Aaron Bergman has written up a review of my book and posted it over at the String Coffee Table. It’s quite sensible and makes reasonable points, so I’m very glad he wrote it. Here are a few comments of my own about the points raised in the review. I don’t have time to discuss everything in it right now, but if someone feels that I’m not addressing an important point of Aaron’s let me know.
It’s true that the book isn’t “even-handed” in the sense of repeating many of the arguments made for string theory. One reason for this is that I assumed that essentially all my readers would have read at least something like one of Brian Greene’s books. I originally intended my book as something that would be published by a university press and be aimed at people with some background in the subject. The fact that it ended up being published by a trade publisher wasn’t my first choice, and the wide attention it is getting from people who know little about physics is a surprise to me, something I wasn’t counting on.
Instead of repeating many of the what seem to me highly over-hyped claims made for string theory and spending a lot of time explaining exactly how and why they’re over-hyped, I decided to just write down as accurately as possible how I see things. The black hole entropy calculations are an example of what I mean. I do mention these, but I think Aaron’s description of them as a “holy grail” vastly overestimates their signficance. It’s also true that string theorists still have not been able to do calculations for the case of physical 4-dimensional black holes. A truly honest description of the situation would require a detailed examination of exactly what has been calculated, and what remains still not understood. This is a highly technical business, not easy to extract from the often hype-filled literature, and I just didn’t think that even if I put the effort into doing this well, it would work as part of the book. Similar comments apply to the AdS/CFT story, where sorting through the hype and clearly distinguishing exactly what has been achieved and what hasn’t would be even more difficult.
People can compare what I have to say to what string theorists have to say, and see that there’s a different point of view on many things. If they have some expertise, they can look into these more deeply and decide for themselves. Aaron describes the book as “tendentious”, but I think it’s much more scrupulously accurate in its descriptions, honest and even-handed than any of the many books promoting string theory, essentially all of which contain vast amounts of misleading hype designed to give the reader an inaccurately optimistic view of the theory.
About the CC and supersymmetry: I re-read that section after Lubos’s review complained about it, and it was not clearly written. But the argument that I’m not giving SUSY credit for being wrong by 1060 instead of 10120 doesn’t make sense to me. Both are obviously in the same category of being completely off-base in a very fundamental way. The situation with SUSY is actually worse than non-SUSY, because in a non-SUSY theory the vacuum energy is not something that you can calculate even in principle. In a SUSY theory (before you turn on gravity), it’s the order parameter for supersymmetry-breaking, so has to have a scale of at least 100s of GeV to explain the lack of superpartners. Your theory of quantum gravity is supposed to ultimately explain the CC, and, for doing this, supersymmetry not only doesn’t improve the situation, it introduces a huge new problem you have to find some way around.
About the section on mathematics, and that I’m being petty about denying credit to string theory. Again, I think what I write is far more honest that just about anything string theorists have to say about the relation of string theory and mathematics, much of which is based on alotting to string theory purely QFT results.
About S-matrix theory, Chew, Capra. I think the lesson of what happened with S-matrix theory is an incredibly important one, and suspect that someday history will repeat itself. Before asymptotically free theories, people were convinced they had a good argument that QFT couldn’t be fundamental, just as many people are now convinced that problems with quantizing gravity imply that QFT can’t be fundamental. The arguments from Chew and Capra about getting rid of symmetry arguments and QFT in favor of the bootstrap are all too similar to things one hears these days from some string theorists. As for the denial of reality by Chew and Capra, post-QCD, there is no analog yet in the case of string theory. But, if someone finds a better way of quantizing gravity and getting unification, I’m willing to bet that, just like in the case of S-matrix theory, most theorists will move on, but some will refuse to ever give up on string theory and deny reality. We’ll see what happens. Eastern religions are a lot less popular in the US these days than they were in the 70s, so I don’t think there will be a new “The Tao of Physics”. But, already, if you take a look at Susskind’s “The Cosmic Landscape”, it holds up as science no better that Capra’s book.
About describing string theory as a cult with Witten as its guru. I believe Joao Magueijo in his book explicitly does this, and I can think immediately of three well-respected physicists or mathematicians who have, unprompted, used this description in conversations with me. Based on my experience, I’m pretty sure that if you sample non-string theorist physicists, you’re going to find many people who would describe the behavior of string theorists as “cult-like”. This behavior is described by Lee Smolin as “groupthink” and he has a lot to say about it. I wrote that I don’t think it’s useful to describe string theory as a religious cult, because the phenomena are significantly different, but I would characterize the behavior of some string theorists in recent years as “cult-like”. Some people exhibit a disconnect from the reality of the problems of the theory that is much like the way members of a cult behave in face of evidence contrary to their beliefs. Lubos is an extreme case, but there’s lots of others, of varying degrees. Describing Witten as the field’s “guru” I think is actually uncontroversial. There’s nothing wrong with having “gurus”, as long as you realize they are sometimes wrong. People who have demonstrated great amounts of knowledge and wisdom deserve to be listened to very seriously, but no one is ever right about everything.
About the Bogdanovs. The main reason I wrote about the Bogdanov story, (besides for its entertainment value), is that I think it shows conclusively that in quantum gravity in general, many people have lost the ability or willingness to recognize non-sense for what it is. Sure, this is not specifically a string theory problem, but it’s also not a problem specific to non-string theorists doing quantum gravity. This was swept under the rug at the time, and attributed to a few lazy referees, rather than dealt with as a serious problem that needs to be addressed if the field is not going to drown under an increasing tide of crap, and I think this was a big mistake, with the tide rising since then. I don’t apologize at all for writing about it in the book. As for the inclusion of the e-mail describing the reaction of the string group at Harvard, I don’t know its author, but I was assured by its recipient that it was legitimately from someone who was visiting there at the time. One member of the string theory group at Harvard is Lubos, and he has repeatedly defended the work of the Bogdanovs on his blog as legitimate science, no worse than much else of what is published in this field.
About Hagelin. Again, I wrote about him in the context of a chapter examining the difficulties involved in deciding what is science and what isn’t. More specifically, how do you tell who’s a crackpot and who isn’t? There are plenty of people out there whose ideas about physics are uniformly incoherent and easy to dismiss, but there are also cases like Hagelin, who combines excellent research credentials with crackpot ideas about science. How do you decide who is a crackpot and who isn’t? What about Lubos, what about Susskind? Many string theorists seem to hold the opinion that I’m one. Lacking the normal sort of discipline that comes from confrontation with experiment, a scientific field is in a very tricky state, and needs to be careful to enforce high standards of what makes sense and what doesn’t, and not let pseudo-science take over. Aaron notes that most of the audience at the Toronto panel discussion voted against the anthropic landscape, but he doesn’t mention that anthropism seemed to be a majority opinion amont the panelists, who are the ones who hold power. This is an extremely dangerous situation for this field. I don’t think the possibility that some readers of my book are going to get the impression that most string theorists are not doing science is anywhere near as much of a problem as the fact that quite a few powerful ones definitely aren’t anymore.
About comments on this blog. Please avoid adding to the noise level by posting non-substantive or off-topic comments, engaging in repetitive arguments that go nowhere, promoting your own ideas that have nothing to do with the posting, or generally making comments that have nothing new to say that hasn’t been said many times here already.
About Shamit Kachru’s comment,
I’d like to point out that I make a very serious effort here to be as accurate as possible, although I’m sure I don’t always succeed. When discussing someone’s views, if possible I try and quote their own words, completely and in context. In the case of the Landscape, I’ve at times been so appalled by what I see going on that I’ve expressed myself in excessive ways that were not wise.
Presumably he’s responding to my characterization of him as a proponent of the anthropic landscape point of view, and suggesting this is less than accurate. This characterization is based on some of his talks, and of the following quote from his colleague Susskind (see page 351-2 of his book):
“At Stanford University – my home – there is pretty near unanimity on the issue, at least among the theoretical physicists: the Landscape exists. We need to become explorers and learn to navigate and to map it Shamit Kachru and Eva Silverstein, both in their early thirties, are two of the world’s young leaders. Both are busy constructing the Landscape’s mountains, valleys and ledges. Indeed, if I were to attribute to anybody the title of the Modern Rube Goldberg, it would be to Shamit. Don’t get me wrong; I don’t mean to say that he makes bad machines. On the contrary – Shamit has brilliantly used the complicated machine parts of String Theory better than anyone to design models of the Landscape. And the Anthropic Principle? It goes with the territory. It’s part of the working assumption of all my close colleagues at Stanford, young and old.”
Susskind presumably has extensively discussed this with Kachru. If his characterization of Kachru’s views is inaccurate, Kachru’s problem is not with blog postings like mine, but with a published book of his senior colleague. A blog might actually be an excellent place to set the record straight if Susskind’s published version is incorrect.
Kachru is quite right that some of these issues are complicated and discussions of them have sometimes invoked oversimplified or incorrect descriptions of his views or those of other people. But I don’t think he’s right that this medium is inappropriate for serious discussions of these issues. He and anyone else who wants to carefully explain their views on the issues discussed here is strongly encouraged to do so. I’ll happily post here anything of this kind that he or anyone else who feels similarly is willing to write.
I am certainly drastically oversimplifying things here, but if I am to believe Shamit Kachru and Peter Woit, not only are the loud string theorists spouting nonsense, but some of them are also claiming that everybody agrees with their nonsense. And as I said,
Dr Kachru:
In business, management and even law, there is often the issue of how to allocate resources to views proposed by different experts with sharply contrasting points of view.
Assuming that one is not going to read every bit of everyone’s work before deciding, what does one rely on:
1. Credentials
2. A documented track record of successes
3. The relative amount of support for the differing points of view among those in the know
My only window on this contraversy are these blogs, the magazines and talking to other people that enjoy the occasional read of ‘Scientific American’ or ‘New Scientist’.
My best guess is that to the casual, neutral observer whose first opinion on string theory is primarily derived from the Nova special and seeing Brian Greene at their school (as I definitely did) … I would say that for that sort of person, the recent contraversy about string theory seems pretty plausible.
I think to the general neutral party, the idea that one would need evidence to support a particular point of view is pretty uncontraversial and this line of reasoning would make sense to an engineer, a lawyer or even a banker.
I think it has become fashionable with the magazines to play up the contraversy as this is the sort of thing that sells magazines: Time, Scientific American etc
I would actually really appreciate if a few people from the string community seriously debated Dr Woit. From my observations of the blog, Dr Woit seems very earnest about allowing fair debate.
Normally, I would say this sort of debate is the internal business of the scientific field involved but at least since the Nova special, many issues of string theory have become public interest.
I too would hope Shamit Kachru would post a long detailed reply somewhere. A blog posting is an ideal place, in my opinion.
I would suggest that it is a HUGE mistake for prominent string theorists to ignore criticism from Peter Woit and others and dismissing opinions of outsiders as ‘crackpots’. Maybe some get satisfaction by “High-Five-ing” insults of Peter and Lee by some string theorists, but it is not helping change the perception of string theory or string theorists among outsiders.
For all the criticism of string theory by Peter(sometimes unfair, I think), it is INFINITELY BETTER than what a prominent string theorist did by writing popular books on “Cosmic Landscape and the Illusion of Intelligent Design”. It won’t be long before the “illusion” part is dropped in the popular perception of the subject. Perceptions matter.
It does not help when patently false/exaggerated statements are made to promote the subject. Please stick to the remarkable results that have been of great interest to mathematicians; that is impressive by itself. And admit failure of string theory in uniquely predicting physics beyond the standard model(obviously, compatibility with anything coming out of the LHC is not the same as a prediction).
Ultimately, credibility of physicists, and ultimately science is at stake. Scientific thinking is under assault, but not from Peter. Look further AND closer….
Lubos Motl Said:
Well, Sylvester James Gates, Jr. (the Jim Gates of the superstring site) states in a NOVA interview:
I agree with Jim Gates.
Juan R.
Center for CANONICAL |SCIENCE)
Dear Peter,
I don’t know much about Shamit Kachru’s views on the issue, but I don’t see how the Susskind quote implies that he is a proponent of the anthropic approach.
anonymous,
“the Anthropic Principle? It goes with the territory. It’s part of the working assumption of all my close colleagues at Stanford, young and old.”
the quote pretty explicitly claims that the Anthropic Principle is Kachru’s working assumption in his Landscape research. Presumably he’s a proponent of his own research and its assumptions. Undoubtedly, as he says, his views about this are more complicated. But I wasn’t purporting to give an accurate and full description of his views, just listing him among others who are propounding a research program that invokes the Anthropic Principle, and Susskind clearly identifies him as part of this group.
Most of responses I have so far heard to Peter’s criticisms by people who state that they are string theorists are often angry and of the “I will not dignify this with a response” variety.
I had gradually been coming to the conclusion that Dr. Motl is some kind of crazy person. As far as I can tell. I have observed him having fights with several people on string theory and several other things. I am astounded that he teaches at Harvard. I assume he is tremendously knowledgeable on what he has been hired to teach about. However, he seems very bad at everyday causal reasoning … in my opinion.
I was also disappointed in the episode where Susskind says “There’s another fellow who has his own theory, I won’t tell you who his name is or what his theory is, but he writes lots and lots of theories and his theories go glub, glub, glub to the bottom of the sea before he even gets a chance to put them out there.” … with consequent fall in my opinion for both him and Stanford … Anyway, I digress.
I am somewhat curious about whether this sort of disdain extends not just to the ‘stupid’ physicists but if it also extends to the ‘stupid’ public. After all, I assume the point of the many attempts to popularize the subject was to bring the public into their otherwise insular world. And of course, quite a few of their endeavours require public good will and support and most importantly public money.
Just as a matter of interest … how long has it taken you to get to this realisation?
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Although I’ve been looking forward to the American release of your book, Peter, I must admit I was worried that it might bog down on the details at the expense of giving a nice sweeping view for the lay reader (or a scientist in a totally different field like me). Your comments indicate that I have nothing to worry about and make me anticipate it even more. Also, I think it is great that a trade firm that might push hard (who knows?) to the mass market is publishing your book. I look forward to seeing you on Oprah as the monthly book selectee (joking).
J.F. Moore,
General advice to readers of the book is that there are certain sections, especially in the earlier chapters, that are aimed at a more specialized audience, but the book is written so that if you skip ahead you should still be able to follow what is going on.
By the way, I just got a big carton of books delivered to my office, and it looks to me like the thing is available for sale on Amazon.
Lubos,
You’ve published your own criticism of loop quantum gravity, on wiki as “objections to loop quantum gravity” for which lee smolin and others have written their rebuttals (you called tweet-tweet’s facted-based responses to your list of objections “vandalism” on wiki)
so how is Peter’s book any different from what you did for wiki? Esp since popular books on string theory, such as michio kaku’s and briane greene’s, make almost no mention of the problems string theory has? as a scientific emprical theory, string theory does have problems you must admit.
you strongly object to lqg as doing science, yet you object to people who object to string theory as science.
Hello tweet,
It was also my impression that the original “objections to loop quantum gravity” in the wiki article contained inaccurate assertions, thanks for trying to correct them! I believe that section was eventually removed from the wiki LQG article, was it not?
To get back to the Aaron Bergman review, I think it has misleading statements on page 5 which could be corrected. This is a key section where he presents a justification for continued string research, perhaps THE most often used justification—that requires giving a false impression of progress achieved in non-string QG, so as to make the “game in town” point.
I will quote the review and bold some places where I think what Aaron says is questionable, as may be seen by consulting recent papers on arxiv such as
http://arxiv.org/abs/gr-qc/0604044
Graviton propagator in loop quantum gravity
http://arxiv.org/abs/gr-qc/0604016
Hidden Quantum Gravity in 3d Feynman diagrams
“One exception is the collection of ideas generally termed Loop Quantum Gravity (LQG)… It is a radically new class of theories that has as yet been unable to make any contact with the major results of the usual style of quantum theory. In contrast to string theory, the theory of quantum gravity so produced has not been able to demonstrate even the attraction known to Newton hundreds of years ago… ”
thanks.
Having read both of those papers, I think Bergman’s statement remains (for the present) completely accurate.
But I guess a critical discussion of those papers would be “off-topic” as far as Peter is concerned.
Anon,
Yes, please, I don’t think any light would be shed here by going over that same argument again. It is certainly worth pointing out though that many people working on LQG would disagree with Aaron’s characterization of the subject. But another venue moderated by someone else would be the place to discuss this.
Peter, could you post here (or send me by e-mail) the IP address of this likely sock puppet ? I could easily checked if it’s Igor/Grichka or not.
BTW, It is clear from Lubos’ comment that he didn’t even try to check the actual content of the Bogdanov’s papers, neither did he checked all the distateful parts of this affair (falsifications, sock puppets, treats, misquotes – even he is one of their victim), he merely instrumentalizes this affair against you because you happen to have pointed out their blunders. This conduct of him backfired on his face. I do not think that someone able to support crackpots in order to attack one of his collegue deserve any respect.
YBM,
Thanks for looking into this, it does appear that this comment came from one of the Bogdanovs. Thanks also for the news of their forthcoming book: Voyage vers l’Instant Zero.
http://ybmessager.free.fr/epiphysique/forums/phpBB2/viewtopic.php?t=183
In case some of this blog readers would like to comment on the specific issue of the Bogdanovs affair, which is quite off-topic here : the forum accepts posts in english.
hello who,
yes lubos article is not in wiki, but is in the lqg talkback. it does not pass wiki’s npov.
anon, perhaps the physics forum is the place to discuss the two papers?
Dear Peter,
You say,
—
“the Anthropic Principle? It goes with the territory. It’s part of the working assumption of all my close colleagues at Stanford, young and old.”
the quote pretty explicitly claims that the Anthropic Principle is Kachru’s working assumption in his Landscape research.
—
I still don’t think it is fair to base the claim that Kachru promotes the anthropic approach on this quote by Susskind, so I guess we just disagree on this issue.
Motl> “Profs. Bogdanovs from the University of Belgrade…”
1. The Bogdanovs brothers have never been professors
2. There is no link between them and the University of Belgrade, they got their Ph. D. from University of Bourgogne, in France (Dijon)
3. The Bogdanovs have never been members of any laboratory or university since they’ve got their Ph. D (the lab they’ve been in Bourgogne has even been dismissed right after that !)
Motl really took time to examine what he’s talking about. Anyway he’ve admitted having the same views on science as a whole as the B. Does he mean that misquoting people, forging thesis reports and falsifying documents are standard behaviour ?