Causes of loss of interest in String program

tom.stoer

There's a vicious circle:

First many reseach program like string theory or LQG have serious physical problems (work-in-progress for decades, non-uniqueness, not testable at low energies, ...).

Second some physicists think that discussing these problems weakens the position of the research program; Lubosz is a famous example. That results in supressing discussions and therefore hinders, slows down or even stops progress of science.

Third (and this is a kind of self-fulfilling prophecy) unfairly dismissing objective criticism strengthens the position of the critics. Woit and Smolins books are the best examples; they exist simply due to the fact that certain discussions have not taken place. They cause more harm than a prior open discussion would have done.

So in there very end research programs and communities with blind spots are not able to address these blind spots; they remain as a thorn in the flesh; they do not go away simply by ignoring them.

Please have a look at the early decades of quantum mechanics. Almost every position was wrong or inconsistent; nearly every two of positions were contradictory, nearly every correct result was pure luck. But these decades with their substantive discussions were necessary in order to construct the final theory. One reason why we do not make more progress today is that we always insist on the fact that we are right and the other party is wrong and that we do not listen. This is b...sh.. With some distance - as I am not directly involved in string theory nor LQG - I have to state that many discussions (some of them unfortunately here in this forum) are infantile.

Nature is the laughing third - and believe me, nature it is not made of strings or loops; both programs (as of today) are far from being able to provide the ultimate answer. But they have a certain value which could very well rest in their failure rather than in their success.

negru

Right, however the problem is that Marcus always tries to portray an image of the string program which is completely disjoint from reality.

tom.stoer

I am not so sure; I think he simply follows and continuously criticizes a way taken by a small minority of string theorists.

marcus

Thanks Tom, excellent points! Emotional ad hom defensiveness is just another symptom.

There is, I think, some factual and useful information in this thread (and related ones) of a sort that our string-friends would do well to heed.

All the defensive noise tends to drown out the information content, so I will try to recall and summarize a few essentials.

marcus

I think any objective observer realizes that the String program is in a period of difficulty and is in flux. There is, for the time being, no clear direction.

It does not hurt the program to acknowledge this, and try to understand it. We are not playing some "I'm better than you" game of scoring prestige points. A better understanding can actually help.

I would like to understand the reasons. I can't discover them by myself although I have some guesses and suspicions. Some of the discussion in the "real disappointment" has shed unexpected light on underlying physics issues.

atyy

As we now know from relative locality, marcus is in his own momentum space with respect to "an objective observer of string theory."

marcus

Heh heh, by the principle of relative locality, so is each one of us including you, Atyy
ABJM? Anybody for twistors? Anti-deSitter condensed matter?

One trouble seems to be that the mirror in which String looks at itself is broken into many pieces.

String experts have decided after several decades experience that one should NOT think in terms of strings and branes in a geometry with compactified extra dimensions. What is the theory if one discards the central paradigm?

atyy

Yeah, but actually I'm searching for relative nonlocality

marcus

Tom, I'm curious. What is this "way taken by a small minority"?

I realize there is a general trend to abandon compactified extra dimensions, but I don't criticize this. I am actually glad to see it!

Pointing out that the program is troubled is not the same as criticizing some line of theoretical development. I don't criticize trends I see today, like getting away from explicit string/brane models. I welcome several of these visible research trends.

Maybe what you meant by the "minority way" was Anthro Landscape Multivism , but I suspect that is largely dead among the researchers now and is mainly pop-market fodder. I heartily deplore it but don't waste much time criticizing it.

My main concern is not with criticizing individual research gambits (some of which I actually welcome!) but with the fact that the program seems to have lost an overall Gestalt and direction. It needs to find its way.

fzero

You keep saying this, but your evidence is scant. With all due respect to surprised, both Haelfix and I have explained several times now how CY compactifications are thought to be universal in the space of critical superstring CFTs. You will find very few string theorists that have "discarded the central paradigm," which is tied to a mathematical construction and particular interpretation of the degrees of freedom that it represents. At the same time, it is no doubt worthwhile to also study different formulations to find other consistent string theories. So far as I can tell from the literature, many of these theories are probably related to CY compactifications, though the connection is not as well established as for standard Gepner models. Many of the ones which are not have physically undesirable properties, such as massless fractionally charged particles.

It may very well be that there is a description of nonperturbative degrees of freedom in which spacetime geometry is less fundamental. This would not invalidate the CY description at scales sufficiently below the string scale, though it might cause us to reassess whether or not there is any physical limit in which extra dimensions are large. If there is no phase of the universe in which they are large, then it probably doesn't make sense to call them true dimensions, but we can still use the techniques of CY geometry where they apply.

marcus

Thanks fzero! I think what you are showing me is that it is controversial. Many in the String program (but not all!) have concluded that strings/branes in compactified extraD are the wrong way to go. I can't say which POV is in the majority and maybe that does not matter.

You commented about evidence. Here is some supporting evidence. This is a sample of famous stringsters whose names just happened to occur to me and to PAllen. I didnt look at their papers first before deciding to put them on the list. DESY librarians make a professional classification of papers---they decide which papers to tag "string model" and "membrane model". The indication is that the top people USED to write papers explicitly involving strings/branes and that they do that much less. Not HARD evidence, but a suggestive straw in the wind.

This seems to support what a respected Pro said here earlier about "many" String people. I'll not paraphrase since I might unintentionally err. But I would say this suggests that among the top people there has been a huge shift out of explicitly string/brane research proper. If you want the Spires links, go back to post #63.

One wants to ask how one characterizes what these people are working on NOW. Is there a coherent form and direction to it? What is the String program about if you ditch parts of the core paradigm?
Or "de-emphasize" if you prefer.

I can't avoid noticing that the big decline happened 2003-2006, which is also when there was a huge drop in overall String-of-any-kind representation in the Spires Top-cite Fifty.

And those sharp drops happened right after the 2003 KKLT paper and Susskind's IMHO panicky reaction to it. There could be no connection but it could be argued that these things that surfaced in 2003 MIGHT have something to do with those changes in research focus and ratings.

fzero

This is incorrect. There are a handful of groups studying alternatives and much of the results in this direction are by two separate groups involving Faraggi and collaborators and Schellekens and collaborators. The vast majority of model building papers focus on CY compactifications (the U Penn and Lust groups are representative).

I've tried to explain multiple times why the DESY keywords cannot be completely trusted. In some cases they are correct, in others they are misleading. Since I was looking at recent Lust papers, here's another example: Direct Production of Lightest Regge Resonances. The paper is a model-independent analysis of production of the lightest massive string states in intersecting D-brane models. DESY has chosen not to label it as "string model" or "brane model," though it is certainly objectively within one or both of those classes. There is no substitute for having an expert actually looking at the paper to decide what it is about. As far as I understand the DESY process, this is supposed to be done to some extent, so perhaps the errors are due to a subjective analysis of the best N keywords and others are left off.

In any case, DESY keywords not withstanding, many string theorists are working on topics such as AdS/CFT that are not model building, or otherwise exploring topics in gauge theories that may or may not be string inspired. The best that can really be said without asking these people directly is that they're working on topics which are more interesting and directly productive for them than others. The choice of research topics is often not decided by which are the most important problems, which are usually very difficult, but also by the requirement to publish, both to secure funding and jobs for younger collaborators. Also, most ideas do not survive to be published. Looking at publications does not show you what topics were pursued and abandoned as incorrect or incomplete.

Since most physicists do not publish their thoughts on broad topics not directly related to their technical publications, it isn't possible to rely on paper titles or DESY keywords to tell what they think. As I've mentioned previously, one place in which physicists do lay out their broad beliefs is in grant applications. Most of the NSF funded proposals are a matter of public record, so you could look some of those up and see if there's evidence there that most string theorists have abandoned the possibility that strings might be the correct description of nature. I believe that the vast majority of these grants will include language such as "string theory remains the best candidate for a theory that unifies general relativity and the Standard Model of particle physics," independent of what precise topics are being directly proposed.

fzero

In post #24, I made a detailed analysis of Witten's publications, being very conservative about which papers should be considered string theory. There was no evidence that he had shifted out of string theory.

You are free to quibble over what constitutes string theory proper by using some keywords that are associated to model building papers. In this regard, the vast majority of papers since 1995 are not about string theory proper. Even the string duality papers of 1995 and beyond were not strictly about model building, but were about much more abstract topics.

I'm sure that you would see a similar phenomenon if you were to study lattice gauge theory papers over the last 2 decades. A certain reasonably large fraction might be about explicit calculations of hadronic mass spectra, but an equally large fraction would be about technical details or unphysical nonphenomenological models that still have something to teach us about harder problems.

marcus

No indicator is perfect. I see a huge decline and I doubt that there is a conspiracy on the part of the librarians to engineer a systematic misclassification.
This is informal of course---suggestive straws in the wind that can contribute marginally to trends many of us acknowledge.

==quote fzero==
... many string theorists are working on topics such as AdS/CFT that are not model building, or otherwise exploring topics in gauge theories that may or may not be string inspired...
==endquote==
RIGHT! Thanks for acknowledging this!

This is a large part of the point I wanted to make in this thread. There has been a major shift in research activity---sometimes I refer to it as research "interest" but what I'm looking at is objective stuff like citation counts and papers written and what topics get featured at the annual Strings 2010 or 2011. At least quality-wise, in terms of highly cited papers, there has been a decline of activity in core areas of the program.

Naturally one wants to know why. And what the new picture is that is taking shape.

I see that you have offered some reasons for the shift of research attention by "many string theorists". This is just the sort of thing that I was looking for in this thread---hopefully some objective physics reasons, but basically any kind of cause whatever that may have contributed to the observed change.


BTW may I assume you mean the grant requests that people put in for funding? Not the grants themselves but the grant proposals?
==quote==
I believe that the vast majority of these grant [proposals] will include language such as "string theory remains the best candidate for a theory that unifies general relativity and the Standard Model of particle physics," independent of what precise topics are being directly proposed.
==endquote==

fzero

Like I said in my other post, even many papers written from 1995-2000 probably do not fit into the narrow area of string theory proper that you want to apply to recent papers. If you wanted to discuss a couple of papers for comparative purposes, I could probably help. Otherwise it's hard for an expert to objectively say that a particular paper on say heterotic/type II duality is more or less a core string paper than one that examines a new facet of the AdS/CFT correspondence. Neither one is probably telling us that there are three generations of matter or what the electron mass is, but both are probably saying something deep about the core theory anyway.

Yes, if you go to http://www.nsf.gov/awardsearch/ you can obtain information about grants awarded. This includes the investigators, the institution, and the abstract included in the grant proposal, among many other sundry details. Full proposals are not distributed (which would contain details of ongoing research that should really be kept confidential for many reasons), but the abstracts are probably still useful for the suggested purpose.

unusualname

yawn, yet more attacks on marcus and his perfectly reasonable attempts to portray the modern research programs in fundamental physics,

geez, you string guys had your time, we got it, fundamental reality might be 1d oscillating strings, or it might be 0d branes (ie points ala feynman e^i.theta) or it might be higher dimensional branes.

yawn again. maybe you're just partially correct like everybody else, maybe all that oh so friggin difficultly constructed mathematics will fit in , but it's a convoluted way to construct reality.

Just sayin'

smoit

It does not matter for him, fzero! He'll keep ignoring this point over and over and over again because it does not fit his agenda. He'll copy and paste a part of your response that he finds useful to promote his propaganda. Marcus has reposted his "data analysis" about 10 times now, while fzero's much more careful estimate is buried in the middle of the thread. This is a classic strategy - "If you repeat a lie often enough, it becomes the truth." The end result is that some lay people will be left with impression that there is indeed some decline, not because Marcus is right, but because he's better at repeating the garbage. At the same time, in a different thread, Marcus is promoting an idea that some papers on the theory of angular momentum, computing 12j and 15j symbols, constitute research on LQG . Any well informed person realizes how ridiculous that is but it does not matter.

They do not confront what? The positive cosmological constant? Have you ever looked at the title of the KKLT paper, which came out in 2003? FYI, it it called "de Sitter vacua in String Theory".