Not Even Wrong

The FY 2006 budget requests to Congress are out today. In the parts relevant to funding for mathematics and physics, the information about the NSF request is here, and information about the DOE request is here.

One should really be a lot more expert on the details of government science funding than I am to be sure what these numbers mean, but here’s my interpretation:

NSF: Funding request for mathematics is precisely flat at about $200 million. The only real change from last year is that $3 million is being moved from “Enhancing the Mathematical Sciences Workforce” (which funded things like the VIGRE grant our department used to have) to fund things like summer schools, workshops, conferences, etc. One strange thing is that mathematics is listed as one of four NSF priority areas, but still gets a cut in real dollars. Some of the other “priority areas” have very large cuts. I guess this means the NSF is changing its priorities.

The NSF physics request is up 2.3% to about $230 million. $13.5 million of this is for operations of the LHC detectors (CMS and ATLAS), $14.7 million for CESR and $32 million for LIGO. The part of the budget that includes research grants in high energy physics increased by $6.4 million to $152.4 million and theoretical physics is listed as a priority. Maybe string theorists will get more money. “POU”, or Physics of the Universe, is listed as the highest priority, with emphasis on the question of “What about that dark matter and dark energy?”.

DOE: The high energy physics budget request contains a large cut, going from $735.4 million in FY 2005 to $713.9 million in FY 2006. Highest priorities are listed as the Tevatron and NuMI at Fermilab and the B-factory as SLAC, but overall experimental HEP funding is down. Theoretical physics funding gets a small increase, from $49.0 to $49.1 million, so at least the string theorists will be all right, even if the experiments aren’t.

More details on all of this should be available at the HEPAP meeting next week.

Of course this is just the request to Congress. Something very different may emerge later this year from the Congressional committees.

Update: A document with just the HEP part of the DOE budget is here.

Michael Douglas gave a colloquium at City College this afternoon, with the title “Are there testable predictions of string theory?” I went up there to the talk, figuring that I knew more or less what he would say, but he really surprised me. Douglas has given many talks over the last year or so about his program for trying to get predictions out of string theory by doing statistical analyses of string vacuum states. He has concentrated on what looks like the most promising case, trying to see whether vacua with low-energy supersymmetry breaking are favored over ones where supersymmetry is broken at much higher scales (e.g. the GUT or Planck scales). If he could make a prediction that the LHC will see supersymmetry, that would count as the first real prediction of string theory, and in 2008 or so we would see if it was right. I was expecting Douglas today to explain this whole program, report on what he had achieved so far, and offer hope that he and his collaborators would have a yes or no answer about supersymmetry sometime soon.

Instead he very much downplayed hopes for this kind of prediction, answering a question about it by Nair at the end of the talk by explaining some of the difficulties. Presumably he now agrees with recent claims by Dine that it is too difficult, even in principle, to decide whether or not the landscape predicts supersymmetry. Given this, in the conclusion of his talk, I was expecting him to answer the “Are there testable predictions” question in the negative. Instead, he did something very strange. He announced that string theory does make predictions, lots of them, adopting the Lubos Motl definition of a “prediction” of string theory as being anything consistent with string theory. Examples he gave included Polchinski’s cosmic string networks, where one could tell from the behavior of the network whether the strings were fundamental or not, and short distance modifications to GR. Of course these are not in any sense real predictions; all sorts of different modifications of GR at short distances are compatible with string theory, as are either no visible fundamental cosmic strings, or visible ones with a huge variety of possible different properties.

The weirdest part of his talk was when he explained what he considered the best prediction of string theory. This involved the negative prediction that the fine structure constant can’t have varied with time in the early universe, since effective field theory arguments would imply a corresponding variation in the vacuum energy, something inconsistent with observation. So his best prediction from string theory isn’t really a prediction of string theory at all, but actually a prediction of effective field theory. Furthermore this “prediction” is the purely negative one that something that hardly anyone expects to be true actually isn’t true.

In the question section, some obnoxious guy who has a weblog asked him whether it was really true that the best prediction string theory could come up with was the no variation of the fine structure constant one that was really an effective field theory prediction, and didn’t that mean there was no hope of string theory ever really predicting anything. For some reason this made him rather defensive, and he began by saying it depended on the meaning of the word “prediction”. After having it explained to him what most physicists consider a prediction to be, he launched into a sequence of analogies designed to explain why you can’t get real predictions out of string theory. They all were of the same genre: imagine some situation where you can only observe phenomena that are related in a very complicated and hard to calculate way to the underlying fundamental theory, and somebody tells you what the fundamental theory is. Shouldn’t you work on it and believe in it?

This argument makes it clear where the whole subject is going to end up. The standard scientific method of deciding whether a theory is true or not by figuring out its implications and comparing them to observations is no longer operative. In the case of string theory there’s a new method. You just believe because authorities tell you to, and from now on the activity of professional theorists will consist solely in the construction of elaborate scenarios designed to explain why you can’t ever predict anything. Feynman’s line that: “string theorists don’t make predictions, they make excuses” has been changed from a criticism into a new motto about how to do science.

Jacques Distler has a new posting about multi-loop string amplitudes. It’s mainly devoted to the Berkovits superstring formalism, and explains in some detail the possible problems with this formalism that one might worry about. I’d alluded to some of these in the comment section of my posting about this last week, responding to commenters claiming that Berkovits had a proof of finiteness of multi-loop amplitudes. At the time, all I got in response was abuse about how ignorant I was. Presumably the same people will be either showering Jacques with abuse, or apologizing to me. Funny, for some reason Distler doesn’t mention what I’d written about this. He also seems to have somehow neglected to put “Not Even Wrong” in his list of links to physics weblogs.

Slashdot today has something pointing to Larry Osterman’s weblog where he tells the story of my ex-roommate David Weise’s career, much of which has been spent at Microsoft. David is generally credited with almost single-handedly making Windows a viable product, when in 1988 he figured out how to get Windows to run on the 286 processor in “protected mode”, something people thought couldn’t be done. At the time Microsoft was planning on abandoning Windows and moving to IBM’s OS/2, but David’s work changed everything.

Osterman gets some things wrong. David, Chuck Whitmer and Nathan Myhrvold were fellow physics graduate students and my roommates at Princeton, not at MIT (for more about Nathan, see an earlier posting). David was in biophysics, Chuck was a student of Steve Adler’s doing lattice gauge theory, and Nathan worked with Malcolm Perry on quantum gravity. It is true that David and Chuck were associated with the MIT blackjack team (this was the early eighties, just after casinos opened in Atlantic City, not the 70s as Osterman has it). There was a lot of practicing of card counting techniques and computer simulation of non-randomness in shuffles going on in our apartment during those days, although I never got really involved in it myself.

After getting their Ph.Ds, Nathan, Chuck and David (together with Nathan’s brother Cameron) founded a software company called Dynamical Systems Research in Oakland, which they ended up selling (along with themselves) to Microsoft. They all ended up getting obscenely rich, with Chuck retiring quite a while ago, Nathan leaving more recently, and finally David is now leaving to work in molecular biology.

John Ellis’s weblog has a new entry on Future Particle Accelerators which discusses prospects for a linear collider. The plan for an “International Linear Collider”, or ILC is now in its design phase, with work proceeding on a detailed design for a .5-1 Tev collider. No one has yet figured out where this would be sited or how it would be financed. The agencies responsible for this funding seem to have agreed to put off a decision about going ahead with the project until 2010.

By that time there should be a couple years of data available from the LHC, and if the Higgs particle or superpartners are found, it would be clear whether the ILC design would have enough energy to study them usefully. Also around that time is should be clear whether CERN’s more ambitious design for a linear collider, called “CLIC” and perhaps capable of reaching 3-4 Tev, is really a feasible one. If the decision is made to build the ILC design, the hope would be to have construction finished in 2015 (although this sounds overly optimistic to me), allowing several years of joint running of the LHC and ILC. If no Higgs or superpartners are found, or their mass is too high, the decision would be made to concentrate on CLIC, with construction done at the earliest in 2021.

Back in the present, the Tevatron at Fermilab is now seriously back in business after a long shut-down, recently reaching record values of luminosity. To follow what is going on there, you can keep up with the weblogs of Tommaso Dorigo and Sandra Leone of the CDF collaboration, as well as Gordon Watts and Ursula Bassler of D0.

An expository article by the the algebraic geometer Yuri Manin always has something interesting in it, and his latest, entitled The notion of dimension in geometry and algebra is no exception.

In this article Manin discusses various ideas related to the notion of dimension, ranging over fractal geometry, non-commutative geometry and theoretical physics. He begins with a quote from Glenn Gould, which is quite amusing, but of obscure relation to the notion of dimension. Then he goes on to some history, from Euclid to Leibniz, finally veering off into a fascinating discussion of the relation of algebra and geometry, and ending with the sociological comment that visual mass media is leading to a dominance of right-brain mental faculties, and thus “projects us directly into dangerously archaic states of collective consciousness.”

The body of the article includes comments on Hausdorff dimension, dimensional regularization of path integrals, the theory of operator algebras, non-commutative geometry, a weird digression on databases, and supergeometry. He also discusses “Spec Z” (the “space” naturally associated to Z, the ring of integers) making various comments about it and giving arguments for its dimension being 1, 3 and infinity. Next there are some comments on modular forms, and finally a section on fractional dimensions in homological algebra.

Its not clear how seriously one should take all of this, but Manin’s article is definitely thought-provoking.

Ken Lane has written a letter to the editor of the Boston University student newspaper to complain about its article about string theory and the BU physics department discussed in a previous posting. Lane is annoyed about not having been given a chance to respond to Vafa’s ad hominen attacks characterizing him and the BU physics department as “foolish” and “childish”. He also complains that the author didn’t seek other opinions about Vafa’s claim that string theory is what the “youngest, most brilliant physicists” are all doing.

I don’t remember whether they had shop classes at Harvard, but if they do now, maybe they should be talking to Vafa. According to the blurb for a recent talk by Jim Gates at Brookhaven, string/M-theory is “a 21st century lathe – a machine capable of remarkable precision and versatility, but requiring a skilled and experienced operator for its success.” Funny, back in the last millennium I remember when string theorists were claiming that string theory was a 21st century “supercomputer” or “spaceship” that had fallen into the 20th century.

A couple weeks ago, three string theorists, (Nicolai, Peeters and Zamaklar) posted on the arXiv a critical assessment of loop quantum gravity. Today I received from Lee Smolin something he wrote responding to them, and I’m posting it here with his permission. Lubos Motl also has put up Smolin’s text on his weblog this morning, but I thought it would be a good idea to provide a version that doesn’t include Lubos’s interspersed rantings. Smolin has some very interesting things to say, and his comments are well-worth reading by anyone who wants to understand what is going on in this field.

Somewhat off-topic, I’d also like to mention a paper by Freidel and Starodubtsev from earlier this week called Quantum gravity in terms of topological observables. The idea of trying to use topological quantum field theory to understand quantum gravity is one that I’ve always found appealing, and this paper is an interesting attempt to make this idea work. I don’t think I find it completely convincing, for one thing they seem to be breaking the topological invariance by hand. For another, TQFTs are very subtle QFTs, and the kind that might be relevant to gravity is still very far from well-understood.
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Eric D’Hoker and D.H. Phong this past week finally posted two crucial papers with results from their work on two-loop superstring amplitudes. The first one shows gauge slice independence of the two-loop N-point function, the second shows that, for N less than 3 and for low-order terms at N less than 4, there are no two-loop corrections to the low energy effective action.

D’Hoker and Phong have been studying superstring amplitudes for nearly twenty years, and are justly proud of their recent results, which are a tour de force of careful calculation. Over the years there have been many claims made about two-loop amplitudes, but until their work, no one had managed to really sort out the gauge dependence issues and write down gauge-independent amplitudes. For some comments about some of the issues involved at genus 2 and higher, see postings by Jacques Distler here, here, and here.

I don’t think D’Hoker and Phong will be coming out with complete results for genus 3 anytime soon, so the state of the art is that there is now a finite and well-defined version of the two-loop superstring amplitudes, with the problem of higher loops still open. While claims abound about the finiteness of higher-loop amplitudes, before believing them one should first take a look at the tricky problems that D’Hoker and Phong had to overcome to get well-defined two-loop amplitudes.

Update: Jacques Distler has a new posting about multi-loop amplitudes and potential problems with the Berkovits version of the superstring (he explains in more detail the possible problems with the BRST and picture-changing operators I mentioned). For some mysterious reason Jacques neglects to refer to my posting or comments about this. I encourage those commenters who seemed convinced I didn’t know what I was talking about to now take up their arguments with him.

If you’ve been following the story of the “Landscape” over the past year or so you’d remember that its proponents felt that if it could predict anything it should be able to predict whether or not there will be supersymmetry at low energies. They had great hopes for making this prediction before 2008 when the LHC presumably will tell us whether there is supersymmetry at LHC energies.

Well, tonight one of the biggest proponents of this point of view, Michael Dine, has a new paper out with two co-authors, entitled Branches of the Landscape. In it they conclude:

“From all this, it appears that it is difficult, in principle, to decide whether or not the landscape predicts supersymmetry.”

So, many string theorists now seem to believe that:

1. String theory predicts a landscape of possible vacua.

2. Given the existence of such a landscape, one can’t predict whether or not there will be low-energy supersymmetry (or anything else either).

One wonders it these string theorists ever studied elementary logic and can draw the obvious conclusion from 1. and 2.