring theory

Shouldn't this article be titled "Superstring theory"? The phrase "string theory" is a popular shortening of the original term. -- BRIAN0918 02:41, 1 Mar 2005 (UTC)

In fact, superstrings refers to supersymmetric string theory, which is a supersymmetric formulation of standard string theory. The "super" in superstrings does not come from a shortening of the original term but rather from an extension of the theory. FXBN132.203.184.77 20:52, 3 April 2006 (UTC), 3 Ap 2006

what about the philosophy of a sphere?

we know , a mathematical back ground concerning the origin of any sphere is a bit complex too ,a sphere is that it has no start and no end ,. absolutely we can find the end of a sphere [ sphere of radius R ] it is a preety simple question [ if parameters of diff.. eq n provide] ; but are our minds are ready enough to find the origin of any sphere. if we say a point matter then also that same is too a sphere , if we say a differential of a space then the ouestion is redirected to the constant k of our space time concept. here word sphere ,i mean to say any originating ball or a body [equivalently], a potential field, uniform lump matter of same constituent originating in space time co-ordinates . what ever we do , how hard we try , my above question is a question to all explorers of fundamental science, including me.

i think , as per mathematics says, we can only talk about matter formation[ hence energy] or the meta physics, if and only if the above puzzle is cracked through mathematics , hence getting nearer and nearer to the truth . this will certainly risk free the possibility of any wrong truth/ model of any prediction what ever we make towards universe.

further questions; connect: e2t_solar@rediffmail.com

do you have a problem : i too is having a part of problem

let us solve together [ contact me if interested in my question] (unsigned I prabhat)

I say improving the article will make masses happier. --Cool Cat ^{My Talk} 15:47, 20 Mar 2005 (UTC)

Trouble with this article

I think this article is very biased.

"As of 2005, string theory is unverifiable. It is by no means the only theory currently being developed which suffers from this difficulty; any new development can pass through a stage of unverifiability before it becomes conclusively accepted or rejected. As Richard Feynman noted in The Character of Physical Law, the key test of a scientific theory is whether its consequences agree with the measurements we take in experiments. It does not matter who invented the theory, "what his name is", or even how aesthetically appealing the theory may be—"if it disagrees with experiment, it's wrong."

String theory's perdiction of cosmological constant is wrong. (55 orders of magnitude)

In fact, some would argue string theory is not even a theory given that even if the amazing particle accelerators which would supposedly show evidence of the smaller dimensions could be built, string theorists still don't predictions on what exactly would be seen.

Please see http://www.math.columbia.edu/%7Ewoit/strings.pdf

Question about time

Time is not a dimension, right? Right? Can somebody please explain, when I search information some sites tell me that time is the fourth dimension and some tell that it's not a dimension. Is it a matter of opinion until we understand a little more about how the world works?

It is the perspective of essentially all theoretical physics since Einstein that time is a dimension. However, you should probably find an actual discussion forum if you want a more complete explanation (perhaps you could try the Usenet group "sci.physics", which you can access through Google Groups); this page is only intended for discussion of how to improve the content of the article on String theory.--Steuard 20:52, Apr 21, 2005 (UTC)

garden hose thing

thank god. without the garden hose thing i'd have been lost. 70.177.90.39 03:06, 11 May 2005 (UTC)

Question

Recently someone made a new theory based on the sting theory and the kazula klein theory, where everything is explained only using flexion of the space. I cant remember who this is. Does anybody know this theory?

How does string theory explain matter/anti-matter anihilation?

As a non-physicist following string theory through Scientific American and Nova, one question I've always wanted to ask about string theory is "How does string theory describe the anihilation of matter and anti-matter". I would expect that there must be some mathematical symetry between the vibration mode of a string that results in an electron vs. that of a string that results in a positron. When two such vibrating strings collide, just what happens?

Thanks,

Mark Z.

Extra Dimentions

I read with interest the theory that extra spatial dimentions exist. However, this view is at variance with one expressed by Professor Stephen Hawking, who remarks that "if there were more than three spatial dimentions, the orbits of planets around the sun or electrons around a nucleus would be unstable and they would tend to spiral inward" --Derek R Crawford.

That description of gravity would certainly be accurate if the extra spatial dimensions were "accessible" to us in the same way that the usual three are: the (approximate) force of gravity in D spatial dimensions falls off at large radius r as r^-(D-1). (I suspect that the comments about electron orbits aren't as relevant once quantum mechanics gets involved: QM doesn't allow for "spiraling inwards" at that scale.) But we already know that any extra dimensions would have to be different somehow, because we can't see them.

The most common explanation in string theory is that the extra dimensions are "curled up" in small circles (or some other compact space). I've tried to explain that concept a little bit on this slide in an overview of string theory that I wrote. The slide compares a human being's perception of a tightrope to an ant's: the person can move in only one dimension, but the ant can move in two.

If that were the case, then measurements on very small scales in our universe would see gravity falling off faster than r^-2. But once the radius of the extra dimension became small compared to r, we would be back to r^-2 again (you can imagine that the small circle has "filled up" with gravitational field: there's nowhere else for it to dissipate in that direction). Last I heard, direct measurements have only verified that r^-2 gravity holds down to about 0.1 mm (which is quite large, when you think about it). So there's lots of room for the extra dimensions required by string theory.--Steuard 19:41, Jun 21, 2005 (UTC)

Not testable?

Why does this article still say string theory presents no testable predictions? What about measuring the CMB? This isn't even mentioned in the article. String theory has advanced beyond the Elegant Universe book and TV show.... -- BRIAN0918 15:06, 22 July 2005 (UTC)

No, the article is wrong. String theory cannot be tested by measuring the CMB, although some specific string-inspired ideas could be ruled out. –Joke137 18:52, 22 July 2005 (UTC)

I went to a colloquium a few months back where the speaker pointed out that subatomic-scale strings might have been stretched by the Universe's inflation until they were of cosmological size. Hence, some of the calculations done for cosmic strings back in the '80s would be valid again. These uber-elongated superstrings would radiate gravitational waves, which we could detect using LIGO et al.

For your entertainment, it may be worth checking out T.W.B. Kibble's "Cosmic strings reborn?" paper, astro-ph/0410073.

Anville 15:41, 26 July 2005 (UTC)

Actually, that was the test of which I was originally thinking. -- BRIAN0918 15:49, 26 July 2005 (UTC)

I've added a pop-sci exposition of the "Cosmic strings reborn" material. It looks like the CMB observations are less likely to yield interesting stuff than the gravitational wave and lensing experiments. After all, we already know the CMB doesn't support a high density of cosmic strings wandering the Universe. Anville 18:34, 26 July 2005 (UTC)

Good stuff there, Anville. I wonder, though, if the Kibble quote might give the wrong impression to the layman that cosmic strings have actually been found. Given that he has a significant stake (as the originator) in the success of cosmic strings, his opinion might not be the best to use. S.N. Hillbrand 04:21, 27 July 2005 (UTC)

So can we now change the article to say that string theory is testable? -- BRIAN0918 04:37, 27 July 2005 (UTC)

I don't think that's a good idea. Testing a theory requires that the test be capable, at least in principle, of falsifying the theory. Not finding cosmic strings would not falsify string theory, whereas not finding gravitational deflection of light by the sun would have falsified general relativity. While there are a lot of measurements that could be made that would suggest that string theory is on the right track, there is nothing, at present, that is a "test". –Joke137 13:54, 27 July 2005 (UTC)

Joke137 has a good point. And in the case of CSL-1, the astronomers have not yet ruled out a binary system and theorists have not yet determined how a cosmic string could exist so close to us without our being able to detect any radiation. S.N. Hillbrand 04:14, 29 July 2005 (UTC)

Problem with String Theory Problems

An anon editor inserted the comment "some scientists have asked if it even deserves to be called a scientific theory". I was considering removing this because it seems to be a cop-out. It gets a derogatory jab in while stating it in terms that are difficult, if not impossible to refute. Perhaps we could say "while string theory continues to be actively researched, a growing number of scientists, most prominently Professor Such-and-such, believe that string theory will never be able to be tested." This would also provide a much better transition to the next paragraph. Any objections? How about prominent anti-string theorist scientists? S.N. Hillbrand 20:00, 10 August 2005 (UTC)

I tried to fix this up yesterday, but frankly I still think the section is pretty colloqiual in places and could use some work. One prominent scientist is Nobel laureate Philip Anderson who has written several New York Times editorials opposing string theory. Although he is not particularly prominent, Peter Woit runs an anti-string theory blog, Not even wrong, which is linked from the string theory article. It might provide some more information. –Joke137 20:36, 10 August 2005 (UTC)

Multiple Dimensions

Can't multiple dimensions exist in a way that allows a particle to be in two places at once. If so, our whole universe could be a single particle (entity) that can be veiwed from an astronomical number of locations.

If there are more than 3 dimensions, I've seen references to 9, 11, and 19 dimensions in different readings, then what are those different dimensions? Could imaginary numbers have something to do with it? What about negative numbers? The first 3 dimensions are length, width and height, everyone knows that. I've even thought of time as a dimension since acceleration takes place in square seconds (units per second squared). Anyway, could the next three dimensions be negative dimensions? Could they correspond with imaginary numbers (square root of any negative number)? Is there a possibility of "imaginary" and "negative" dimensions? If there is, then there are 9 dimensions, not including time, if time even is a dimension, which I'm still debating. I know it sounds impossible, but a lot of these things sounded impossible until they were explained. The problem is, I don't know much about this stuff, and I have nobody to ask. Any input at all would be awesome. E-mail: amazinsk8r@hotmail.com. If anybody has anything you can tell me about this, please do so. Thanks in advance.

Read up on Alain Aspect's experiments on Action at a distance. They may seem unrelated to your "particle in two places at once" question at first, but think about seeing two particles in two different places acting the same way with no mediator. You may be seeing the same particle in two places at once, where in fact the space they occupy may be the same when perceives from a higher dimension. TCorp 16:50, 17 January 2006 (UTC)

What is wrong with string theory?

[1] Fundamental physical ideas should not only be sound in details but it also must be sensible conceptually.

General relativity says that non-gravitational physical processes occur on the geometrical framework created by gravitational field. We observe the physical processes through and with respect to the gravitational field. If you have a theory which includes the gravitational dynamics then in it the physical processes must happen with respect to each other (relationally) with out any reference to a background structure.

In string theory the strings move, vibrate, merge, split etc. These strings are not like spinors existing in an internal space. They are similar to classical high school textbook strings: Elastic and dynamical objects. If string theory includes gravitational field then it must not have any other background structure in which the strings exist. If it is a fundamental theory then it must not have any other forces that is responsible for the string dynamics. But string theory assumes background structures and string dynamics which is completely absurd.

String theory may be interesting mathematics but it is not physically reasonable because it ignores the conceptual lessons of Einstein's general relativity which is the foundation of our current understanding of time, space and everything.

String theorists often talk about Einstein's dream of unification when they talk about string theory in their websites and programs. But if Einstein have been alive, he would be very disappointed with string theory because of its complete disregard for general relativity.

Once does not require a thousand explanations to disqualify a theory. By a simple reasoning one could clearly see that something is wrong with it.

Visit Universalwatch.blogspot.org [Universalwatch.blogspot.org] for discussion on various related issues.

This is a theory, one that many many scientist agree with and are working on it. While it's true that it is still unproven, and that people find issues with it, as exposed in the "Problems" section, it does not invalidate it. While you may be convinced its falsed, lots of brilliant people are convinced its true, so this remains a valid, encyclopedic theory. Elfguy 16:59, 15 September 2005 (UTC)

Consciousness

Doesn't modern physics allow for the possibility that all living organsims are identical in terms of conscious identity and have the same one consciousness. This would mean that we are all in effect the same being living out our lives as a different person/animal/organism. That there is no differentation between me or you. "I am you"

Yes, obviously, we are the borg! Elfguy 17:01, 15 September 2005 (UTC)

The question is not whether it is possible, but rather whether this is the way we are.

This question is probably meaningless (unless you are a philosopher of course) and certainly doesn't have anything to do with string theory. --MarSch 12:55, 28 September 2005 (UTC)

If modern physics allows it, then it has to do with string theory. The point is that we may all be the same person. Nature may only allow a single counsciousness (whatever you want to call it) in the universe and that is quit disturbing. Science has yet to distinguish the mechanisms for consciousness in our brains. [[User] 18:01, 28 September 2005 (UTC)

Just becuase this question is not directly related to string theory does not mean that string theorists should not pursue it. The idea that there are infinite possible conscious identities in the universe is absurd.[[User] 18:01, 28 September 2005 (UTC)

I think it depends on how you want to think about it. Say you're a Christian. Everyone has a soul. A separate, non-shared soul. I don't really believe that there is only one concious identity, because wouldn't everything be more closely related thought wise? Take any animal vs. a human being for example. A human being has an imagination, no other animal has that. That's how we think up all this stuff about our world and that's why all other animals are still stuck on the 'food, safety and reproduction' thing. I guess you could say with humans and animals separately there might be only one "conciousness" for each respectively, but not one for every being all together. Then again, I guess just about anything is possible, right? D_Luz

Well, it could be said that either side could be right, depending on which explanation you wish to use. One could say that there are a finite number of basic strings that make up matter and that they could therefore only ever produce a finite number of consciousnesses. This, however, could be cause for confusion when you remember that the universe is infinitely large, and therefore any and all possibilities must play out somewhere at some time. This would mean that an infinite number of consciousnesses are needed to satisfy logic, but only a finite number could ever be produced from a finite number of string "ingredients". On the other hand, you could look at it as being similar to DNA. Although there are only a finite number of combinations, the differences are too subtle too notice. This, however, could be argued with by saying that, if so many different combinations are possible, then why are there so few types of known particles and only 4 known forces? It would appear as though more particles and more forces would be necessary in order to justify this explanation. This, however, creates a paradox, as String Theory's purpose is to unite all the known forces into 1 force that manifests itself in different ways. It really could go either way.

Shadowbeckoner 17:54, 14 February 2006 (UTC)

people working on string theory

exactly how many people are working on string theory? in the article there is like only 20, which is just too few to be believed. or are they just notable ones?

Exactly how many is hard to say but every major cosmology department in the world has at least one string theorist. Many people are even complaining that the sheer number of talented students studying string theory is detrimental to other areas of physics.

On a separate note, one might point out that the validity or conversely the spuriousness of any theory cannot be tested by merely by the number of its adherents. Even claiming that it is a neccesary but not sufficient condition to be accepted would lead one into a morass of mob rule. Understandably, this is not a situation where one can adequately judge the quality of research for oneself. However, this merely means that we should assume a skeptical agnosticism regarding proclamations of proof or disproof. S.N. Hillbrand 16:19, 23 October 2005 (UTC)

Question - Re Popper

"some scientists have asked if it even deserves to be called a scientific theory: it is not yet a falsifiable theory in the sense of Popper." What is the reference for this, please? I cannot find this anywhere, and this is not footnoted. KillerChihuahua 14:14, 15 November 2005 (UTC)

I think most string theorists agree with this statement, that there is no experiment that could conceivably be conducted in the next few years that would refute string theory. There are experiments that would provide strong evidence for string theory (cosmic string lensing, Kaluza-Klein particles or supersymmetric particles at LHC, a short-distance fifth force, etc...) but little that would refute it. Some prominent and semi-prominent people who have been arguing this are Philip Anderson, Sheldon Lee Glashow, Lawrence Krauss and Peter Woit. I'm sure there are many others. –Joke137 19:02, 15 November 2005 (UTC)

Well, as a non-physicist (which puts me right there with most of the people who consult WP) I confess to some confusion. If ST is falsifiable even if the methodology for that does not yet exist, then that's not a reason to say its not a theory. OTOH, if that is exactly the issue, that scientists are not sure if it will ever be falsifiable, then surely a source should be placed on the page? KillerChihuahua 19:06, 15 November 2005 (UTC)

I agree there should be a reference. Philip Anderson says "My belief is based on the fact that string theory is the first science in hundreds of years to be pursued in pre-Baconian fashion, without any adequate experimental guidance. It proposes that Nature is the way we would like it to be rather than the way we see it to be; and it is improbable that Nature thinks the same way we do." (NYT, 4 January 2005) You can also see the interview with Glashow at the NOVA Elegant Universe site [2], Peter Woit's blog [3] or forthcoming book, and Krauss' recent book and NYT editorial ("Science and Religion Share Fascination in Things Unseen", NYT 8.11.05) in which he states "String theory, yet to have any real successes in explaining or predicting anything measurable, has nevertheless become a fixture in the public lexicon, and the elaborate and surprising mathematical framework that has resulted from over three decades of theoretical study has been enough for some to argue that even a thus-far empirically impotent idea must describe reality."

There is a continuum of opinion among these people. Woit would probably argue that string theory in its current form makes no testable predictions, whereas the others might agree that there are testable predictions but there is no foreseeable way to ever construct an experiment to actually implement the tests (because the machine would have to be, say, the size of Jupiter), whereas others would argue that regardless of the issue of testability, spending thirty years constructing a theory in a vacuum is a bad idea. I can't remember where the reference to Popper is from. –Joke137 19:21, 15 November 2005 (UTC)

I would appreciate it if you would determine what would provide the best source, and add it as the cite. For Popper, the best I could do was a Guardian article which quotes Woit: [4] which is a source but not as good as a published paper. I am not competent to judge what sources are decent and which are undergrad slop, so I appreciate you taking up my concern. KillerChihuahua 20:19, 15 November 2005 (UTC)

Well, those are the most prominent critics I could think of, so I just added a corroborating footnote. –Joke137 22:03, 15 November 2005 (UTC)

Well done and thank you! Kudos. KillerChihuahua 22:06, 15 November 2005 (UTC)

The string theory is very interesting and needs to be furhter studied to be widely accepted. There is always the field of religion that is the blockage of a majority of science related tools.

For a complete statement of Popper's ideas concerning falsifiability, consult his "The Logic Of Scientific Discovery" which is entirely devoted to the matter. Hi There 07:17, 4 May 2006 (UTC)

Some basic caveats added by 67.169.24.49

Could you give some sources where your "backgrounds" and "the flat spacetime solution of string theory" are described? So far, your remarks (or "caveats") seem irrelevant. Kurochka 16:24, 24 November 2005 (UTC)

Can we get rid of the stupid sidebar? It is much too big and distracting. We already have a list of string theory topics (from which the sidebar was copied) for navigation. I'm putting the sibebar up for deletion. -- Fropuff 16:18, 2 December 2005 (UTC)

Okay, I rewrote the sidebar as people didn't want it deleted. Comments are welcome. -- Fropuff 18:27, 9 December 2005 (UTC)

Kurochka 11:46, 12 December 2005 (UTC)

I disagree. What about, oh, say Polchinski, Polyakov, Klebanov, Seiberg, Gross, Ovrut, etc... ? There is no clear criterion for including or excluding anyone. What about a link to "List of string theorists" or something? –Joke 15:00, 12 December 2005 (UTC)

Ok. That would be fair. Kurochka 15:41, 12 December 2005 (UTC)

I strongly disagree with having string theorists listed on the sidebar. The list will just get way too long. We already have a list of string theorists at list of string theory topics (which is listed on the sidebar). There is no need to create a separate article. Create a redirect if you would like. -- Fropuff 16:44, 12 December 2005 (UTC)

Pataphysics criticism added by 172.135.99.87

Pataphysics has nothing to do with string theory by the definition of pataphysics itself: a philosophy dedicated to studying what lies beyond the realm of metaphysics. See also the protoscience article. Kurochka 07:27, 20 December 2005 (UTC)

Dimensions and Measurement.

I have looked in many places, but have yet to find a clear answer to the question I have in mind. What are all these additional dimensions measuring? We need three dimensions to define space and can reasonably use a fourth dimension for space-time.

This is not such a hair-raising problem. Using more than three dimensions is not so weired if you think about it for a moment. It is even possible to apply numerous dimensions to a chess game, two for location on the board, one for whose turn it is, another for material and, last but not least, one for time. You can apply these same mathematical/epistemological tools to any number of problems, from assessing the value of tanks to the efficacy of baseball teams. Notice, however, that all these dimensions measure SOMETHING. They are not applied to the problem in an arbitrary way.

If we need as many as 26 dimensions to explain the universe, what are we measuring with 22 of them?

I am NOT criticizing the theory here, but its exposition. Let's face it. If this theory has no basis in fact, you're telling a whopper. If it does indeed have a sound basis in fact, you are STILL telling a whopper. The only way to tell a whopper is to make it as plain as you possibly can. Otherwise, people think you are trying to slip something by them.

From what I have been able to gather after consulting many, many sources, these additional dimensions are for establishing locations, volumes, and magnitudes in space. In other words, the are no different from the three space dimensions we use every day but are only applicable on the scale of these very tiny strings. Unfortunately, no article I have found says this outright. I'm still left wondering if they are not measuring something I do not know about, energy levels, or quantum states, or some such.

And here is an interesting quote from Georg Friedrich Bernhard Reimann:

"The realm of the small seemed particularly important, Riemann noted. “Knowledge of the causal connection of phenomena is based essentially upon the precision with which we follow them down into the infinitely small,” he said. “One pursues phenomena into the spatially small in order to perceive causal connections, just as far as the microscope permits."

Here is the link to the quote:

http://www.nap.edu/books/0309084075/html/221.html

70.116.68.198 00:35, 1 January 2006 (UTC)Don Granberry.

Pataphysics a valid addition to the critical nomenclature of string theory

Respecting Kurochka's edit, I must add that the secondary (as it were) definition of "pataphysics" as describing anything that is "speculation based on speculation" has undeniable value in the context of string theory discussion.

Just as the definition of the word "red" need not include a description of an apple, the definition of pataphysics need not mention string theory for the word to have critical value in the context of a discussion of string theory.

Pataphysics accurately describes a criticism of string theory that so far does not seem to have proper nomenclature.

When certain physicists complain that string theory is a 'philosophy' (which has a very broad meaning), they are really saying that string theory is now a mathematical world of its own (i.e., a completely speculative mathematical model run amok, rather than a verifiable description of the physical universe).

In this context, the word "pataphysics" accurately encompasses the complaint, as "pataphysics" describes a world of speculation that is twice removed from reality (first by a theory, then as a theory based on a theory!).

No matter what your ultimate opinion on the validity of string theory, "pataphysics" correctly describes what string theory is said (by opponents) to have become: a speculative mathematical universe unto itself, and one that is based on prior speculations (in this case, the mathematics of quantum mechanics and general relativity, themselves unproven), and is thus "verifiable science twice removed".

Speculation based on speculation = pataphysics = string theory.

Unfortunately, I have to repeat my arguments more clearly. First of all, string theory is NOT philosophy in the very sense of the word, whatever "certain physicists" imply. If you need a proper nomenclature for string theory, I will give you. String theory is a protoscience. It does not need to be verifiable, it need to falsifiable. That's the problem, and the article tells us about it. Finally, you don't have to prove quantum mechanics and general relativity because they ARE falsifiable, and none of many experiments has disproved these theories so far. Kurochka 12:15, 5 January 2006 (UTC)

False Vacuum Decay

According to string theory the universe is only meta-stable. A sufficient jolt of energy in the right way could cause a spontaneous quantum flip, causing the vacuum decay into a stable state from the source at the speed of light. This would be catastrophic and destroy everything in the universe. Although we are currently unable to create such a fuse, advanced civilizations elsewhere in the universe should be able to create a energy density necesarry induce vacuum decay. Hypothetically, the oldest form of intelligent life in the universe is only a few thousand years older than us due to gamma-ray burst sterilization of galaxies. If the gamma-ray burst theory proves to be incompatible with evidence, the oldest carbon based civilizations in the universe would be 3 billion years old. At any moment we could be sent into the dustbin of cosmic history by the advancing front of a vacuum phase transition triggered by a civilization years ago. In fact, if there truly are other intelligent civilizations in the universe, the phase transition (or any other of the many forms of distruction) may have already been triggered in different points throughout the universe. It may be only a matter of time before we feel the effect. (search: "RHIC disaster scenarious" on google)--Aero77 16:09, 7 January 2006 (UTC)

See false vacuum, in particular the reference to Coleman and de Luccia, where you will find:

The possibility that we are living in a false vacuum has never been a cheering one to contemplate. Vacuum decay is the ultimate ecological catastrophe; in the new vacuum there are new constants of nature; after vacuum decay, not only is life as we know it impossible, so is chemistry as we know it. However, one could always draw stoic comfort from the possibility that perhaps in the course of time the new vacuum would sustain, if not life as we know it, at least some structures capable of knowing joy. This possibility has now been eliminated.

It may not help you sleep at night. Take comfort in the fact that the case they considered is ever so slightly different from that considered in string theory. –Joke137 18:01, 16 November 2005 (UTC)

I assume that since i am getting no new responses everyone agrees with me. Aero77 16:09, 24 March 2006 (UTC)

That would be a particularly foolish assumption. -- Fropuff 19:45, 24 March 2006 (UTC)

Prove me wrong. Aero77 14:23, 3 April 2006 (UTC)

Please see the usage statement at the top of this page. –Joke 22:21, 3 April 2006 (UTC)

I believe this is in full compiance of the usage statement. ;Aero77 12:57, 6 April 2006 (UTC)

Assessment comment

The comment(s) below were originally left at Talk:String theory/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

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)

Last edited at 07:50, 9 June 2008 (UTC). Substituted at 22:08, 3 May 2016 (UTC)