Has string theory been totally written off?

[pivoxa15]

How likely is it that string theory will be the final complete theory? I've heard lots of negative things about it. Has it been totally written off? Has it been reduced to a maths theory only?

By string theory I mean all the versions of it like superstrings etc.

 

[marcus]

How likely is it that string theory will be the final complete theory? I've heard lots of negative things about it. Has it been totally written off? Has it been reduced to a maths theory only?

By string theory I mean all the versions of it like superstrings etc.

Has it been totally written off as a source of partial answers? Certainly not!

You probably have been hearing about planned CUT-BACKS. The government funding advisory panel HEPAP just issued a report indicating that US physics departments planned an overall cutback of 20 percent in the number of string theorist faculty over the next five years---that is between now and 2012. For more info see Figure 3 on page 43 of the High Energy Physics Advisory Panel report
http://www.science.doe.gov/hep/ugpsreportfinalJuly22,2007.pdf

This is not "negative things" about stringy philosophy (there is no one string theory but rather a bunch of related approaches, as you indicate: many versions). What benefits a line of research is not always identical to the material welfare of some particular group of persons.

A cutback might turn out to be highly beneficial to string theoretical development!
Hopefully if the planned downsizing occurs it will shake out mediocre people selectively and give the creative and resourceful ones more to do.
=======================

How likely is it that string theory will be the final complete theory?

It would be naive and foolish of anybody to try to estimate the probability of that. there are various approaches to unifying particle physics with the theory of spacetime geometry and since nobody knows which will eventually contribute part of the solution, or prove to have something to do with nature, the natural thing is to spread your research bets. Europe, Canada, and the UK are somewhat ahead of the US in getting a diversified multipath approach going, but the US will probably be following suit.

Again, having competing approaches supported will not necessarily be bad for string development, on the contrary it might help it move forward.

However about "final" and "complete" you might want to read what Brian Greene currently is saying about that. He seems to think that it was unfortunate that string was ever claimed to offer that prospect and basically says that mentality was "youthful exuberance" from back in the 1990s. You should read that recent Edge interview and especially what Brian Greene says, to get a more solid up-to-date picture. I will get the link for you.

Here's a PF thread discussing the September 2007 Edge interview
https://www.physicsforums.com/showthread.php?t=185954
Here's the interview itself
http://www.edge.org/3rd_culture/einstein07/einstein07_index.html

You can see that in no sense does Greene actually "surrender*", what he does is redefine the string support position.
Since he is one of the most articulate and aware people doing that, it is important to read carefully what he says.

*I think "surrender" was merely a humorous expression referring to the way he is caught off-guard and basically says "duh" at one point in the conversation---if it were a fencing match, he would accidentally drop his foil at that point and have to stop and pick it up. But that is just some comedy, not the main content of the dialog.

 

[marcus]

Pivox,
you may be confused about something. Nowadays I think an intelligent string supporter like Brian does not talk about prospects of FINAL AND COMPLETE
because he recognizes that as hype that damages string community interests.

Here is that pivotal interview again
http://www.edge.org/3rd_culture/einstein07/einstein07_index.html

I suppose you could say that earlier string hype has in some sense been "written off".
But the research activity ITSELF has certainly not been written off that would be ridiculous. I am delighted to see it continue (with a reduced number of researchers.)

to illustrate, last year Ed Witten came out to Berkeley and gave three talks, each about 90 minutes, on what he is interested in and working on these days. I attended all three---it was really a long talk divided into three parts. He never once mentioned string theory.
Then at the very end, in the questions session after the third talk, someone in the audience asked "What about string theory?" Witten said he believed that it would turn out to "have something to do with nature."

he did not elaborate. the message was clear----dont offer people FINAL and don't offer people COMPLETE. We are not talking about something unique and ultimate. We are talking about what is possibly one step along the way.
The "only game in town" message is out the window, IMHO. Being realistic is the best policy, and so forth.
====================

We sometimes get a certain amount of whining when it is pointed out that the "only game in town" business has been largely discarded and things are on a different footing.
It is considered hostile to mention that there are now other interesting approaches to unifying particle physics with dynamical geometry (gravity). I don't think it is hostile but people whine and complain mightily all the same I just put this on ignore.
====================
What I hope is not that string research would be "written off" but that we may be able to move to a situation in the US that is more like what they have at Perimeter Institute.
There you have string theorists and non-string QG people busily at work in neighboring offices. But that is Canada. In the US, string is still dogging the manger and there's still a ways to go to catch up with the rest of the world.

 

[josh1]

]

How likely is it that string theory will be the final complete theory? I've heard lots of negative things about it. Has it been totally written off? Has it been reduced to a maths theory only?

By string theory I mean all the versions of it like superstrings etc.

The truth is - as you can verify just by visiting the webpages of university physics departments all around the world - confidence in string theory among physicists remains extremely high and has been and continues to be the mainstream approach to quantum gravity. It is also the only approach that unifies all the interactions, including gravity. In fact, it is so mainstream that a growing number of string theorists (this was edited from the original word "physicists" to prevent a misunderstanding as per ZapperZ's concern) believe it no longer makes sense to make students wait until they enter graduate school to learn string theory and so a growing number of top univesities are offering courses in string theory at the undergraduate level. These include for example, MIT, Stanford, Carnegie Mellon, and the University of Toronto. There has also been an explosion of textbooks on all aspects of string theory.

There is NOTHING like this happening with any of the other approaches. You must be careful to remember that these forums are not reliable dispensers of information about string theory because of the way that the whole field of quantum gravity and high energy theory has been heavily politicized in the public arena which has nothing to do with what is actually going on in physics. The bottom line is that if you want to understand twenty-first century research in quantum gravity and high energy theory (this was edited from the original word "physics" to prevent any misunderstanding as per ZapperZ's concern), you must learn string theory. If you want accurate information, take a look at the introductions of any of the textbooks on string theory published in the last year and also go to the websites of the physics department of any of the top (or almost any)universities to find the email addresses of graduate students or faculty doing string theory and just ask them or read about the descriptions of their research often written for a lay audience or undergraduates.

 

[ZapperZ]

]

The truth is - as you can verify just by visiting the webpages of university physics departments all around the world - confidence in string theory among physicists remains extremely high

I don't know how you draw such a conclusion, since the APS and AIP never polled physicists regarding their views of String Theory. In fact, I'd say that the majority of physicists in condensed matter (and I am one of them) would say that they find the rabid popularity in String Theory to be extremely puzzling based on how we do things in physics and especially condensed matter. Prominent physicists such as Phil Anderson and Bob Laughlin have, in fact, belittled the utter devotion to String theory.

Note that I'm not arguing here about the validity or lack thereof of String. I am countering your claim that physicists, in general, have "extremely high ... confidence" in it. This is utterly false.

Zz.

 

[josh1]

...I'd say that the majority of physicists in condensed matter...would say that they find the rabid popularity in String Theory to be extremely puzzling...

I meant the experts in this sort of physics. But it sounds like you disagree with marcus and agree with me. He likes to post that the interest in string theory is waning and the field is in some sort of malaise. Yet you - a physicist - characterize the interest in string theory to be "rabid". I wouldn't use the term "rabid" because it suggests that the experts in this field are irrational and that hasn't been my experience. But I do know that string theory continues to be a vibrant and exciting field, and also the one that most of the people in quantum gravity and high energy theory have the most confidence in. My personal opinion is that people would never get that impression from the way that marcus frames his posts. Note that I'm not actually defending string theory. I'm just saying that when people ask what are the ideas that dominate this field of physics, the correct answer, for better or for worse, are those that come from string theory.

 

[ZapperZ]

I meant the experts in this sort of physics. But it sounds like you disagree with marcus and agree with me. He likes to post that the interest in string theory is waning and the field is in some sort of malaise. Yet you - a physicist - characterize the interest in string theory to be "rabid". I wouldn't use the term "rabid" because it suggests that the experts in this field are irrational and that hasn't been my experience. But I do know that string theory continues to be a vibrant and exciting field, and also the one that most of the people in quantum gravity and high energy theory have the most confidence in. My personal opinion is that people would never get that impression from the way that marcus frames his posts.

No, I do not agree with you. The "rabid interest" in string theory are within those who are in that field. It isn't anywhere near rabid outside of it. I've just illustrated to you 2 Nobel Laureates in Condensed Matter who are not just "unrabid", but downright hostile towards string theory.

Saying that people who are already experts in string theory have "extremely high confidence" in it is saying nothing. That's like saying Fleishman and Pons have "extremely high confidence" in their cold fusion. Well of course they do! However, physicists in general are not that enthusiastic on it. And last time I checked, those who are working in String theory comprise of a very small fraction of the number of practicing physicists.

So I would strongly caution you next time you make any statement about physicists in general.

Zz.

 

[josh1]

Okay, ZapperZ. Please take a deep breath because our lines seem to be seriously crossed here.

No, I do not agree with you. The "rabid interest" in string theory are within those who are in that field.

I am saying that marcus is wrong when he intimates that somehow people in quantum gravity and high energy theory are in the process of giving up on string theory. This is untrue and that is my point. Whether their interest in string theory is “rabid” is a matter of personal opinion, and I characterized mine as such.

It isn't anywhere near rabid outside of it. I've just illustrated to you 2 Nobel Laureates in Condensed Matter who are not just "unrabid", but downright hostile towards string theory.

I’m not arguing anything one way or the other about condensed matter physicists or the public. That is not the issue for me. It is marcus who is always talking about the importance of public opinion, not I. Most recently loop quantum gravity took up this issue with marcus, but without success.

Saying that people who are already experts in string theory have "extremely high confidence" in it is saying nothing.

So what expression would you substitute for "extremely high confidence"?

That's like saying Fleishman and Pons have "extremely high confidence" in their cold fusion. Well of course they do!

Again, I don’t disagree (well, maybe I disagree a little bit). As I posted, I’m not assessing string theory, but rather only the attitude of string theorists towards it, and in my opinion it is more positive than some of the posts around here might suggest to those who don’t know any better.

However, physicists in general are no that enthusiastic on it.

As I said, I’m not talking about physicists in general. However, my opinion is that physicists in general tend not to worry themselves one way or the other about string theory.

And last time I checked, those who are working in String theory comprise of a very small fraction of the number of practicing physicists.

Again, this is irrelevant to the point I’m trying to make.

So I would strongly caution you next time you make any statement about physicists in general.

Again, there was no intention on my part to make claims about physicists in general.

Perhaps I should caution you?

 

[ZapperZ]

As I have expected, the main point that I made in my earlier posting is lost. Note the post that you made to which I was replying to:

]

The truth is - as you can verify just by visiting the webpages of university physics departments all around the world - confidence in string theory among physicists remains extremely high and has been and continues to be the mainstream approach to quantum gravity. It is also the only approach that unifies all the interactions, including gravity. In fact, it is so mainstream that a growing number of physicists believe it no longer makes sense to make students wait until they enter graduate school to learn string theory and so a growing number of top univesities are offering courses in string theory at the undergraduate level. These include for example, MIT, Stanford, Carnegie Mellon, and the University of Toronto. There has also been an explosion of textbooks on all aspects of string theory.

There is NOTHING like this is happening with any of the other approaches. You must be careful to remember that these forums are not reliable dispensers of information about string theory because of the way that the whole field of quantum gravity and high energy theory has been heavily politicized in the public arena which has nothing to do with what is actually going on in physics. The bottom line is that if you want to understand twenty-first century physics, you must learn string theory. If you want accurate information, take a look at the introductions of any of the textbooks on string theory published in the last year and also go to the websites of the physics department of any of the top (or almost any)universities to find the email addresses of graduate students or faculty doing string theory and just ask them or read about the descriptions of their research often written for a lay audience or undergraduates.

No where in what I have highlighted above were you referring specifically to those who were working in string theories, or you would have stated as such. If you don't know how to make a specific reference to them, they are called "string theorists", not just "physicists". Considering that you were trying to uphold the "truth" in that post, I'd say that if I didn't challenge what you have said here, someone else reading this would have thought that physicists in general have extremely high confidence in string theory. So how high of a degree of "truth" do you think such an impression is, especially considering that only a SMALL minority of physicists are actually working in that field and thus, are "extremely confident" in it?

Zz.

 

[josh1]

I'd say that if I didn't challenge what you have said here, someone else reading this would have thought that physicists in general have extremely high confidence in string theory.

Okay, this I understand. My response to you that I meant only string theorists was true. I should've edited my post to avoid any misunderstanding. I have now done so and indicated what was edited and why. However, at the end of that post I did say that:

“If you want accurate information, take a look at the introductions of any of the textbooks on string theory published in the last year and also go to the websites of the physics department of any of the top (or almost any) universities to find the email addresses of graduate students or faculty doing string theory and just ask them or read about the descriptions of their research often written for a lay audience or undergraduates.”

So how high of a degree of "truth" do you think such an impression is, especially considering that only a SMALL minority of physicists are actually working in that field and thus, are "extremely confident" in it?

Even though they are a small minority, I think if you want to understand the reasons why string theory is worth pursuing, the place to start is with string theorists and not with condensed matter physicists (even nobel prize winning ones) or the public or polemicists like smolin or woit (or, IMHO, some of the members posting in this forum who habitually violate the spirit, if not the letter, of the posting guidelines).

Btw, besides researchers in QGHET (quantum gravity and high energy theory), who do you believe should be involved in deciding what kind of funding string theory should receive?

 

[pivoxa15]

The main negative thing I've heard about string theory is that it is like a maths theory where you have to put data of our universe to get data of our universe. i.e It dosen't tell us new stuff about our universe like QM or GR does. So string theory is like a maths theory like calculus rather then a physics theory. SO it is unfalsifable like calculus isn't. People like Lee Smolin could have addressed these problems. So it seems like a fundamental problem in that regards.

 

[Demystifier]

There are two kind of physicists: Those that dream about the final theory of everything and those that don't. For the first group, the only hope at the moment to make their dream true is string theory. That is why they do it. Dreamers may be only dreamers, most of dreams never become true. Still, the most valuable achievements in the history of mankind was done by dreamers. The mankind needs them too.

 

[Fra]

> Can string theory (still) be the final theory?

Since string theory currently isn't a complete theory, it's a framework without as it seems without a clear method of evolving models, it begs the question what "string theory beeing a final theory" means in the first place? It seems that at minimum, something is missing.

Could the string framework finally *evolve into something* that might qualify as a TOE or TOE-like thing? It seems to me foolish to reject such a possibility, but the question is how much such a final thing would have in common with "string theory" as we know it now, and it would still count as "string theory"?

The first question I see is to decide in what direction where to invest further research to make sure we get most benefit out of the investments. At least for my tax money, I'd like to see more fundamental research which is less speculative. More focus on information theoretic appraoches combined with adaptive models.

I think there are interesting elements of string theory, but I think it needs a better and deeper foundation, and be completed with a method of discriminating between generated possibilities. It's too much ad hoc and arbitration to please a philosophically inclined mind.

/Fredrik

 

[arivero]

Final theory is an excessive label; what we dream of, is of a theory able to calculate most of the parameters the standard model has left free. But, most of these parameters are about the electroweak symmetry breaking, the only hope to use modern Planck scale string theory to calculate these is to get an accurate description of the GUT content and then to run all the yukawa couplings down to electroweak scale. This hope seems to be in danger.

I proposed recently (other post, last week) to abandon Planck scale and to try again string theory as a theory of the interactions in subnuclear energies. If in this way, or similar ways, we get some prediction of standard model parameters, I will be happy with strings even if they are not the final theory including gravity.

 

[ccdantas]

I believe any truthful physicist in the world is highly interested about a 'final theory of everything' in one way or another. But indeed there are only 2 groups of them: those who are able to work towards it and those who aren't (be it because they don't have the chance to, are unqualified to, or do not wish to).

 

[ccdantas]

Final theory is an excessive label

I agree with you. That's why I used ' ' in my previous post.

 

[josh1]

Final theory is an excessive label

Excluding those who've for whatever reasons decided to worship the "god of there can be no final theory" (or the "god of there can be no final theory named string theory"), given that there are only four fundamental interactions that we know of and that string theory includes all of them in a unified way, I do not think the label "final theory" is irrational.

 

[arivero]

Excluding those who've for whatever reasons decided to worship the "god of there can be no final theory" (or the "god of there can be no final theory named string theory"), given that there are only four fundamental interactions that we know of and that string theory includes all of them in a unified way, I do not think the label "final theory" is irrational.

Problem is, I do not see strategies in Planck scale string theory (nor in the work orientation of string theoretists) to aim to determine some of the free parameters of the standard model. If final means we keep with our actual level of knowledge, well we are already finished.

 

[josh1]

Problem is, I do not see strategies in Planck scale string theory (nor in the work orientation of string theoretists) to aim to determine some of the free parameters of the standard model. If final means we keep with our actual level of knowledge, well we are already finished.

So it's not string theory per se, it's the choices string theorists make about what to focus on?

 

[arivero]

So it's not string theory per se, it's the choices string theorists make about what to focus on?

Indeed, it is not theoretical physics per se; it is the choices theoretical physicists do about what to focus on. If they do not focus on narrowing our set of parameters, we can perfectly keep where we are, with QFT+Relativity.
EDITED: But, let me to add, sometimes the choices they do are already constrained by the postulates. If it were the case, if they can not focus on narrowing parameters because the postulates of modern string theory do not allow them to focus on it, then perhaps we should consider some change in the postulates.

 

[pivoxa15]

Rereading some of the posts, none of you actually suggested why string theory is getting less popular. I pointed at an answer to that in post 11. Is that the main reason?

 

[Fra]

Less popular among physicists?

Then maybe that would be an interesting question to ask those used to advocate strings, but no longer do (maybe Smolin and possibly others?), or to potential physicists who choose to direct their attention to other, supposedly more promising things from start.

10+ years ago I used to think I wanted to work with researching fundamental physics, but I changed my plans when I was made aware of the unattractive reality of research politics. It never changed my opinion and fascination on physics but it did change my opinion on the concept of choosing a profession.

My supervisor implicitly signalled that the future of theoretical physics is string theory (so take it or leave it).

For ME string theory really doesn't address the fundamental questions I have, that is reason enough to determine MY motivation, because I have only one life, and a limited number of "trials" to make and I see no way whatsoever to motivate myself to not _aim_ in the middle. I find ST to be speculative, off the point (meaning off _my_ points), but to me, my point are what counts and I expect that the same logic applies to most people.

/Fredrik

 

[marcus]

This seemed like a reasonable proposition! It didn't get much attention perhaps because it falls between two mental frames.

Final theory is an excessive label; what we dream of, is of a theory able to calculate most of the parameters the standard model has left free. But, most of these parameters are about the electroweak symmetry breaking, the only hope to use modern Planck scale string theory to calculate these is to get an accurate description of the GUT content and then to run all the yukawa couplings down to electroweak scale. This hope seems to be in danger.

I proposed recently (other post, last week) to abandon Planck scale and to try again string theory as a theory of the interactions in subnuclear energies. If in this way, or similar ways, we get some prediction of standard model parameters, I will be happy with strings even if they are not the final theory including gravity.

This viewpoint has something in common, in spirit, with the recent opinion piece in Nature by Hermann Nicolai.
https://www.physicsforums.com/showthread.php?t=192464

I think in separate ways both this post and the Nicolai article say Forget about final, ultimate, fundamental! Don't talk about "ToE", let's use it to CALCULATE something.

Zealots for whom the string philosophy is a final total vision apparently do not like this partial effective attitude. And perhaps singleminded detractors on the other side cannot even HEAR it.
So unpropagandistic discussion by Nicolai and others may get missed.

Joseph Stalin had this slogan "Ni shagu nazad!" Not a step back! Might sound good, but it can be a recipe for no progress at all.

 

[Phred101.2]

I postulate that eventually we will not be able to postulate anything. All conjecture will necessarily be already not just possible, but in fact true, thanks to M-theory. This means any imagined thing will cease to be a "fantasy" and will pop into existence...
Of course, I could be wrong (or kidding).

 

[marcus]

The last is a definite possibility.
I postulate you're kidding.

 

[Fra]

All conjecture will necessarily be already not just possible, but in fact true, thanks to M-theory. This means any imagined thing will cease to be a "fantasy" and will pop into existence...

Perhaps your kidding like Marcus said but...

...it seems you suggest that any answer can be true, but who is asking? If anyone can ask, then I guess we any question make as much sense as any other, and any answer is as reasonable as any other. I think that problem appears due to lack of self-reference. The mistake is to assume that there are objective questions and objective answers. Then, given any question and any answer, is there a subject, who matches this?

Just given a particular description of say a vaccuum, can be define an "observer" where this vacuum is uniqe? If we don't know who is asking, how can we expect a unique answer? OTOH, if we expect the answer to be independent of the questioner, then the question is, what is that question?

Perhaps this is just the next realisation of an uncertainty principle, relating questions, answers and questioners

/Fredrik

 

[arivero]

This viewpoint has something in common, in spirit, with the recent opinion piece in Nature by Hermann Nicolai.
https://www.physicsforums.com/showthread.php?t=192464

Indeed, but while Nicolai only gives stringers the "silver bridge" to proof themselves useful, my proposal was to try really not a dual escape but the real thing: gauge bosons from closed strings, leptons from open oriented fermionic strings, quarks from open unoriented, and mesons and diquarks from the bosonic partners.

 

[Demystifier]

The last is a definite possibility.
I postulate you're kidding.

He probably does, but Max Tegmark does not in his very similar postulate (not related to M-theory) of the mathematical universe.

 

[marcus]

He probably does [kid], but Max Tegmark does not...

for people who don't want to read the Tegmark original, its gist is succinctly summarized in this sequence of photographs by Hossenfelder
http://backreaction.blogspot.com/2007/09/imaginary-part.html

 

[Demystifier]

for people who don't want to read the Tegmark original, its gist is succinctly summarized in this sequence of photographs by Hossenfelder
http://backreaction.blogspot.com/2007/09/imaginary-part.html

They can also read a 3-page summary written by Tegmark himself:
http://xxx.lanl.gov/abs/0709.4024

 

[Fra]

Thanks for the link Demystifier.

I read Max Tegmark's essay and I share some questions but I'm not sure I like his from what it seems apparently strong reductionist approach. But I haven't read any other of his papers.

If I am not mistaken he wants to find the birds view, and then find the projection onto the frogs view. The problem is that we are the frogs, and he then advices the frog to resort to some kind of antrophic principle? I question to what extent the frog can even properly relate to probabilities of a particular birds view? This doesn't quite make sense to me at least. It seems to contain some subtle circular reasoning I'm not sure how he breaks?

Is anyone reading this the same or is it just me beeing a frog? :)

/Fredrik

 

[marcus]

We get polls like this from time to time.
In this one to date 10 people said it could not be written off (Yes it had a chance at eventually developing into the final all-encompassing theory.)

And 25 people said it could be written off (No it could not turn out to be the final theory.)
===============

Basically what do polls and discussions about them communicate? I think the main thing is that the situation did change around 2003, with the KKLT paper and Susskind's Anthropic Landscape. The mood changed. Research output has declined since then and, more importantly, citations have declined markedly.

Another signpost was the Edge interview with Brian Greene (and Paul Steinhardt) where he changed his tune considerably----talk in the 1990s about a unique final inclusive theory was "youthful exuberance"---the claim now is to SOME relevance to nature, not to being the unique fundamental theory. Brian Greene was clearly reacting away from the earlier overhype.

Some people don't realize the mood has changed. Or they sense this in others but wonder why. they ask about it. Polls and threads can help answer those questions.

however, it is worth repeating that we cannot know the future of research and we can't answer these questions. all we have is hunches, impressions, guesses about the future.
When you don't know what is going to pay off, it can be helpful to diversify and have some people continue with string while others branch off in other approaches.

So I'd say "totally written off" would be an exaggeration unless you just mean as a final Theory of Everything. But I guess that is what Pivoxa was asking, and what the poll is about. His poll question was:

Can string theory (still) be the final theory?