Not Even Wrong

For some insight into the difficulties associated with being an untenured professor and trying to get an NSF grant in astronomy, see this post (and comments) by Rob Knop. For those innocent of the ways of academia, there’s a post by Doug Natelson on what a well-organized faculty search is like (both of these via Angry Physics).

This week Witten will be giving two series of talks on gauge theory and geometric Langlands, one at Berkeley, and one at Harvard. Unfortunately I won’t be able to make it to either, perhaps someone who does attend some of the talks can report on what Witten has to say, in particular on what might be new since his long paper with Kapustin on the subject earlier this year.

Some of the talks from last month’s workshop on axions at the Institute for Advanced Study are now on-line.

Honeywell is sponsoring an educational program involving Nobel Laureates in chemistry and physics, called the Honeywell-Nobel Initiative. They already have material on-line from Leon Lederman and Horst Stormer, and from one of their promotional ads it looks like Frank Wilczek will also participate.

The Perimeter Institute has a new, improved web-site, with many online talks, both scientific seminars and talks for the general public.

The Templeton Foundation also has a new web-site. This month the featured “Life’s Big Question” is Do we live in a multiverse?

The European Mathematical Society has a newsletter.

Several people have noticed that the cover of the UK edition of my book is being widely emulated, see here and here.

The folks at Axes and Alleys have a review of my book in their latest issue. It seems that the members of the Royal Tractor Repair and Maintenance Society of Outer Mongolia found the book quite confusing. I guess this is only fair, since I’ve always found them quite confusing…

In case anyone is worried about the supply of unadulterated hype about string/M-theory drying up, there’s a new book out by John Gribbin which I took a look at yesterday in the bookstore.

Since the KITP does such a great job of providing a video record of the activities there, informal talks at the string theory phenomenology program have provided a fascinating public record of the way in which well-known string theorists are struggling with the all-too-obvious collapse of any reasonable hopes for getting predictions out of string theory. Last week there was an informal discussion with Michael Douglas of the String Vacuum Project, which was quite fascinating to listen to. I had trouble hearing what David Gross had to say, which was a shame, maybe someone with better ears who listens to this can report what they hear. Douglas encountered objections from the audience when he claimed that if one could get virtually any low energy physics out of one string vacuum or another, there was not any point to the whole project, with someone making the now standard claim that this situation is no worse than that of QFT.

Starting tomorrow there’s a workshop in London entitled M-theory in the City, in some sense celebrating the 11th birthday of M-theory. There will be a reception on Thursday evening, and the organizers of the workshop are noting that:

Recently there have been a variety of publications presenting a sceptical view of string and M-theory. These have been reported extensively in both the national press and various popular science journals.

and encouraging journalists interested in this topic to attend the reception and use:

the opportunity to discuss with the participants and question where string theory is heading and address the recent criticisms string theory has faced.

Various and assorted quantum gravity news:

The latest Physics Today has an article by Lee Smolin entitled Quantum Gravity Faces Reality (available only to APS members). People concerned about open access to the scientific literature should note that sometimes professional societies like the APS are among the worst offenders. It appears that Physics Today is one of relatively few scientific publications that universities and other institutions are not even allowed to buy electronic access to. I’ve been told that this restriction of electronic access to subscribers is an intentional tactic of the APS to keep up its circulation figures and thus advertising rates.

The latest Nature Physics has a report from Ashtekar about recent developments in loop quantum gravity.

There’s a new paper on the arXiv by Baratin and Freidel that looks quite interesting. It’s too bad that Christine Dantas has given up her blog that provided an excellent location for discussion of this kind of quantum gravity research. I hope someone else will pick up where she left off. Blogger Sabine Hossenfelder has a recent arXiv preprint on Phenomenological Quantum Gravity.

I heard from my sister-in-law that NPR yesterday ran a segment on string theory, but it was mostly about soccer. I found this hard to believe, but she was right, the story is on-line here. NPR’s Richard Harris covered a soccer game in Santa Barbara between visiting string theorists and laser physicists. The string theorists were trailing much of the game, but finally won on a penalty kick they got due to a misunderstanding by the laser physicists. The story does have some remarkable quotes from string theorists about the prospects for the theory. Steve Giddings “is actually feeling somewhat more optimistic about the fate of string theory these days”, arguing that maybe the LHC will start producing strings (the article does note that “even most string theorists say this is a real long shot”). David Gross says that the reason to do string theory is that “…there’s nothing else. There’s no other game in town.” He acknowledges that string theorists don’t even know what the theory is, and are out on a limb and trusting in faith:

Even those of us who work in the field aren’t really sure what string theory is or what it’s going to be, Gross says. So when you’re in this kind of speculative, exploratory science, it’s important to have faith because you’re out on a big limb. So I think it’s really a question of whether we believe this is the right direction; and that I do believe rather firmly.

Update: Lee Smolin has put up a letter on his web-site in response to queries and criticisms he has received in response to his recent book.

Yesterday at the KITP in Santa Barbara, George Johnson gave a second talk and led a discussion on the subject of the “String Wars”. The rather remarkable first session was discussed here, here and here. This time people were much better behaved, and the main topic was the media coverage of physics in general, and the past history of the media interest in string theory, and what effects this might have had.

Johnson has put on his web-site copies of various articles from the NYTimes about string theory. The first mention of superstrings was in a piece by Walter Sullivan back in May 1985, just a few months after the “First Superstring Revolution” really got going. This piece included cautionary comments from C.N. Yang about the lack of even “a single experimental hint” and from Michael Green that “I’ve seen many bandwagons come and go.” Interestingly, already at this time the main suggested test of string theory was astrophysical or cosmological, with the Times referring to a recent Nature article about the possibility of seeing effects of the “shadow matter” that one gets from the other E8 in the E8 x E8 model popular back then (and still popular to this day).

Much of the KITP discussion concerned what effect news stories and popular books promoting string theory have had, with several people noting that they think they have been responsible for the large number of students they have seen wanting to do graduate work in string theory. Someone in the audience also pointed out that the continual use of the modifier “super” seems to get people’s attention, with students showing up wanting to study “supersymmetry” even though they didn’t know what it was, and it was much harder to get them interested in, say, “diffractive scattering.”

The latest Nature Physics has a fairly sensible editorial (Tied Up With String?) about the string theory controversy. Popular promotion of string theory continues today at Stanford, where the Wonderfest Festival of Science is featuring Raphael Bousso and Leonard Susskind discussing “Is the World Made of Strings?”

This week in Honolulu there’s a major particle physics conference going on, a joint meeting of the Division of Particles and Fields of the APS, and the Japanese Physical Society, called the Joint Meeting of Pacific Region Particle Physics Communities. Slides from the talks have started to appear here.

The conference is huge, with hundreds of talks (for some reason, attending a conference in Hawaii seems appealing to many people), and I haven’t had time to look at more than a few of them. Barry Barish gave a talk on international cooperation in HEP, Dave Schmitz one about the status of MiniBoone, which is “in the endgame” of a blind analysis of their neutrino experiment, with the black box containing their results to be opened in the not too distant future.

Lots of talks about string theory, including a plenary talk by Polchinski partly about AdS/CFT and attempts to use it to get information about QCD, partly about the landscape and string vacua. There was also a remarkable talk by Wati Taylor entitled Can String Theory Make Predictions for Particle Physics? Taylor begins by noting that “If we could do experiments at greater than 10¹⁹Gev, answer would probably be Yes”. “Probably” is different than the usual claims about this… His summary of the current state of string theory and particle physics goes like this:

• String theory need not make predictions for particle physics below 100 TeV
• We can’t define string theory yet
• The number of suspected solutions is enormous, and growing fast
• Nonetheless, constraints on low-energy physics correlated between calculable corners of the landscape may lead to predictions
• If not, probably need major conceptual breakthrough to have any possibility of predictivity for low-energy particle physics
• Raison d’etre for string theory: quantum gravity

I don’t know why he chose 100 TeV here, presumably just because it is probably an upper-bound on the likely energy scales particle physicists will be able to explore during the lifetimes of anyone now living. He could just as well have picked a much higher number. The only hope he sees for getting any kind of prediction using current versions of string theory is by finding correlations between things like numbers of generations and gauge groups when you examine large numbers of string vacua (this is similar to the conclusion reached by Michael Dine, described here). In work with Michael Douglas, he has found no evidence for this. Taylor also explains that the standard 10⁵⁰⁰ number often given for the number of string vacua seems to be a dramatic underestimate, and that it is even quite possible that the number is infinite when one takes into account non-geometric compactifications. Fundamentally, his conclusion seems to be that there is only a vanishingly small hope remaining of getting any predictions about particle physics out of string theory, so it has to be sold purely as a theory of quantum gravity, unless a miracle happens.

Taylor does make the case that string theory has found potential uses not in unification, but in studying strongly coupled gauge theory (AdS/CFT) and in suggesting new structures to try out in model-building. But at this point, he characterizes low energy physics predictions from string theory as unlikely, their appearance would just be an “unexpected bonus”. So, I guess the answer to the question of his title is basically “No”. Despite this, he does end by advertising the String Vacuum Project and listing the 17 prominent theorists who are asking the NSF to fund it.

From the “First Superstring Revolution” on, there have always been skeptics, even though they often were not very vocal. Perhaps the most well-known piece of such criticism was Paul Ginsparg and Sheldon Glashow’s Desperately Seeking Superstrings, which appeared in the May 1986 issue of Physics Today. I recently became aware of some other similarly critical articles by Noboru Nakanishi, and copies of them have been made available to me. They are:

Comments on the Superstring Syndrome (also from May 1986)

“Superstring Theory” Syndrome (published in the popular magazine “Parity”, September 1986)

Can the superstring theory become physics? (January 1993)

This last paper claims that “the bubble of superstring theory has … bursted”, which, in 1993, was rather premature.

The main argument generally given for working on string theory is that it’s the only way to get a finite theory of quantum gravity. One often hears claims that gravity can’t be quantized using QFT, that string theory is needed to “smooth out the violent space-time fluctuations at the Planck scale”, or some such explanation for the inherent non-renormalizability of quantum field theories of gravity. From the earliest days of their study, it was hoped that supergravity theories would have better renormalizability properties, with the maximally extended supergravity, N=8 supergravity, the most likely to be well-behaved.

For years the general belief has been that N=8 supergravity is non-renormalizable, based on the existence of possible counterterms at high enough order. The problem has always been that calculating the coefficients of these counterterms is too difficult, so one cannot be sure that one would not get zero if one actually did the calculation. Last year I wrote here about a talk by Zvi Bern in which he mentioned that twistor space methods for doing these kind of calculations were giving indications that these coefficients might be zero. Tonight there’s a new paper out by Green, Russo and Vanhove suggesting the same thing. Their arguments involve M-theory and consistency conditions relating supergravity and the low energy limit of 10-d superstring theory.

It would be quite remarkable if it turns out that this work by Michael Green, using string theory and M-theory techniques, ends up shooting down the main argument for why one has to abandon QFT if one wants to do quantum gravity.

Update: Next month at UCLA there will be an entire workshop devoted to this question, entitled Is N=8 Supergravity Finite?

Seed has a new article out by Stephen Ornes, called The Proof is in the Blogging, about the way the story of Penny Smith’s solution to the Navier-Stokes problem played out here. I’m quite fond of the photo included in the Seed article.

I’m not sure there’s anything more to be said about the Navier-Stokes story. One of my colleagues pointed out that mathematics is one of very few subjects in which bringing together a bunch of people with opposite views on what is true generally leads to one or more of them agreeing that they were wrong.

There’s also a short article about this on Slashdot. Taking advantage of the arXiv trackback mechanism, the author found the discussion of this on Lubos’s blog. I was going to take the opportunity to complain about the arXiv censoring links to this blog, but it turns out in this case there is one there. The ways of the arXiv are endlessly mysterious, I have no idea what their trackback policy is these days.

Maybe it’s also relevant to mention that for some reason the hot news retailed here about the proof of finite generation of the canonical ring is not attracting the kind of attention indicated in the Seed picture.

This week’s Science News has a quite good article about the string theory controversy by Peter Weiss, unfortunately available on-line only to subscribers. The title is “Fit to be Tied: Impatience with string theory boils over”. There’s nothing much in the article that will surprise anyone who has been following this story here. It includes some accurate quotes from me and some from Lee Smolin, with the string theorists represented by Zwiebach, Polchinski and Strominger.

Polchinski claims that experiments will soon probe some elements of string theory, promoting the possibility that the LHC will observe extra dimensions. Zwiebach points to work on black holes: “In string theory, the black hole can be seen as built from strings and branes. It’s a spectacular insight.” Strominger on the one hand is quoted as finding it inappropriate that Smolin and I are criticizing how string theory research is conducted, while also saying he thinks that the way string theory has been promoted has given the public the wrong impression: “I’ve felt for a long time that the general public’s impression of what string theory had accomplished and how much of it was correct was too positive.”