String Theory for Undergraduates

I hadn’t realized how many of the physics departments at the top universities in the US have instituted undergraduate string theory courses.  The only one I was aware of was MIT’s 8.251, String Theory for Undergraduates, taught by Barton Zwiebach, who developed a textbook for the course, A First Course in String Theory. 

Maybe now that there’s a textbook, that is what has caused other institutions to follow suit.  Caltech has Physics 134, String Theory, and Carnegie-Mellon has Physics 33-652, An Introduction to String Theory.  Stanford goes its competitors one better by having two undergraduate courses in string theory: Physics 153A, Introduction to String Theory I, and Physics 153B, Introduction to String Theory II. This last course even promises to explain to students how string theory is connected to particle physics. 

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119 Responses to String Theory for Undergraduates

  1. D R Lunsford says:

    Needless to say, this is absurd. Is physics trying to commit suicide? In fact there is no longer any need or use for American scientists and engineers, only Home Depot clerks and the matching consumers, so I guess they figure – why not?

    It’s as if law schools were to begin teaching from Deuteronomy. Let’s bring back Aristotle and Pliny!


  2. Kea says:

    Gulp! In my country we don’t even have any String theorists.

  3. LDM says:

    It is probably not too unreasonable to state that many critics of the theory have not studied string theory even at the level of Zwiebach — and even Feynman said (read the letters book for the exact quote) he did not believe in it, but he admitted he did not know enough about it to say why…

    As long as the undergrads have the necessary background, I think this is an EXCELLENT decision — to offer undergrads courses, so they can judge the merits (or lack thereof) of string theory themselves.

    They will also then be in a position to judge when its supporters have let their enthusiasm overpower their scientific better judgment (As an example, Zwiebach’s recent letter comes to mind — it was, unfortunately, egregiously biased and overstated — however, one can only really make these judgments if one has studied string theory sufficiently to realize Zwiebach was exaggerating its results ) — OR when the beauty of its ideas and its partial results, despite the current lack of experiments, justify a continued optimism that that the theory has substance and is worth continued investigation.

  4. z says:

    After a cursory look at Zwiebach’s course page, it seems to me some mathematics only at the sophomore or junior level is required – PDEs, linearity, multivariate calculus. What exactly do they hope to accomplish with such courses other than to inculcate a new generation of graudate students and benefactors? Connections explored in these courses to experimental tests is superficial at best, in my opinion.

    I’m not saying these courses are worthless — there’s a lot of neat mathematical tools an undergraduate could learn to apply in them. However, an undergraduate education in physics should be firmly based in reality. Speculative theories such String Theory and even LQG should be in the domain of graduate school or applied mathematics, not undergraduate physics.

  5. biophysicist says:

    I took the class myself a couple years ago back when we were still given the typed manuscript for free (there now I’ve definitely given away my identity for a couple readers of the weblog for sure) and even though obviously I chose a different branch of physics for my graduate work I have to say that the course was simply outstanding and Barton Zwiebach is one of the finest teachers I’ve ever had. Yeah string theory as science has definitely seen better days, but the class itself is a great way to learn a lot of the tools used in modern physics. The way Barton teaches it also makes it a neat way to see how different theoretical underpinnings can come together – the calculation of the Beckenstein-Hawking entropy result for example played a big role in my personal decision to pursue statistical mechanics as a graduate student (now of course, as a statistical mechanician, I can laugh at all you particle guys whose work is simply an input into our theories 😉 ).

    Also I’d like to point out that while the class started with probably 60 people (including 30 or so undergrads) the year I took it, we only ended with 6 undergrads by the end I think and about 20 graduate students. So before anyone gets too worried about Barton’s corruption of us youth I think it’s worth thinking about the positive aspects of the class – I of course cannot speak to the other institutions’ courses, but I learned a lot of useful tricks in 8.251 that I use to this day.

  6. Richard says:

    String theory for undergraduates is excellent for students who want to think about classical mechanics and E&M in a more abstract way in preparation for graduate school. Additionally, these courses can serve as “capstone” courses for physics majors who aren’t planning on going to graduate school. Most students who are interested in theory will take either GR or QFT instead. Perhaps a course that would serve both groups of students better would be an introduction to conformal field theory with applications to condensed matter for undergraduates, but no one has written a book for that subject comparable to Zwiebach’s.

  7. Doug says:

    I would like to take the course, if nothing else just so I can get the answer to one question:

    Why does David Gross and others say that they don’t know what string theory is? What does this statement actually mean?

  8. Jimbo says:

    After 10 yrs of college physics teaching in Calif., Colo., Florida and Oregon, I can guarrantee that 99.9% of the undergrads, at 95% of US universities, contemplating signing up for an intro string course out of Zwiebach’s book, will drop the course in less than 2 weeks !
    In the 5% I am excluding, are of course Caltech, Harvard, Stanford, Princeton, Cornell, UC, CU, UWash, etc.
    However, even at prestigous schools, where undergrads have excellent preparation, faculty are overcommitted to teaching std. req’d courses, and will probably be reluctant anyway, in the dubious light of anything stringy these days.
    Mike Duff was very harsh on the mathematical unfitness of physics American students, and I can personally vouch for the veracity of his comments on this sad state of affairs.

  9. misslemon says:

    Re: LDM’s arguement:
    “I think this is an EXCELLENT decision — to offer undergrads courses, so they can judge the merits (or lack thereof) of string theory themselves.
    They will also then be in a position to judge when its supporters have let their enthusiasm overpower their scientific better judgment ”

    Would you say, then, that it’s also an excellent idea to teach “creation science” to biology students? Not to say that string theory is in the same class, but this IS the arguement often used for allowing creationism into the biology curriculum.

  10. MathPhys says:

    The first half (or so) of Zwiebach’s book is good because he assumes so little, so he has to explain lots of basic physics before hand, so you can think of this, indeed, as a motivated introduction to general physics.

    I’m not so sure I like the latter parts of the book, where he introduces those aspects of string theory that he’s interested in. That makes the book less than suitable as a standard textbook.

  11. D R Lunsford says:

    Richard said

    String theory for undergraduates is excellent for students who want to think about classical mechanics and E&M in a more abstract way in preparation for graduate school.

    I can’t see this as being in any sense true. In fact, having wrestled with both things at length, I declare it categorically false.

    All the hotshots I ever knew had glaring holes in their understanding. I assume hotshots everywhere are similar. One has to work at rounding out one’s understanding, and it ain’t comin’ from string theory. There is a magisterial tone in your misunderstanding that illustrates the actual source of the current unpleasantness.


  12. A problem with Zwiebach’s book is that it is very easy to follow in the first part but it is at the end expected to be taught by an expert of the field, because when it goes into complications it just promises that in the real research papers all the questions are rightly answered. SO you are forced into Ponchiski’s are GSW and it is not undergraduate anymore.

    Still, it is interesting for an undergraduate to think about the quantisation of extended objects.

  13. X says:

    maybe it is interesting for undergraduates that already understood quantization of point particles?

    I think that an undergraduate needs to get some idea about what string theory did/will accomplish, to decide if it is worth to study it. While learning some details of string quantization (at the expenses of not learning other physics) is not a good idea.

  14. Warren says:

    Stanford is on the quarter system, so it’s really more like 1 1/3 courses.

  15. LEJ Brouwer says:

    I would love to see a textbook on modern string field theory in the Batalin-Vilkovisky formalism of which Zwiebach was a pioneer. The beautiful thing about Zwiebach’s work, and I think this is shows through in all his research papers, is his emphasis on clarity and rigour, despite the inherent complexity of the subject matter.

  16. Doug says:

    But, again, how can a university course, based on a textbook, teach something that nobody can identify? What is it that I’m missing here? What do string theorists, like David Gross, mean, when they say that they don’t know what string theory is?

    Please, can someone take a moment and explain this to me? Books, pro and con, are flying off the presses about something no one understands, but everyone feels so strongly about.

    I can understand the idea of strings vs. point particles. I can understand the difference between the 26D bosonic string theory and the 10D superstring theory with its five dualities and how the 11D M-theory unifies these. I can even understand how compactified dimensions make it possible to have n-dimensional equations of motion in a 3+1 manifold, but what do they mean when they say they don’t know what string theory is? This I don’t understand.

  17. Kasper Olsen says:

    Dear Peter,
    did you read the book? It is – in my opinion – actually quite good; all of it might not be important for eventually going beyond the standard model, but don’t you think it is important to learn about the most promising ways of going beyond the SM? If somebody wanted to give a course on LQG or twistor theory, don’t you think it would be OK?

    – regards, Kasper

  18. Jason says:

    Relax, people.

  19. Peter Woit says:

    It’s very simple. What is known about string theory is how to construct a (divergent) series, one that is supposed to be a perturbation expansion of some still unknown exact theory, and thus an asymptotic series in the string coupling for the true result. There are lots of partial, conjectural ideas about what properties this non-perturbative true theory will have, and some conjectured constructions in special backgrounds that don’t look like physics. But no one has a good idea about what this exact, underlying theory is. There has always been a lot of speculation about how it will be something completely new and different, involving new ideas about space and time.


    No, I don’t think it would be OK for a physics department to set up an undergraduate course in LQG or twistor theory. This kind of highly speculative stuff involving advanced mathematics belongs in upper-level graduate courses, not undergraduate courses where the students still have yet to learn many of the most basic things about physics and the most basic mathematical techniques needed. I know of no other example ever where multiple US physics departments have instituted undergraduate courses in a subject for which there is no experimental evidence.

    Yes, I own a copy of the book and have read some of it, although it covers material I’ve read about many times in other string theory books and expository papers over the last 20 years. It’s a good exposition of the subject from a true believer, but it’s completely inappropriate for undergraduates. There are many, many more useful things for them to study than the details of how to quantize the string in light-cone gauge.

    I completely disagree with you that string theory is a promising way of going beyond the SM. It has completely failed at this, something you won’t learn by reading all the hype in Zwiebach’s book. Even if it were a promising way of going beyond the SM, undergraduate students don’t even yet have the background to understand the SM, and they need to do that first. It is becoming a huge problem in particle theory that students are being trained in the details of string theory before they have really mastered the details of the SM.

  20. D R Lunsford says:


    The time would be better spent on, among other things, an intensive course in “Intuitive Relativity”. I found that very few undergrads understood relativity at all well. I think a history course with readings of original papers would be good (e.g. the “Dreimaennerarbeit”, Pauli’s review articles, Einstein’s big papers etc.)


  21. LEJ Brouwer says:

    I agree that string theory is not a useful topic to study at the undergraduate level. However I think the study of Clifford algebras and their applications to physics (see e.g. the book “Geometric Algebra for Physicists”) could prove to be a useful broad framework for those intending to carry out future research in theoretical physics.

  22. Doug says:

    Thanks Peter. Does the book explain that, or is it assumed that an undergrad physics student would ordinarily realize it?

  23. James says:


    It might be a shocker for you but several European universities offer undergraduate string theory courses and have been doing so for at least 15 years (that is what I am aware of). Examples: Amsterdam, Groningen, Utrecht, Brussels, Budapest, Prague, Moscow and I’m sure there are plenty more.

    Mind the fact that there are loads of old professors for whom the phrase “string theory” means something from the 70’s and that is what they teach. It would be very difficult for you to convince them that this material is some new age hype when they were studying it 30 years ago.

    Of course there are European universities where the more modern approaches are taught to undergraduates under the banner “string theory”, e.g. Amsterdam and I suspect this area is where you actually target your criticism.

    My observation is only to enlighten anyone who thinks that “string theory” is a large monolithic blob which can be commented on and criticised in one go.

    Hope this helps,

  24. James says:


    You write “What is known about string theory is how to construct a (divergent) series, one that is supposed to be a perturbation expansion of some still unknown exact theory, and thus an asymptotic series in the string coupling for the true result.” and perhaps you allow me to notice a certain negative tone in this sentence.

    However, I guess you agree that nothing is known about the Standard Model non-perturbatively (except for QCD but that is also not rigorous) and all what is known is a perturbative expansion but that doesn’t cause us any headache. So this particular criticism of string theory is not really honest as you could say the same for the Standard Model as well. Put it this way: a rigorous non-perturbative definition is *not* a requirement for a good physics theory.

    I can already hear you saying that the Standard Model has been confirmed experimentally and string theory has not, which is completely true but in your above mentioned criticism you brought up the lack of a non-perturbative definition and haven’t talked about experiments. In other words just because one valid criticism exists does not mean that *any* criticism is valid.

    Hope this helps you understand why string theorists and other high energy physicists do not respond to your book in a serious way and why string theorists and other high energy physicists do not take you seriously over all. If they are looking for criticism of string theory (plenty exists surely, lack of experimental evidence being one) they go to the experts who are also plenty. Even plenty of string theorists exist who are critical in a reasonable way, unlike you I am sorry to say.

    Again, it is my intention to help you understand the reason for your considerable isolation in high energy circles especially since you yourself asked the question in one of your postings why there is no serious string theory reaction to your book.

    All the best,

  25. Chris Oakley says:

    Hi Anonymous James,

    I don’t think that your observations are very relevant. Many of us have come to the conclusion that the String community is not capable of reforming itself and therefore the change has to come from outside. This is where writing books for the general scientific audience comes in. Peter is surely in the vanguard here, but if he had not taken it upon himself to draw the world’s attention to the extent to which fundamental physics research has poisoned itself, someone else would.

  26. anonymous says:

    Dear James, the main problem is not the lack of experimental evidence, but the lack of any experimental signal. I hope you agree that, if strings have nothing to tell to experimentalists, the lack of a rigorous non perturbative definition is solved as: who cares?

  27. Peter Woit says:


    The problem with string theory is not that it doesn’t have a rigorous non-peturbative formulation, the problem is that it has no non-perturbative formulation at all (other than on unphysical backgrounds). This is especially problematic because the vacuum state people want to use in string theory can’t be the perturbative one. This is why you can’t predict anything in string theory. You don’t have a non-perturbative theory that can tell you what the possible vacuum states are and allow reliable calculations in these states.

    This is completely different than the standard model, which has a well-defined non-perturbative lattice formulation. This definition is completely rigorous, the only thing non-rigorous is that you can’t prove that it actually has all the properties you expect. You can do approximate calculations, either perturbative or semi-classical ones where appropriate, or fully non-perturbative ones using Monte-Carlo methods. All the results of these approximate calculations are consistent with the non-perturbative theory having the properties one expects.

    For the electroweak part of the SM, the vacuum state is the perturbative one, you can do perturbative calculations, and these have been confirmed experimentally to very high accuracy. For the strong interactions, the low energy behavior is non-perturbative, you can calculate it using Monte-Carlos methods, and, within the accuracy of the calculations you get agreement with experiment. At high energies because of asymptotic freedom, you can use perturbative methods also in QCD, and get good agreement with experiment there too.

    The situation of the SM is just completely different than that of string theory, and the fact that you don’t know this seems to indicate that you don’t know much about this subject at all. I don’t know who you are, since you choose to hide behind anonymity, but you give every appearance of being an undergraduate who has no idea what is going on here.

    As for my “isolation in high energy circles”, I can assure you that that is not the case. I regularly talk to high energy physicists of many different stripes, and find that the only ones who significantly disagree with me are the more fanatical among the string theorists. From my conversations with many physicists in recent years, my impression is that the great majority of the physics community now has a low opinion of string theory (often lower than mine). Even the majority of string theorists that I talk to think the state of the field is highly problematic. Several of the people who regularly comment here, but choose to remain behind pseudonyms because of fear of retribution from fanatics, are known to me and are theorists who work on string theory.

    I wasn’t asking about why no one agreed with me, most theorists do. What I’m curious about is why those string theory true believers who disagree with me refuse to publicly answer any of the criticisms I make of the theory. So far, the only one willing to do so is Lubos, and he is crazy. The only others heard from are people like you, who don’t seem to know what they are talking about and can’t answer any of my criticisms, but yet insist on attacking my competence to make them in a cowardly fashion using pseudonyms. This kind of defense of string theory is not going to work. It is becoming widely realized in the physics community that string theorists are not able to answer the scientific criticisms being made, and the way they are choosing to respond to their critics is rapidly stripping them of any credibility.

  28. Peter Woit says:


    I haven’t looked at everything in the book carefully, but it certainly was my impression that the book did not explain exactly what the problem is with having no non-pertubative formulation. I have no idea whether Zwiebach explains this to his students, but his recent letter to the WSJ not only didn’t mention this problem, but tried to imply that it doesn’t exist or is not serious.

  29. Hi Peter,

    I hope you’re well.

    A few things:

    (1) I can think of numerous times when well-known non-crazy string theorists have answered your criticisms, on this blog and on others. The problem is that you choose to forget the answers and keep repeating yourself. So people have gotten terribly bored with the whole thing I suspect. It’s nothing personal, at least not on my part, just really really boring, I’m afraid. How about searching your own blog’s archives for some of the answers? And those of CV? There’s really been no significantly new discussion points since last August or so, so all this stuff is hard to distinguish from a PR exercise to sell a book. Not that there’s anything wrong with PR exercises per se, and I am of course not accusing you of engaging in one, just making an observation.

    (2) The only time you seem to come over and join in a discussion (or whatever) over on CV about strings is when you’ve something negative to say. Why not come and join in the other discussions (there and elsewhere) where we are all publicly visibly learning new things about ongoing research in the field as we go along? Not doing so while continue to make the same old answered points again and again -your current practice- might lead the uninformed observer that maybe you have a fixed idea about what you want to believe and will only discuss results consistent with that. See my last two sentences of (1).

    (3) You speak with certainty that string theory has failed as a theory of Nature. Actually, you don’t know if that is true, and nobody knows that. It is your hunch that it is so, and it is my hunch that it is not so, and we are entitled to our hunches. It is a subject of ongoing research. That is as much as anyone can say. To say more is hype. I thought you did not like hype. See my last two sentences of (1).

    (4) You say that the majority of string theorist that you talk to think that the state of the field is highly problematic. I cannot dispute that you got that impression, but I do question the validity of the sample that you have ahda access to. I and several of the people I work with or meet regularly in the field (from many of the most active groups around the world) don’t seem to have that strong an opinion. But that’s consistent with the fact that none (or few) of these people have actually met you at any conferences or meetings. (Unless they are meeting with you in secret?) So there seems to be little or no intersection between the set you are meeting with and the set that I and my colleagues and collaborators are meeting with. Interesting, don’t you think? You’re a smart guy and ordinarily would not make such an empty point unless….. oh…see the last two sentences of (1).

    (5) The real reason I came on to comment (since I’ve said much of the above before) is to ask whether you really think that (as a faculty member of a respectable university, but we’ll let that pass) it is consistent to publicly beat up on an undergraduate (if that is what James actually is), and call him or her ignorant about string theory and other issues in the very comment thread of the post you wrote saying that undergraduates should not be taught string theory? Also, he/she made some interesting historical and factual points that you chose to ignore. How come? This all seems a little odd to me.

    Summary: With all due respect, please change or update the refrain of the song. It’s got rather boring. Stop being so transparently selective about what you choose to mention about the string theory program. Try harder to apply the same standards of rules of engagement in discussion that you apply to others. (I know this latter is hard…. I fail sometimes too).

    Anyway, the repetitive refrain and the selective memory about what has been addressed…. these the main problems. It is just boring. Nobody wants to play anymore, and standing on the mound beating your chest yelling “why will nobody fight me?” is looking a bit silly. I’d stop that if I were you. (Although it is good for book sales and press attention. The press and the public love the old tired “underdog vs the establishment” story.)

    Ok, I’ll go now. I hope to have a pleasant, reasonable, and new discussion wth you sometime soon.



  30. cvj:

    I don’t see anything wrong in what Peter is doing. We had enough “PR exercises” of different kind – “The elegant universe”, and Kaku, and all that. We all heard how M-arvelous and M-ysterious the string theory is. Now it is time to hear a second opinion. I find it refreshing and healthy that a person like Peter spends time and effort to debunk stringy hype attempts.

    If Peter is right, then the question of scientific validity of the string theory may never be resolved by scientific methods. It looks like it is impossible to prove this theory wrong, and there are no visible signs of experimental evidence in favor of strings. Nobody wants to forbid stringy research. The question is how much of taxpayers’ money should go there? String theorists enjoyed enormous amount of public trust for a couple of decades. The question is whether we should continue to trust them, or better start investing in something else?

    Peter, I also don’t like when you attack your commenters (even anonymous ones) on a personal level. This doesn’t make your position stronger.

  31. woit says:

    Hi Clifford,

    Thanks for stopping by. Sorry I don’t have much time time to respond. Actually I’m leaving early tomorrow morning for a very short vacation in LA. From CV, I gather you’re not there, but enjoying the south of France.

    I do pay close attention to the responses I have gotten here and elsewhere from string theorists to my criticisms of the theory. They’re a mixed lot, ranging from offensive personal attacks by Lubos and followers at one extreme, to much more sensible comments from you and others. I’d characterize your response to my criticisms of string theory as roughly “it’s still too early to evaluate, we’re working on it, look at the progress we’ve made in AdS/CFT for instance”. This is fair enough, it’s a point of view I can understand and respect, although I don’t fully agree with it (22 years is a very long time, the amount of progress is exaggerated, etc….).

    The main problem with your point of view seems to me to be that you’re pursuing one set of goals (e.g. for instance better understanding AdS/CFT, topological strings, 2d strings), which are reasonable, but selling the subject to the outside world as a much more ambitious program, without acknowledging that it has failed. Your work on non-critical string theories may or may not someday lead to something interesting, but what is being promoted to the public is the idea of unification via a critical 10 d string (or 11d M-theory). This has created a whole industry of people investigating an infinitely complicated variety of “backgrounds” for such a string, and ultimately led to the landscape fiasco. This has been a disaster, and it needs to be acknowledged before it leads to more damage to the field than it has already caused.

    When I say that the majority of string theorists I talk to find the state of the field problematic, the main thing they often have in mind is the landscape, which often completely appalls them. Besides this, most also feel that there has been a depressing lack of exciting new ideas in the subject, across the board. I can’t believe you don’t also find many if not most of your colleagues disturbed by the landscape. As for the number of exciting new ideas question, this can be quantified by looking at what papers are being cited in new ones coming out, and I can back up what I say with some very solid data.

    In terms of people I talk to or exchange e-mail with, my sample size is small, but it’s non-trivial. When I go to conferences, it is often (but not always) to mathematics or mathematical physics ones, since that’s where my research interests lie, but I have been to and even given talks at conferences or workshops where there were quite a few string theorists. On the whole I found when talking to them that they shared many of my concerns about the subject. Unfortunately, some string theorists have very much isolated themselves from the rest of the physics community. Sorry to have to tell you this, but many of your physics colleagues tell me they think the field of string theory has become a bit of a closed religious cult. Skeptics aren’t welcome there and have little motivation to try and participate. The last physics conference I was at was last week, here in New York, the one about group theoretical methods in physics. I talked to more than a few physicists then, and I can assure you that the level of hostility to string theory and how it is currently being pursued surprised even me.

    About “James”. I have no idea who he is or whether he’s an undergraduate, quite possibly he isn’t. If he is one, he has no business writing ignorantly in here to attack someone who knows far more than he does. My conduct towards him was significantly better mannered than his towards me.

    As for CV, I do post comments there when I think I have something worthwhile to say. Often they’re not about string theory at all. When they are associated with one of the postings about the string theory controversy, they’re often respectfully disagreeing with a much more positive take on string theory due to one CVer or another. Sorry if you find my objections to string theory “boring”. I find the endless continuing overhyping of the subject equally “boring”, but feel that someone should do something about it. I’d be very happy if it wasn’t me.

    As for your endlessly repeated attempts to pin this all on my trying to sell books, just come off it. This has nothing to do with that. I’ve been making these criticisms privately for 20 years, publicly for more than five years, long before there was any book. This is a complicated business and the book is my best attempt to lay out what I’ve learned in a long career, and explain a point of view about where the subject of particle theory is now that I strongly believe in and hope people will pay attention to. Sure, I definitely think people should read the book, I’m arrogant enough to think that I have something important and valuable to say. But if it’s a complete failure as far as the publisher is concerned and doesn’t make a dime, but a sizable fraction of the particle physics community reads it and thinks about what I have to say and whether my point of view makes any sense, I’ll consider the project to have been a huge success.

    Hope you’re enjoying Marseilles and meeting some mathematicians, they do some very worthwhile things…


  32. Jimbo says:

    I spoke recently with an Indian string theorist (Tata Instit.), and he basically wrote off Peter & Bert Schroer as “disgruntled whiners, without any significant research in years”. My retort was, might we add Veltman, Glashow, Richter, & Gates to that list as well, and who knows how many other field theorists that might emerge from the closet to signal their opposition to the dominant paradigm in HEP ?
    Pro or Con, we are all college educated people, and how do they settle arguments: Forensic Debate. Lets gather together 5 prominent stringers, and 5 prominent anti-stringers, and have a live debate, with theorists from neutral camps for judges. The media would devour it !
    In addition, why not CLOSE the N.E.W. blog Peter, now that your book is out, the Discover article is months old, and get on with your life & research ? It must be very taxing doing this 24/7, and lets face it, the word IS out, and I don’t think the stringers will get carte blanche much longer, when in just a few years, the LHC tallies up evidence.
    Who knows if you close, Lubos might just as well too.

  33. Peter Woit says:


    The one criticism I get for how I’ve been spending my life the last couple years that I do agree with is that I’d be better off spending more time on my own research ideas. I’m hoping to spend less time on the blog and more on research, and perhaps changing the emphasis of the blog so that it’s more about research level topics I’m thinking about. Urs Schreiber’s blog is an interesting example of this kind of thing. Unfortunately this may not be so easy the next few months. Clifford thinks I’m spending my time trying to get people interested in my book, but it’s not quite like that. There’s a lot of interest in it already, and it is taking a signficant amount of time now to respond to people who contact me about it for one reason or another. The response has been very gratifyingly positive, but dealing with it does take time away from other things. Current plan: try and find as much time this summer as I can to work on research, write off September as hopeless since the book is coming out and a new semester will be starting, then hope by later in the fall things quiet down, my job is done, everyone agrees with the NEW critique of string theory, so that part of the blog can fade into irrelevance.

  34. Anonymous says:

    Pro or Con, we are all college educated people, and how do they settle arguments: Forensic Debate.

    Really? To me that phrase conjures images of unreasonable people talking as fast as possible, emphasizing the same points repeatedly, and not listening to the people they’re talking to. Oh, wait, that sounds familiar….

  35. Why not compile the course descriptions and see what is being taught by whom, perhaps with what textbooks?

    From Caltech’s catalog:

    Ph 134. String Theory. 9 units (3-0-6); third term. Prerequisites: Ph 125 ab, Ph 106 ab. A basic course in string theory designed to be accessible to a broad audience. The main topics include the motion of relativistic point particles and strings, actions, world-sheet symmetries and currents, light-cone quantization, and the spectra of relativistic open and closed strings. The course will conclude with an exploration of D-branes, T-duality, or string thermodynamics, depending on student interest. Instructor: Schulz.

  36. JC says:

    I wonder if Lubos will write his own string theory book for freshman undergraduate students. 😉

  37. Michael says:

    “changing the emphasis of the blog so that it’s more about research level topics I’m thinking about”

    YES!! Tell me all about your interesting new ideas, especially the off-diagonal ones. 😆

  38. Peter Woit says:

    Always charming to hear your witty remarks Michael/Dan/whoever you are. Now go back and play with your big brother Lubos…

  39. Hmm says:

    Perhaps, before making grandiose statements about the past and future
    directions of theoretical physics, and especially before “correcting”
    people with authority, it would be useful for you to understand, say, some
    elementary quantum field theory?

    Lets take your response to James about the difference between
    non-perturbative effects in the Standard Model vs. string theory. You
    contradicted James and said that the Standard Model has a perfectly
    rigorously defined lattice formulation. Even ignoring gravity, this is
    nonsense. Hypercharge is not asymptotically free and hits a Landau pole at
    a scale \Lambda–so there is no “perfectly well-defined” lattice formulation. The Standard Model by itself simply isn’t “well-defined”–there are effects of order \sim E^2/\Lambda^2 \sim e^{-1/g^2} that *can’t even in principle* be calculated, as they depend on the details of what would UV complete the theory above \Lambda. This is trivial field theory (pardon the pun) which you don’t seem to understand. Of course string theory doesn’t have this sort of problem, but there isn’t any point discussing this till you understand the simpler field theory case first.

    So James was right on the money, both in his physics point and more
    broadly. Much as you like to think that experts aren’t paying any
    attention to you because you’re an outsider declaring uncomfortable
    truths, and much as the journalists covering your book eat up this story,
    the real reason you’re ignored is very different. String theorists have
    many harsh critics, and are fully aware of all the criticisms themselves.
    Many of the well-known critics have spectacular records of research
    accomplishment, which means that they not only understand the basics of
    the field, they also have a sense of the ebb and flow of ideas and the
    creative process of discovery. String theorists respect these people and listen to them. Of course you don’t have a real record of research accomplishment (and it is funny to blame your blog for this–what were you doing before that?). But your gaffes with non-diagonal SU(2), your above lack of understanding of landau poles and countless other instances also reveal that you don’t even solidly understand the basics. We are all familiar with the annoying undergrad who thinks he knows it all, knows all the fancy words and catchphrases, but can’t do any calculations and doesn’t really understand physics. I’m afraid that all external indications are that you are like that undergrad writ large–except you don’t have the excuse of youthful naivete and the undergrads aren’t going around making pompous pronouncements about the sad state of particle theory. Most beginning grad students could give better, harsher, more incisive criticisms of string theory than you can–but of course with a solid command of the fundamentals and a close-up view of the research frontier, they are also in a better position to understand why it is still so compelling.

    I am glad to hear that you are finally going to devote yourself to
    research. Best of luck–it is a far more worthwhile endevor than your
    blogging, and much more difficult and challenging. I daresay you have a lot of catching up to do. If you don’t mind the advice, the field has come a long
    way since you were last active–you might want to sit in on a refresher
    QFT course at columbia before you dive back in.

  40. Peter,

    Thanks very much for choosing to give a level headed reply. On some things we can just agree to disagree, on others, there is a right and there is a wrong. With that I will refer you to my point (3) above.

    (3) You speak with certainty that string theory has failed as a theory of Nature. Actually, you don’t know if that is true, and nobody knows that. It is your hunch that it is so, and it is my hunch that it is not so, and we are entitled to our hunches. It is a subject of ongoing research. That is as much as anyone can say.

    The other point that I regularly make to you is that you should not characterize all work in string theory as what is being done by a relaive few people. Anyone who reads your blog would assume that there are hundreds and hundreds of people all working on the landscape. That is an mischarcterization of the state of research of the field. I think that the program of invesigation there is interesting, actually, and it is important for some people to explore some of that program. But it is not my cup of tea. But that’s fine, its enough to know that we’ve got some good people working on it, and I can focus on other stuff. That’s not atypical. There are hundreds of people focusing on other stuff, chipping away at the problems and learning a lot about what we’re doing. You hardly ever acknowledge their existence when you talk about the program of research in string theory, and characterize it in sometimes amusingly apocalyptic terms. Case in point: You mention my work on non-critical strings, which you can of course learn about from blog posts I’ve written and a quick search on SPIRES. So in about 5 minutes you can learn about the existence of this. But then you characterise it as essentially nothing to do with the program of connecting strings to Nature. How do you know that? A closer look (which you have not done, it seems) will reveal that this work is focused very much on trying to understand in a controlled environment several of the key ingredients and stringy phenomena that are used in constucting the landscape vacua! Our best models of various non-perturbative phenomena in string theory are to be found in such models….. It is as though you are saying that studying the Ising model will teach us nothing about phase transitions in the laboratory. Another case, and this one is typical: I recently did a post on CV about a new result in understanding tachyon condensation in the critical bosonic open string. You evidently read the post, and made no comment, as have and will others. As usual, this post will probably be largely ignored in this way as compared to the other type of post about string theory which is all about people just coming and and yellling “it’s all crap” or “the program has failed”, and others yelling “no it’s not” or “no it has not” back and forth. So as a result, once again the whole thing is skewed. People -including some impressionable young people in the field- get the impression that its all about the landscape, when in fact that result may be one of the single most significant and beautiful results to be presented in the field for several months. Rather than contributing to a discussion about what it might mean for the program of string theory, or even asking some questions to find out more about how it might affect -one way or another- your view of the program of research, you instead choose to ignore the existence of this kind of work in the field, or at least you don’t inform people that it is going on very much. In fact, there’s much more work of this kind going on than just a ton of people sitting chatting about the Landscape.

    I could go on with this, but I won’t. I just want to say that it is very important to stop this distortion of what is going on the field. This sort of explains this impression you have obtained from people about the “state of the field”. If “the field” is characterised entirely in terms of the landscape discussion, then of course if you meet several people who don’t like it (and may themselves be deluded into thinking that is all that is going on in string theory because they’ve been decieved into think ing that way by a variety of sources) then you’re going to come away thinking that there’s a whole bunch of disgruntled string theorists.

    I’d like to say in closing that there is a wealth of exciting work going on in the subject. We are not all currently working in lock step on the shock wave of some new explosion or revolution of ideas, and that’s simply ok. It is a healthy time indeed to have a large number of different problems be worked on. It is naive of you and those few apparently immature string theorists to whom you seem to have been talking to measure current progress by how far we are from the last time we all were writing papers on the same thing. Sure, revolutions are nice. I love them just like the next string theorist, but I don’t sit around waiting for them to happen and get drepressed that there’s no progress. No, instead I carry on chipping away gathering results that -along with those several others who are doing the same that you again and again don’t mention in your characterisation of the program of research- may well contribute to the next great leap forward, or at the very least, the steady march forward.

    This is just how research is done, and how it always has been done in any field of science. It is not done by public talks and TV shows and books and counter-books and yelling matches on blogs. That sort of public “yes it is-no it isn’t” stuff is just a soap opera that feeds the press, deludes the public, and serves as meagre nourishment for the timid and impressionable individuals in the research game who need to be told what to think. (Reaching out to the media is important in general, and sure it is nice to try to temper the extraordinary claims of the stringevangelists from time to time, but the tail should not wag the dog.)

    I love a soap opera like the next guy, but that’s all it is. I hope that the members of the press and publishing industry who are reading this also take note of what I said. You’re focusing on -and feeding- a soap opera that is a huge distortion of what is actually going on with research in the field. If you, members of the press and publishing industry, truly believe that your mission is more than about selling newspapers and copies of books (but I do understand that you have to pay the bills), and if you still remember that you may have come into journalism and publishing to actually inform people about what is going on in science, then please stop always focusing on the soap opera aspects. Take a broader look at what is going on. Don’t frame all discussions of string theory research in terms of pro- and anti- landscape.

    That’s not all that there is.


  41. woit says:


    Ahh, yet another string theory partisan who wants to lecture me about my incompetence from behind the cover of a pseudonym. It’s amazing how many of you there are up in Boston.

    Believe it or not, I’ve actually heard about the problem of the lack of asymptotic freedom of the U(1) part of the standard model. It’s discussed on page 98 of my book. There was a limit to the amount of detail I was willing to go into in my response to “James”. I was oversimplifying for the sake of concision, this point has nothing to do with the issue at hand. For the U(1) theory perturbation theory is not valid at high energies, but that is irrelevant to the argument I was making.

    Sorry, but your Lubosian tactic of dealing with my criticisms of string theory by insulting me and trying to paint me as an incompetent by sleazy methods isn’t going to work. You just make my point even stronger that there is a real sickness in how string theory is being pursued. The problem is not just Lubos, but quite a few other people it seems who are as pathetic characters as him.

  42. cvj,

    did you voice the same passionate opinion against publicity vs. science after “The Elegant Universe” was released? Peter is just restoring the balance. That’s all.

  43. Hmm says:

    Sorry–given how wildly silly your SU(2) ideas are, its hard to know what you do and don’t understand; and there was no need for “concision” in your response to James. There is no “rigorous” formulation of the standard model on the lattice, and no reason to bring it up.

    And indeed, it does have to do with the point you are trying to make. The non-pertubative phenomena invoked in modulus stabilization–e.g.gaugino condensation–are in fact non-perturbative properties of the low-energy effective theory, and at least as in control as the computation of the eta’ potential in QCD. That *you* don’t understand would make me think you’re one of those annoying undergrads I mentioned who doesn’t understand the issues involved, if I didn’t know better.

    And shame on you for being so condescending to James, telling him *he* doesn’t understand the physics, when what he said (minimally about physics) was precisely correct, while your “concise” statements were trivially wrong.

    But enough of this–I agree with cvj that its really really really boring. And like Michael, I look forward to seeing the fruits of your research labors. Even better than blogging about it, why not write a paper, filled with concrete predictions stemming from your studies of the the glory of Dirac operators?

  44. Hmm says:

    Actually, come to think of it, since you always complain that people call you incompetent when you’re not, here’s an opportunity to shut them all up. Its about exactly the subject we are discussing–non-perturbative effects in string theory. Lets make it easier, and ask about non-perturbative phenomena in SUSY gauge theories (thats at least QFT which you should know all about right?). If you profess to have some understanding of the issues involved, surely you can tell us what gaugino condensation is, and how (and in what sense) we know it exactly. I think understanding this is simply a prerequisite to even talking about modulus stabilization, and since you go on and on about how we can’t use non-perturbative phenomena in a theory we only understand perturbatively, you should minimally know about something as basic as gaugino condensation. If you do, you would have no trouble whatsoever writiing a little physics post explaining it to your readers in a nice way, right? It would even be a welcome prelude to a more physics-centered blog. While you’re at it, you can explain how we know the exact beta function in N=1 SUSY theories–this is merely perturbation theory, and surely nothing compared to the glory of Dirac operators. For an extra special post, tell us all about N=1 Seiberg duality. All very beautiful field theory, that I’m sure a QFT master like yourself would have no trouble explaining to the masses. I for one would be disappointed not to be enlightened by your post on the subject.

  45. woit says:


    It’s late and I have to get up early to get on a plane, so I don’t have the time to write the response to your comment that it deserves, and may not have any such time for several days, but let’s see what I can do in a few minutes before bed.

    First of all, I’m trying to have an intelligent, respectful conversation with you, but I’m starting off in a really foul mood, after having to deal with the “Michael”s and “Hmm”s that infect the world of string theoryand hide behind pseudonyms. An incredible degree of arrogance and conviction that anyone who criticizes string theory is an incompetent infects the field you work in. Lubos is an amazing example of this, but he is far from the only one. It’s completely disgraceful that many people in your field behave in this unprofessional way, and I’ve seen extremely little evidence that anyone has much of a problem with it. Given what I have to put up with from people like this trying to bully me into silence, you may find me less than sympathetic to some of your criticisms, for instance that I was not nice enough to “James”, whoever he was.

    I’ve been kind of surprised over the last year to see to what degree there is an increasingly widespread negative view of string theory. Among journalists I talk to, there is a backlash against much of the hype they have been fed about the subject over the years. Among non-string theorist physicists, there is a revulsion at the kind of viciousness and arrogance demonstrated by Michael, Hmm, Lubos, and others. Over the next few months and years, if you want to know why you’ll be seeing anti-string theory hostility, this is a large part of it. You may not be personally responsible for hype and ignorant arrogant behavior, but your field has far too much of it.

    I do understand what you’re trying to do by better understanding non-perturbative string theory in toy models. I try and follow this kind of work, although I obviously don’t have the time to become an expert and fully understand all of it. From everything I’ve seen, it seems to me you may ultimately learn many interesting things, and may have real success at understanding QCD, but I just don’t see any evidence at all other than wishful thinking that any of this can solve the deadly problems that afflict the idea of trying to get unification using strings in 10 dimensions. When I say that string theory has failed, it is that failure I’m talking about. This is an issue that can be intelligently discussed: I don’t see a plausible way that you’re going to get around the well-known problems, if you do I’m interested to hear about it. You need to have a better answer to this question than just “we don’t understand the theory, when we do maybe the problem will go away” If you don’t it looks like your research program is based on wishful thinking.

    I’m well aware that not all string theorists work on the landscape, but I don’t think your attitude towards it holds water. If it really exists, string theory as a unified theory is just dead. You’re welcome to the view that it doesn’t really exist and you’re trying to better understand the theory to show why. Susskind and others will tell you you’re in denial. Personally I agree that it remains an open question until you truly understand non-perturbative string theory. I just don’t see much in the way of progress towards this in recent years, or much reason to believe that in my lifetime anyone is going to be able to answer the question.

    While I think refusing to admit that the landscape is there and trying to get rid of it is a reasonable scientific position, what is remarkable about the landscape issue is that a large number of prominent scientists accept it, and yet refuse to admit the obvious fact that it kills the idea of string theory unification. This behavior is just irrational, and bizarre, and the fact that it is going on at such a high level is seen by many people as a scandal and as evidence that there is something seriously wrong with the way string theory is being pursued. There seems to be no way to get the people involved to ever admit that things are not working. This is an amazing story to watch, and you’ll find journalists are not going to resist the appeal of telling it.

    There’s more to say, but no time now, perhaps another…

  46. woit says:


    Even if it wasn’t late at night, I’d have no interest in submitting to your little tests about my knowledge of supersymmetric gauge theory. I’ve written a long book about the things at issue here and hundreds of pages here on the blog. People are welcome to judge for themselves whether I know what I am talking about based on those. And I’m definitely not going to waste any more time discussing anything with you unless you tell us who you are. Doing what you are doing from behind the cover of anonymyity is incredibly unprofessional behavior.

  47. Hmm says:

    You keep complaining about “arrogant” behavior. I think it is amazingly arrogant to pontificate on the sad state of particle theory when you haven’t actively participated in it for over 15 years. People are working hard, with little guidance from experiment, and poring years of their lives into studying these questions. On the other hand you left the field, have done little or no research (the hard work in this business!), and yet wax away on how lousy everything is. You complain about Lubosian tactics, yet bully those who bring up valid physics points–James isn’t the only case–there are many instances where you pull rank on someone by saying they’re “probably an undergraduate who doesn’t know what is going on”. You say that scientific giants like Weinberg, Wilczek and yes even Susskind have sold out the field–when they probably know a thing or two about science. This is all breathtakingly, stunningly arrogant. And I don’t say this because you’re a critic of stirng theory. I know and hugely respect many people who are very critical of string theory. If I want a critique of string theory, I’ll take it from ‘t Hooft or Wilczek or Glashow, not you.

    You also always, *always* back down from serious, technical physics discussions. You always refer to authority. The trouble with loop quantum gravity? “Don’t know, haven’t studied in detail”. What about modulus stabilization? Same thing. How about gauge coupling unification in SUSY? Ditto. These are all questions that any working theorist should have an informed opinion about. You have to understand, Peter, that being a dilletante with a passing word-level knowledge of the field is fine for a silly blog, but is completely worthless for physics. Without *some* demonstrated expertise in areas that actually matter, you don’t have any credibility with anyone other than your adoring blog fans and the equally uneducated science press. But in the long run it isn’t their opinions, or mine or yours that matters–its the physics that matters, and your approach to it–not being an expert at anything, while loudly complaining about other research programs without doing anything yourself–doesn’t further the cause at all. The cause it does push is the attainment of your 15 minutes of fame. Enjoy.

  48. Chris Oakley says:


    I certainly will, even if Peter does not. Everyone focusing on the next, biggest, trendiest thing has been the bane of HEP. One would think that HEP theorists have given up individual thought altogether. Hmm mentions the word dilettante (spelled like this, by the way), but that is exactly what most theorists now are: a far cry from the hard-bitten sceptics like Pauli who would accept nothing unless they could derive it for themselves. But without the likes of Pauli we would have nothing of value at all. I wonder what he would have thought of this un-physically-motivated mass migration to ten dimensions?

  49. anonymous says:

    to Hmm: I try to answer to your points about “physics”:

    1) The Landau pole at 10^40 GeV is irrelevant, because we do experiments at 100 GeV, with less than 80 digits of precision. Probably the Landau pole is cured by quantum gravity at 10^20 GeV, but again quantum gravity seems irrelevant for the same reason.

    2) I am surprised of hearing that “there are effects of order \sim E^2/\Lambda^2 \sim e^{-1/g^2} that *can’t even in principle* be calculated”. What are these effects? Do you mean that works on baryogenesis/leptogenesis, where e^{-1/g^2} effects are computed and crucial are crap? If instead you again confused physics with mathematics and your point 2) is something as irrelevant as 1), please don’t loose time in answering.

    To Woit: please don’t explain us gaugino condensation in hidden sectors.

    To Clifford: I think that this debate remains interesting for two reasons. First, it is an unusual phase in the history of (high-energy) physics. Second, it is unusual that inner problems get publicly discussed. These two dangerous things are slowly moving; after a few years we will see where they are going.

  50. Believe it or not, I’ve actually heard about the problem of the lack of asymptotic freedom of the U(1) part of the standard model. It’s discussed on page 98 of my book.

    Funny, we mentioned this issue past yesterday at physicsforums, see post 15 at

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