More Scenes From the Storm in a Teacup, V

At the (K)ITP the other day there was a journalist-led discussion/presentation on the largely-media-driven “controversy” about string theory. You know my opinion on this -it’s a largely made up story based on two inaccurate chariacatures (in book form) of research in the field- told by the same journalists and editors who some time earlier brought you the glossy stories about string theory that played up the excitement and promise, and played down the often-said but often-ignored cautionary remarks. The irony of all of this seems to have been lost on most. (I’m not saying that string theorists are entirely blameless in this, but I’ve seen how hard it is to get a balanced remark -about the basic process of seeing a complex scientific program through to its end- to survive next to a glossy one-liner).

The point is that the story being told now in the press is simply the one that journalists and editors want to tell now – a David vs Goliath story. It has little or nothing to do with what is actually going on in the science research. The journalist -George Johnson- does a good job of pointing out supporting evidence for this by going through a number of stories from a decade ago and looking at their structure. (You can see the video archive, as I did, on the web here.) He points out many things, such as the fact that journalists don’t actually write their own headlines for the story and sometimes these have only a loose connection to the actual words written in the body of the article. (There were expressions of surprise from the assembled scientists at this – I find myself amazed at the very fact that they were surprised – Have they not been paying attention to any of this over the last several years?) He points out many other things about the processes involved in getting these stories to appear in the newspaper as well. Worth listening to, if you have not heard this sort of thing before. (Have a read of a report that I and another blogger did on a similar topic, presented by science writer KC Cole in a physics department colloquium a while back.)

Anyway, please have a look/listen to the archived video (find it here). Particularly interesting (in addition to the above description of things as seen from the journalist’s world) is the reaction of lots of physicists in the audience to things that he says, and particularly to a long series of comments that Lee Smolin sent to Jim Hartle that he gave permission to be projected up onto a screen. You have to listen carefully, but have a listen to remarks from Gross, Horowitz, Srednicki and others at various points about Smolin’s moving-target approach to this entire discussion (e.g. how can you claim to be “not anti-string” for the purposes of appearing to be “just wanting to have a discussion” while pushing a book with a title that explicitly links string theory to the fall of science?), and both Smolin’s and Woit’s inconsistent standards of criticism about what constitutes a good research idea that young people should be working on (as opposed to them working on the supposed string theory dead end, you see).

There’s some useful discussion here overall, with good comments from the audience both serious and humorous (I love the joke (I don’t know who called it out): “Do you need higher dimensions to be both one-sided and two-faced?”. I know I’m going to get yelled at for repeating it, but it’s just funny.)

Most importantly, I hope that George Johnson takes on board some of the remarks from the audience about what science reporting could be in the greater scheme of things, beyond the current silliness. We’ve talked about that here a lot – first and foremost, getting across a clearer idea of how science actually works. What it can and cannot do, it’s role in society, etc. But I fear that he’s heard that all before, and that there’s little to be done without changing the business model of what Science journalism is fundamentally about. The model currently has very little in it about the agenda of getting the actual science out there. Until that changes, none of this sort of misrepresentation will change. This is why some of us blog.

Overall, the lesson to take away from this discussion is -as I have said above- that there’s just a huge amount of this discussion (about 95% of it, in my opinion) that has nothing whatsoever to do with the science issues facing string theory or any other approach in this area of physics. You, a reader trying to get an impression of what is going on in the field really have to be aware of that. As usual with any reading, be careful what you read out there… question the motives of those journalists, editors, and also those scientists who are writing popular-level books.

On the latter, be *especially* careful when a scientist writes a popular-level book which is almost entirely an attack on a body of work by others, rather than a description of some new ideas that they happen to be interested in or excited about. That’s probably a big clue that the science is not really their primary concern.

-cvj

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97 Responses to More Scenes From the Storm in a Teacup, V

  1. amanda says:

    “On the latter, be *especially* careful when a scientist writes a popular-level book which is almost entirely an attack on a body of work by others, rather than a description of some ideas that they happen to be interested in or excited about.”

    I fully agree, *but* to be honest I feel that there are some books out there describing “some ideas that they happen to be interested in or excited about” which are just as harmful as the kind you are criticising. I’m particularly disturbed by pop-sci books that try to give the impression that the particular angle they like is “generally agreed” to be the only sensible one, and that anyone who disagrees is either an idiot, if they are not famous, or *secretly* in agreement [“in the closet”] if they are. Of course I’m thinking of Leonard Susskind’s book, which for these reasons is every bit as bad as Smolin’s. Maybe I’m wrong, but I think that books like LS’s are really harmful.

  2. Clifford says:

    A quite fair point. One must be careful to not misrepresent opinion of others about the status of your own idea, that is true. That’s indeed a bad thing too, as it is again misleading. Not having read Lenny’s book, nor discussed it with him, I can’t comment on his in particular. But *if* he does what you say, that would indeed be bad.

    Cheers,

    -cvj

  3. M says:

    What makes easy to over-criticize string theory is that everybody can see its bad side: no concrete results like “for LHC we predict SUSY with broken R-parity…”. Only experts can see the good side of string theory: black hole entropy,… But experts lost credibility due to over-hype.

    Now, you blame journalists for over-hype.

    This is true only in part. Amara proposed one counterexample: journalists did not wrote the Susskind book. One could write a list of better counterexamples; hopefully you do not need to see it.

    I think that this criticism (or storm in a teacup) will have a healty effect. String theory seems dangerously close to failure and in past years too many string theorists reacted focussing on mathematical details and trying to believe that it was interesting. Now you must do good physics.

  4. Clifford says:

    M:- Please read what I wrote, and please watch the video. You’ve rather over-simplified what I said. Also, Susskind is not equal to the whole of string theory. Also, we’ve been carefully trying to make contact with experiment for a while now. The work continues on many fronts. (See the discussions in earlier threads of this series for example.) Pushing inaccurate portrayals of what we are doing in the public domain is not the method by which physics gets done faster. If anything, it has the opposite effect.

    Thanks,

    -cvj

  5. M says:

    of course I read what you wrote (while the video is too long, sorry). My oversimplified point is that the fact that journalists have some responsability is true but irrelevant; the only way out is to get good concrete physics. This is a healty message for some string theorists that seem only interested in discussing entropy of black holes, studying pp waves, etc.

    WWII showed how a strong pressure can make progress faster, maybe “string wars” will have this effect.

  6. John says:

    When journalists write about science, it is almost always, to a certain degree, oversimplified and sometimes even sensationalized. This is probably necessary for them to attract attention from the public who in general, even interested, know little about the various aspects of scientific research. It is not at all a bad thing, as their writings do, in an oversimplified fashion, inform the public about what is happening in science. In addition, when writing for or against both sides of the debate, journalists as a group seem to oversimplify roughly equally. So at least the reports are somewhat balanced.

    Personally, I think debate is healthy and good for science. It raises interest in science from the public and the public interest in science cannot be that bad.

  7. Clifford says:

    M:- Yes, I agree. Finding concrete Physics is first and foremost the most important thing in this discussion. We are -and have been- in the middle of doing that very thing. However, misinforming the public -who funds our science and so to whom we owe at least the common courtesy of trying to tell them a straight story- is *not* irrelevant. It is a mistake to think that it is irrelevant.

    John:- Misrepresentation on both sides of a debate has *never* balanced out to have a net null result. That’s incredibly naive, with all due respect. What you end up with is *at least* twice the misrepresentation… more likely the square. How is that helpful to anyone in the practice of science?

    I agree that debate is healthy, and good for the public to see. But it should be informed debate about the *science*, which is not what this nonsense is about.

    Cheers,

    -cvj

  8. John Branch says:

    Having worked in journalism off and on for more than two decades, and having talked to people at panels and in other ways, I know there are many things about the way journalism works that aren’t obvious and aren’t what people expect. (This is probably true of any field that’s complex, been around a long time, or both.) Clifford mentioned one good example regarding headlines. In case it helps, I’ll mention a few other things about journalism. One caveat: this is what I’ve seen to be true, but since I haven’t quite attained perfect knowledge yet, it’s probably not all exactly true everywhere.

    * The whole thing is a collaborative process. The writer doesn’t choose the headline (as Clifford reported); that was probably written by a copy editor at a newspaper, or by one of the staff editors at a magazine. The writer probably doesn’t choose the accompanying artwork, if any, or write the captions. He/she may have thought of the subject, or may have had it dumped in his/her lap, or anywhere in between. Any article you see in a newspaper or magazine was probably chosen from a handful of possibilities that were rejected for any number of reasons. Space is always at a premium; a fine 2,000 word article may get cut to half or less just because there wasn’t room. It may also have been altered by a copy editor, an editor, another writer, a legal editor, or all those. And newspapers, as far as I know, don’t have fact checkers; magazines usually do, but they make mistakes, and their first concern is usually legal.

    * Edit space is quantized. I’ve heard people ask things like “Why can’t the paper devote one extra page to the arts [substitute your own favorite subject here] every day or every week?” A newspaper can sometimes insert a single sheet, which is two-sided and results in two extra pages, but it can’t insert a one-sided sheet. (I don’t know whether magnetic monopoles exist, but one extra page in a paper doesn’t.) Mostly it can only insert pages four at a time. Pull the outer sheet off a newspaper the next time you have one and you’ll see why. Magazines are in roughly the same situation. An advertiser may pay huge amounts of money and have something special, which they printed elsewhere on their own stock, bound into the issue. But the publisher is limited to sheets and signatures.

    * Edit space depends on ad space. To put it simply, they sell ads for a while, then they fill the remaining space with editorial content. An eight-page newspaper science section may be very cramped because ad sales are just below the threshold where they add four more pages. Or it may have a big “edit hole” because ad sales are just above the point where they’ve bumped it up to 12. Magazines are somewhat different, because publishers can sometimes be persuaded to subsidize extra pages, but they basically work the same way. For general-interest magazines, you see big issues in the fall through December, then small issues for a few months because ad sales are small early in the year, and so forth.

  9. Peter Woit says:

    Clifford,

    I won’t bother to respond to your characterization of Smolin and I as not primarily concerned about science and the debate over our books as “nonsense”, because it’s, well, nonsense.

    I also urge people to watch the Johnson KITP video, during which you’ll see supposedly serious scientists making cat-calls about “Swolin” and about Smolin being a crackpot. You’ll also see the loudest string theorist there going on at length in a completely uniformed way about the books, ignoring Johnson’s repeated advice to her that she should at least take a look at one of them. She also thought it was a good idea to complain that there is a “backstory” about Smolin that explains why he shouldn’t be listened to, one that she didn’t get to share with the audience, but that I would guess is just one of the many things about himself and his career that Smolin deals with in detail in the book she didn’t read. If anyone in the audience had a problem with this performance, they didn’t say so. If Clifford does, he doesn’t think it was worth mentioning here

    Johnson (the NYT one…) is quite right that the two books have gotten a lot of attention because the press likes a story, and because the fact that they came out at the same time made this an obvious one for them to cover. There certainly has been a lot more attention than I ever expected. It’s my impression that few people at the KITP seem to be bothering to actually read either of the books. They also seem to be unaware that the main controversial point of both books (that string-theory based unification doesn’t appear to work, so it would be a good idea to encourage research on alternatives) is not some crackpot fringe opinion, but actually corresponds to what is quite possibly the majority opinion about the status of string theory within the overall physics community.

  10. Pingback: Not Even Wrong » Blog Archive » The String Wars

  11. Clifford says:

    Hi Peter,

    (1) Nobody is stopping anyone from working on alternatives. Please help us provide alternatives for people to work on so that we can proceed with the physics. This would be great! As I’ve said before, this is the natural process by which science proceeds. It does not proceed by suddenly deciding that an entire field should stop work on one approach (because some individuals don’t like it) and sit and wait for ideas to fill the void. Science has never worked that way. So please, start listing alternatives, working on ideas, and convincing your peers through the usual channels that these ideas are worth working on, by virtue of their merits. Will you do that please? It would be a much more positive use of your time than the other thing.

    (2) Yes, there were some moments of levity in the discussion, inevitably, and some thigns were said in a way that perhaps were ill-judged… but don’t try to use that to invalidate the entire discussion. There were several important points made by several others very clearly, if less loudly, that are worth hearing, even though they may have been hard to hear (I don’t mean physically) for some. We are not perfect, by any measure, and we don’t claim to be… we are human, and collectively don’t say things in the best way all the time, but that’s a long way from writing attack-books, in my opinion. I just think that is the wrong approach.

    It is a flawed discussion, yes, but overall I think that I’m glad the video is there to be seen by all. It helps a little to set the record straighter on some of the issues, after the distortions. If only we could do that with the actual physics content too, that would be great.

    Best,

    -cvj

  12. nc says:

    Dear Clifford,

    You are right that Peter Woit might do well at some point to assemble a list of alternatives and try to encourage a deep analysis of them somehow, but his ‘NOT EVEN WRONG’ book does include concise and very lucid accounts of tha basics behind some alternative ideas, including the representation theory and loop quantum gravity, although he doesn’t hype them.

    He simply doesn’t seem to see much point in fighting the string theory hype with hype of alternatives!

    His attacks on string theory are strictly limited to the hype of it, not personal attacks what is plainly the arrogance of some people who defend it as being ‘the DNA of reality’ etc.

    Kind regards,
    nc

  13. Clifford says:

    “His attacks on string theory are strictly limited to the hype of it”

    Manifestly not true! And even if that were thus limited… isn’t it ironic that he would resort to hype as a form of attack?

    Cheers,

    -cvj

  14. Clifford says:

    nc also said: – “his ‘NOT EVEN WRONG’ book does include concise and very lucid accounts of tha basics behind some alternative ideas, including the representation theory and loop quantum gravity”

    Ok, good. So should he not be writing papers (i..e not only popular books) about them and deriving new results and trying to convince the research community of their promise by doing something with them ? That’s how we’ve done things in the past. Why not now? Are we stopping him from doing this somehow? I’ve not seen this obstruction demonstrated convincingly.

    -cvj

  15. nc says:

    Dear Clifford,

    Pauli resorted to hype to discredit Heisenberg: Pauli drew a painting of an empty frame and labelled it: ‘Comment on Heisenberg’s Radio advertisement. This is to show the world that I can paint like Titian. Only technical details are missing. W. Pauli.’

    Woit explains:

    ‘With such a dramatic lack of experimental support, string theorists often attempt to make an aesthetic argument, professing that the theory is strikingly ‘elegant’ or ‘beautiful.’ Because there is no well-defined theory to judge, it’s hard to know what to make of these assertions, and one is reminded of another quotation from Pauli. Annoyed by Werner Heisenberg’s claims that, though lacking in some specifics, he had a wonderful unified theory (he didn’t), Pauli sent letters to some of his physicist friends each containing a blank rectangle and the text, ‘This is to show the world that I can paint like Titian. Only technical details are missing.’ Because no one knows what ‘M-theory’ is, its beauty is that of Pauli’s painting. Even if a consistent M-theory can be found, it may very well turn out to be something of great complexity and ugliness.’ – Dr Peter Woit, ‘Is string theory even wrong?’, American Scientist, March-April 2002, http://www.americanscientist.org/template/AssetDetail/assetid/18638/page/2#19239

    Maybe if string theorists listened in 2002, his book would not be causing problems now. All he clearly wants is a bit more balance in the arena of ideas.

    Best wishes,
    nc

  16. Jeff says:

    Clifford,

    …and now for something completely different…cosmic superstrings are bad news…check out the first two minutes of this

    http://www.youtube.com/watch?v=LwGLodGDNvk

    Cheers
    Jeff

  17. Peter Woit says:

    Clifford,

    I’m not about to argue with you or anyone else who points out that it would be a good idea for me to spend more of my time working on positive things. I agree with you.

    Neither Lee nor I are calling for the abandonment of research into string theory, but rather for an end to the overhyping of it, a much more realistic view of its prospects, and a serious discussion about whether it is possible to find ways to encourage people to find alternatives. Sure, I have a permanent position and no one is stopping me from working on what I want to work on. But it’s all too possible that I’m neither smart enough nor energetic enough to make the kind of breakthrough that is needed. Personally I’m most concerned about the environment for people just starting out. Can something be done to encourage them to try really new things, not just follow down the same well-worn path that does not clearly seem to be leading anywhere?

    nc,

    Please, thanks for the attempts to defend me, but what you’re doing is not a good idea. My views are getting plenty of attention these days, I might even agree with some string theorists that they’re getting too much. If I think more needs to be said about them, it’s much better if I do so myself.

  18. Clifford says:

    Hi Peter,

    We are all concerned about people just starting out. This is why several of us already do try to make sure that their students are well-trained in as many techniques and ideas that they can get to grips with before graduating. Given the broad reach of what string theory uses to achieve its goals, it turns out to be a really good training ground for lots of thigns from field theory to gravity to group theory to geometry… etc etc. But several people who are known as string theorists train their students in areas that are not part of (or not central to) string theory as well. So I am not sure why you think that we are leading them down the garden path quite so much. I would argue that they are as well-prepared to tackle new ideas as they would be trained in other areas. Given that we do not *know* what the right approach is, the best we can do is make sure that people are trained to think and research well, and that they are exposed to lots of techniques and ideas. This is the responsibility of the students’ and postdocs’ advisors and mentors…. we can do little else unless we somehow change the system in some drastic way (see below).

    It is hard to get a breadth of training of course, given the model of training for graduate students (the finite time, limited postdoc positions, etc), and also given the model of postdoctoral positions, and what happens after. But this is a structural problem for theoretical physics in general – it is not a new one at all – and it is nothing to do with string theory. If this is the issue you want to discuss, why dress it up as an attack on string theory, claiming that you know it’s wrong, and that we are all deluding ourselves, etc, etc. This damages the whole field of theoretical physics itself… Why not just come out and talk about your concerns about the career path in theoretical physics in general? Would that not serve your cause more directly and positively?

    Best,

    -cvj

  19. Alejandro Rivero says:

    Do you need higher dimensions to be both one-sided and two-faced? IIRC, you need 7 dimensions if you are a static 3-dimensional being, but about 90 if you are a 3+1 dimensional being to be embedded in a Loretzian metric. Was this the answer of the joke? Actually it is a backfiring joke, I guess that the last thing a string theoretist wants is to see his theory presented as if it the extra dimensions were coming from the embedding theorems.

  20. TheGraduate says:

    Dr. Johnson,

    I thought what you just said sounded rather reasonable. I have only lately started to understand the kinds of pressures professors in the sciences can face concerning research, tenure, grants etc. From a student’s perspective, the job of professor seems thoroughly secure.

    In a personal sense, Dr. Woit/Dr. Smolin are interesting to read in that they are both putting things forward in an unvarnished way that one might never hear reading a science magazine or a textbook. They focus on string theory but I can’t say I doubted for a second that everything they said was relevant to other branches of physics and to a lesser extent branches of other physical sciences.

    When Smolin says that some in the physics community can be disparaging of minorities and women for instance, this is not something one will read in, say, the Harvard brochure. However, one only has to read Lubos Motl’s blog to get a sense of whether that might or might not happen. For someone, who may happen to be female or a minority, this is a useful thing to see written down as few others will ever say it and will instead imply deficiencies on the candidates behalf. And while I do believe that in America, anyone can make it with hard work, graduate school is hard enough and personal deficiencies are often numerous enough.

    I also think Dr. Smolin touches on something true when he alleges that for the advancement of his or her career, a professor will often select graduate students who are capable and inclined to perform extensive calculations. (In other words, cheap work horses.) For someone starting out, these are important things to know. The reason is not that this practice is particularly nefarious but that it is often not explicit. (I have seen people leave graduate school with a lot of unnecessary pain.)

    Whether, Drs. Smolin and Woit intended to or not, I think they provided some valuable insight into issues that do supersede what is going on in the string theory community.

  21. Alejandro Rivero says:

    It does not proceed by suddenly deciding that an entire field should stop work on one approach (because some individuals don’t like it) and sit and wait for ideas to fill the void. Science has never worked that way.

    Well, and in the cases it has worked this way, we claim that the previous idea was not science at all. Pascalians versus Aristotelians, speaking of the void.

    Perhaps the point is about how “suddenly” is “suddenly”. Is it still a 50-years long process? Is it ever slower due to the greatest number of scientists, compared to ancient times? Is it suppossed to be faster due to the hitech communication media and the high frequency of scientific meetings? Sometimes it is about a three-hours process: the travel of Bethe in the train back from Shelter Island. Ok, three years if you want, up to six if you consider the time it took for the dust to settle.

  22. Alejandro Rivero says:

    ?
    I assume this question mark was addressed to me. If not, please delete this comment. In fact, I was recalling incorrectally (“IIRC=If I recall correctly”). Whitney embedding theorem states that any smooth m-dimensional manifold can be smoothly embedded in Euclidean 2m-space. I was thinking 2m+1. The answer is different if you want to keep the Riemannian structure in the embedding, and it is again different if you want to keep the lorentzian metric, but just know I can not find the exact bound in the number of dimensions you need to embedd a 3+1 manifold into higher dimensional minkowski space, I am pretty sure it was about 90. I was telling that the joke was a backfire because of course the extra dimensions in string theory are completely unrelated to the extra dimensions you need here in topology and geometry.

  23. John says:

    “Do you need higher dimensions to be both one-sided and two-faced?”

    The answer is of course: no, if you are familiar with Picasso’s work. It was a joke, and it should be treated as a joke. So, just LOL, even in the middle of a heated debate. I can see that some scientists start to lose their cool, and more importantly, their sense of humor.

  24. M says:

    I am not sure that strings still are a good arena where post-docs can show what they can do, before possibly getting a tenure and start doing whatever they want. Years ago strings were relatively simple, seemed a promising speculation, and were the easiest path towards a permanent position.

    Now strings require long studies (such that competitive post-docs end up in knowing only strings), the initial hopes are gone (strings did not become the mainstream because in 1984 Witten saw their potentiality as an approximate model for RHIC data!), and the job market was saturated by previous fast development.

    This was expressed in the 2001 Xmas recital of the CERN theory division (available somewhere on the net), where post-docs dressed as talibans spent all time studying GreenSchwartzWitten and whispering “why are we doing this?”.

  25. youngonion says:

    Dear Mr. Woit,
    I am a young onion in the garden and I have some comments on your comments.
    First of all, as no one stops you from doing more serious research, I must say you would probably have been more influential if you had done any insightful science recently. That will make young guys like me trust your opinions more. No offenses or hard feelings, but without that, you may serve well as a public figure, but not a good science mentor to any student seriously thinking about a career in theoretical physics.
    “I’m not about to argue with you or anyone else who points out that it would be a good idea for me to spend more of my time working on positive things. I agree with you.”
    Good, we all see to agree on that one.

    “Neither Lee nor I are calling for the abandonment of research into string theory, but rather for an end to the overhyping of it, a much more realistic view of its prospects, and a serious discussion about whether it is possible to find ways to encourage people to find alternatives.”
    I don’t get what you mean by overhyping. Is it possible to have such overhyping when the show-down at LHC is immediate? I think you’re overly worried. And again, why not Mr. Smolin and you also worry more about science like string theorists and particle theorists do? I mean, not just worrying about not getting the right answer, but actually practicing it more persistently, I guess that’s the least to ask of a theorist?
    I am also utterly confused as a young person as where to look for alternatives. If I look up to you or Mr. Smolin, I don’t think I get any great idea except that not to look at string theory. As for the alternatives you guys discuss in the book, their prospects are rather doomed in my opinion. It’s not too bad if a theory looks like that at the beginning, but those theories always looked like that. I would hate to hear one day the alternative theorists all gave up and admit they were wrong all along.

    ” Sure, I have a permanent position and no one is stopping me from working on what I want to work on. But it’s all too possible that I’m neither smart enough nor energetic enough to make the kind of breakthrough that is needed. ”
    I think I agree with you, and I sincerely admire how you were able to get a permanent position. And you’re apparently at least smart and energetic in non-scientific matters.

    “Personally I’m most concerned about the environment for people just starting out. Can something be done to encourage them to try really new things, not just follow down the same well-worn path that does not clearly seem to be leading anywhere?”
    we get by, although a lot of poisoning is going on right now, we enjoy the ride. and we are much smarter than usually perceived. if string theory turns out ugly, we’d drop it immediately. and please save some hype about prospects, if theorists were all so concerned about prospects we won’t have any theorists will we? what kind of a crap theory is it if it’s a theory totally devoted to prospects? it’s a unnecessary theory, as good as the facts. if you think elegance and effeciency doesn’t justify anything, we should all give up the whole theory business, as a totally ugly and confusing theory wouldn’t lead us anywhere in the department of understandings. since when serious mathematicians are so concerned about prospects?

    geez, what gave me all this hype to type so much empty words on a great blog. it’s an annoying prospect that so many comments like this will be produced and consumed in the blogsphere. I seriously prefer spires.

    TheGraduate Oct 28th, 2006 at 6:23 pm

    “I also think Dr. Smolin touches on something true when he alleges that for the advancement of his or her career, a professor will often select graduate students who are capable and inclined to perform extensive calculations. (In other words, cheap work horses.) For someone starting out, these are important things to know. The reason is not that this practice is particularly nefarious but that it is often not explicit. (I have seen people leave graduate school with a lot of unnecessary pain.)”
    Dear theGraduate,
    I completely agree with you. But I guess the only secret medicine to ease the pain suffered is to hold on. At times the no-brain kind of ideas offered by certain not so rooted in their thoughts scientists are ridiculous. as there are many formulae and easy stuff on the market, a half brain-dead can assemble a paper with certain minial points which falls under a big subject title. the practical way out is probably to suck it up and save more interesting ideas for later.
    it is very depressing when this happens, the issue is however definitely not unknown before these two books. it’s usually more underground, and I do hear postdocs in all subject areas discussing such things as well. it is after all a hierarchy, although not a integralbe one:)

  26. nc says:

    young onion,

    Have you actually heard of Woit’s paper “Quantum Field Theory and Representation Theory: A Sketch”, http://www.arxiv.org/abs/hep-th/0206135 where he comes up with a tentative representation of the standard model on page 51?

    Or his extensive papers on http://www.math.columbia.edu/%7Ewoit/repthy.html ?

  27. Tony Smith says:

    Clifford said in a reply to a comment by Peter Woit: “… Nobody is stopping anyone from working on alternatives. Please help us provide alternatives for people to work on so that we can proceed with the physics.
    …. should he not be writing papers about … alternative ideas … and deriving new results and trying to convince the research community of their promise by doing something with them ? That’s how we’ve done things in the past. Why not now?
    Are we stopping him from doing this somehow? …”.

    As to the environment with respect to consideration of alternative ideas by the high energy physics community, here is a timeline of some of my personal experiences:

    1993 to 2002 – I posted papers on the Los Alamos (now Cornell) arXiv working on construction of a Clifford algebra based model, leading to physics/0207095 at which stage my model described the particles and forces of the Standard Model and Gravity. Its calculations of particle masses, force strengths, and Kobayashi-Maskawa parameters were (and still are) substantially consistent with experimental observations.

    2002 – I was blacklisted from posting further papers on the Cornell arXiv, which said that I was in ” a large pool … typically flagged by reader complaints … “. Since arXiv has refused to tell me who complained, or the substance of any complaint, or to give me any opportunity to respond to any complaint, I find my situation to be Kafkaesque.

    2004 – Based on a sci.physics.research discussion involving John Baez, Lubos Motl, Urs Schreiber, and Aaron Bergman, I constructed a (non-supersymmetric) string theory version of my model. Being blacklisted from posting on arXiv, I posted it on the CERN preprint archive as CERN-CDS-EXT-2004-031.

    2004 – CERN terminated its EXT part of its preprint archive.

    2005 – I presented a talk and poster at the APS DPF meeting in Tampa, but my audience was small and I received no substantive feedback or comments.

    2004 to 2006 – Continued work yielded further results, including a calculation of the Dark Energy : Dark Matter : Ordinary Matter ratio that is substantially consistent with WMAP results – see http://www.valdostamuseum.org/hamsmith/Aug06SuppDMDE.pdf

    The facts that my work is blacklisted by arXiv,
    and the CERN EXT service was terminated,
    and the response of the community of high energy theoretical physics is limited to such as Harvard Professor Motl calling me a “moronic crackpot”, with no substantive discussion/criticism of my model,
    lead me to think that the community of high energy theoretical physics is indeed
    “… stopping [me] from doing this [alternative model] somehow? …”.

    Tony Smith
    http://www.valdostamuseum.org/hamsmith/

  28. youngonion says:

    nc,
    is there some breakthrough in that paper by Mr. Woit according to your opinion? I don’t see anything new. and it’s not hard enough for graduate students to be interested 😀 that was a joke. yeah, I’ll have a look. I am expecting a lot more work than that from a senior person in an Ivy League school though. don’t you?

  29. youngonion says:

    NC,
    point two:
    this kind of sketch is exactly the titan drawing behavior Pauli was against. don’t you think? if you’re a lazy smart guy, stop asking for credit, cause there ain’t any if you didn’t work your excellent alternative ideas out.
    what’s so hard to understand about that in the case of Mr. Woit? Dr. Smolin works harder, and even though he has other habits of a nature not so admirable, he’s a level up from Mr. Woit in their camp.
    Put differently, if a theory is never worked out, it’s just “not even wrong”. In the other case, at least people can say it’s wrong.

  30. Clifford says:

    youngonion:- Ok. I think we should not descend into the quagmire which lies just beyond. Let’s leave it there for this particular line of inquiry, ok? Thanks for the other comments and questions though. Very good to hear from young people about what they think, instead of us just sitting about with furrowed brows “worrying about them” on their behalf. Any other young onions out there wanting to share thoughts?

    Best,

    -cvj

  31. nc says:

    Dear Clifford,

    Thank you very much for your comment! Maybe I can also very briefly respond to Tony Smith and ‘Young Onion’?

    Tony Smith has made the point that anyone seriously putting forward a detailed alternative is automatically censored. Young Onion just proves this, by trying to ridicule at a detailed extensive set of research by Woit

    Like Tony Smith and many others, I’ve been partially censored (I did get papers which had been rejected as ‘speculative’ by CQG, PRL etc published instead in Electronics World). For my view of Woit’s and Smolin’s ideas see https://nige.wordpress.com/

    Sadly the danger is that anyone like myself supporting Woit will do far more harm than good. It would be far better if some string theorists would take Smolin and Woit more seriously as viable alternatives!

    Best,
    nc

  32. hackticus says:

    You paint a picture of irresponsible journalists taking string theorists’ measured remarks over the years and converting them into misleading hype. Have you ever heard of a gentleman named Michio Kaku? He is ten times worse than any journalist, and he has been a leading popularizer of string theory for over a decade. In my experience string theorists will privately aknowledge that he is a joke, but publicly have done nothing to reign him in, because he’s on their side. So I do think the “two faced” joke is funny, but it works twice as well when directed against the string theorist than against Smolin.

  33. moveon says:

    “[Kaku] is ten times worse than any journalist, and he has been a leading popularizer of string theory for over a decade. In my experience string theorists will privately aknowledge that he is a joke, but publicly have done nothing to reign him in, because he’s on their side. ”

    Indeed he’s ten times worse, but it’s a free world and there is no way to stop nonsense (that’s also why those books attract attention today) – it is not simply because he’s on their side. It is embarrassing to have him on the same side, in fact.

    What bothers me a lot is that a whole generation of earnestly hard working scientists is taken responsible for this kind of things, is accused of hyping, being dishonest, oppressive, what else.

    The point is that there is no such thing as “the” string theorist. There are many different opinions, working styles, work ethics, beliefs, goals, reasons why one is doing this research, etc. Any one of the claims made in those books may have a trace of truth in it, and may fit to certain people – like to Kaku in the present discussion of hype. It does however not do justice to countless other physicists who never said this kind of things, and simply do not think this way. Not every string physicist thinks that LS’s book is a good idea, and thus does not want to be held responsible for it. Not every string physicist thinks that “string inspired model building” is a good idea, and thus does not want to be held responsible for exaggerated claims. Not every string physicist lives in the US and thus does not want to be criticized for how jobs are given there and other aspects of sociology. And so on.

    The undifferentiated presentation given in those books is one of the reasons, among others, why these books are considered as grossly misleading and are not taken seriously by insiders. On the other hand, journalists who have no deeper insights naturally become victims of this propaganda and take these claims for face value. And due to how things work, what finally appears in the newspapers are sometimes even more exaggerated claims. For example, I was reading recently that string theory would not have any achievements, not even theoretically. I am sure that the authors of those books feel “soo sorry” about how the media strenghtened their message?

  34. pendergast says:

    I had the pleasure of reading Lee Smolin’s book and felt his criticism of string theory to be interesting.

    I arrive to this opinion; physics has been confronted to many crises in its short history. Gravity, relativity, quantum mechanics had their challenging moments. Many thought there was not much more to study; I remember this quote from Clauser in Quantum [Un]speakables about his difficulties to be heard from the untouchables of physics (“it needs no further testing”) and that sometimes, physics turn into a religion with high priests. Well, history knows better. String theory may be at this turning point.

    What I witnessed from the video is very defensive behavior from people who should be objective (behave as scientists, ideally). Defenses from uninformed people, by the way; this means that most reactions were made from prior knowledge rather than the books presented. That does not look good.

    Scientists are territorial creatures like anyone else. This comes as no surprise that the whole thing is tagged as a “war” and that reporters will feed from it (after all, they have to sell papers, whether there is content or not, and I am not pointing fingers to anyone here).

    So once a territory is threatened, it is quite normal to see people defend it. If reporters get on it, well, you get the echoes from non-specialists which in return, will create more vulgarization which will not be as instructive anyway. There is no end to that cycle, except through the end of the hype. This wheel of money-making popularity is here to stay, and comments like “people need to understand” have absolutely no value whatsoever besides being cash cows unless these people “who need to understand” start to do some of the maths themselves.

    Now, I am not a physicist, but I do have an opinion, and I have questions. Most and foremost, where is the answer to this question: What are the actual testable physical theories, and are physicists working on these?

    I think that would answer all questions the public might want regarding appropriateness of funding.

    This media interlude, to me, is all smoke and mirrors, including the discussions between scientists over who is right or wrong, and especially about the dirty laundry which I am sorry I was a witness of.

    Smolin’s book may not have all the answer, but it does ask questions and I am looking for those answers. I did not feel he has them, not one minute.

    I think Johnson was fair in his presentation by stating clearly that the books were worth a read before having an opinion. That was probably the most relevant comment made. But then it was just a “talk”.

  35. Lee Smolin says:

    Dear Clifford,

    I just saw this and I’d like to respond briefly. My impression is that the claims that I am a “moving target” come primarily from people who have not read the book. For example, several people have quoted to me a comment by David Gross that in a conversation I agreed that the Maldecena conjecture implied string theory was, in a certain sense background independent, while I don’t say this in the book. I don’t know if they quoted David correctly, but the assertion is not true, as anyone can see by opening the book. On page 189 I wrote : ”…if the strong form of the Maldacena conjecture turns out to be true —which is also consistent with the present evidence — then string theory provides good quantum theories of gravity, in the special case of backgrounds with a negative cosmological constant. Moreover, those theories would be partly background-independent, in that a nine-dimensional space is generated from physics in a three-dimensional space….There is other evidence that string theory can provide a unification of gravity with quantum theory…”

    and on page 240 I repeated the point: “In a certain limited sense, if the strong form of the Maldacena conjecture (see chapter 9) turns out to be true, a nine-dimensional geometry will emerge out of a fixed three-dimensional geometry. It is thus not surprising to hear Edward Witten say, as he did in a recent talk at the Kavli Institute for Theoretical Physics at UC Santa Barbara, that “most string theorists suspect that spacetime is an ‘emergent phenomenon,’ in the language of condensed matter physics…”

    I then go on to explain what I mean here by “limited”: briefly, there is a stronger definition of background independent that we talk about in quantum gravity, which requires that the formulation of the quantum theory not involve any classical metric or global symmetry. This is not the case of AdS/CFT, but it is the case for other realizations such as LQG in the spatially compact case.

    If I can say it, there seem to be two issues. One of them is that my views are not classifiable as for or anti string theory. I feel some of the results of string theory are strongly compelling, while others are strongly worrying. I wrote a book partly to try to sort out what to do about this. My conclusion is not easily reducible to a sound bite, but it includes the following from Chapter 12“String theory succeeds at enough things so that it is reasonable to hope that parts of it, or perhaps something like it, might comprise some future theory…So string theory is certainly among the directions that deserve more investigation.” At the same time, I make it clear that there are other directions that I also believe are worthy of investigation.

    Now people don’t accuse me of being anti LQG because I also find some merit in string theory and have written papers in the subject. But if I say that string theory is one of several approaches worthy of attention I am called “anti-string theory.” Why is that? Well, I am not anti-string theory but I am strongly anti- the view that there is only one approach to fundamental physics now worth supporting or paying attention to.

    The other problem is that some of the ad copy and flap copy, including the subtitle, is more provocative than the text of the book. I apologize for this, I had no idea people would be so sensitive. In fact, the editor and I argued for months over the cover; she would have preferred something far more provocative and I would have preferred no subtitle at all. It is not clear I could have done more, as contractually an author has no control over anything on the cover- including the title. But it never occurred to me that the issue was that serious because I assumed anyone interested in what the book said would actually read it.

    But for me the bottom line is that it is unprofessional as well as unwise to publicly criticize a book or paper you have not read. I take very seriously all comments from colleagues who have read the book, and I’ve taken pains to reply to all of them. I am not sure what to do about people who insist I’ve done something damaging while at the same time they insist on not reading the book.

    One thing I hear is that people are worried that journalists are misled. But if you look at the reviews, you will see that the majority characterize my book correctly as balanced and some even praise it for presenting a positive and even “loving” account of string theory, while discussing the issues we all agree are there. That is, it seems to me that most readers do get what I meant to communicate, which is that string theory has both very compelling and very worrying features.

    For example, I just received an email from a lay reader who concludes, “I’m impressed that the reader cannot detect any hint of bitterness on your part, and that your cogent writing on the subject is so fair minded.” I get a lot of messages like that, some from lay readers, some from colleagues. I gave a talk based on the book at U of Toronto last week and was told that one of the string theorists in the audience said that my talk presented a strong case for working on string theory. So I don’t have a lot of evidence that the book is being misunderstood by those who read it but, just to be sure, as I’ve said before to others, if there is any need for me to clarify that the book is not “anti-string” I am happy to do this.

    Finally, as to your last caution: as most readers appreciate, the book is not an attack on string theory, it is an extended inquiry into the current state of our field and what to do about it. Part of the problem, in my view, is your assertion that I am trespassing into a domain that is not mine (“a body of work by others”). How could this be? I have worked my whole life on the problem of quantum gravity, including years of work and 18 technical papers, plus reviews, and books, on string theory itself. Why is the state of the field not as much my concern as it is yours? Once I have done the hard work of mastering the technical side of the field so I can evaluate the evidence in detail, what should matter is the correctness of the arguments I put forward. My book is constructed around a number of arguments and what you can do if you don’t like the conclusions is examine the arguments and explain why they are wrong. Rather than doing this, a number of people just question my motives and my right to contribute to a discussion about the central questions in our field. In fact, I made my motives and motivations quite clear in the book, and I don’t think anyone who reads it in good faith can doubt that my main concern is the present status and future of our field.

    Thanks,

    Lee

  36. Aaron Bergman says:

    I continually get the feeling, Lee, that you have no idea how you come off to others in your writing.

  37. then go on to explain what I mean here by “limited”: briefly, there is a stronger definition of background independent that we talk about in quantum gravity, which requires that the formulation of the quantum theory not involve any classical metric or global symmetry.

    I understand the “classical metric” part. But the “global symmetry’ part seems like yet another case of moving goalposts.

    AdS/CFT does not fix a classical metric. But it does fix the asymptotic behaviour of the metric to be that of asymptotically anti-de-Sitter.

    I don’t understand how any formalism can avoid doing so. Without it, you don’t have a globally hyperbolic problem.

    This is not the case of AdS/CFT, but it is the case for other realizations such as LQG in the spatially compact case.

    And what about LQG in the spatially noncompact (asyptotically AdS) case?

    Frankly, I am convinced that AdS/CFT is exactly as “background-independent” as any formulation of quantum gravity in asymptotically AdS spactimes could ever be (misleading discussions of quantum gravity in the spatially compact case notwithstanding).

  38. Lee Smolin says:

    Dear Jacques,

    There is no moving of the goal posts. The absence of global symmetries has always been implied by the definition we used in quantum gravity of background independence (or manifest background independence). In a number of places in the writings of Barbour, Stachel, Rovelli, myself and others you will find the concept of background independence traced back to Leibniz’s “principle of the identity of the indiscernible.” The statement of that principle is that if two entities have the same properties they are to be identified. This implies the absence of global symmetries. Part of the background to the concept is also a proof, by Karel Kuchar, of the absence of a global symmetry (a conformal killing field) on the configuration space of GR for compact boundary conditions.

    On your other points, there is some work on asymptotically AdS in LQG. There is more to do but for example, work of Starodubstev suggests that there is an asymptotic algegra of charges, which is quantum deformed and thus doesn’t exponentiate to a symmetry group. There is stronger evidence for this in 2+1.

    Dear Aaron,

    I do get the feeling that there is a bimodal response. Many people find my tone to be reasonable and even handed. Others don’t like it. I am very concerned about those people and I would be grateful for any advice about how better to communicate with you and them, either here or off line.

    Thanks,

    Lee

  39. There is no moving of the goal posts. The absence of global symmetries has always been implied by the definition we used in quantum gravity of background independence (or manifest background independence). In a number of places in the writings of Barbour, Stachel, Rovelli, myself and others you will find the concept of background independence traced back to Leibniz’s “principle of the identity of the indiscernible.” The statement of that principle is that if two entities have the same properties they are to be identified. This implies the absence of global symmetries.

    You have the direction of implication precisely backwards. If two entities differ in their transformation properties under global symmetries, then they are distinguishable and hence should not to be identified.

    Moreover, I think we can probably manage a discussion of 21st Century Science, without lapsing into citations of Leibnitz.

    Part of the background to the concept is also a proof, by Karel Kuchar, of the absence of a global symmetry (a conformal killing field) on the configuration space of GR for compact boundary conditions.

    Again, you keep changing the subject. We were talking about asymptotically AdS spacetimes. Why do you keep returning to the case of compact spatial topology?

    There is more to do but for example, work of Starodubstev suggests that there is an asymptotic algegra of charges, which is quantum deformed and thus doesn’t exponentiate to a symmetry group. There is stronger evidence for this in 2+1.

    Which paper of Starodubtsev are you referring to?

    And, whatever his results are, how do they affect my main point, which is that AdS/CFT is as background-independent as any theory of quantum gravity in anti-de Sitter spacetimes could ever hope to be?

  40. Elliot says:

    Aaron,

    I am not sure what you mean? Is it the message or the messenger you have an issue with? Without getting into the validity of Lee’s position(s) (which I am completely unqualified to do), I think his tone is and has always been extraordinarily civil. Am I missing something?

    Elliot

  41. Plato says:

    Being lead by the physics is important?

    Knowing these jump off points, consensus, might have formed to theoretical prospects?

    Does theoretical positions answers where the physics has been leading perspective? As a lay person I want to think like a scientist and lead by their example. So I find it hard to throw one position out for another becuase it didn’t prove anything, yet in string theory reductionists views have pointed out the way?

    One of the most important assumptions we’ve made is that, for very intense collisions, the quark-gluon plasma behaves according to hydrodynamic calculations in which the matter is like a liquid that flows with no viscosity whatsoever.”

  42. Lee Smolin says:

    Dear Jacques,

    I thought I was addressing your point. The suggestion was that an asymptotically AdS quantum sector of quantum gravity could have a weaker symmetry than that obeyed by the Maldacena correspondence, which is a quantum deformed algebra of charges, which does not exponentiate into a symmetry group. (The reference to Starodubtsev is hep-th/0306135, there are also references in 2+1, for example, hep-th/0306134).

    But before going further with clarifications about the distinctions between how quantum gravity may manifest itself in a situation with and without boundary conditions, and the different meanings of background independence in the two cases, can we return to the prior point. At the KITP discussion a claim was made that I am “a moving target” My purpose in writing to this thread was to address this.

    One reason that was stated was that my views in conversation are not the same as what I write, and specific mention was made of a conversation with David Gross about the sense in which AdS/CFT would, if true in the strong form, imply a form of background independence. I am told it was said that I agreed about this in conversation but this is not what is written in my book. I answered this with explicit citations from my book showing that this is indeed mentioned in my book. Now, can we get closure about this? Either Gross was misquoted, or I have answered the issue, in which case I would think that I am owed an apology.

    Another reason that was stated was that the cover of my book is more provocative than the actual text. I answered this also, acknowledged it and apologized for not having argued strongly enough with my editor to get the cover copy toned down. Can we have some acknowledgement of this as well?

    Thanks,

    Lee

  43. Aaron Bergman says:

    I think his tone is and has always been extraordinarily civil. Am I missing something?

    Yes. Tone really isn’t particularly relevant or interesting. Content is the issue. (I am entirely too tired at the moment to get into this discussion yet again, but you can google to find some of my issues.)

  44. The reference to Starodubtsev is hep-th/0306135

    I’m sorry. I fail to see why that paper has anything to do with the subject at hand. Starodubtsev is studying the case of a positive cosmological constant, not negative. He is picking a closed 2-surface inside a spatial slice of de Sitter space, excising the interior/exterior (since we have compact spatial topology, they’re the same) and replacing it by boundary conditions on the 2-surface. Moreover, the boundary conditions he imposes are not remotely like what is required for the AdS case.

    (Don’t even get me started on the whole idea of expanding about the Kodama state. Regardless of whether there’s any sense to what Starodubtsev is doing, I don’t see that his construction has any relevance to the current subject of discussion.)

    The suggestion was that an asymptotically AdS quantum sector of quantum gravity could have a weaker symmetry than that obeyed by the Maldacena correspondence, which is a quantum deformed algebra of charges, which does not exponentiate into a symmetry group.

    Even if this suggestion were true (and there is, so far, zero evidence that it is), it remains the case that, to obtain a globally hyperbolic problem, you need to specify the asymptotics of the metric in aymptotically AdS spacetimes, exactly as is required in AdS/CFT.

    Perhaps, for large (negative) cosmological constant, things might be different. But for small cosmological constant, the mere existence of a semiclassical limit makes this a foregone conclusions.

  45. Blake Stacey says:

    Our esteemed blog-host wrote:

    I’m not saying that string theorists are entirely blameless in this, but I’ve seen how hard it is to get a balanced remark -about the basic process of seeing a complex scientific program through to its end- to survive next to a glossy one-liner

    I couple years back, I wrote up a description of Barton Zwiebach’s “string theory for undergraduates” class, intended for an MIT physics department annual publication (glossy, full-color, etc.). In my few paragraphs, I tried to set everything down in clarity: the fun stuff at the beginning, the snowstorm of equations in chapters 11–12, and the rewarding stretch of fun stuff after that until the end of the term. I indicated how the list of prerequisites given in the course catalog was complete balderdash (partly because the sophomore-level physics classes at MIT are so weak it doesn’t matter whether you’ve taken them or not).

    And even this brief, eminently utilitarian description didn’t survive the editing process. It was boiled down to a bare nubbin, with almost all of the useful stuff — like what a student needs to know going into the class — stripped away. That’s for a glossy magazine put out by the MIT physics department. I can only imagine what a journey through the full vulgarization machinery can do.

  46. Mark Srednicki says:

    Lee, what was the “far more provocative” subtitle that your editor preferred over “the rise of string theory, the fall of a science, and what comes next”?

  47. Lee Smolin says:

    Mark: the first issue was the title. Perhaps it is surprising to people who have never published a popular book that one sometimes has to negotiate over the title and cover copy, but it is typical. I vetoed “All strung out” and “The rise and fall of string theory” and insisted on a title that made no reference to string theory. In return I compromised on the subtitle, my own strong preference was to have none at all. I could go into more details, but given that I have already apologized for the subtitle being provocative , I’m not sure it would be helpful. What would be nice would be if, in return, one could hear a public apology for being called a crackpot, having our names made fun of, having my integrity questioned, or having people claim my book is full of errors, without being able to name one? I am very willing to move on from here positively, and for example, take steps to underline the fact that my book is not nearly as provacative as people who have not read it seem to think, and indeed was written to make a constructive contribution to the field. But I do think that there are also things that people who were at that meeting could do that would be very helpful. For example, it would help a great deal if some of the senior people there made a clear public statement that these kinds of childish and personal attacks are out of bounds in discussions about and with professional colleagues.

    Lee

  48. JC says:

    Blake,

    I’ve heard of some motivated freshman students with only a background of freshman physics and calculus, actually reading and working through Zwiebach’s string book. In principle it’s actually doable with minimal prerequisites, such as knowing how to solve basic differential equations like the classical wave equation. Any motivated enough kid can go on from there.

  49. Elliot says:

    All,

    To follow up. I am not going to speak to technical issues here but I think everyone needs to listen to Lee’s point about the process of getting a book published and the “give and take” that occurs between the author and publisher. Whatever noble or ignoble motivations an author may bring to a project, the goal of the publisher is to sell books and this inevitably alters the deliverable. If you have not been through this process you might think that the author has a great deal of control over this. In reality it is less than you might think.

    Elliot

  50. Blake Stacey says:

    @JC:

    My background was not so much stronger than that! Motivation counts for a great deal, as does good fortune in having taken classes which were useful instead of those the catalog blithely required. I was lucky enough to take an advanced E&M class earlier than most of my fellow undergrads (as a first-term sophomore, instead of a junior or senior). That filled me up with tensors, Lorentz invariants and other goodies, and it was in fact a better treatment of special relativity than what we got in our dedicated relativity class.

    (Yes, we had to do an entire semester on special relativity. It took four weeks to build up to Lorentz transformations, and most of the homework problems were of the genre, “Alice rides a spaceship traveling at 0.8c for 5 years. . .”)

  51. anon. says:

    Elliot,

    What you miss by not taking into account the “technical issues” is that in most of these online conversations between Lee and other more mainstream physicists, he seems to be systematically disingenuous. He dismisses well-established physics by appealing to “theorems” which, on closer examination, never say what he claims they do. He then appeals to his own work on string theory as some sort of proof that he is neutral, even while outright attacking the work of others. The “tone” is always reasonable, but it’s covering up a thoroughly unreasonable viewpoint. He may not sound like he is attacking people, but if you pay close attention to the content, he always is. His criticisms never stand up on valid technical grounds, but when people criticize his own work on valid technical grounds, he dodges the question, either making grand claims unsupported by evidence or appealing to his results as promising but not yet completely worked out. It’s annoying, and anyone with a good understanding of quantum field theory can see many reasons why Lee’s claims simply don’t make sense.

    This is one of the most annoying aspects of the public nature of these attacks on string theory; the debates are public but the public does not have the tools to appreciate the technical nature of what’s going on. No one has any desire to prevent people from working on other theories of quantum gravity. It’s just that there are none, so far. If there were, lots of people — including string theorists — would be excited about it! If people doing LQG have trouble getting jobs, it’s probably because their work just doesn’t make sense. For the most part, people in the community are friendly and don’t like making public comments demeaning the work of others. But when Lee is publicly attacking perfectly reasonable and competent people who are just doing their best to understand how quantum gravity works, I don’t think it’s unreasonable to point out to the public that Lee is a fringe figure whose work is not entirely sensible. Was it too harsh for people at the KITP to call him a “crackpot”? Probably. But he is not a great physicist, no matter how much he seeks to set himself up as one.

    I say all of this as a field theorist, not a string theorist, to the extent that that distinction even makes sense these days. Clifford, feel free to delete my comment if it seems too harsh.

  52. JZ says:

    All,

    I second Elliot. In addition, is “you can not judge a book by its cover” still applausable?

  53. Peter Woit says:

    One of several things that has really astounded me over the last couple years is the willingness of some string theory partisans to engage in disgraceful and professionally unethical behavior, of an extremely cowardly sort. I have no idea who “anon” is, but the idea that any professional scientist would consider it acceptable behavior to launch this kind of ugly personal attack on someone from behind the protection of anonymity really boggles the mind.

  54. Lee Smolin says:

    Dear Anon,

    Please be specific and we can discuss point by point:

    -Which theorem did I quote that meant something different from what I said?

    -Which of the criticisms of string theory did I make that did not stand up on technical grounds?

    -Which work by LQG people “does not make sense”?

    About your general characterization of my work, you might check for example, my citation record. Do you think that all the papers that cited mine were written by people who were somehow wrong about the significance of the results they cited? Then check my career, do you think that the different hiring, promotion and tenure committees, and grant referees were fooled?

    And yes, I agree with Peter, it is unethical to make an unsubstantiated personal attack without identifying yourself. Beyond that, I can also assure you that it does not help your case, in the eyes of most scientists, to respond to reasonable criticism with nasty personal attacks. If you cannot take constructive scientific criticism, offered reasonably, and respond to it respectfully and professionally, it gives the impression you cannot be trusted to evaluate reliably either your own work or anyone elses.

    Finally, note that I was making what in essense was a peace offering, admitting some fault for having not been able to block too provocative a cover. I still am hoping that somewhere on the other side of this debate there are people who knows how to carry on an honest and respectful discussion about differences of opinion among experts.

    Thanks,

    Lee

    Thanks,

    Lee

  55. JC says:

    Blake,

    I remember several of my old professors mentioning that there’s only so much stuff they can “cram” into a particular course, during the semester/quarter. In those days I was wondering why the “ground” covered by so many physics and math courses, was kind of on the flakey and/or “weak” side. Most profs just told me that if I wanted to know more about a particular thing in greater depth and detail, I should just read a particular book and/or paper and work out some of the details myself without any “grading” nor any expectations for academic credit.

    At the time I didn’t know they were encouraging me to be more independent minded, and that “classroom” lectures were a very inefficient means of passing on detailed subject information. (Initially I thought they were being complete jerks!)

    Zwiebach’s undergrad string course and textbook look quite impressive, in how much stuff can be crammed into an undergrad one-semester length course without being too “confusing” (along with “minimal” prerequisites). Though at times I wonder whether a course like that is really appropriate at the undergrad level.

  56. Evidently, avoiding the technical issues is much more satisfying.

    But, to return to the point of contention, we have the proposition:

    AdS/CFT requires specifying the asymptotic behaviour of the metric (and other fields) but does not require a choice of background metric. This is exactly as much “background-independence” as one can possibly require of a theory of quantum gravity in asymptotically anti-de Sitter spacetimes.

    Lee, in his book, asserts that AdS/CFT does not satisfy the requirements of background-independence. David Gross, apparently, asserts that Lee does so, despite having assented privately to the above proposition.

    Here, Lee responds that he never assented to the above proposition and, instead, offers a conjecture (unsupported by any evidence) that, perhaps, in the quantum theory, the anti-de Sitter algebra is deformed. Even if this conjecture were true, it — in no way — addresses the truth or falsity of the above proposition.

    So am I supposed to be reassured that Lee does, in fact, believe that the above proposition is false?

    Note that this is, one would have thought, a completely uncontroversial statement about gravity in asymptotically AdS spacetimes (and the requirements of global hyperbolicity, etc). It has nothing to do with the truth or falsity of the Maldacena Conjecture.

    Lee’s perfectly free to poke holes in the Maldacena Conjecture, arguing that no one has proven that N=4 SYM exists as a quantum field theory (in fact, no one has demonstrated the existence of any nontrivial 4D QFT), or that, perhaps, it doesn’t really have vanishing beta function, or that Rehren’s Theorem proves that the Maldacena Conjecture cannot be correct or …

    But his statement about background independence seem to me to be just plain false. And I don’t see why it matters that he ‘really believes it.’

  57. Clifford says:

    Dear All,

    Please try to return to some semblance of moderation here. Responding to a naive remark from above about us supposedly being required -as scientists- to be dispassionate, I for one do not believe that we should argue like robots, or bad science fiction chariacatures of scientists. We are human beings, like it or not, and so we have passions. I love science and being a scientist partly because of the passion and emotion that can be involved. I don’t want to eradicate that. And we should not lie to the public and cover up our humanity (well, not too much!) That said, we must be careful all the same, and strive to at least keep the ratio of substance to emotive baggage as high as we can in our comments. That way we all stay engaged in the arguments and discussions because we’ll see the worth of the whole enterprise. But the ratio will vary from comment to comment, I’m sure. Just like in regualr conversation. I don’t have a problem with that. On rules of engagement when making the stronger remarks:- Generally, if you want to go for the jugular, it does lend more weight if you attach your name to the dagger.

    Dear Lee,

    For what it is worth, I do not buy the “it was out of my control” argument. This is not the same as a magazine or newspaper article. If you felt so strongly about ethics, you would simply have refused to sign a contract to give the publisher control of the book if you did not like the title. Anyone can see that such a title/subtitle combination would be perceived as extremely negative…great for book sales of course, but you claim that you wanted to have a civilised discussion. That title is not a good opening move for such a discussion. It undermines the whole thing. On to ethics again, since you brought it up: Is it not damaging to theoretical physics in general, and to your own integrity as an author/scientist, to knowingly put out a title that claims tht a subfield is destroying physics when (you claim) this differs from the content of the book? You cannot wiggle out of it by saying that you did not think we would be “so sensitive”.

    In short, it’s a lame excuse. This is, I suspect, part of the “moving target” aspect we all find frustrating.

    As I said to Peter above (please read the comment here)…. if you want to discuss research idea alternatives, and resources, let’s do that. Preferably through the usual channels. If you must write a book, write a book that is about that… But don’t write books trying to drag down an entire research effort -trying to damage its reputation in the eyes of the public- and then claim that it is about somethign else. …. when challenged on it, claim that it is not your title choice? You have to accept responsibility for the whole book. Stand up and be counted, as it were. Are you going to start attributing things in the actual text of the book to having been put there by the copy editors, and not you? I hope not.

    Thanks,

    -cvj

  58. Blake Stacey says:

    @JC:

    The introduction to Zwiebach’s book lists the chapters which the MIT class (8.251) covers, and it suggests options for different chapters to emphasize based on the time allotment and desired sophistication of the class.

    I could rant much more fully about the MIT physics curriculum, but such a rant would be even less germane to this comment thread than anything else I’ve said so far, so I’ll refrain.

  59. Peter Woit says:

    Clifford,

    I also don’t have a problem with people arguing passionately for what they believe in but you seem to have a double standard here, attacking Lee for putting before the public some emotionally-laden negative expressions about string theory and the current state of theoretical physics, while at least seeming to excuse if not encourage the highly emotional response this has generated in some string theory partisans.

    While passion has its place, it must be constrained by intellectual honesty. I think both Lee and I wrote books that are passionately felt and also rigorously honest. We both took great care to get facts right and to make arguments for which we believe we have strong evidence. Quite possibly we’re each wrong about some things. I certainly don’t agree with some of what Lee wrote and I’m sure he feels the same about my book. I’ll be glad to argue with anyone about what’s actually in my book and doubtless Lee feels the same way about his. What I’m seeing far too much of is people who want to argue about the covers and jacket copy of books they haven’t read, instead of dealing with the serious and important issues these books address.

  60. Clifford says:

    Peter, I’m pretty sure you can tell the difference between passion on the one hand, and an untruth on the other. Consider this in re-reading your first paragraph. Consider this in re-reading your recent post on your blog where you just decided to make up random facts about me in an effort to undermine my reputation. That’s not being passionate.. that’s just making stuff up. I am not encouraging that.

    With regards your book being “rigorously honest”, I have to disagree. Recall that on the last thread where we had a discussion about the central argument of your book … the main reason people will take it off the shelf to read -that string theory is wrong, that it can make no contact with experiment- you found yourself, after being asked again and again, unable to supply us with the “well known” (your words) evidence of this. You’re confusing your personal gut feelings, which you are entitled to, with a fact. You should be clear about that with your readers.

    As to the issue of the serious and important issues…. We talked about what seems to be the main issue at hand – it has nothing to do with string theory and is more about the career path in physics in general…perhaps all of science. Sure, lets have a discussion….. I’ve said some things above that you did not respond to on this point… would you like to pick up the baton and carry it on….? Also, you did not respond to the comment of one or more of the very young people that you’re so concerne about. Would you do that please?

    Thanks,

    -cvj

  61. Lee Smolin says:

    Clifford,

    Thanks for that. About the cover, if I feel there is an atmosphere of good faith I’d be glad to further discuss the circumstances, which were long since the contract had been signed. But good faith would mean I sensed a willingness to actually read my book and respond to the arguments written in it.

    For the present, it seems I have just to repeat myself. Jacques writes: “Lee, in his book, asserts that AdS/CFT does not satisfy the requirements of background-independence. David Gross, apparently, asserts that Lee does so, despite having assented privately to the above proposition.”

    It seems that Jacques did not read my first post to this thread, so let me repeat here the substance:

    On page 189 I wrote : ”…if the strong form of the Maldacena conjecture turns out to be true —which is also consistent with the present evidence — then string theory provides good quantum theories of gravity, in the special case of backgrounds with a negative cosmological constant. Moreover, those theories would be partly background-independent, in that a nine-dimensional space is generated from physics in a three-dimensional space….There is other evidence that string theory can provide a unification of gravity with quantum theory…”

    and on page 240 I repeated the point: “In a certain limited sense, if the strong form of the Maldacena conjecture (see chapter 9) turns out to be true, a nine-dimensional geometry will emerge out of a fixed three-dimensional geometry. It is thus not surprising to hear Edward Witten say, as he did in a recent talk at the Kavli Institute for Theoretical Physics at UC Santa Barbara, that “most string theorists suspect that spacetime is an ‘emergent phenomenon,’ in the language of condensed matter physics…”

    OK, get it: I did in the conversation with David in July agree to what was already in the final text of the book, which is that there is limited or weak sense in which, were the strong form of the Maldacena conjecture true, it would satisfy a certain weak form of background independence. So I did not contradict myself, and I think I am owed an acknowledgement of that.

    Jacques wants to argue about something else, which is what should be the right form of background independence in different circumstances, I am happy to continue that discussion but it is irrelevent to answering the charge that I contradicted myself and I would prefer to have this settled first. If I get some acknowledgement that what I wrote is indeed consistent with what I said, and perhaps even an apology for having my integrity questioned, then I would be happy to continue to discuss the science. But first things, first.

    Thanks,

    Lee

  62. Peter Woit says:

    Clifford,

    You’re the one engaging in untruth here. I’ve repeatedly explained to you that I wrote a very long posting on my blog responding to your question as to what are the problems with making contact between string theory and experiment, again, see:

    http://www.math.columbia.edu/~woit/wordpress/?p=473

    Remarkably, string theorist Michael Dine recently gave a talk at the KITP entitled “Prospects for a string phenomenology” (see http://online.itp.ucsb.edu/online/bblunch/dine/) in which he accurately explained what the problems are with getting particle physics out of string-based unification. His conclusion was that the only possible way to do this would be by the statistical calculations he is pursuing, and he then explained what Witten’s arguments were for why this won’t work. I’m with him on the first part of this Witten on that issue.

    These are serious scientific arguments, not my gut feelings.

    As for “youngonion”, he wasn’t even claiming to have read my book, much less trying to argue with what is in it. Sorry, but life is short, and responding to hostile personal attacks from anonymous people on your blog is not high on my list of priorities, so I’m going to pass on dealing with that one.

    As for any thing I may have written anywhere about you that is not accurate, it’s certainly possible that I’ve made such a mistake. However so far you haven’t bothered to explain what precisely I’ve written that is inaccurate. It might be a good idea for you to privately contact me and inform me exactly what the problem is, and I’ll be happy to make any appropriate corrections of what I wrote.

  63. Clifford says:

    Peter,

    What you’ve explained is your dislike for the approach. You have not presented “well known evidence” that the approach cannot work. THe research has not even been finished yet…the theory only partly developed. How on earth can you know? I’ve pointed this out before.

    I have not looked at Michael Dine’s talk, and so cannot comment on it. I hope that others might be able to. I repeat my comment that the theory is very poorly developed right now. I cannot imagine how anyone can make a sweeping statement about string theory’s prospects without understanding it better. I’m betting that Dine’s remarks are not as sweeping as yours. I could be wrong.

    Funny that you’ve said nothing about your bizarre accusations about me. How so?

    Cheers,

    -cvj

  64. TheGraduate says:

    In defense of the book title thing, it really is (as far as I know) a pretty standard thing to sign away a large part of the rights concerning the promotion of the book. Journalists don’t write their titles, Authors don’t pick their titles. It’s really not that controversial.

    “Actually, the books rarely carry Phil’s original titles, as the editors usually wrote new titles after reading his manuscripts. Phil often commented that he couldn’t write good titles. If he could, he would have been an advertising writer instead of a novelist.”

    — Philip K. Dick’s wife on why the film adaptations of his work often have different titles from the books

    Maybe there is an ethical concern but this is how things often are done. The practice really is quite similar to the academic practice of senior researchers putting their names on the papers of junior members of their research group even if they were only marginally involved in the work; which they do for what might be called ‘marketing’ reasons.

  65. Clifford says:

    TheGraduate:- Thanks. But this is not about the entertainment industry, it is about (supposedly) and academic discussion about research. Or at least, I thought it was. I’m not so sure any more. Maybe it is all entertainment…..

    -cvj

  66. Mark Srednicki says:

    Lee, EVERYTHING is negotiable in a book contract. I know, I negotiated one last year (for a textbook, but the principle is the same). If one publisher won’t agree to your terms, find another (it helps to negotiate with two at once); if none will, post it online yourself, and forgo the money. And issuing an apology for the cover of your book deep in the comments section of someone else’s blog does not really do much to change the situation.

    For what’s it worth, I do not endorse, and explicitly repudiate, the childish name distortions that were employed at George Johnson’s seminar. (In real time, I was wincing at their mention, but did not speak up and say so.) As for the “crackpot” comment, here is what happened (not fully captued on audio/video). Johnson said something like “No one thinks Smolin is a crackpot.” I raised my hand. This was intended as a joke (and indeed produced the round of laughter that can be heard), but was also intended to convey the point that (in my opinion) the various flavors of loop quantum gravity do not have anywhere near the intellectual heft of string theory, and that Johnson was wrong (in my opinion) to assume (based on what he read in your book) that they did. Bottom line: I do not think you are a crackpot, and I apologize for conveying that impression. However, I do believe that the line of research that you are persuing is extremely unpromising.

    I also deny in the strongest possible terms that I am “blind to” or “dishonest” about the “naked prejudice” against women and blacks in physics. No, you don’t mention me by name, but I surely must be among the sort of people you had in mind when you wrote page 336.
    .

  67. Peter Woit says:

    Clifford,

    It’s completely hopeless to try and discuss this topic with you, you just ignore everything I write, characterizing it as being about what I personally “like” or “dislike”. This has nothing to do with that, this is about the technical reasons that no one is able to produce testable, falsifiable predictions about particle physics out of string theory. The problem is not that string theorists are lazy and more graduate student years are going to get it done. You’re welcome to believe that some future new understanding of string theory will change the current situation and testable predictions will become possible. That is something that seems to be purely based on feelings, yours.

    As for the “bizarre accusations”, again, you seem to have trouble reading the words I write here, here they are again:

    “As for any thing I may have written anywhere about you that is not accurate, it’s certainly possible that I’ve made such a mistake. However so far you haven’t bothered to explain what precisely I’ve written that is inaccurate. It might be a good idea for you to privately contact me and inform me exactly what the problem is, and I’ll be happy to make any appropriate corrections of what I wrote.”

  68. Moreover, those theories would be partly background-independent,…

    I did in the conversation with David in July agree to what was already in the final text of the book, which is that there is limited or weak sense in which, were the strong form of the Maldacena conjecture true, it would satisfy a certain weak form of background independence.

    The Maldacena conjecture does not “satisfy a certain weak form of background independence.” It satisfies the strongest possible form of background independence consistent with quantum gravity in asymptotically anti-de Sitter spacetimes.

    Perhaps, David Gross gave you credit for having said something more sensible than what — you say — you actually told him back in July. Not having been a party to the conversation I am not in a position to judge.

    Personally, though, I tend to be relieved when my physics mistakes are “corrected” by the faulty recollections of my interlocutors.

    But that’s just me …

  69. anon. says:

    Peter, don’t you find it a little questionable to make accusations and then state that it is the responsibility of the accused to correct them if they are wrong? That’s not exactly civil discourse….

  70. TheGraduate says:

    anon.:

    I think what he said was that he did his best to make sure it was accurate but if it isn’t let him know and he’ll fix it.

    (There is enough to disagree about in this debate without picking at the small potatoes don’t you think?)

    Reasonable people have been known to disagree. It’s someting to keep in mind.

  71. Clifford says:

    Peter… ok.. No progress on the first paragraph then. Fine. You believe there is “well known” evidence for the failure of a research program that is still ongoing. Ok.

    And yes, I missed what your last paragraph was about. Did not mean to ignore. Anyway, I agree with anon. You get to just make random stuff up out of whole cloth about someone, and it is up to them to come out and correct you? You really believe that is the way things are supposed to be done? Wow. Are these the same standards you use to judge that string theory is wrong?

    -cvj

  72. Clifford says:

    TheGraduate:- What did he do to make sure it was accurate? He made something up about me, something I was supposed to have done….and then put it on his blog. Is that his best!? That’s utterly ridiculous. And certainly not reasonable, I hope you agree.

    -cvj

  73. Lee Smolin says:

    Jacques,

    “The strongest possible form of background independence consistent with quantum gravity in asymptotically anti-de Sitter spacetimes.” according to you, does not satisfy the standard definition of background independence (or in Greene’s terms, manifest background independence) which is that no classical metric and no global symmetries are required to state the laws of the theory. But it does satisfy something weaker than that and because I respect the facts I have been careful in speaking and writing to state clearly the situation. I don’t argue from my feelings, when there is a clear logical case for something I acknowledge it and try to state it clearly. It seems like the pay back I get for trying to be accurate about the facts and precise in my characterization of them is to get insulted and slammed by people who deliberately twist a subtle distinction to make it look like a contradiction. I am still waiting for someone to acknowledge that they had the impression that I did not mention in the book that the Maldacena conjecture could satisfy some (any!) form of background independence, and that, having read the quote from the book, they recognize that impression was wrong. I would like to get some recognition of the fact that on many issues, including this one, my book describes the factually correct situation.

    Dear Mark,

    I accept your apology, I hope you can accept mine. In fact, one cannot walk away from a contract signed years earlier a few weeks before publication over a dispute over advertising copy, without being in breach of contract. But please be assured that I was not referrring to you or making any terrible accusations towards you or anyone in particlar, in my brief discussion of prejudice in hiring. I was only saying that we all have at some point in our career observed some unconscious prejudice in action, whether in ourselves or in some-but by no means all of our colleagues in physics.

    Thanks,

    Lee

  74. Elliot says:

    Mark,

    Sure everything is negotiable if you prepared to walk… But in good faith negotiations there is give and take.

    What is very clear to me is that this thread itself is not “background independent” 😉

    Elliot

  75. ‘When I use a word,’ Humpty Dumpty said in rather a scornful tone, ‘it means just what I choose it to mean—neither more nor less.’

    “The strongest possible form of background independence consistent with quantum gravity in asymptotically anti-de Sitter spacetimes.” according to you, does not satisfy the standard definition of background independence

    Sorry, Lee, but unlike Humpty Dumpty, Physics does not allow us to choose what “background independence” in asymptotically anti-de Sitter spacetimes is supposed to mean. If what is allowed by the Physics doesn’t accord with your “definition”, then that is an inadequacy of your definition.

    This has nothing to do with the correctness (or completeness or whatever) of Maldacena’s Conjecture. Maldacena’s Conjecture could be completely wrong. That still would not pave the way for a “more background independent” theory of quantum gravity in asymptotically anti-de Sitter space.

    If you want to insist that any theory of quantum gravity in asymptotically anti-de Sitter space obeys only a “weak form of background independence,” go right ahead. But to insist that AdS/CFT suffers from this defect (with the implication that some alternative theory would not) is dishonest.

    That is not meant as a slam, or as an insult.

    If David Gross misrepresented (or misremembered or misinterpreted) your conversation in July, that’s unfortunate, but it’s something you’ll have to take up with him. It doesn’t change the physics one iota. And, I have to say, I am rather disappointed at the arc of our conversation about the latter.

  76. TheGraduate says:

    Dr. Johnson,

    Sorry, I really didn’t mean to interfere too much. I was just hoping to promote some good faith discussion.

  77. Clifford says:

    Please interfere…. not a problem. It is ok for us to disagree on the previous, if you wish.

    Cheers,

    -cvj

  78. gerry atric says:

    Sorry, maybe somebody can clarify things for me. It seems to me that LS is saying that any theory that insists from the outset on using asymptotically AdS spacetimes is not *completely* background-free, which seems pretty reasonable until you ask: what would a completely background-free description of this situation look like?

    Relatedly: I keep seeing the words globally hyperbolic. AdS isn’t globally hyperbolic, so I don’t quite see what is being claimed.

  79. Mark Srednicki says:

    Lee, I do accept your apology. Of course I would not expect anyone to walk away from a signed contract, but I agree with Clifford that each of us is responsible for the ultimate results of contracts we sign. And just to be clear, the issue is not “advertising copy”, but rather the subtitle of the book, a subtitle that amazon, barnesandnoble, and bordersstores all display as part of the title itself.

    As for prejudice in physics, you wrote that “blatant prejudice” is responsible for the relatively small numbers of women and blacks, and that anyone who claims (as I do) not to have seen “naked prejudice” in action is “blind” or “dishonest”. You now seem to be backing off from these claims, using the rather milder phrase “unconscious prejudice”. Precision in language in discussing hot-button issues is something we should all strive for.

  80. Relatedly: I keep seeing the words globally hyperbolic. AdS isn’t globally hyperbolic, so I don’t quite see what is being claimed.

    Exactly the point!

    If you don’t nail down the asymptotic behaviour of the metric, you don’t have a well-posed initial value problem, even classically. Once you specify appropriate boundary conditions, however, you obtain a hyperbolic problem.

    You can have a theory that is background independent, to the extent that you don’t have to specify a background metric (over the “interior of AdS”). But you can’t avoid the necessity of specifying the asymptotic behaviour of the metric. This requirement, which is basic to the formulation of AdS/CFT, is generic to any would-be quantum theory of gravity in asymptotically AdS space.

  81. gerry atric says:

    “If you don’t nail down the asymptotic behaviour of the metric, you don’t have a well-posed initial value problem, even classically. Once you specify appropriate boundary conditions, however, you obtain a hyperbolic problem.”

    I’m not sure I get you, sorry. The initial value problem in GR asks you to specify a metric, energy density, extrinsic curvature etc. *everywhere* on an initial slice. [I know you know this, just stating it so we are not talking about different things.] A typical spatial slice for AdS would be a 3D space of constant negative curvature. Now it seems to me [wrongly?] that what you are saying is that it is ok to deform this metric deep in the interior, provided that the 3D metric still has approximately constant negative curvature far away. Then the system will evolve to something like “AdS deformed deep in the bulk” but still asymptotically AdS; intuitively, the conformal boundary of the 3D negatively curved space evolves into the timelike conformal boundary of the deformed AdS.

    But is all this really true? Won’t the evolution lead to a Big Crunch, generically? The point is that non-globally-hyperbolic spacetimes like AdS *cannot* usually be obtained by the usual evolution from initial data. The existence theorem guarantees the existence of an essentially unique *globally hyperbolic* solution of the field equations, but that unique solution won’t be the spacetime we want, except in the case of *exact* AdS [where the maximal Cauchy development can be analytically continued to all of AdS]. Note that the singularity theorems apply here!

    Actually all this is what I had in mind when I asked Prof Smolin what he could possibly mean by a *fully* background free formulation of the AdS/CFT setup. Background-free here can’t mean what he wants it to mean, because you can’t treat asymptotically AdS spacetimes as if they were cosmological models. The best you can do is to agree at the outset that you are only going to talk about spacetimes with timelike conformal boundaries — which I think is what you are saying.

  82. TheGraduate says:

    Hello Dr. Srednicki:

    On the issue of disparaging views of minorities and women held by physicists at good universities, you can take a look at the following if you wish (also I suggest reading the comment section):

    [Links to motl’s blog removed by cvj]

    I think, if Dr. Johnson has some kind of spam detection, it might kill my post if I add any more links so I will stop here.

  83. I am, indeed, going to restrict myself to spacetimes with timelike conformal boundaries. And one is, indeed, (severely) restricted in what initial data can be evolved forward without leading to a big crunch.

    All of these feature are incorporated in the AdS/CFT conjecture, as clarified by Witten and by Gubser-Klebanov-Polyakov, following on Maldacena’s original suggestion.

    Of course, I’m not (just) interested in things which have a semiclassical description in terms of smooth supergravity solutions.

    One generalization is to consider boundary conditions which correspond to relevant perturbations of the boundary CFT. Even semiclassically, these do not give rise to smooth interior geometries. But they can have interesting descriptions in the full string theory.

    And if the magnitude of the cosmological constant is not small (in Planck units), then, even in the case of an exactly conformal boundary, the bulk theory is far from being well-described by semiclassical supergravity.

    But, before wandering off into such topics, one should — at least — have a formalism which, in an appropriate limit, reproduces known features of the semiclassical physics.

    And, like you, I don’t see how such a formalism could possibly be “background independent,” in the sense Lee would like to use the term.

  84. TheGraduate says:

    Dr. Johnson,

    About the links, I didn’t know there was a policy about that sort of thing. Can you tell me what your policy is?

  85. Clifford says:

    When it comes to matters of race and gender, among other topics, I find myself unwilling to look at, or to point others in, the direction of rather deliberately objectionable writings on the subjects. I’d rather not have links to that sort of material either.

    I don’t have a policy against links in general.

    Best,

    -cvj

  86. JZ says:

    To Jacques Distler,

    Have you read Lee Smolin’s or Peter Woit’s book?

    To Mark Srednicki,

    Have you read Lee Smolin’s or Peter Woit’s book?

    I am just curious to what extend one side of the debate knows the position of the other side.

  87. Aaron Bergman says:

    I’ve read all of Peter Woit’s book. I’ve also read chapters 16,18,19,20 of Lee Smolin’s book and skimmed the rest.

    It’s worth pointing out that both Lee and Peter have participated in these various internet fora for a while now, so it’s not as if either of their positions on various subjects are unknown.

  88. Peter Woit says:

    Clifford,

    Again: I acknowledge that I sometimes make mistakes, and if that’s the case here, I’m more than willing to try and correct the record and issue any appropriate apologies. I can’t do this if I don’t know what it is that you are claiming that I got wrong. In this case you continue to be unwilling to communicate to me what the mistake in question is supposed to be and instead seem intent on pursuing it purely as a way of tarring me as dishonest, in particular using it to claim that my criticisms of string theory are dishonestly made. This tactic strikes me as, well, dishonest.

  89. Mark Srednicki says:

    JZ, I’ve read through the parts of Lee’s book that are relevant to the debate, and skimmed the rest. (I believe that, for example, I know the history of particle physics well enough not to need to read Lee’s version closely.) I have also heard Lee and othes working on LQG speak many times, read a number of their papers, and followed some of the recent technical debate at the String Coffee Table and Jacques Distler’s blog. I have not read Peter Woit’s book, and have not commented on it, here or elsewhere.

  90. Tony Smith says:

    Clifford, you said “… When it comes to matters of race and gender, among other topics, I [Clifford] find myself unwilling to look at, or to point others in, the direction of rather deliberately objectionable writings on the subjects. …”.

    Isn’t failing to “look at … objectionable writings” an ostrich head-in-the-sand approach?

    If you don’t “look at” the bad stuff,
    and also
    don’t “point others … in the direction of” the bad stuff to show them that it exists and how bad it is,
    then
    aren’t you aiding the bad guys by hiding from them instead of confronting them ?

    Or, are you just trying to protect your fellow superstringer Harvard Professor Motl by trying to limit discussion about what he is saying on his blog ?

    Tony Smith
    http://www.valdostamuseum.org/hamsmith/

  91. Clifford says:

    Tony Smith,

    Please think what you want about my policy.

    Thanks.

    -cvj

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