Is String Theory A Waste Of Time?

[Juan R.]

ST can predict much with slight adjustments in the theory.

Like for instance: the internal geometry of the "strings."

Unfortunately, its predictions cover the gamut of current enigmas, which theoretical physicists are loathe to discuss in detail. Probably, for fear their house of cards and their grants and sinecures will fall.

On non-technical article cited above I talk of physical predictions.

In a this year preprint, Giddings even admits that he wait that string theory could not finally predict anything.

Some celebrated string theorists as Susskind begin to accept that the theory
cannot explain anything and this has caused some recent trouble. Susskind
adds:

More and more as time goes on, the opponents of the idea admit that
they are simply in a state of depression and desperation.

The famous “cyber-string” theorist Luboš Motl has recently wrote

Some people really seem to be excited by the very fact that they can
embed a relatively convincing framework into string theory whose
conclusion is that we can't predict anything.

Etc

 

[RandallB]

Fall

I will stand (or fall) on my basic statement.

(Did you miss the phrase, "he set the groundwork"?

That basic statement was; (His Nobel was a "slap in the face"; as, he didn't believe in QM ...)
The issue in 1911 to 1922 was that relativity was controversial, AND he was German; WW1 political issues between Nations etc. that obviously only got worse and these issues affected the Noble Committee.
Not a slap in the face prize, but a reluctant giving by a committee forced to give due to popular worldwide demand for the man and for SR & GR. So, even if they refused to put SR & GR in the award, that’s what really got him there - wide acceptance of his new "scientific innovation".

Yes, the prize highlighted Light as quantum – setting the groundwork from 1900 for Quantum Physics, not Quantum Mechanics. The groundwork for Quantum Mechanics wasn’t set until 5 years later, thus that QM issue with Einstein did not start until after 1925.

I’ll vote for FALL

 

[selfAdjoint]

if I remember correctly, they discovered that traditional quantization is not sufficient 5 years ago

You have said this before. Could you gives us a statement or link to clarify it? Is it light cone quantization you are talking about or something else?

 

[Berislav]

Is it light cone quantization you are talking about or something else?

I don't think he's referring to that. He mentioned something about:

LPS in Gelfand triplets!

in post #32.

 

[brunardot]

That basic statement was; (His Nobel was a "slap in the face"; as, he didn't believe in QM ...)
The issue in 1911 to 1922 was that relativity was controversial, AND he was German; WW1 political issues between Nations etc. that obviously only got worse and these issues affected the Noble Committee.
Not a slap in the face prize, but a reluctant giving by a committee forced to give due to popular worldwide demand for the man and for SR & GR. So, even if they refused to put SR & GR in the award, that’s what really got him there - wide acceptance of his new "scientific innovation".

Yes, the prize highlighted Light as quantum – setting the groundwork from 1900 for Quantum Physics, not Quantum Mechanics. The groundwork for Quantum Mechanics wasn’t set until 5 years later, thus that QM issue with Einstein did not start until after 1925.

I’ll vote for FALL

The intent of intellectual discussion should be that all participants remain upright with a broadened vision.

There was plenty of time before the morning of April 19, 1955 to award a Nobel for SR and GR if the original intent was not a "slap in the face" by the inside academic elite.

Don't forget that for many of these years Einstein detested the cavalierness of Oppenheimer, which was reciprocal if you carefully read "between the lines.".

I raise salient issues throughout this thread and other threads on this forum; yet, everyone attacks minutia and stops/locks large threads without letting me reply; yet, there is a loud "ignore"-ance on the important issues that I raise for discussion.

Am I to understand the salient issues that I raise are accepted without discussion as being correct; and, only the minutia requires tweaking?

Where is sensibility and intellectual inquiry within theoretical physics, which I continue to insist is entirely based on metaphysical concepts of forces and mathematics.

 

[Juan R.]

String theory is a waste of time. Maldacena quote

People, laymen, young undergraduate students are rather wrong about real status of string theory. One reads articles in popular magazines like Scientific American, news on New York Times or simply read methaphysical books by Kaku, Greene, etc. and one say Woh! string theory is fantastic.

But when one take courses, read articles, and study last advances in the topic, non-commutative strings theory, spacetime foam non critical, M(atrix), TFD-Dp-brane theory, etc., one discovers that:

i) many string theorists are very arrogant.

ii) the theory is not sophisticated in a number of points.

In fact string theory is very trivial in a number of aspects. They ignore the work of others and are working in a theory that others know that is childish. For example, in the 60 Nobel laureate for Chemistry Ilya Prigogine developed novel mathematical thecniques that begin to be used on string theory now! But now Prigogine has developed at least three new versions of his old theory. Again string theory is completely outdated, as claimed by many many many specialists.

iii) The "success" of string theory is, on own words of Peter Woit, on public media.

People know string theory but the flaws of theory are always "hidden" on public talks and books. In Elegant Universe you learn about by string theory shows that universe like 4D. But some years after Witten states in an interview that nobody know that (?) and add that string theorists have not reply.

I said during last years that idea of prediction from string theory is completely false. From string theory one can rigorously compute nothing. All claimed exageratios one can derive parts of standard model, or dimensionality of universe, or predicting gravity, or the entropy of Black holes, or obtaining Einstein GR are as follow.

String theory says A = x + y. We know that y = 5.

- Hey guy, what is the experimental value obtained for A?
- 12.

Then x = 7. String theory predicts the correct value A = 12!

Obviously that is not a prediction. And, morever, as denunciated during decades by others theorists, string theory can predict anything and contrary to anything. If experimental value was -12 then they would take x = -17.

I am increasing my personal collections of recent quotes from string theorists. The last is from Maldacena.

I agree with Fredrik that studying the Landscape is very important.
It would be nice to find a smaller number of vacua, so that
predictions are possible.

so that predictions are possible. But 1) nobody has found the correct vacua and cannot predict and 2) last studies show that the number is "infinite", 10^500 or more.

Exceptics of the quote can find it here

http://cosmicvariance.com/2005/07/21/two-cheers-for-string-theory/

 

[Juan R.]

light cone quantization? No thanks!

Is it light cone quantization you are talking about or something else?

I am talking of serious stuff. No Berislav, string theorists are totally outdated. They yet unkown RHS quantization of LPS, that was discussed (if i remember correctly in the Solvay Conference of 1996), i suspect that string theorists will discover that around 2015 or so.

Then, as always they do, will omit all quote to people of conference or in usual literature and call to that string theory. In fact, that is normal unethical phylosophy on that field

string theorists are arrogant enough that whatever comes up in their
research, they will call it string theory.

I was talking of new vector states |Phy>> (which are not Dirac states |Phy>), the new thermal vacuum, the new tilde operation, the new doubled hamiltonian, etc, etc.

On page 10 and 11 of

www.canonicalscience.com/stringcriticism.pdf[/URL]

you will find more information. After use a simply literature engine and learn that material. I am sorry but i have no time now for search literature for you. I am with the translation of material to new sede of the Center.

Moreover, i am preparing an small, rather revolutionary, article for submision (probably Phys Rev letters). If i am correct, and did no error, then this article shows in a convincing form that string theory is completely wrong.

 

[marcus]

I am sorry but i have no time now for search literature for you. I am with the translation of material to new sede of the Center.

Moreover, i am preparing an small, rather revolutionary, article for submision (probably Phys Rev letters). If i am correct, and did no error, then this article shows in a convincing form that string theory is completely wrong.

Hello Juan, what direction are you translating: is it for example Spanish to English? I don't understand your phrase "new sede of the Center", my first guess is that you are preparing a new web-page or a new web-site. Did you mean to write "new site for the Center"?

I wish you success in preparing your article. I hope that you are able to post it on arXiv, in preprint form, so that those of us who wish to can have a look.

the main reason for my posting is that I would like to add two papers to the discussion of the fruitfulness (or barrenness) of string research.

these papers suggest that the answer to your original question could be a QUALIFIED NO. One possible position one could take, it seems to me, is to say that NO, the research would not be a waste of time IF it is directed towards constructing a formulation of string which is BACKGROUND INDEPENDENT.

A possible avenue is offered here
http://www.arxiv.org/abs/hep-th/0503140
A quantization of topological M theory
Lee Smolin
20 pages
"A conjecture is made as to how to quantize topological M theory. We study a Hamiltonian decomposition of Hitchin's 7-dimensional action and propose a formulation for it in terms of 13 first class constraints. The theory has 2 degrees of freedom per point, and hence is diffeomorphism invariant, but not strictly speaking topological. The result is argued to be equivalent to Hitchin's formulation. The theory is quantized using loop quantum gravity methods. An orthonormal basis for the diffeomorphism invariant states is given by diffeomorphism classes of networks of two dimensional surfaces in the six dimensional manifold. The hamiltonian constraint is polynomial and can be regulated by methods similar to those used in LQG.
To connect topological M theory to full M theory, a reduction from 11 dimensional supergravity to Hitchin's 7 dimensional theory is proposed. One important conclusion is that the complex and symplectic structures represent non-commuting degrees of freedom. This may have implications for attempts to construct phenomenologies on Calabi-Yau compactifications."

and an argument that a correct theory of quantum gravity must be background independent (together with a discussion of what this means) is given here
http://www.arxiv.org/abs/hep-th/0507235
The case for background independence
Lee Smolin
46 pages
"The aim of this paper is to explain carefully the arguments behind the assertion that the correct quantum theory of gravity must be background independent. We begin by recounting how the debate over whether quantum gravity must be background independent is a continuation of a long-standing argument in the history of physics and philosophy over whether space and time are relational or absolute. This leads to a careful statement of what physicists mean when we speak of background independence. Given this we can characterize the precise sense in which general relativity is a background independent theory. The leading background independent approaches to quantum gravity are then discussed, including causal set models, loop quantum gravity and dynamical triangulations and their main achievements are summarized along with the problems that remain open. Some first attempts to cast string/M theory into a background independent formulation are also mentioned.
The relational/absolute debate has implications also for other issues such as unification and how the parameters of the standard models of physics and cosmology are to be explained. The recent issues concerning the string theory landscape are reviewed and it is argued that they can only be resolved within the context of a background independent formulation. Finally, we review some recent proposals to make quantum theory more relational."

 

[Juan R.]

Hello Juan, what direction are you translating: is it for example Spanish to English? I don't understand your phrase "new sede of the Center", my first guess is that you are preparing a new web-page or a new web-site. Did you mean to write "new site for the Center"?

I wish you success in preparing your article. I hope that you are able to post it on arXiv, in preprint form, so that those of us who wish to can have a look.

the main reason for my posting is that I would like to add two papers to the discussion of the fruitfulness (or barrenness) of string research.

these papers suggest that the answer to your original question could be a QUALIFIED NO. One possible position one could take, it seems to me, is to say that NO, the research would not be a waste of time IF it is directed towards constructing a formulation of string which is BACKGROUND INDEPENDENT.

A possible avenue is offered here
http://www.arxiv.org/abs/hep-th/0503140
A quantization of topological M theory
Lee Smolin
20 pages
"A conjecture is made as to how to quantize topological M theory. We study a Hamiltonian decomposition of Hitchin's 7-dimensional action and propose a formulation for it in terms of 13 first class constraints. The theory has 2 degrees of freedom per point, and hence is diffeomorphism invariant, but not strictly speaking topological. The result is argued to be equivalent to Hitchin's formulation. The theory is quantized using loop quantum gravity methods. An orthonormal basis for the diffeomorphism invariant states is given by diffeomorphism classes of networks of two dimensional surfaces in the six dimensional manifold. The hamiltonian constraint is polynomial and can be regulated by methods similar to those used in LQG.
To connect topological M theory to full M theory, a reduction from 11 dimensional supergravity to Hitchin's 7 dimensional theory is proposed. One important conclusion is that the complex and symplectic structures represent non-commuting degrees of freedom. This may have implications for attempts to construct phenomenologies on Calabi-Yau compactifications."

and an argument that a correct theory of quantum gravity must be background independent (together with a discussion of what this means) is given here
http://www.arxiv.org/abs/hep-th/0507235
The case for background independence
Lee Smolin
46 pages
"The aim of this paper is to explain carefully the arguments behind the assertion that the correct quantum theory of gravity must be background independent. We begin by recounting how the debate over whether quantum gravity must be background independent is a continuation of a long-standing argument in the history of physics and philosophy over whether space and time are relational or absolute. This leads to a careful statement of what physicists mean when we speak of background independence. Given this we can characterize the precise sense in which general relativity is a background independent theory. The leading background independent approaches to quantum gravity are then discussed, including causal set models, loop quantum gravity and dynamical triangulations and their main achievements are summarized along with the problems that remain open. Some first attempts to cast string/M theory into a background independent formulation are also mentioned.
The relational/absolute debate has implications also for other issues such as unification and how the parameters of the standard models of physics and cosmology are to be explained. The recent issues concerning the string theory landscape are reviewed and it is argued that they can only be resolved within the context of a background independent formulation. Finally, we review some recent proposals to make quantum theory more relational."

Hello Marcus, thanks by your proffesional advice!

First i would apologize by my lasts errors on posts. Since that it is so important for you, let me to say the trick "translating -> moving" and "sede -> 'office'".

No, I do not post it on ArXiv, it was submited.

Let me be highly sceptic of the "QUALIFIED NO".

Even if you obtain a BACKGROUND INDEPENDENT formulation of string theory the reply continues to be not NO.

Thanks by articles, but are not of utility for me. M theory is waste of time and relationism does not work (in fact, it is wrong).

 

[Berislav]

First of all let my apologize for not responding sooner. I've been away and didn't have access to the internet.

You appears rather confounded, I recommend to you The book “Hiding in the Mirror: The Mysterious Allure of Extra Dimensions,” to be published this year by Krauss.

Thank you, but I would prefer a technical account of string theory's suppossed fatal flaws. Pop-science books would make me even more confounded.

You begin from a 4D formulation (initially people did not leave dimensionality unknown) but quantizing the open bosonic string, you obtain the spectral decomposition for the first excited state... etc.

Yes. I think that you will find exactly that after applying the spectral theorem to the operator I mentioned. And like I said I agree with you that this doesn't seem elegant.

I wish you success in preparing your article.

I too wish you success, Juan R.

 

[Telos]

There are many different pursuits within string theory that might be a waste of time, but the basic ideas certainly are not.

But string theory has done something WORSE than be a waste of time. It has been the poster child for a harmful and misleading crusade against young people - that physicists are near the end of their journey and we don't need anymore help thank you very much. Championing string theory via the Elegant Universe to the public while in its current form was shameful and irresponsible.

 

[marcus]

There are many different pursuits within string theory that might be a waste of time, but the basic ideas certainly are not.

But string theory has done something WORSE than be a waste of time. It has been the poster child for a harmful and misleading crusade against young people - that physicists are near the end of their journey and we don't need anymore help thank you very much. Championing string theory via the Elegant Universe to the public while in its current form was shameful and irresponsible.

that's an interesting point of view, Telos. basically you are disapproving of the hype to the public, and not the internal hype and self-indulgence (among initiates) or the over-investment of brain-time. I think quite a few people would agree with you, can't say that I would entirely.

 

[Juan R.]

Thank you, but I would prefer a technical account of string theory's suppossed fatal flaws. Pop-science books would make me even more confounded.

On that book you will find references to modern work.

 

[marcus]

You appear rather confounded, I recommend to you The book “Hiding in the Mirror: The Mysterious Allure of Extra Dimensions,” to be published this year by Krauss.

On that book you will find references to modern work.

Juan you have made me curious. How do you know? Have you seen a draft copy, or some preprint sections, of Larry Krauss' book? Please share what information you have about the book.

 

[Juan R.]

There are many different pursuits within string theory that might be a waste of time, but the basic ideas certainly are not.

The basic ideas also were a waste of time. For instance:

- the idea that a single parameter could be used for predicting all (False).
- The idea of unidimensional strings explaining all (False). The hundred of elementary particles would be reduced to a single string vibrating in different modes (False). M-theory is many times more complex that QFT, with all kind of unobserved objects from pointlike particles (D0) to nine-dimensional objects, passing by membranes, etc.
- The idea of that field theory pointlike behavior was "stupid", a heavy approximation to elegant math of extended objects (False).
- The idea of quantum gravitation WAS a spin-2 perturbation on a classical flat metric (False).
- Etc.

For example, i remain atonished that string theorists have a special facility for hiddeing to public that the formulation of M-theory known is a quantum mechanics of pointlike particles: the D0-branes. The old concept of string -as other extended objects of old theory- arises like an approximation.

 

[marcus]

The basic ideas also were a waste of time. For instance:

Dear Juan, I do wish you didn't SOUND so opinionated. Sure we probably all are opinionated in some ways but we don't express it quite so categorically, and the conversation benefits, I think, from that restraint. But maybe that is just your STYLE and I shouldn't quibble about stylistic oddities.

By the way thank you for informing us about Krauss book, scheduled to come out in just two months (October 20)!

You appear rather confounded, I recommend to you The book “Hiding in the Mirror: The Mysterious Allure of Extra Dimensions,” to be published this year by Krauss.

On that book you will find references to modern work.

I didn't know about this book until you mentioned it just now. I found this on google

 

[marcus]

My goodness!
Following Juan's pointer I went to Amazon and found Krauss book ("the allure of hidden dimensions, from Plato to String Theory") due out 20 october, but I also came across this!



All Strung Out

by Lee Smolin!

For sale at Amazon.co.UK, the price is 19.15 sterling.
Apparently the publisher Basic Books brought it out on 3 July.

 

[Telos]

Juan, I do not think it is a waste of time to show that something is false.

Interesting book, though!

 

[Juan R.]

Juan you have made me curious. How do you know? Have you seen a draft copy, or some preprint sections, of Larry Krauss' book? Please share what information you have about the book.

No i did not see the book. I was informed about him talking with a friend. Moreover, it appears that its publication data has been delayed but i am not sure.

 

[Juan R.]

Dear Juan, I do wish you didn't SOUND so opinionated. Sure we probably all are opinionated in some ways but we don't express it quite so categorically, and the conversation benefits, I think, from that restraint. But maybe that is just your STYLE and I shouldn't quibble about stylistic oddities.

Marcus, i understand that talking about quantum gravity is often a heated debate. But you would appreciate my evaluation of the theory. I am not alone here. Many other scientists have said similar words about string “theory” and lot of them assure like I am doing that string theory is a waste of time, including a previous student that began a PhD on string theory and abandoned the fields because considered that was a waste of time.

You can be sceptic of my evaluation of the theory (that is not a problem for me). But my evaluation is, exactly, that string theory is a waste of time (and money). I could search other words for you but the message would be the same.

You are well-versed Marcus and probably know the history of Albert Einstein, who failed in his search to find a unified theory of forces in the universe, spending the last three decades of his life isolated from the scientific community.

Glashow (the Nobel laureate) said,

So when one person spends 30 years, it's a waste, but when thousands waste 20 years in modern day, they celebrate with champagne. I find that curious.

Einstein unified field theory was a waste of time because Einstein did not follow the scientific method (Einstein ignored experimental data on nuclear forces for instance).

String theory is completely outdated. It is based in concepts and ideas of the 90s. To work in it is a waste of time (and money).

 

[marcus]

Juan, I do not think it is a waste of time to show that something is false.

Interesting book, though!

I see the book Juan mentioned (that amazon says is due out in October) is by the same physicist/cosmologist/popular author who wrote "The Physics of Star Trek" and "Fear of Phyics: a Guide to the Perplexed".

Telos, you are definitely on to something about time spent drawing testable conclusions from a theory so that it may be shown false.

 

[marcus]

You can be sceptic of my evaluation of the theory (that is not a problem for me). But my evaluation is, exactly, that string theory is a waste of time (and money). I could search other words for you but the message would be the same.
...

I am skeptical of the broad way the evaluation is stated. There are several things to say. One is that your opinion is shared (in a qualified way) by a growing number of physicists, for reasons that were mentioned in this earlier PF thread:
https://www.physicsforums.com/showthread.php?t=80760

In this thread, which Ratzinger started in June 2005, some knowledgeable PF people like Haelfix, selfAdjoint, Ohwilleke, concisely reported some reasons why there has been a decline, over the past 3 years or so, in interest and popularity of string research.

Increasing worry and pessimism among string researchers was reflected in the Toronto discussion video.
https://www.physicsforums.com/showthread.php?t=84585
One encounters expressions of disillusion among graduate students---some of whom are changing fields---and symptomatic efforts being made by string-loyal bloggers (such as Motl and Distler) to shore up morale among the graduate students.

We also see some statistical indications of the decline in string interest, popularity, optimism. One can always argue about how to interpret the various statistical measures, however.

I must say that observing this string "downsizing" going on has increased my respect for the honesty and courage of certain researchers such as Andy Strominger. He made an excellent two minute statement in the Toronto discussion at time 1:28:20
It put me in mind of a story in the Bible where a general tells his soldiers that anyone who wants to can go home, and about half of them leave (this is called "downsizing"), then the remaining ones go on to win the battle.

Anyway Juan, I will try to say what I think about your message that string theory is a waste of time.

 

[marcus]

...Anyway Juan, I will try to say what I think about your message that string theory is a waste of time.

1. it doesn't mean anything unless you say FOR WHOM it is a waste of time.

2. increasing numbers of people seem to be deciding that FOR THEM it is a waste of time, and so they are getting out of the field, or they are not writing so many research papers as they did. (However on arxiv I see a growing number of string papers by people at Beijing Normal and other large Chinese universities. These people do not think string is a waste of time for them and they are responsible for an increasing fraction of the research postings.)

3. your statement does not have a clear meaning unless you specify a waste of time AS WHAT. I think a lot of people would agree that string theory can lead to ideas and results that are interesting AS MATHEMATICS.

4. your statement would not apply to a mathematically gifted young person who goes into string and discovers something interesting and valuable AS MATHEMATICS. You cannot say that such a person is wasting their time!
What gives mathematics intrinsic WORTH is the interest it evokes from other mathematicians. It does not need to be a fundamental testable model of nature.

5. however your message, suitably qualified and restricted, is a very helpful one to have expressed---and voicing it actually DOES STRING THEORISTS A FAVOR by increasing the pressure on them to arrive at a nonperturbative background independent formulation that makes falsifiable predictions. This is the only way to be sure that string theorizing is not a waste of time AS PHYSICS.

 

[Telos]

Telos, you are definitely on to something about time spent drawing testable conclusions from a theory so that it may be shown false.

Wish I could say I thought of it myself!

 

[marcus]

Wish I could say I thought of it myself!

the important ideas are like that. you only pass them along, instead of originating them

 

[Juan R.]

As said, I do not think that the decline of string research program is just temporary one. In the past, there were difficulties but now people is seeing that each year original objectives of string theory are far, and far, and farther. String theory history looks like a divergent asymptotic series.

I must say that observing this string "downsizing" going on has increased my respect for the honesty and courage of certain researchers such as Andy Strominger.

Said I the contrary? I am against half-true that many string physicists popularized as the new standard in scientific communication. I am also against arrogance typical of many string theorists (of course not all).

Now, let me reply your very interesting comments.

1. it doesn't mean anything unless you say FOR WHOM it is a waste of time.

I disagree; I provided abundant data in all aspects of the theory (geometry, hidden dimensions pointlike behavior, spectral decomposition, relativity, arrow of time, reductionism, etc.) and already explained that I was talking of string theory like a TOE on post #5.

As said by Nobel laureate P. Anderson this year, string theory is a futile exercise as physics. I substituted “futile exercise” by “waste of time” but my evaluation of string theory continues being correct.

I would state that string theorists provide none serious argument why we would believe on string theory, only bold statements like "it is the most promising way" or wrong claims like "is the only was to quantum gravity". I see an injustice here with people that are not string believers.

2. increasing numbers of people seem to be deciding that FOR THEM it is a waste of time, and so they are getting out of the field, or they are not writing so many research papers as they did. (However on arxiv I see a growing number of string papers by people at Beijing Normal and other large Chinese universities. These people do not think string is a waste of time for them and they are responsible for an increasing fraction of the research postings.)

I am sorry to say this Marcus but this kind of argument is childish. A theory (or hypothesis) is not a “futile exercise as physics” on function of the number of papers or researchers working in it. Or would I remember to you the number of papers in early investigation of perturbative quantum gravity until was shown that QGR was nonrenormalizable on independence of parameter of expansion taken. All previous work in dozens of attempts to quantize GR directly were a waste of time.

3. your statement does not have a clear meaning unless you specify a waste of time AS WHAT. I think a lot of people would agree that string theory can lead to ideas and results that are interesting AS MATHEMATICS.

The premise is obvious when one know why was formulated string theory. String theory is a “theory” of physics. Its main objectives are unification of forces quantizing gravity, systematization of the standard model, and possibly the explanation of some cosmological mysterious.

Has string theory been interesting on mathematical topics? Of course, but that does not justify the hype around it and its study on physics dept. Moreover, let me say that the impact of string theory in the whole of mathematics is not so huge, at least, it is not more important (by orders of magnitude) that impact of some field theoretical techniques. For example, contrary to popular belief, Fields Medal awarded to Witten was not by the application of pure string theory methods to math, most of mathematical work of Witten was from field theory. Atiyah, who is many times more smart and versed that i in these topics, affirms that string theory has had an impact on mathematics which has been really quite extraordinary. Well, he said that in a popular interview. However, far from popular claims, I see not radical advances on mathematics as provided by the own Atiyah on "index theorems" (theory of quantum operators in quantum field theory).

4. your statement would not apply to a mathematically gifted young person who goes into string and discovers something interesting and valuable AS MATHEMATICS. You cannot say that such a person is wasting their time!
What gives mathematics intrinsic WORTH is the interest it evokes from other mathematicians. It does not need to be a fundamental testable model of nature.

Already replied. That young mathematician, if interested in string “theory”, would focus on the mathematical branches below string physical theory, including non-commutative geometry, G2 manifolds, K theory, topology, and news branches of analyses and algebra, etc. Of course, with an eye in the “physical” stuff.

5. however your message, suitably qualified and restricted, is a very helpful one to have expressed---and voicing it actually DOES STRING THEORISTS A FAVOR by increasing the pressure on them to arrive at a nonperturbative background independent formulation that makes falsifiable predictions. This is the only way to be sure that string theorizing is not a waste of time AS PHYSICS.

This is a very, very astonishing simplification of the problem. Background independence is not the magical cure to all problems of string theory. Even if one day a background independent version of string theory is achieved (I doubt), string theory will continue to be a waste of time like a TOE. Moreover, it will continue to be as non-predictive like is now.

Do not forget that LQG is claimed background independent whereas continue to be an “inefficient” approach to quantum gravity. In fact, there is no possibility for obtaining a consistent classical limit converging to GR after of 40 years from Hamiltonina gravity: geometrodynamics, Astherkar QGR, LQG, etc.

Smolin, as others loop theoreticians, assumes that relationism is correct, but it is not as already said. The idea of that causality becomes a fuzzy notion because of fluctuation of light cones is completely wrong.

 

[lightcone]

i am sure strings are going to disappear and first sign of this is the idea os landscape of vacuua. it is such a comic trash that during seminar you feel like quiting physics because such are the things promoted as future directions.

but stringers cannot fool th world much long and more so because some of them are serious researchers with a conscience still alive.

plase read freeman Dyson: disturbing the universe and you will know hy string theory qualifies as a failure.

The problem of delay in this being branded a failure is obvious, INERTIA. there are too many researchers persuing it who are trained as stringers unlike the masters who were all high energy physicists. S now we have this young generation of ignorant people who doesn't even know where to find mistake to stop doing it since they simply do not know physics. It is just poor quality mathematics.

 

[marcus]

i am sure strings are going to disappear and first sign of this is the idea os landscape of vacuua. it is such a comic trash that during seminar you feel like quiting physics because such are the things promoted as future directions.

but stringers cannot fool th world much long and more so because some of them are serious researchers with a conscience still alive.
...

I agree with the respect you show for serious and principled researchers
"...serious researchers with a conscience..."

Public support for physics ultimately depends on the trust that nonspecialists have in the self-critical, "self-policing" ability of theorists to remain engaged with empirical reality. So your perception that there are some who are not indulging in a mathematical escapade is very important.

 

[marcus]

"inefficient"

CDT path integral has not given any signs of being an inefficient approach to quantum gravity, and to the extent that one can compare the two rather different approaches I would say that it is MORE background independent than canonical LQG.

Among tested, well-established theories, General Relativity is the most background independent model we have. When quantizing Gen Rel, it is obvious to try to preserve the B.I. feature if one can. The comparative success or failure of various attempts to do this is not relevant to the validity of the effort.

With both String and canonical Loop experiencing difficulties, one sees that it is actually the most background independent approach that is currently making the most progress.

 

[RandallB]

Marcus
On Strings I feel it’s future may well becoming a waste land. But I believe it has been very valuable in identifying the 11 dimensions issue. Lack of progress indicates that this idea is likely just wrong. But ANY future theory that proves 11 D as wrong, should also be able to explain why the 11 D issue appeared to be viable at all. Just this additional ‘test’ of future theories, I think that can be worth quite a bit.

Also, You mentioned something else I could use a little help on “how I think”

Among tested, well-established theories, General Relativity is the most background independent model we have.

Having never really put it into words before, but I’d though of GM as background dependent. That is with the “warping” of space time was still a manipulation of a background dependent interpretation of space and time.

Your comment tells me I need to Fine Tune my thinking a bit. Does the following make sense:

SR Special Relativity - background dependent
Works on a ‘dependant’ background of space and time in a classical manner. Just the Newton formulas were inadequate and the measures of space or distance over time need to be understood by the better formulas provided by relativity.

GR General Relativity - background independent
The use of a warping of time and space into “space/time’ to understand gravity, releases us from a background dependent measure. That is the physics we see, relativity included, is not dependent on any background traceable measure in either distance. But rather only dependent on the “relationships” between physics events that cannot be tied down to a measurable background reference of space and time.

A fine point but seems an important one I’d not fully recognized.

In a similar fashion :

Quantum Theory - background dependent
Quantized the minimum amount of energy to be found in light “packets” now photons. And set minimum size of change in measure we could expect to ever make in both time and distance (space). Natural limitations associated with this made near impossible to make significant progress until.

Quantum Mechanics - background independent
Instead of “warping” the relationship of time and space, used the uncertainty principal to allow measure and predictions at the quantum level to become understandable.
Thus one way to explain the inability of combining the physics of QM and GR even though they are both “background independent” is that they arrived at their independence in dramatically different forms (warping vs., probabilities) that we so far have been unable to interrelate.
(I'd previously considered not being able to combine the two as a dependent vs. independent issue)

Is this a reasonable tune up to my thinking?
Let me know if I’ve gone off track on the “background” issue as it is a bit new to me.

Also are there any other “well-established theories” that arrive at their background independence though some other manner than GR or QM? I’m assuming that most all, like M-Strings, have their foundation in QM.

Thanks
RB

 

[marcus]

Marcus
On Strings I feel it’s future may well becoming a waste land. But I believe it has been very valuable in identifying the 11 dimensions issue. Lack of progress indicates that this idea is likely just wrong. But ANY future theory that proves 11 D as wrong, should also be able to explain why the 11 D issue appeared to be viable at all. Just this additional ‘test’ of future theories, I think that can be worth quite a bit.

Also, You mentioned something else I could use a little help on “how I think”

Among tested, well-established theories, General Relativity is the most background independent model we have.

Having never really put it into words before, but I’d though of GM as background dependent. That is with the “warping” of space time was still a manipulation of a background dependent interpretation of space and time.

Your comment tells me I need to Fine Tune my thinking a bit...

this is a sign we need a link to basic Differential Geometry primer where the idea of a "differentiable manifold" (often a "smooth manifold") is defined

does anyone have an Intro to D.G. or Intro to Manifolds link?

Randall there are two abstr. math. ideas you need that are actually very simple and easy to get-----Manifold and Metric-on-the-manifold.

For 150 years the fundamental paradigm for a continuum that everyone uses is a Manifold (defined by Riemann around 1850).

the most common meaning of B.I. is you start with a Manifold without a metric.

in a B.D. theory you start with a manifold and give yourself a metric on it to start with as well

have to go back later

 

[marcus]

Randall it is soooooo simple. I wish you would take a moment and think it over and come back and say honestly that you understand perfectly clear as day.

the reason we accumulate math concepts over the decades is ultimately MENTAL ECONOMY. they make thinking more efficient. and this is a case

the fundamental object in D.G. is the manifold which corresponds to the idea of a continuum without geometry. it is a blob that has coordinate functions defined on it
(local charts that are smooth and compat where they overlap)
but does not have any dingus or appliance that can tell you the distance between two points

because it has coordinates, at any point on the manifold you can explore all the possible directions in which you can take the derivative!
All the possible DEE-EXES, and when you think calmly and patiently about this for a while you realize that this collection of all possible dee-exes IS the tangent space. it captures the essence of what we want the tangentspace at any give point to do for us. and it is intrinsic (defined without reference to anything surrounding the manifold)

this is a fundamental Idea of Western Civilization, like the freedom of the individual and the rule of law etc. this is the Idea of the Continuum which has been standard for 150 years

It is INTRINSIC. it doesn't have to be embedded in any larger space for you to know its tangent space at each point and be able to do calculus etc, and it STILL HAS NO IDEA OF GEOMETRY built in.

to do geometry you introduce a "metric" gizmo which is a bi-linear dingus defined on the tangent space at every point blah blah
and once you have a metric g(m) defined at every point m of the manifold then you can compute distances, angles, areas, volumes etc.

The most common meaning of B.I. is that you start with a manifold without a metric.

In Gen Rel you start with a 4D spacetime manifold and some matter and you set up this equation and Presto! you PULL THE METRIC OUT OF THE HAT! (EDIT: selfAdjoint objects to the wording. I mean that you solve for the gravitational field, which is the metric. more discussion of details of this in later posts...)

the metric, or geometry, can be totally freeform and it is determined dynamically by interaction with matter through the equation of the model.

This is VERY DIFFERENT FROM perturbative STRING THEORY where they start with a manifold that already has a prior-chosen metric defined on it.
Having a prior chosen metric let's you define the twangy equation by which the little thangs be vibratin'. Without that prior metric you got nothing to start with, stringywise.

 

[selfAdjoint]

In Gen Rel you start with a 4D spacetime manifold and some matter and you set up this equation and Presto! you PULL THE METRIC OUT OF THE HAT!

That's not quite right. You don't need the matter, it's strictly geometry. You don't pull the metric out of a hat, you introduce it as a general symmetric quadratic form, the coefficients of which turn out to form form a symmetric rank two tensor. This is just a generalization of Pythagoras's (or Lorentz's) rule. You can then express the very special connection (Levi-Civita) in terms of derivatives of the metric tensor, and from the connection coefficients you define the curvature tensor (Riemann-Christoffel tensor). In Riemannian geometry the metric comes before everything else.

 

[marcus]

the fundamental string stumbling block is that in over 20 years nobody has succeeded in doing string without prior-choosing a metric

but to truly do Gen Rel you cannot choose the metric because geometry is a dynamic thing that comes out of the model----the geometry of the manifold is gravity and you do not stipulate it in advance

in standard vintage Gen Rel the gravitational field IS the metric g(m)
and it is what you solve for
it is the unknown distance function that the Einstein equation is about.

this is the basic obstacle that string research has always been up against

----------------------------

an amusing behavior of string theorists, which you can see recently over at the Coffee Table blog, is that whenever anybody reminds them of this major roadblock they immediately start talking defensively.

they don't stop, take a breath, and say "Yes that is right, we really need to put some effort into a nonperturbative, background independent formulation!"

Instead, they start making excuses and talking about the INADEQUACIES OF LOOP which is really irrelevant. They get into this complicated distracting discussion about how String "really" doesn't need to be B.I. and how it "really" is B.I. (if you define B.I. right) and how Loop is not "really" B.I. (if you define B.I. a certain way), and sometimes they start complaining that it isn't NICE of anyone to point out this defect because it might give non-experts the idea there was something wrong.

We just had an example of this at a couple of stringy blogs this month when folks were reacting to Smolin's paper "The Case for Background Independence". That paper was friendly advice, and the reaction was defensive, as if it were an attack. Check this out:

http://golem.ph.utexas.edu/string/archives/000621.html

I am waiting for someone like Andy Stromiger (who I suspect has guts) to come out with a clear statement on this and say "yes we need a B.I. formulation that we can really calculate with, and we ought to give his high priority and work on it, and we can do it"

 

[marcus]

... In Riemannian geometry the metric comes before everything else.

I agree totally. what I mean by pulling the metric out of a hat is that you SOLVE for the metric.

all the terms in the equation are defined based on the metric, so the metric comes before all that other stuff---curvature tensor like you say.

the idea I am trying to get across is somewhat simpler and more basic:

the gravitational field IS the metric
you don't start off knowing the metric
you SOLVE for it


exactly as you say, part of solving for the metric is going through stuff like the Riemann-Christophel tensor whose definition is based on the metric

thanks for adding some clarification, selfAdjoint.
would be great to have some standard links to basic D.G.
and a standard exposition of what B.I. is about
I appreciate your help