An interesting short interview with Ed Witten in this week’s New Scientist. Mostly straightforward stuff, but it’s always good to hear what smart people are thinking. Witten is spending the year on sabbatical at CERN; like many people, he was sort of hoping to be there when the first physics results from the LHC appeared, but reality intervened an that’s looking increasingly unlikely. Happily, CERN has developed electronic means of communication whereby interesting findings may be promulgated to researchers who are not within close physical proximity to the lab.
Longtime CV readers may be interested in Witten’s take on the String Wars:
The 1980s and 90s were dotted with euphoric claims from string theorists. Then in 2006 Peter Woit of Columbia University in New York and Lee Smolin of the Perimeter Institute for Theoretical Physics in Waterloo, Canada, published popular books taking string theory to task for its lack of testability and its dominance of the job market for physicists. Witten hasn’t read either book, and compares the “string wars” surrounding their publication – which played out largely in the media and on blogs – to the fuss caused by the 1995 book The End of Science, which argued that the era of revolutionary scientific discoveries was over. “Neither the publicity surrounding that book nor the fact that people lost interest in talking about it after a while reflected any change in the intellectual underlying climate.”
That sounds about right. For the most part, actual string theorists simply went about their business, trying to figure out what this fascinating but difficult theory really is. The irony is that a major point of the anti-string books was that the public hype concerning string theory didn’t paint an accurate picture of its more problematic features — which was true. But the backlash books gave the public a misleading impression in the other direction, leading to the somewhat amusing appearance of my own piece in New Scientist explaining that the theory was for the most part chugging along as before. Hype cuts in every direction, and it feeds on drama, not on accuracy.
There is certainly some feeling that the near-term growth area in high-energy theory is not string theory, but phenomenology (or arguably particle astrophysics). Certainly those are the people who seem to be getting the jobs these days. The explanation there is pretty straightforward: data! Or at least the promise thereof. It’s hard to do physics with little to go on other than thought experiments, but one gets by when relatively few real experiments are available. Increasingly, that’s no longer the case.
But it’s been a long time since we’ve had a good string-wars thread, so here you go. For old time’s sake.
– OOps – -that’s: “THEIR HALLS”, dag-nab-it! [orig.= “Land of Michio”, BTW]
THREE STRINGS FOR TEN-THOUSAND-THINGS UNDER THE SKY,
SEVEN FOR DETERMINISTS IN THEIR HALLS OF STONE,
NINE FOR MORTAL MIND DOOMED TO PI,
ONE FOR THE QUARK LORD ON HIS QUARK THRONE
IN THE LAND OF M-BRANE WHERE THE THEORIES FLY.
ONE STRING TO RULE THEM ALL, ONE STRING TO FIND THEM,
ONE STRING TO BRING THEM ALL AND IN THE QUARKNESS BIND THEM
IN THE LAND OF M-BRANE WHERE THE THEORIES FLY.
… Vex Vuthor /aka/ Doctor Static …
I read Lee Smolin’s book and one of the problems he had with String Theory is that it can never be disproved. Say, for example, when dark matter was first “detected”, the String Theorists revised their theory to accommodate it. It still didn’t make any useful predictions or produce any experiments whatsoever.
Even if other theories make better predictions and have far more robust models, String Theorists will never let go of their theory simply because they believe it’s too pretty, to be wrong.
To me, a layman, String Theory seems to be a collossal waste of time for a vast number of people far smarter than I. I can understand why they would be reluctant to let it go. But let it go, they must.
To me, another layman, this sentence makes me wonder why you think your opinion on the topic is worth anything relative to the opinions of people far smarter and more informed than you! Have you considered that these people might disagree with Smolin about whether String Theory is in principle testable?
Peter, I think it rather depends on what one means by “falling on hard times”. You seem to suggest that it means that string theory has fallen out of favour with physicists, who no longer believe it is the correct path to a fundamental theory. Jamie, on the other hand, is merely pointing out that it faces increasingly difficult challenges, without a clear way to surmount said challenges – this may be “falling on hard times”, but not in the sense you mean. If you think you’ve chosen the right path to a final destination, you don’t change your mind just because the path gets a bit boggy.
Jeff,
I’m not arguing that there aren’t many string theorists who are keeping the faith and still believe string theory will someday give a successful unified theory. What I am arguing is that fewer and fewer non-string theorists believe this, and the evidence for this is that fewer and fewer are willing to support hiring string theorists.
If you look at the history of any failed speculative idea about physics, what you’ll find is that the proponents of the failed idea rarely publicly admit that it’s wrong. Instead they start making excuses about how it could still be right, but it’s just too hard to make progress. While some drift off to other things, and some keep working on the idea for the rest of their careers, their colleagues see what is up and stop being willing to hire new people who work on the failed idea. This is what is happening to the speculative idea of string-based unification.
Peter Woit wrote
“If you look at the history of any failed speculative idea about physics, what you’ll find is that the proponents of the failed idea rarely publicly admit that it’s wrong. Instead they start making excuses about how it could still be right, but it’s just too hard to make progress. ”
Can you give a historical example of something like this? I am having a tough time coming up with something that fits the bill that wasn’t a total crackpot idea that only a few people ever took seriously.
Ja Muller,
It is quite unusual for an idea that attracts a large following to be completely wrong. I’d be curious if you can think of a wrong idea that attracted a large following, and when it was shown to be wrong, its proponents publicly admitted this reality.
Some cases I was thinking of are:
1. Heisenberg’s unified field theory
2. Chew’s S-matrix theory of the strong interactions
3. Cold fusion
2. is a complicated story interrelated with string theory. But, one aspect of the story is that in 1973-74 it became clear that QCD was the correct theory of the strong interactions, but there were quite a few people who for the next decade wouldn’t admit this. With AdS/CFT, some of the string theory ideas that grew out of this period did get connected to gauge theory and turned out to be useful. By analogy, I think it’s entirely possible that in the future some very different way of thinking about string theory and unification will have something to do with reality. The problem is that all known ways of doing this have failed, and that’s something proponents are not willing to admit.
Woit: “With AdS/CFT, some of the string theory ideas that grew out of this period did get connected to gauge theory and turned out to be useful. By analogy, I think it’s entirely possible that in the future some very different way of thinking about string theory and unification will have something to do with reality. The problem is that all known ways of doing this have failed, and that’s something proponents are not willing to admit.”
Wha..??? You just said AdS/CFT is useful!
Either way, this is a purely hindsight-based argument. Hindsight is something we don’t have right now, by definition. What we do know is that work on string theory has given us new insights into black holes, gauge theories, quantum gravity, etc. Insights we did NOT have before. You and your idiot-army either don’t know enough to understand the significance of these, or they consciously ignore them. Mind you, I am not saying that string theory will ultimately turn out to be the final theory, but I do think it has useful lessons to teach us about the final theory, so it is certainly important to work on it, until we have the “final” theory.
The problem with your book and blog is that they do not offer any way of making progress – all they do is call for a shutdown of string theory (which as you yourself admit above, has lead to useful things). What do you recommend as a better, concrete, alternate way of making progress? Lets hear it, dammit. Please pay attention to the word “concrete”. I emphasize it because revolutionary breakthroughs would of course be nice, but there is no algorithm for making them happen.
I should probably stop, because arguing with your malicious, cynical propaganda is really making me angry and frustrated. But it is addictive precisely because I KNOW it to be bullshit.
Peter Woit,
Fair point, I can’t think of a widespread idea that was falsified and very quickly recognized by its proponents. I mean there are things like Einstein and the cosmological constant but that was a pretty minor part of a successful theory and not a huge collection of information like string theory. (Though this is not that relavant since string theory seems so unlikely to be shown completely wrong by experiment or theory in our lifetimes) The main point I was trying to make is that if string theory does end up being left behind in the future without ever even having a precise formulation of what the theory even is, it will be a very unique situation. I agree with your last point as I think what is called string theory now is such a broad collection of techniques that it seems unlikely that 100% of it will be unusable.
“jamie”
Get a grip on yourself, whoever you are. I’ve many times pointed out what I see as positive things that have come out of research on string theory, from ideas about strings as calculati0nal methods for strongly coupled gauge theories, to a lot of ideas that have had a big impact on mathematics (“mirror symmetry” maybe the most important of these).
What I see as a big negative coming out of string theory is the ideology that the way to unify particle physics and gravity is via a 10/11d string/M-theory. This is the idea that I think has completely failed. Not only has it led to nothing good, it has led a lot of the field into bad pseudo-science (anthropics, the landscape, the multiverse…), and this has seriously damaged the reputation of the whole subject.
My main point has always been that string theory partisans need to stop hyping the entire subject, and start paying attention to what works and what doesn’t. The unification idea doesn’t work, mirror symmetry does. But instead of doing this, people keep publicly pushing the same failed idea, discrediting the subject completely. In the process they have somehow managed to discredit the whole idea of using sophisticated mathematics to investigate QFT and string theory at a truly deep level, convincing people that this was a failure caused by not being “physical” enough. Instead, it was a failure of a specific, “physical” idea: that you can get a unified theory by changing from quantum fields to strings.
If you want concrete suggestions for what to work on, note that we don’t understand the electroweak theory non-perturbatively at all. There are all sorts of questions about non-perturbative QFT that we don’t understand. Sure, these are not easy problems, but then again, all the problems in string theory are now supposed to be too hard, why not instead work on QFT problems that are too hard? Personally I’m currently fascinated by the BRST formalism. There are all sorts of problems with it, and I have what seem to me some promising ideas about how to do better. If you don’t have any ideas yourself about what to do in this field, why not stop doing it, and do something else? The world is full of interesting work to be done, you can leave particle theory to others.
With analytic continuation one can extent the domain of definition of a function from any infinitesimal patch, where it is defined by whatever means.
By analogy, if string theory ever develops a model which overlaps with a range of observable phenomena, and these all agree with observations, then provided (as would presumably be the case) the whole thing is one rubic, united as tight as a drum, there would be no reason to doubt those aspects that couldn’t be observed any more than those which had been experimentally verified.
Yes, when cornered, you have a way of saying that there are things in string theory that you find promising, and that you are only against the hype. Please get real. The truth is that your entire blog is a hate-parade aginst string theory, and an occasional fine-print statement like the one above, only emphasizes that you are a cynical propagandist. Granting you good faith is simply impossible in light of the kind of consciously misleading rubbish (aimed at unarmed laymen) that you write on your blog.
And about your research advice for me: don’t you think it is more prudent if I took advice from somebody who has, you know, actually made it in academia??? Sorry if I am being harsh … thing is, I don’t respond kindly when I am being patronized…
“jamie”,
You’re just becoming more and more of a frantic ranter spouting insults and nonsense.
I have no idea at all who you are, whether you’re a high school student or a tenured faculty member somewhere (one remarkable thing I’ve learned the last few years is that, as far as anonymous commenting goes, you sometimes see similar behavior in both groups, especially when they’re on the losing side of an argument).
So I don’t know whether you’re someone who “made it” in academia or you’re just hoping to. I do know that these days there are a lot of resentful and unhappy people in this business and that I’m not one of them, but am very pleased with where I’ve ended up and the extent to which I may or may not have “made it”.
Peter, I cannot let you sidetrack the discussion into another direction yet again. So: what is this that you plan to accomplish with this BRST thing that you talked about? If everything went perfectly without glitches, where do wwe get? What fundamental problem do we solve? More bluntly, how on earth can a formalism alone be enough to discover new physics? Where is the dynamics?
I looked around and found your postings on “BRST” and all I see is a fairly standard, if a bit formal, presentation of representation theory. I asked you for your favorite research program that can substitute string theory in our quest for high energy physics, and you give me a course on representation theory?
“incognegro”, I haven’t read Smolin’s book, but what you’re saying about dark matter doesn’t make sense. Supersymmetry provides a dark matter candidate, and supersymmetry is incorporated into string theory for other reasons, not tacked on as an explanation of dark matter.
“jamie”,
I think you’re the one who is side-tracking the discussion from the topic here of the problems of string theory. Getting into what I’m doing with BRST and why is a long story, and actually at the moment, in another window of this computer I’m trying to write up a too-long-delayed document about this (the notes I posted online so far just are introductory parts). Once that’s done I’ll let it speak for itself. Here’s a very brief explanation.
Mathematically, one of the main ideas I’m working with is to try and understand how BRST works in terms of something called “Dirac cohomology”. The idea of defining this “Dirac cohomology” and using it to study representations is a rather new one in the mathematics of representation theory, it’s not part of the standard presentation of the subject. At the moment I’m a long ways from understanding how these ideas work out in the interesting cases in physics where the symmetry groups are infinite-dimensional. But, I see a lot of interesting possible uses of these new ideas, for the simple reason that symmetries and representations are such an essential part of fundamental physics, that a new approach to them should lead to something new. The fact that this new approach has a version of the Dirac operator at its center is quite striking.
If you want motivation more from the physical end, no one has really made sense of the BRST formalism for treating gauge theories outside of perturbation theory. The general assumption has been that this is a formal problem of no physical significance, but I suspect that’s not true. We’ll see. Anyway, I should get back to writing, I hope to have a finished long paper this summer, maybe something I can blog about earlier.
Let me clarify that we are not talking about doing cutesy mathematical physics. We are not trying to cross the t’s and dot the i’s in what we already know. That is cool, but what we really want is to understand the unknown unknowns in high energy physics. So a substitute for string theory should also tackle the same difficult issues.
You have sidestepped the crucial questions about your BRST program: “If everything went perfectly without glitches, where do we get? What fundamental problem(s) do we hope to solve when that happens? More bluntly, how on earth can mere formalism (for handling redundancies) be enough to discover new physics? Where is the dynamics? What is the physical input?”
You haven’t answered these questions (not even partially), so your BRST thing is more like a brain-fart, not a research program, at this stage. On the technical side, I will reserve judgment about your so-called non-perturbative BRST, until your paper comes out.
“jamie”, what has string theory done for you lately?
As someone who is far far removed and not well-informed about string theory, I would like to offer some historical perspective:
In the early days of quantum theory, up until Heisenberg invented the rudiments of matrix mechanics, quantum physicists worked on all sorts of complicated models and half-baked theories that actually make no sense at all, from today’s point of view. Strange electron orbits, all kinds of classical perturbation theory, complex techniques from celestial mechanics: Anything that someone might possibly shed some light was enlisted. Up until months before his breakthrough insight, Heisenberg was still fine-tuning (and publishing) what seems to me like a Rube-Goldberg explanation for the anomalous Zeeman effect – a conundrum of notorious awkwardness at the time. Bohr and his collaborators in Copenhagen had just proposed a radical view of radiation, that got shot down almost immediately, and it seemed to take down with it quite a bit of what physicists thought that they had understood about atomic physics. It seemed a dark time for quantum theory.
Two points of interest, however:
– Although many of the ideas dreamed up during the early phase of quantum theory were later to be tossed out, some large fragments and elements made the transition into the new quantum mechanics, albeit with a very different interpretation.
– The breakthrough eventually came through people who actually were busily involved in the struggle, trying to make what progress they could. If you don’t play the game, you can’t win.
So the exact nature of the modeling – the physical picture – may, from the perspective of 80 years from now, prove to be less important than we think today. Perhaps some relatively small detail may prove to be the magic button that opens the cave entrance.
“Instead, it was a failure of a specific, “physical” idea: that you can get a unified theory by changing from quantum fields to strings.”
Except that this statement fails to recognize that strings represent certain types of irreducible fields
“jamie”
You could make exactly the same argument that all methods developed over the years in physics to exploit symmetries are not “dynamics”, have no “physical input”, and thus are nothing but “brain farts”. I don’t agree.
String theory definitely has helped with the nonperturbative aspects of field theory. In fact i’d say that along with supersymmetry and supergravity, the primary mover for nonperturbative physics in the last thirty years has come directly from research in s.t.
This isn’t vacuous or wishful thinking, we now have webs of dualities that translate directly from one language into another and can probe the strongly coupled sectors of previously intractable problems. Moreover, powerful renormalizability and integrability theorems now exist, Seiberg-Witten elucidates all sorts of fascinating physics in a wide class of almost physical models and so on and so forth.
Peter knows this of course, and its just a matter of personal taste whether or not one thinks this will continue to yield unanticipated research goldmines and if that says anything encouraging about the fundamental nature of quantum gravity.
I have no stake in the process, but i’d guess that indeed it will continue, if perhaps at a slower pace than hoped for -shrug-
As a young Ph.D. student in India working on experimental/design aspects in Astrophysical instrumentation, I am very curious about the attitude of theorists in general and string theorists in particular about experimentation.
In India, there is something of a “caste system” in academia, with string theory as the brahmins and experimentalists as absolute untouchables. While not everyone displays or even has this attitude, it is prevalent enough that opening of laboratories in India is a strict no-no.
This is why, despite having leaders in experimentation like J.C. Bose and C.V. Raman, India still has no proper astrophysical instrumentation laboratory. Every time someone asks for money for a lab, eyes are rolled and one of the following is usually spewed:
1. Indians cannot / should not do experiments
2. India is a poor country (yeah right! Every year, 2 billion USD worth of money is returned unused by the Indian research community to the government, which is getting exasperated with scientists who say they cannot handle so much of money!)
3. Theory is the only thing worth doing
4. Experiments are useless
5. All data is fabricated anyway
I am not against any kind of theory, but this attitude has harmed me and my fellow experimentalists in a way perhaps unimaginable in the West.
Just curious if the US might ever tilt this way…
Shankar
Neal J.King, you have hit the nail right on the head. Working on string theory is interesting because it involves all the various threads in high energy physics, and the solution to the challenges emerging in these threads can only be found by working on them. String theory is really nothing more than a structure that manages to relate all of the various ideas that have been useful in physics in the past hundred years. Scientifically, it is a huge fallacy to think that you can GAIN anything, by dumping string theory. Its like saying that we should ignore some of the connections we found between various existing ideas, in our future research.
Shankar, what you say really does sound bad. But it should also be kept in mind that often, the way people try to fix a past error is by making a compensating error. So blaming theoretical physics and/or string theory for the situation sounds like a bad idea to me (not that thats what you are doing here, but it is easy to make that mistake). I am certain that even the string theorists in India will find your above comment (if true), absolutely reasonable. In the West, my impression has always been that experimentalists are the ones who get most of the money, partly because many of them can get industry support. But I might be wrong about this. Either way, I have certainly never heard of money being returned to a funding agency.
Back to the flame:
Woit says: “You could make exactly the same argument that all methods developed over the years in physics to exploit symmetries are not “dynamics”, have no “physical input”, and thus are nothing but “brain farts”. ”
Again you try to mislead and subtly redefine the issue, like the politician you are. There is nothing wrong with working on whatever you want (assuming of course, you have something non-trivial to say). The problem is when you present it as an alternative to fundamental theory, while NOT addressing the challenges of fundamental theory at all.
What is despicable about you is not even your visceral hatred of string theory, but your underhanded attempts at creating the impression to the general public that you have more influence in the HEP community than anywhere near what you have. If you do not like string theory, fine. If you do not like the string hype, thats even more fine. But when you try to create counter-hype which is much more malicious to science than anything the string theorists have ever done – by trying to hurt the public perception of theoretical physics itself, by lying to the public, eg., about the current status of string theory in the HEP community, by claiming to wage a scientific battle while actually waging a public-relations one – it is high time that somebody spoke up and called you out on what you really are.
`jamie’ answer these.
What is space?
What is time?
What is a particle?
Why the quantum?
Why relativity?
Why the particular particles we have, why their masses, etc.?
Why the cosmological constant we have, and what is it anyway?
Is the 2nd law of thermodynamics really a law?
Etc.
How does string theory even begin to address questions that are actually fundamental?