Peter Woit, noted blogger and string-theory gadfly, has written a book about his objections to string theory: Not Even Wrong, to be published next year by Jonathan Cape.
Good. I completely disagree with Peter’s opinions about string theory, and think that his accusations that the Landscape is non-scientific are completely off the mark. But his objections are not crazy, and his dislike for the theory is grounded in an informed scientific judgement. (Sometimes more than others, but that’s a matter of personal opinion.)
The whole discussion is a nice contrast with the Intelligent Design mess. The fact is, we don’t know what is the correct theory that unifies particle physics with gravitation. String theory is far and away the leading candidate, but its status as leader is a reflection of the educated judgement of the experts, not any airtight evidence. This judgement comes from looking at various pieces of information — what we know about gravitation, and quantum mechanics, and particle physics, and the history of ideas in physics, and the mathematical structures underlying gauge theory and general relativity, as well as an intuitive feeling for what principles are most important and what clues most worth pursuing — and deciding which path toward progress is likely to be fruitful. When people like Peter (or Lee Smolin) read these tea leaves, they come to a different conclusion than most scientists in the field. But it’s healthy disagreement among professionals working at the edge of what we know and don’t know — not politically-motivated intervention from people who have no clue, just an agenda, and operate completely apart from the scientific mainstream. To people looking in from the outside, I hope an accurate picture comes across: there is a widespread feeling that string theory is the best hope for a quantum theory of gravity, but it’s not a settled issue, and we’re working in good faith on moving forward.
So I’m happy to see this side of the argument represented in the popular press, even if I disagree — we shouldn’t be afraid of the free market of ideas. If people don’t agree, they should explain the sources of their disagreement rationally. There is always the danger of misprepresentation of course, and in this case there is an obvious worry — that a spate of stories will appear about how string theory is in trouble, and a house built on sand, and so forth. That might be true, but certainly isn’t the impression I have from talking to string theorists. In any event, I hope that we defenders of the theory can stick to the high road, and welcome this intervention in the discussion of these important ideas.
It seems that quantoken has single handedly destroyed any progress that Sean has been so assiduously and eloquently been making in this blog in defining the issue with ID, namely, there is no issue. Intelligent design is, in my humble opinion, nothing but a religious agenda. While one might arguably consider a building to be a product of “intelligent design”, whereas one must have faith for the brand of ID the scientific community is concerned about, I don’t think much faith is required to recognize the existence of the architect who’d designed that building, and if you still do doubt that, look in the yellow pages and give her/him a ring. Let’s not try to be dodgy about this subject by trying to be kind to the theory of ID and considering how it just might contain a valid point. As has already been stated, exclamed, cried and lamented in this blog, ID does not enjoy the priveleges nor rights of a full-blooded scientific theory.
Dear Peter,
As a result of several discussions on other comment threads on this blog, I was under the impression that we’d all made some progress in sorting out what were well-posed disgreements you have with some approaches research in string theory, what were “gut-feelings” that you have (over which we can simply agree to disagree), what were misconceptions based on not being an active researcher in the field, and –very importantly– what were simply your misattributions of a minority view to that of the whole field. Recall that I spent a fair amount of time trying to clear these up. I refer you to the comment thread of the Landscape post, for example. I thought we arrived at some agreement that your views about what is actually going on in the field need a bit of re-balancing. If so, will these refinements be incorporated into the book before it is published? Or will your pre-cosmicvariance position be published? I do hope that these “finishing touches” might involve significant rebalancing some of your emphasis to reflect the outcome of the enlightening discussions that have taken place here. Otherwise, it will be a missed opportunity for you to put out a book that is a useful alternative view, and not just a view based on an exaggerated chariacature of research in string theory.
I’d like to ask you to pleaase make the effort. It probably won’t delay publication at all, and even if it did, it will be worthwhile: It will improve your book, and thereby enhance your reputation. If it comes across as an uninformed rant, however, you’ll do service to nobody’s cause at all, which would be sad, at the very least.
Cheers,
-cvj
Dear Peter,
I refer particularly to your comment # 67 in that thread, although it is worth reminding yourself about the discussion that led up to that point. Quoting you entirely:
So, will the refinements of your views mentioned by you in the above be reflected in the book? (Not to mention other points I mentioned which you agreed with elsewhere on the thread?)
Cheers,
-cvj
Hi Clifford,
Yes, the discussion here has had an effect on some of the changes I’m in the middle of making, specifically the new insight into the falsifiability issue that discussion here helped me with is one of those changes.
As for the other issues you mention, I should point out that I have a somewhat different point of view about parts of our discussion. In some cases what to you may have appeared to be a clearing up of misconceptions on my part to me seemed to be just my clarifying some things that I hadn’t written carefully enough, allowing them to be too easily misunderstood or misconstrued. In any case, the book manuscript is written more carefully and at greater length than my web comments, so it shouldn’t have so much of this kind of problem.
One thing you’ve properly taken me to task for is sometimes attributing to all string theorists views held only by a minority, or at least appearing to do so. To some extent this is hard to avoid. The sheer complexity of the range of different opinions is hard to do justice to in any piece of expository writing about these issues, so one has to oversimplify to some degree. I’m well aware that many if not most string theorists are eminently reasonable people I can agree with about most things, who don’t hold unreasonable or indefensible views. Some of my best friends are string theorists, and I never have trouble talking about the subject with them.
On the other hand, there are a significant number of string theory partisans out there who seem to me to be unwilling to engage in rational discussion of the issues surrounding string theory, and often engage in the offensive behavior of assuming anyone skeptical about the theory is just stupid and ignorant. I’ve had a lot of this to put up with in the last day or so since publicly announcing my book project. These people are presumably overrepresented in internet forums, and range from fools hiding behind pseudonyms like F. Uckoff, to Harvard junior faculty, to respected senior faculty at major research institutions. I’ve just wasted some of my time trying to respond on Dave Bacon’s blog to Greg Kupferberg, a mathematician string partisan who holds the unshakeable belief that my objections to string theory are of the same sort as Intelligent Designers’ objections to the theory of evolution and that my only motivation is unwillingness to do the hard work necessary to learn string theory. I think Lubos Motl’s comments here and elsewhere speak for themselves.
So, while I’m willing to believe that the majority of string theorists are reasonable sorts, that’s not so clear from what goes on on the internet, and some of my experiences somedays leave me feeling not especially charitable. While there are certainly some stupid comments left on my weblog by people bashing string theory, I’d like to think that if any of these were coming from serious people in respected positions (e.g. Harvard faculty members), I’d be taking them to task for their behavior and I can’t help noticing that this doesn’t seem to be something any string theorists are willing to do.
About the landscape: my own view of the issue is extremely simple. Any theorist working on a theory who ends up deciding the theory leads to something that ugly and that unpredictive has to just acknowledge failure and do something different. I understand that there’s a wide range of opinions about this among string theorists, but don’t think this is a subtle issue. The book was largely written in 2002 before the landscape controversy got going, so material about it is kind of added on, and given the way I see this, I haven’t had the interest or energy to go into too much detail about the various issues that people often get into when talking about this.
Finally, I don’t want to put you on the spot in public, but will soon contact you privately with a proposition about the issues you raise. Maybe you can help me out…
Ok Peter, we’ll talk. Just at least try to do a good job of giving a balanced view of the types of activity going on in the field, and the types of people you can meet too! Books last longer than blog comments.
Cheers,
-cvj
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Dear Clifford,
Can I add that these discussions have been extremely helpful as my own writings on the subject have progressed, especially with regard to the range of views among workers in string theory? So many thanks. I don’t know what Peter will propose but, if I may, could I make two suggestions of ways in which you and others could help myself and others obtain a more balanced view of the range of views among string theorists?
-If you have the time, some recountings of private discussion illustrating the range of views on crucial issues would be very helpful.
-Any documentation of the range of views would also be helpful. This could be pointers to papers, talks on line, posts etc by string theorists disagreeing with expressions of views by leading string theorists on crucial issues.
This would be helpful as one of my projects is a kind of intellectual history, and I am very aware I could have, as you correctly suggested before, a skewed view. I should also emphasize that recently I have sensed things changing as there is strong disagreement among string theorists about what to do concerning the landscape. So I am talking about the past, say before 2002.
Let me give some examples.
A number of string theorists have told me privately in the last year that they are happy to believe in the landscape because they never believed in the idea that there was a unique unification leading to unique predictions. But to my knowledge, none of them published their views, at the time. If you can find papers or talks by string theorists prior to 2000 favorable to the now current views on the landscape or expressing doubt that there would be a unique and predictive string theory, I would be most grateful.
In this case I have some relevant experience. Beginning in 92 I wrote several papers (and a book in 97) proposing that there was a landscape of string theories, that there would be no unique predictability, and that environmental or statistical reasoning would be required to get predictions from string theory. I also gave reasonably many talks about this, some at major string places, a few at conferences attended by some string theorists. So if there was then a spectrum of views on this, I would think I would have heard, and I didn’t. What I recall hearing was many assurances by string theorists not to worry, that there would be a unique vacuum in the end.
There are other issues on which it would be very good to have evidence of a range of views, such as the status of the major conjectures such as finiteness, S-duality, and AdS/CFT duality. I have done some literature searches, and I am afraid that you would be unhappy with my characterization of what I’ve found. But I would much prefer to believe that you are right, and that there was a range of views, which I somehow miss finding the evidence for. So I would be most grateful to be pointed to papers and talks that illustrate a range of views on these issues. Also useful would be pointers to reviews that give careful, critical and correct statements about what was known and not known at the time about these and other key issues.
Finally, here is what I would really like to see: we drop completely the distinction between who is “a string theorist” and who is not, and stop worrying about the range of views among “string theorists” and instead just think about all of us as theoretical physicists working on quantum gravity and unification. That way, the views of someone like myself, who has written actually fairly many technical papers about string theory (17) but for some reason is not considered “a string theorist” could be counted when you consider how wide is the range of views in your community. How about it? If all people who worked on quantum gravity thought of themselves as one community, who had, say, common conferences, and research groups, in which people from different research programs felt equally at home, then we would automatically get to be part of a community with a broad range of views. Wouldn’t that be the best thing for all of us, scientifically?
Again, let me express my thanks for the high quality and openness of the discussion here.
Thanks,
Lee
cvj said:
“Ok Peter, we’ll talk. Just at least try to do a good job of giving a balanced view of the types of activity going on in the field, and the types of people you can meet too! Books last longer than blog comments”
We live in the age of the artificially generated “controversy”, as followers of the ID campaign know all too well. And the favoured weapon of the artificial controversy exponent is to get himself into a debate with a real scientist. Even if he gets clobbered, he can still claim to have been taken seriously enough to be debated, and it is a short step from there to “teaching the controversy”. The notion that string theory is “not even wrong” is no more controversial than the idea that eyes have to be “designed”, and it would be regrettable if the public were given any other impression. However, I’m confident that cvj won’t fall for this, though it may require him to be a bit more blunt than he would like to be.
Hi Lee,
Thanks for the kind comments about the kind of discussion that’s been encouraged and maintained here, so far. I hope it’s worth it.
I would like to say that I have not elected myself as some sort of barometer of the field’s opinion. I have no special knowledge, and I’m certainly not leading an anti-establishment movement within the field. Further, my knowledge of the literature is not encyclopedic, so I won’t claim to be able to give you long lists of supporters of one view or another. Actually, I don’t think anyone can. All I’ve been saying is that there are a lot of string theorists out there, and a wide range of motivations for working on the subject (an impression you can get by just talking to people in the field at conferences, etc). Alternatively, just pick a random day on hep-th and read the introductory paragraphs. They are not all talking about the landscape. They’re not all talking about uniqueness either. They’re just getting on with working on trying to understand the theory, since most people know that we can stand around talking about which of the two it is all day long, but it won’t actually determine the outcome. We have to do the research, which is the point I keep trying to make, but nobody seems to hear this as they want to see a fight. Nobody knows the answer, so why have a live or die controversy over the result of a guess? This puzzles me, but anyway, let’s move on. So all I’ve been saying to Peter is that it is an exaggerated impression that he often gives by talking about the program of string theory entirely in terms of the landscape. Just as I spoke strongly against your post on the Landscape thread which again gave a very one-dimensional view of what motivates people working in the field.
I’m amused by your well-motivated (and I hope you don’t mind me saying, ironic) comment about wanting discussions to stop talking in terms of “string theorists” vs everyone else. I agree, it would be good if we could all move beyond that. So let’s try.
-cvj
Personally, I’ve always referred to myself as a “high energy theorist,” rather than as a “string theorist.” I don’t think it makes sense to label oneself by the particular research program one happens to be pursuing.
(On those grounds, I might prefer “theoretical physicist,” but that’s a little too vague for most purposes.)
A good point Jacques. Actually, I rather like to just think of myself as a physicist. (I have a hope to get a chance to do a useful experiment again one day!).
-cvj
How about “fundamental physicist“, or maybe “physics fundamentalist“? 🙂
What some considered the biggest success of super string theory, I considered the biggest failure of super string theory, i.e., the derivation of a spin-two zero-rest-mass particle which you call graviton.
The existance of graviton is very troublesome and that’s exactly where GR and QM are incompatible, or quantum gravity is none-renormalizable. Equivalence Principle requires any mass or energy, must gravitate with each other, no matter how small a quantity they are or how far they separate. If the gravity is exchanged by graviton, it requires every single particle in the universe exchanges lots of gravitons with every other particle in the universe, and of course gravitons themselves have energy and exchange gravitons amounst themselves, too. If you tally up the number of gravitons flying around you get an infinite integer. And certainly nature does not allow anything in infinite quantity.
Even worse, all those gravitons occupy certain quantum states, if you sum up entropy represented by these quantum states, you easily surpasses the Hawking-Bekenstein entropy bound.
My opinion, like those of Einstein, is that gravity should simply be explained as a geometric effect of spacetime curvature, NOT a force mediated by bosons.
Any string theoretist has any thought how to resolve the paradox, and rescue graviton from quantoken? I especially want to hear Lee Smolin’s comment since he has been meantioning the word “information” a lot more in recent years, an indication he may be exploring towards the right direction, though not quite there yet.
Quantoken
“And certainly nature does not allow anything in infinite quantity.” — Quantoken
Why?
Richard
Hi Fyodor Uckoff,
I’m a bit curious about who it is that is hiding behind anonymity to accuse me of not being a “real scientist”. Whatever you think of my views, I always attach my real name to them and am prepared to take personal responsibility for them. If you want to evaluate my qualifications to comment on string theory or other issues in physics, there are several ways you can easily check up on these. Could you tell us who you are, or at least what your qualifications are to be saying what you are saying?
Dear Clifford,
Thanks, I appreciate of course that the priority is to work and that there is a range of directions and motivations. But just so you understand what I meant when I suggested that the range of viewpoints was too narrow in the past, and don’t take offence, what I was referring to was the range of views that could be found on key unsolved conjectures such as the AdS/CFT conjecture, finiteness, S-duality, the existence of a unique vacuum, the existence and form of M theory, etc. One reason why some people got the impression that there was a narrow range of views is that it was easy to find many papers and reviews just asserting or assuming that these different conjectures are true, while papers that carefully and critically discuss the actual detailed status of the conjectures are rather rare (at least I have found very few.) So someone who wants to think carefully about the status of the different claims has to do quite a lot of searching just to find precise, reliable statements about what is known.
For example, the different versions of the AdS/CFT conjectures made by Maldacena, Witten, Polyakov et al and others have very different implications for what string theory is and hence what should be worked on. It would then be very helpful if there was somewhere a critical review that explained carefully how the different conjectures differ and discussed which version of the conjecture is best supported by present evidence.
If some readers of your blog can help to find such papers or talks, on any of these key issues, I think it would be useful for all of us.
By the way, my proposal is not ironic. I encourage students, postdocs and anyone who asks to work on more than one approach to quantum gravity. I find for myself that the best way to keep an objective view of the field is to work on problems in a variety of approaches.
Thanks,
Lee
Hi Lee,
I agree that it is difficult for someone working outside the field to get a good view of what the status of these things might be (or even opinion about the status), by looking through papers which are more concerned with chipping away at their chosen part of the coalface. It is even difficult to do if you’re working in the field too, since you’re occupied with your own chipping away… Now recall that “absence of evidence is not evidence of absence”, and so I say -again- that this does not mean that everyone in the field has one (or a few) monolithic opinion or motivation.
You have to kind of get steeped into the area of choice, reading the papers, the footnotes, and also listening to the conversations…. This is where you learn that opinion is alive and well, and very varied. From the outside, reporters (and other commentators) just say “String Theorists are thinking…” because it is convenient, and lazy oftentimes.
More particularly though. What different versions of AdS/CFT? I’m already confused there. Most people I know of in the field have only one version in mind. Maldacena made a suggestion, and it was refined and put on a firm computational footing by Witten, and by Guber, Klebanov and Polyakov (which is what I presume you mean by Polyakov et al). They’re all talking about the same thing, Lee. Am I missing something deep here?
-cvj
Dear Clifford,
Thanks. I believe that if one reads the actual conjectures stated in the papers of Maldacena, Witten, Polyakov et al one sees right away that the conjectures are different. I disucssed this in detail in my comparative review for the Wheeler conference, hep-th/0303185, section 6.4.3. Rather than repeat the arguments here, let me refer you there. Please keep in mind that that paper is more than 2 years old, and so will be a bit out of date. But that’s not relevent for whether the original conjectures are distinct.
The key point is that Witten’s conjecture, which I called there conformal induction, falls short of full equivalence, and is hence weaker than Maldacena’s conjecture. I claimed in the paper that as of then (03), Witten’s version explained most of the calculational results, except those that concern relations between BPS states. It was then possible to assert that the evidence was explained by Witten’s conjecture plus the possibility that stronger results hold for BPS states on account of the extended SUSY algebra imposing relations between the spectra of two theories in their BPS sectors that are not true in the full Hilbert spaces. If true, this would mean that there is only a partial relation between string theory on AdS^5 X S^5 annd N=4 SYM. This is still very important, and many results follow from it, but not the claim that “N=4 SYM is proven to give a non-perturbative formulation of a string theory.”
I would be interested in whether recent results have changed this situation. Certainly there is still no proof of the strong (Maldacena) conjecture.
This is an example of what I mean by a range of views. It seems to me that given the fact that neither string theory on AdS^5 X S^5 or N=4 SYM have been precisely defined, it is a reasonable possibility that they are not equivalent but that there is a weaker relation between them, such as Witten’s conjecture. This may or may not be true, but I would hope that experts consider it as a possiiblity, untill proven wrong. If it has been proven wrong I would be very happy to be updated and corrected.
Thanks,
Lee
Thanks Lee. This looks like a rather long conversation to have, because there is a large literature….and this points up why several of us are puzzled by such harsh partisan criticism from your camp (and those of others) when it is clear that the criticisms may well be based on out of date or just wrong information. I will try, but this is going to be brief, as I have to work on several other things.
Now I could be just naive here, and you’re getting at something deeper, so I apologize for the above remark if I am wrong. But it seems to me that you’re just talking about different strengths of the conjecture, one being stringy and one being more restricted to supergravity. As for BPS vs non-BPS, I suggest you have another look at Ed’s paper. That beautiful work very much applies to a much larger setting than just BPS! …. Anyway lot of work has been done of very very stringy tests of the conjecture, beyond just BPS states. For explicitly stringy stuff and non-BPS stuff I mention just for starters Berenstien, Maladacena, Nastase, Gubser, Klebanov and Polyakov, and all the numerous papers that cite them (go to SPIRES to get that). But even without that, several papers have been written (years ago now) which strongly suggest that the full stringy completion of the correspondence is true (the key role of branes, and very stringy effects -such as the giant graviton story, the myers effect, etc…yes, myers – your colleague down the hall?…etc).
There is no proof, but I don’t think you need to get hung up on that. There simply will be no rigourous proofs of any strong-weak coupling dualities or others in that spirit untill we find techniques that go well beyond the current formulations of the theory (no need to start on about background independence here…I get it….). But that’s ok. One point of view is that these dualities themselves are strong hints as to the shape of what we’re looking for.
There are no firm signs (a.f.a.i.k.) of anything being wrong with the various dualities you mentioned. This is not a proof, I’m just informing you as to the state of affairs.
-cvj
am I confused here ?
Lee wrote: [..] Witten’s version explained most of the calculational results, except those that concern relations between BPS states. [..]
cvj wrote: [..] I suggest you have another look at Ed’s paper. That beautiful work very much applies to a much larger setting than just BPS! [..]
Sorry for posting twice in a row …
cvj wrote: [..] There simply will be no rigourous proofs of any strong-weak coupling dualities or others [..]
Since there is not much empirical evidence to keep one on the right track, there is a real danger that this will get you into some sloppy reasoning. Not everybody submitting to hep-th is Ed Witten.
As Lubos Motl once wrote on his blog: “if you cannot disprove the conjecture in 20 minutes, it is probably correct …”
No, I’m confused. I freely admit that I misread Lee’s message on the BPS part. Thanks Wolfgang. Sorry Lee.
Most of my message is not about that, though, and still stands.
Cheers,
-cvj
Wolfgang, you wrote:
Several people in the field are aware of this valuable insight, and mindful of it.
You can at this point start the tedious discussion we’ve had several times on several threads about how this sort of thing means we are doomed because there is no experiment to test the idea….. but I do not think it will help us to repeat all of that (interested parties can go and read those threads). We are aware, as a field, of the limitations of what we are doing. The only other option is to do nothing further in this area, which as I have said countless times, would be at best neglectful. There are others working on other approaches, and I wish them well.
Thanks.
-cvj
cvj,
> You can at this point start the tedious discussion we’ve had several times on several threads about how this sort of thing means we are doomed
This was not my point and I am sorry if my comment made you angry.
My point is that more mathematical rigor is necessary if the experimental guide is missing. I do not think that M-theory/string theory is doomed. At least I hope not.
As fas as I understand, this is also Lee Smolin’s point, but I cannot and do not want to speak for him.
Wolfgang,
You did not make me angry. “You wouldn’t like me when I’m angry”… to quote a famous fictional scientist … 😉
I know what you’re saying and it has been discussed before. My response is that much more research is needed on what we are actually dealing with here as a theory before we can rigourously prove anything mathematically. See my penultimate paragraph to Lee…I said more research is needed….as I do in every thread on this blog when this issue comes up. But people seem to forget…..that’s ok. That’s why we’re here, I suppose.
And while we are on the subject, there are several powerful pieces of physics that have no rigourous mathematical proofs. Rather, new interesting mathematics often flows from the physics – less so the other way around, at least in this field. (Others in the field probably have a different take on that, by the way…I speak only for cvj, not the whole field….let’s not start another “string theorists say…” controversy here…. 🙂 )
Off to the beach to do some computations of ironic experimentally unverifiable stuff now….
Cheers,
-cvj
In case people are wondering what I’m talking about in the third paragraph of my comment above, I’ll just mention the whole framework of Quantum Field Theory, and mention that there are several examples within that framework alone of what I’m talking about. Several results from that field were proposed and studied in the looser physics setting and seen to spectacularly relate to Nature -eventually..these things take time- without us sitting around worrying about whether the Mathematicians had vetted them yet. I see the same things aas possible here…..it will take time…..but the payoffs are worth the wait, in my opinion.
I hope we’re all agreed that QFT is a useful box of physics tricks that is hard to motivate from rigourous mathematical perspectives alone.
-cvj