Not Even Wrong

Terry Tao’s article What is Good Mathematics?, written for the Bulletin of the AMS, is now available at the arXiv.

There’s a new article also on the arXiv by Zvi Bern et al. explicitly constructing the 3-loop 4-point amplitude of N=8 supergravity. They find various extra cancellations beyond those expected from supersymmetry, and argue that this and other calculations “strongly suggest that N=8 supergravity may be finite.” The innumerable claims made over the years at the beginning of pretty much every string theory book or popular article that you definitely can’t quantize gravity just using QFT are now no longer operational. There is quite a lot of interest in this topic, with an array of possible computations that need to be done in order to sort this out. Just at the Mathematics Institute at Oxford the past few weeks there have been talks related to this by David Dunbar, Kellogg Stelle, Bo Feng, and Michael Green. The Resonaances blog has a report about a talk by Lance Dixon, one of the co-authors of the new paper. Also a nice report on a talk about supersymmetry by David Kaplan, who gives an excellent definition of fine-tuning of parameters: “a model is fine-tuned if a plot of the allowed parameter space makes you wanna puke” (accompanied by an illustrative plot of the situation in mSUGRA).

I’m waiting for the above news about supergravity finiteness to hit the media, perhaps some of the people working on this need to get to work on their press releases. There’s yet more press about the Distler et. al. “test of string theory.” The Daily Texan has an article called Test May Prove Far-out Theory, where Distler explains how the LHC seeing effects consistent with unitarity, analyticity and Lorentz invariance will provide “more evidence” for string theory. The reporter who wrote this called me up, and includes a garbled version of what I had to say. I was trying to be polite and stick to just pointing out that the paper at issue was not a string theory calculation and its title had been changed to remove reference to string theory, something I suggested the reporter might want to ask the paper’s authors about. He seems to have not taken up my suggestion. I probably should have just used more straight-forward language, something along the lines of “dishonest bulls**t”.

The US Congress finally finished dealing with the FY2007 budget, sending a bill to the president which he’ll sign. It restores money to the NSF and DOE, avoiding a freeze at FY2006 levels that looked possible for a while and would have forced shutdowns at Fermilab and RHIC.

Finally, Capitalist Imperialist Pig informs us that Princeton is taking the occasion of shutting down its parapsychology lab to also close down its string theory program and redirect the funds to research on global warming. Somehow I suspect this may be a bit of an exaggeration, but they do seem to be making moves away from string theory and towards phenomenology, sponsoring workshops next month on Physics at LHC: From Experiment to Theory, and Monte Carlo Tools for Beyond the Standard Model Physics.

Update: Here’s a link to the Kaplan talks on SUSY.

The March issue of the Notices of the AMS is out. Excellent summaries of the mathematical work of the 2006 Fields medalists and interviews with three of them (everybody except Perelman). By the way, does anyone know if the 2006 or 2002 ICM proceedings are available on-line (the AMS is advertising the published books for the 2006 ICM, 3 volumes for $428)? There’s also an interesting article about Jim Simons and “Math for America”, the New York City based program designed to encourage people with a mathematics background to go into teaching. The program is partially funded by a yearly charity poker tournament attended by various people in the financial industry. I’d heard from one of them about this, but didn’t realize the scale on which they were operating. Last year’s tournament brought in $2 million.

This year’s Fields Medalist Terence Tao has an article submitted to the Bulletin of the AMS entitled What is Good Mathematics? See here for commentary from David Corfield.

Last month McGill University sponsored a large public symposium on the Anthropic principle that attracted overflow crowds, and featured Paul Davies, George Efstathiou, David Gross and Lenny Susskind. Gross and Susskind made more or less precisely the same points they have been making publicly about the string theory anthropic landscape for the last 4 years. You can watch the video for yourself here. Susskind seemed a bit less of an aggressive salesman of the anthropic point of view than in the past, acknowledging that the question of how you put a measure on the multiverse (this is needed if you want to make even statistical predictions) still has no solution. Gross made his usual points that accepting the landscape is premature, since we don’t know what string theory is, don’t understand the “emergent” notions of space and time it seems to lead to, and lack consistent time-dependent states describing something consistent with what we know about cosmology.

Besides the Becker-Becker-Schwarz and Dine fat textbooks on string theory that have just come out, another one is due out soon. It is by Elias Kiritsis and is called String Theory in a Nutshell (at nearly 600 pages, kind of a big nut). Princeton University Press is bringing it out in May. One of the leading physicists chosen to give a blurb is Harvard’s Lubos Motl, who also features on the Dine book. Evidently people who write string theory textbooks and their publishers feel his endorsement will do a lot to sell the books. Some of his recent postings refer to me as a “Communist” of a more “primitive and fanatical” sort than the ones he had to contend with during the Soviet era. I’d like to make clear that my political tendencies lean more toward some combination of anarcho-syndicalism and Clintonism than Soviet Communism. He also refers to the loyal readers of my blog as “human waste” (that’s you, folks…)

Instead of doing the work I had planned, I spent much of today having a very enjoyable time reading the mystery novel The Newtonian Legacy by particle theorist Nick Evans. A copy is available at his web-site here, and there’s a FAQ about the book here (I pretty much agree with his LHC predictions).

The book is well-done, very entertaining, and a good read that keeps you wanting to know what will happen next. It includes lots of popular-level explanations about particle physics and the ideas particle theorists are studying these days, so it might be an excellent way to introduce someone to these ideas. It is set at a fictional theoretical physics research institute in England, and many of the characters are particle theorists of one stripe or another (string theorists, phenomenologists, lattice gauge theorists).

The novel includes quite a few amusing portrayals of characters embodying the current sociology of particle theory: a postdoc trying to decide whether to write into the Rumor Mill to tell them he is on a short list at a place he’d rather not go to in hopes of getting other places to offer him a job, a lattice gauge theorist who stalks out of a string theorist’s talk in disgust, postdocs comparing the string theory landscape to religion, a self-satisfied American physicist from the West Coast convinced that string theory has the answers to the ultimate questions of science, and quite a few others.

The main character, Carl Vespers, is a particle theorist who, besides getting involved in the investigation of a mysterious death and having people trying to kill him, has to contend with more than one attractive woman throwing themselves at him, tempting him away from his long-distance girlfriend. All in all, a highly accurate portrayal of the life of a typical particle theorist. Highly recommended.

The “Reference Design Report” for the ILC was released today, and here’s a presentation about this from Barry Barish, the director of the ILC GDE (Global Design Effort). The most closely held numbers in the report have been the cost estimates (see here for a document about the status of cost estimates that warns “don’t post cost estimates on public web or wiki sites!”).

The cost estimate comes out to $4.87 billion for the technology components, $1.78 billion in site-specific costs, 13000 person-years of labor, and two detectors (no cost estimate for these). In round numbers, roughly $10 billion. The machine would consist of two 11km linacs end-to-end, with an interaction region in which two detectors could be moved in and out. The biggest part of the cost is the cost of the linacs, which would accelerate electrons and positrons to tunable energies with collisions at center of mass energy between 200 and 500 Gev. A possible future upgrade of the machine would take it to 1 Tev.

The plan for the future is to start working on a “Technical Design”, a much more detailed design that would show exactly how to build the machine. The hope is to make a decision on whether to build the ILC around 2010, based on what the LHC has found, and on how much progress CERN has made on the much more ambitious CLIC design. Construction would take 7 years, so the earliest such a machine could be in operation would be around 2017.

The full report is here.

Update: More at Science magazine and the New York Times.

Update: Joanne Hewett has an excellent detailed posting about this over at Cosmic Variance.

Alexey Petrov, a particle theorist at Wayne State University, has a blog worth following called Symmetry Factor. He has news about the 2008 budget request for HEP at the DOE, which according to him includes a 12.7% increase in the final 2007 number and a 3.7% increase for 2008 above that (not sure where his numbers come from). This would be a very healthy increase over these two years. Research in the physical sciences has become a big priority for the Bush administration for some reason, it’s a major part of the “American Competitiveness Initiative”. The NSF is also seeing a large increase in its FY2008 request: 8.7%. For various news stories about this, see here, here, here and here. Still unclear what will happen to this budget request in Congress where the Democratic majority will be in control. They have been sympathetic to science research spending in the past, but may or may not want to go along with the emphasis on the physical sciences embodied in this request. Then there’s the small matter of the huge US government deficits to consider. Somebody, someday might decide to try and do something about them.

Maybe I’ve been a bit unfair in the past to the Templeton Foundation, which recently issued this statement.

The IAS held a workshop last month on Homological Mirror Symmetry, notes are available here. Next month there will be a part two, which will mainly concentrate on Geometric Langlands. The schedule is here.

Via Jonathan Shock, the news that particle physicist Nick Evans has written a particle physics murder mystery entitled The Newtonian Legacy, and is making it available on-line for free. I’ll definitely be reading it soon.

Last evening I gave a talk here in New York downtown at the Cafe Scientifique. I think the talk went quite well: the place was packed, the audience attentive and asked quite a few good questions. Up next month is Glennys Farrar of NYU, who will be talking about dark matter. This event is pretty new, organized largely by Stefanie Glick who just got it started last fall. Also in New York are two other similar monthly science events: Secret Science Club, organized by Dorian Devins at Union Hall in Brooklyn (Janna Levin will be there tonight), and Columbia’s Cafe Science, which features Columbia faculty members (my colleague John Morgan will be speaking with Sylvia Nasar next week).

John Baez has a new issue of This Week’s Finds. He has a lot of interesting things to say about Euler characteristics and how you measure sizes in a category. Among many things I learned from Graeme Segal when he was here last semester was the idea of thinking of the Faddeev-Popov prescription in the path integral approach to gauge theory as reflecting the fact that one should think of gauge fields as a category. The category is the category whose objects are bundles with connection, and gauge transformations are the automorphisms of these objects. The general principle that when you count objects in a category you need to divide by the number of automorphisms provides a sort of motivation of the Faddeev-Popov calculation.

The US FY 2007 budget situation for math and science, which was looking very bad just recently, has taken a huge turn for the better as the House has voted to increase funding for the DOE Office of Science and the NSF. More information about this here, here, here, and here. Looks like Fermilab and RHIC will emerge from the budget process unscathed. Soon the president’s FY 2008 budget proposal will be unveiled, and we’ll see what the new Democratic majority will do about science funding.

This week’s press release announcing a “test of string theory” is from the University of Wisconsin (also here, here, and undoubtedly elsewhere). It’s no competition at all for last week’s spectacular press releases about “string theory tests”, but like the many other examples of the genre it is designed to make claims about string theory highly likely to mislead unsuspecting readers. I made some comments about this here. It’s not really that hard to come up with these “tests of string theory”, since “string theory” now has been invoked to justify studying a huge variety of different kinds of models, and is compatible with just about anything. All you have to do is find one, no matter how complicated, obscure and lacking any evidence or motivation, where you can choose the parameters so as to create effects not visible to current experiments, but perhaps visible to potential experiments, even ones many decades down the road. Without too much trouble you should be able to get a paper about this published, and at that time your university press office will surely be happy to put out a press release for you announcing that “Researcher(s) at University X have discovered a way to test string theory.” This has been going on for years, and people seem to never tire of it.

Sean Carroll seems to find it amusing that many articles on the arXiv can now be thought of as a new form of performance art. John Horgan, who got a lot of grief years ago for accusing physicists of engaging in “ironic science”, should really enjoy this.

Update: The Distler et. al. media juggernaut rolls on, informing the world that : The LHC, due to be finished by and running by the end of the year, may rule out the string theory, as well as the work by Distler and his colleagues offers something profound – a way to actually test string theory, and that if Distler’s bounds are satisfied, it would provide a weak support for string theory. The last article quotes Distler to the effect that string theory is just an “effective theory”, which I’m sure will clarify this for the public.

Update: The Shiu et. al. “test of string theory” press release has also led to lots of misleading stories. For an example check out Physicists devise test for string theory, where you’ll learn that “the University of Wisconsin theorists predict that upcoming experiments on the European Space Agency’s Planck satellite will have the sensitivity needed to prove the case for string theory.” Somehow I suspect string theorists will not give up on string theory if the Planck data doesn’t work out, and there won’t be any press releases…

Just to show that New Scientist doesn’t always get it wrong, there’s an unusually good article in this week’s issue by Davide Castelvecchi about prospects for new discoveries at the LHC. Besides the usual story, he concentrates on the question of how the data will be analyzed.

For one perspective on the problem, he gives an amusing quote from Ian Hinchliffe of Atlas who says:

People always ask me, “If you discover a new particle, how will you distinguish supersymmetry from extra dimensions?”. I’ll discover it first, I’ll think about it on the way to Stockholm, and I’ll tell you on the way back.”

Nima Arkani-Hamed optimistically claims that “The most likely scenario is that we’re going to have a ton of weird stuff to explain,’ and Castelvecchi quotes him and others as promoting a new sort of “bottom-up” data analysis. Here the idea (various implementations exist under names like VISTA and SLEUTH) is that instead of looking “top-down” for some specific signature predicted by a model (e.g. the Higgs, superpartners, etc.), one should instead broadly look at the data for statistically significant deviations from the standard model. Castelvecchi mentions various people working on this, including Bruce Knuteson of MIT. Knuteson and a collaborator have recently promoted an even more ambitious concept called BARD, designed to automate things and cut some theorists out of a job. The idea of BARD is to take discrepancies from the standard model and match them with possible new terms in the effective Lagrangian. Arkani-Hamed is dubious: “Going from the data to a beautiful theory is something a computer will never do.”

While the article focuses on the LHC, the role of such “bottom-up analyses” may soon be explored at the Tevatron, where they have a huge amount of data coming in, and have already put a lot of effort into the “top-down” approach (for the latest example, see Tommaso Dorigo’s new posting on CDF results about limits on Higgs decays to two Ws.) For the next few years all eyes will be on the LHC, but it will be the Tevatron experiments that will have a lot of data and be far along in analyzing it. Maybe lurking in this data will be the new physics everyone is hoping for, and it will be of an unexpected kind that only a broad-based “bottom-up” analysis might find. Doing so may raise tricky questions about what is statistically significant and what isn’t, and require a lot of manpower, at a time when these experiments will be losing lots of people to the LHC and elsewhere.

Lee Smolin’s The Trouble With Physics will be out soon in the UK, available February 22 according to Amazon.uk. This month’s Physics World has a very good review of the book by Michael Riordan, under the title Stringing physics along. Before his current incarnation as an historian of science, Riordan worked as an HEP experimentalist for many years, going on to write one of my favorite books about the development of the Standard Model, The Hunting of the Quark.

The review is very well done, and I especially like his description of string theory as not a theory, but “instead a dense, weedy thicket of hypotheses and conjectures badly in need of pruning.” The one place where I really disagree with Riordan, is where, like many other people, he explains the landscape issue and characterizes the problem with string theory as “it got caught up in its own mathematical beauty.” I don’t think that that’s the problem with string theory in general, and it’s certainly not the problem with the landscape arm of string theory research, which is explicitly devoted to the idea (see for example Susskind’s book) that the universe is something of spectacular mathematical ugliness.

Riordan goes on to make the claim that the way string theory is being pursued is of danger to science in general, since its continual evasion of any possibility of confrontation with experiment is of the same nature as “intelligent design”. Riordan writes “To me, string theory and intelligent design belong in the same speculative, unproveable category.” He ends with the recommendation “The Trouble With Physics deserves a wide, careful reading by all physicists concerned about the future of our discipline.”

The write-up of Larry McLerran’s summary talk at Quark Matter 2006 has now appeared. This talk created a bit of a stir since McLerran was rather critical of the way string theorists have been overhyping the application of string theory to heavy-ion collisions.

McLerran explains in the last section of his paper the main problem, that N=4 supersymmetric Yang-Mills is a quite different theory than QCD, listing the ways in which they differ, then going on to write:

Even in lowest order strong coupling computations it is very speculative to make relationships between this theory and QCD, because of the above. It is much more difficult to relate non-leading computations to QCD… The AdS/CFT correspondence is probably best thought of as a discovery tool with limited resolving power. An example is the eta/s computation. The discovery of the bound on eta/s could be argued to be verified by an independent argument, as a consequence of the deBroglie wavelength of particles becoming of the order of mean free paths. It is a theoretical discovery but its direct applicability to heavy ion collisions remains to be shown.

McLerran goes on to make a more general and positive point about this situation:

The advocates of the AdS/CFT correspondence are shameless enthusiasts, and this is not a bad thing. Any theoretical physicist who is not, is surely in the wrong field. Such enthusiasm will hopefully be balanced by commensurate skepticism.

I think he’s got it about right: shameless enthusiasm has a legitimate place in science (as long as it’s not too shameless), but it needs to be counterbalanced by an equal degree of skeptical thinking. If shameless enthusiasts are going to hawk their wares in public, the public needs to hear an equal amount of informed skepticism.

Another shamelessly enthusiastic string theorist, Barton Zwiebach, has been giving a series of promotional lectures at CERN entitled String Theory For Pedestrians, which have been covered over at the Resonaances blog.

Zwiebach’s lectures are on-line (both transparencies and video), and included much shameless enthusiasm for the claims about AdS/CFT and heavy-ion physics that McLerran discusses. His last talk includes similar shameless enthusiasm for studying the Landscape and trying to get particle physics out of it. He describes intersecting D-brane models, making much of the fact that, after many years of effort, people finally managed to construct contrived (his language, not mine, see page 346 of his undergraduate textbook) models that reproduce the Standard Model gauge groups and choices of particle representations. Besides the highly contrived nature of these models, one problem with this is that it’s not even clear one wants to reproduce the SM particle structure. Ideally one would like to get a slightly different structure, predicting new particles that would be visible at higher energies such as will become available at the LHC. Zwiebach does admit that these contrived constructions don’t even begin to deal with supersymmetry-breaking and particle masses, leaving all particles massless.

He describes himself as not at all pessimistic about the problems created by the Landscape, with the possibility that there are vast numbers of models that agree to within experimental accuracy with everything we can measure, thus making it unclear how to predict anything, as only “somewhat disappointing”. He expects that, with input from the LHC and Cosmology, within 10 years we’ll have “fully realistic” unified string theory models of particle physics.

The video of his last talk ran out in the middle, just as he was starting to denounce my book and Lee Smolin’s, saying that he had to discuss LQG for “sociological” reasons, making clear that he thought there wasn’t a scientific reason to talk about it. I can’t tell how the talk ended; the blogger at Resonaances makes a mysterious comment about honey…

Finally, it seems that tomorrow across town at Rockefeller University, Dorian Devins will be moderating a discussion of Beyond the Facts in Sciences: Theory, Speculation, Hyperbole, Distortion. It looks like the main topic is shameless enthusiasm amongst life sciences researchers, with one of the panelists the philosopher Harry Frankfurt, author of the recent best-selling book with a title that many newspapers refused to print.

Update: Lubos brings us the news that he’s sure the video of the Zwiebach lectures was “cut off by whackos” who wanted to suppress Zwiebach’s explanation of what is wrong with LQG.

Update: CERN has put up the remaining few minutes of the Zwiebach video.

A couple weeks ago I generated a list of the theoretical physics papers that were most heavily cited during 2006, according to the SLAC database, and discussed it here. Today the people at SLAC put out their own lists for 2006, which are quite interesting to go through. Their data is quite consistent with mine, although the numbers are very slightly larger, since a small number of new citations have been added into the database over the last couple weeks, I think mainly from papers which for example appeared on the arXiv in January 2007, but carried 2006 dates (e.g. write-ups from 2006 conferences).

The main list covering all HEP papers is dominated these days by astrophysics-related papers. Out of the 50 papers on the list I count only about 15 particle theory papers, and 3 review articles. The only post-1999 hep-th paper that makes the list is the KKLT landscape paper. To make the top 50, a paper needed to get 152 citations or more.

The list I put together goes deeper, down to papers with 100 citations, but SLAC has also put out something even better: 2006 lists of 50 most-heavily cited hep-th and hep-ph papers. To make the hep-th list, a paper had to have 62 or more citations. Looking over the 20 or so post-2000 papers on this list gives a good idea of what topics have been popular in recent years: the landscape, dark energy, and various aspects of AdS/CFT, and a small number of other topics. There are also several review papers on the list. Anyone interested in understanding what topics are attracting attention in particle theory research these days should find it quite interesting to go through this list, and spend some time taking a look at and learning about any of these papers that are unfamiliar.