Not Even Wrong

Things are not going well for string theory on the public relations front. Someone just pointed me to the poll at Wired magazine they call String Theory Smackdown, where the side arguing for string theory is losing the voting by more than 3 to 1.

The argument that seems to be carrying the day with the public is the simple one that a supposedly unified theory that can’t make a single testable prediction, despite more than twenty years of work, must have something really wrong with it. Many string theorists acknowledge that this is the situation the theory is in, but make the case for what they see as promising aspects of the theory that justify continued work on it.

Unfortunately, some string theory partisans have chosen to react to recent criticism not by acknowledging the fact that string theory can’t be tested, but by making misleading claims that the theory does make predictions and is testable. On Monday here at Columbia, Gordon Kane gave a colloquium talk of this kind, with the title String Theory and the Real World — a “new” subfield, string phenomenology. Kane began by quoting David Gross as being highly skeptical about the whole idea of string phenomenology, arguing “we don’t know what string theory is, how can it have a phenomenology?”. Kane’s claim that “string phenomenology” is a new field is rather peculiar, since it was an active subject back in the early 1990s. It is however true that, for better or worse, it has become a more active one the past few years, as string theorists have reacted to their colleague’s complaints that they do mathematics, not physics, by trying to sell themselves as “phenomenologists”.

Kane mostly actually ignored string theory, concentrating on supersymmetry, which he has been promoting for more than 20 years (he had an article about “Is Nature Supersymmetric” in Scientific American back in 1986). He described seeing supersymmetry as essential, pretty much the only way of getting a “window to the Planck scale”. There was some mention of the idea that string theory makes predictions about cosmology, but the “prediction” was just that in “most” string theories, the size of B-mode polarization in the CMB is unobservably small. He put up plots from this recent paper, claiming that one could distinguish different string “backgrounds”, by their “footprints” on LHC data. Looking at the paper, it appears to be based upon a large number of assumptions (e.g. that one just gets the MSSM), designed to provide enough constraints so that one could not get absolutely anything, but not so many as to be forced into contradiction with experiment.

For another exercise of this kind, take a look at Kane’s 1997 Physics Today article entitled String theory is testable, even supertestable. This included an impressive looking detailed, specific spectrum of the masses of superpartners, implying that it was the sort of thing “predicted” by string theory. Only problem is that by now it looks to me as if these “predictions” are almost all in disagreement with experiment. Back in 1997 Kane was arguing against John Horgan that string theory really was testable, that it “would predict a specific spectrum of particles and superpartners that can be compared with experimental data”. He seems to have backed off on that claim, there were no such spectra mentioned in his talk this week. About the landscape and its exponentially large number of possibilities, he had little to say except that we “have to learn how to think about this”.

He repeatedly made the claim that “String theories DO give predictions” and “String theory is falsifiable”, giving as an example work by 3 graduate students of Mary Gaillard that showed that one specific heterotic string compactification scheme gave no light neutrino masses and thus led to models incompatible with experiment. Another repeated point was that the problem with string phenomenology was just a lack of manpower. If more people (especially graduate students) were doing these calculations, great progress would be made. In the question session, asked about the CC, he said that there were lots of ideas about how to solve it, what was needed was just more people doing calculations.

Evidently many agree with him, since the IAS has just announced that next year’s summer program for graduate students and postdocs will be on Strings and Phenomenology.

I decided not to ask any question in the question session, having the overwhelming feeling that arguing with “string phenomenologists” is now just wasting one’s breath. They have made it clear that, no matter how dubious the arguments needed, they’re going to keep promoting this field as predictive and highly relevant to the LHC. The intellectual “dead zone” of “string phenomenology” will be with us no matter what and perhaps even come to dominate particle theory until LHC results are in. May they stay as close as possible to schedule! (Kane estimates first physics collisions next September).

The latest issue of the Onion has some HEP-related coverage. It includes a nifty graphic, and has this inspirational message from one of our congress-people

“Now, I’m no science major, but if I’m being told by a group of people that the protons, neutrons, and electrons need unifying, then I think we owe it to the American people to go in and unify them,” Rep. Mark Udall (D-CO) said. “After all, isn’t a message of unity what we want to send to our children?”

Various things of interest, ordered in terms of increasing mathematical content:

This week Fermilab has hosted a P5 meeting and an annual program review.

At the P5 meeting, Fermilab director Pier Oddone made the case for planning to keep running the Tevatron through FY 2010. He pointed out that the current LHC schedule has “no float” for any possible delays in putting the hardware together, and only allows for 3 months between first beam and physics collisions, drawing the conclusion that it was unlikely the LHC would have physics results competitive with the Tevatron before the currently planned closure date of September 2009. Presentations from D0 and CDF claimed that, if the machine runs through FY2010 and provides them with a projected luminosity of 6.8 fb^-1, they should be able to exclude the possibility of existence of the Higgs at 95% confidence level over almost the entire possible range of Higgs masses (if it isn’t there!) or find 3 sigma evidence for its existence in some mass ranges (if it is).

At the program review, there was an overview of particle theory at FNAL from Andreas Kronfeld, and a presentation about the LQCD lattice gauge theory project from Paul MacKenzie. Several interesting documents reviewing the state of the lattice gauge theory work are here.

Over the last few months I’ve often told myself that I should learn more about Howard Georgi’s ideas concerning “unparticles” and try and write something about them. Sabine Hossenfelder has saved me the trouble, you can learn about this here.

Last month there was a symposium at Durham on Twistors, Strings and Scattering Amplitudes, a subject which has seen some exciting activity recently. Zvi Bern reviewed progress on computing multi-loop amplitudes in N=4 gauge theory and in gravity theories. He noted that the recently found unexpected one-loop cancellations in N=8 supergravity (leading to the so-called “no triangle hypothesis”) are not due to supersymmetry and are already there in non-supersymmetric gravity. This leads him to conjecture that other gravity theories will be perturbatively finite, he explicitly mentions N=6 supergravity. Nathan Berkovits discussed multi-loop superstring amplitudes in the pure spinor formalism, ending up by noting that there are possible problems caused by needed regularization of ghosts in this formalism, and they affect high-energy contributions to the 4 point 3-loop amplitudes. Not that I’m saying I think this will happen, but it would be pretty damn funny if it turns out that multi-loop superstring amplitudes aren’t finite, multi-loop supergravity ones are…. There’s also a talk by Jacques Distler, who continues his ceaseless quest to figure out how to make physics available over the web in a form that no virtually no web-browser can display properly.

Finally, I strongly believe in advertising equivariant cohomology as much as possible, for mathematicians and for physicists. The new lecture notes by Matvei Libine are a good place to read about it.

This is not a very timely posting, since my readers let me down by not telling me about this when it came out. Last month the Wall Street Journal ran a piece by Lee Gomes about a workshop on the Tate conjecture held recently at AIM, the institute now housed in Palo Alto behind Fry’s Electronics, at some point to move to its own castle. The piece was entitled Math Whizzes at Conference Prove Just How Exciting The Tate Conjecture Can Be, and it gave a good feel for what a math workshop looks like to an outsider. The full piece is not available on-line, but the MAA Math News has an article that quotes much of it.

I noticed two inaccuracies in the piece. It begins with:

One is tempted to feel sorry for mathematicians. In contrast to, say, physicists, mathematicians don’t have their own Nobel Prize; they rarely get hired by hedge funds; they don’t have grand toys like particle accelerators to play with; and their work is usually so recondite that not even their families understand it.

This is pretty accurate except for the part about hedge funds. I know quite a few mathematicians who have gone to work for them, and at some of them mathematicians form a sizable fraction of the people holding so-called “quant” jobs.

At the end of the piece there’s the news:

Progress, though, was made. V. Kumar Murty, of the University of Toronto, said that as a result of the sessions, he’d be pursuing a new line of attack on Tate. It makes use of ideas of J.S. Milne of Michigan, who was also in attendance, and involves Abelian varieties over finite fields, in case you want to get started yourself.

Milne has recently posted an article on the arXiv (also available on his web-site here) that corrects this, noting

This becomes more-or-less correct when you replace “Tate” with the “weak rationality conjecture”.

Milne’s article is actually a write-up of his talk at the AIM workshop, and it does an excellent job of surveying the state of what is known about questions related to the conjecture.

I was going to try and put together some explanation of what the Tate conjecture says and how it relates to other parts of mathematics, but since this is a tricky business, and since experts who really understand this have already done a better job elsewhere than I could ever do here, I’ll mostly just provide links.

The Tate conjecture is an analog for varieties over finite fields of one of the Clay Millennium problems, the Hodge conjecture, which deals with the case of varieties over the complex numbers. For a popular discussion of this, there’s a nice talk by Dan Freed on the subject (slides here, video here). In the number field case there’s another Millennium problem analog, the Birch and Swinnerton-Dyer conjecture. For a popular discussion of this, there’s a video of a talk by Fernando Rodriguez-Villegas (who has a blog here).

These conjectures all revolve around the idea that it should be possible to relate three apparently different mathematical objects associated with an algebraic variety:

There’s no evidence we’re close to a proof of these conjectures, but there are many partial results and the conjectures can be proved in certain special cases. Experts seem convinced of the truth of these conjectures despite the lack of proof, one reason being that they fit nicely into the general philosophy of “motives” first promulgated by Grothendieck. One expert on the Tate conjecture, when asked about the probability of it not being true, responded something like: “Don’t be silly. It’s true.”

For more about the Tate conjecture, there are two documents put together for the AIM workshop that may be helpful: an expository piece for a wide audience here, and a technical summary of the workshop here.

The Edge web-site has something new up they call Einstein: An Edge Symposium (thanks to commenter Hendrik for pointing this out). It’s an exchange between Walter Isaacson, Paul Steinhardt and Brian Greene, nominally about Einstein, but ending up turning into a discussion of whether and how string theory has “crashed”.

Steinhardt forcefully makes the same point I’ve made ad nauseam here: the anthropic string theory landscape is not a valid scientific research program, but simply the kind of thing you end up with when a speculative idea fails.

In my view, and in the eyes of many others, fundamental theory has crashed at the moment. Instead of delivering what it was supposed to deliver—a simple explanation of why the masses of particles and their interactions are what they are—we get instead the idea that string theory allows googols of possibilities and there is no particular reason for the properties we actually observe. They have been selected by chance. In fact, most of the universe has different properties. So, the question is, is that a satisfactory explanation of the laws of physics? In my own view, if I had walked in the door with a theory not called string theory and said that it is consistent with the observed laws of nature, but, by the way, it also gives a googol other possibilities, I doubt that I would have been able to say another sentence. I wouldn’t have been taken seriously…

But what angers people is even the idea that you might accept that possibility—that the ultimate theory has this googol of possibilities for the laws of physics? That should not be accepted. That should be regarded as an out and out failure requiring some saving idea…

What I can’t accept is the current view which simply accepts the multiplicity. Not only is it a crash, but it’s a particularly nefarious kind of crash, because if you accept the idea of having a theory which allows an infinite number of possibilities (of which our observable universe is one), then there’s really no way within science of disproving this idea. Whether a new observation or experiment comes out one way or the other, you can always claim afterwards that we happen to live in a sector of the universe where that is so. In fact, this reasoning has already been applied recently as theorists tried to explain the unexpected discovery of dark energy. The problem is that you can never disprove such a theory … nor can you prove it.

Steinhardt dismisses attempts to hypothesize that maybe the landscape is somehow predictive as follows:

Do you mean as derived from string theory? I don’t believe that’s true. I don’t believe it’s possible…

Well, I believe that if you came to me with such a theory I could probably turn around within 24 hours and come up with an alternative theory in which property X wasn’t universal after all. In fact, you almost know that’s true from the conversation that’s been happening in the field already, where someone says, these properties are universal and these others are not. The next day, another theorist will write a paper saying, no, different properties are universal. There are simply no strong guidelines for deciding…

If a version of string theory with a googol-fold multiplicity of physical laws were to be disproved one day, I don’t think proponents would give up on string theory. I suspect a clever theorist would come up with a variation that would evade the conflict. In fact, this has already been our experience with multiverse theories to date. In practice, there are never enough experiments or observations, or enough mathematical constraints to rule out a multiverse of possibilities. By the same token, this means that there are no firm predictions that can definitively decide whether this multiplicity beyond our horizon is true or not.

After some prodding, Steinhardt makes clear that he is not claiming that string theory as whole has crashed, that it is just the landscape that is the crash. While insisting that people need to acknowledge that the landscape is simply a scientific failure, he holds out hope that some fix to string theory may still be found:

…it’s that point of view which is a crash, and needs a fix. I am not arguing that string theory should be abandoned. I think it holds too much promise. I am arguing that it is in trouble and needs new ideas to save it.

There’s also some discussion about what Einstein would have thought of string theory and the landscape, with Steinhardt of the opinion that Einstein would have liked string theory with its unification via geometry of extra dimensions, but that he would have rejected the landscape:

Einstein took gravity and turned it into wiggling jello-like space, and now string theory turns everything in the universe, all forces, all constituents into geometrical, vibrating, wiggling entities. String theory also uses the idea of higher dimensions, which is also something that Einstein found appealing.

What I was commenting on earlier was where the string program has gone recently, which I described as a crash. I can’t say for sure how Einstein would view it, but I strongly suspect he would reject the idea.

Three years ago I expressed the opinion that the promotion of the anthropic landscape would make Einstein gag, which so upset Joe Polchinski that he used this to argue that trackbacks to my blog should not be allowed on the arXiv (even though this was not about an arXiv paper, but a Scientific American article). At one point I regretted having used that expression, feeling it was somewhat over the top and inappropriate. In retrospect, seeing what has happened over the past three years, I’ve changed my mind. The kind of thing that would make Einstein gag has moved from popular science articles to regular appearance in the lectures and scientific articles of leading figures in particle physics. This would probably not just make him gag, but send him into a serious fit of depression.

Yesterday a new web-site was launched by the DOE and NSF, called US/LHC, which will be devoted to the role of the US in the LHC project. Besides news and descriptions of the science and the experiments, it will also include blogs by several physicists involved in experiments at the LHC. This new web-site joins several other similar ones, most notably one devoted to the ILC, and an umbrella one for US particle physics called Interactions.

I’ve sometimes wondered whether this huge publicity onslaught for the LHC is a good idea. Just as this new web-site is coming on-line, I’m starting to hear unconfirmed reports of possible very serious delays in the LHC startup, ones which may push back the beginning of experiments by a year or more. The current schedule includes no extra time for cooling down sectors of the machine which have to be warmed up to deal with one problem or another, and this cooling is a tricky months-long process. If these rumors turn out to be true, this will be good news for the Tevatron, which will have the energy frontier to itself for longer than expected. But it will definitely be very bad news for CERN and for particle physics in general, both of which have just about all of their eggs in this heavily publicized basket.

Update: From the comments here and e-mail I’m getting, it appears that others are hearing these same rumors: the first physics runs are likely to be in 2009, not 2008, due to problems that have shown up as they have started cooling down some sectors of the machine.

Update: Peter Steinberg at the US/LHC site blogs about the conundrum of whether he should be dealing with “gossip from unverified or anonymous sources”, and decides he’d better not. I suspect one consideration is that his blogging role puts him in a sort of unofficial spokesman capacity, which is rather incompatible with rumor-mongering. On the other hand, I don’t have this problem…

An informed commenter reports in the comment section about details of some of the problems that have cropped up in the last month, and that the “best guess” for the delay that these will cause is about two months. This would move the start of a physics run from next July to next September.

Update: Via the Resonaances blog, here’s the video of a September 13 colloquium talk by Lyn Evans about the LHC commissioning. Evans describes in detail two of the problems that have shown up that motivated some of the rumors: leaks that have appeared during the first cool-down of certain sectors of the machine, and problems with some of the plug-in modules that interconnect the magnets. It remains unclear if these problems will cause slippage in the schedule, and if so, how much. News about what is going on with these problems is posted here.

Despite my abusive treatment of his article Stringscape here recently, Matthew Chalmers was kind enough to send me a copy of the September issue of Physics World, which contains three shorter pieces about string theory (available on-line only to subscribers).

One of the articles is by Fred Goldhaber and entitled Scientific faith put to the test. It’s a scathing attack on the anthropic string theory landscape program, describing it as “antiscience” (rather than my favorite, “pseudo-science”). Goldhaber characterizes this sort of research as “antiscience of the left”, with its adherents promoting the idea that we can’t ever understand some things since they are due to chance. He contrasts this to the “antiscience of the right”, which promotes the idea that we can’t understand things because they come from supernatural origin, and finds both attitudes equally unscientific. As for where antiscience comes from, he has this to say:

On the left, I think that it stems from arrogance (“If I can’t figure it out, no-one ever will”). On the right, I think it comes from defensiveness (“If science is right, religion must be wrong, and that can’t be”). In the end, antiscience on both side boils down to vanity. While we need to stay alert for the vanity of those advocating antiscience, we also should guard against vanity in the name of science.

He ends on a more optimistic note, writing that he does see a difference in those on the “left”. They remain physicists, and if someone finds a “promising route to picking out the right solution to string theory”, they would leap to pursue it. He doesn’t speculate on what they would do if someone shows that string theory just inherently can’t ever predict anything…

Philosopher of science Steven Weinstein has a piece with the title Philosophy pulls strings, which tries to make the case that string theory is leading to some new interaction between physics and philosophy, since it “forces us to tackle issues that cross both disciplines.” As far as one of his topics goes, the anthropic pseudo-science, the main role I see for philosophers is to forcefully point out to the scientists involved that they are doing something intellectually highly disreputable and should stop. He also discusses a much more non-trivial and interesting topic, that of the philosphical questions about space and time raised by quantum gravity, a subject where philosophers may or may not end up having something quite useful to contribute.

Philosphers Nancy Cartwright and Roman Frigg contribute a very interesting article about how scientific theories are evaluated, entitled String theory under scrutiny [available here, thanks to commenter “R” for pointing this out]. The make the important point that immediate experimental testability of a theory is not all there is to deciding whether something is science or not. When scientific ideas are new, they often are not understood well enough to be able to extract definitive predictions from them. Theorists are generally engaged in research programs, the end result of which is supposed to be something experimentally testable. In order to evaluate a research program, you can’t just note that it isn’t predicting anything, you have to evaluate its prospects for reaching its stated goals. They describe good research programs as “progressive”:

Good research programmes are those that are progressive, i.e. those whose theories get better and better, even if individual theories face serious difficulties at certain times.

The fundamental problem with string theory is that, as far as its central goal of unifying physics goes, over the last nearly 25 years it has not only not made any progress toward explaining anything about particle physics, but, quite the opposite. Everything that has been learned about string theory makes it more and more clear that the original hopes for getting unification this way were just misguided and can’t work. The derivative here is the wrong sign.

There are areas in which string theory has had successes, notably in mathematics and in strongly-coupled gauge theories. But these are really different research programs, and the fact that progress has been made in them doesn’t change the facts about the colossal failure of the unification program. Cartwright and Frigg try and put various other “dimensions” on the string theory research program, including that of “elegance and simplicity”, writing that:

Radical string critics would then conclude that string theory is progressive only in the dimensions of elegance and simplicity (in the sense that the theory only contains one class of basic objects – strings – from which all the basic particles and forces follow), while being largely stagnant in the other dimensions.

As a “radical string critic”, I don’t see things this way. According to M-theory, “string theory” is not a theory of “one class of basic objects”. Strings are just part of a hugely complicated picture, one which at the moment is neither elegant nor simple. String theorists hope that there is some elegant and simple underlying theory, but they have not been able to come up with it despite a huge amount of work. Whatever underlies M-theory, it may be something very complicated. Perhaps M-theory is just a rather obscure corner of a story very different than what string theorists are hoping to find, one that may tell us some interesting things, but just doesn’t have anything to say about how to unify particle physics.

It seems that if you’re a Fields Medalist, you now have to have a blog. The latest of these is a new blog from Timothy Gowers. His blog will also function as a blog for the upcoming Princeton Companion to Mathematics that he is editing, and he has started a discussion about the possibility of a wiki devoted to “mathematical tricks”.

Rigorous Trivialities is another new mathematics blog, one of the rare ones not being run by a Fields Medalist.

Mathematics will now have its own “rumor mill” to gather information about job searches, to be called the Mathematics Job Wiki. It appears to have been set up by Greg Kuperberg, “who however recuses himself from handling confidential e-mail and is not the wiki moderator”. All we are told about the moderator is that “someone without a current tenure-track appointment will read e-mail sent to the Wiki Moderator.”

Gerard ‘t Hooft has translated his lecture notes on Lie Groups and Physics from Dutch into English, increasing by about two orders of magnitude the number of people who can read them.

Math and physics geeks are now certifiably cool, as the TV show Numb3rs goes into yet another season, and is joined by The Big Bang Theory. New York magazine got together a group of Columbia physics grad students to take a look at the show and discuss.

The early history of string theory is getting lots of attention these days, especially because of a conference on the subject last May. Some related articles have now appeared on the arXiv, from Di Vecchia and Schwimmer, Ramond and Schwarz. At Caltech, an Oral Histories project has made available the transcript of a long interview with Schwarz.

Hendrik, a commenter here, pointed out that there’s more of the latest string theory hype concerning results from the MAGIC telescope, originally discussed here. Now New Scientist has weighed in with an article entitled Finally, a MAGIC test for string theory? According to the article, Mavromatos and collaborators say that their (non-critical) string theory model “predicts the 4-minute delay exactly”. Polchinski is quoted to the effect that this would falsify (critical) string theory. LQG is completely cut out of the deal, with no mention of it at all. They really need to do a better marketing job. The way things are now, any supposed evidence of quantum gravitational effects is automatically evidence for string theory, in one version or another.

For the latest attempt to market string theory to astrophysicists, see this new article on astro-ph. The abstract begins not by acknowledging that string theory can’t make any predictions about cosmology, but by claiming instead that the problem is

Attempts to connect string theory with astrophysical observation are hampered by a jargon barrier, where an intimidating profusion of orientifolds, Kahler potentials, etc. dissuades cosmologists from attempting to work out the astrophysical observables of specific string theory solutions from the recent literature.

Update: Slashdot has a thoroughly worthless article about this last paper, based on the New Scientist article about it.

It appears that the release of the French edition of Lee Smolin’s book (entitled Rien ne va plus en physique ! : L’échec de la théorie des cordes) has stirred up quite a lot of attention to the string theory controversy over there. A correspondant wrote to tell me that this month’s edition of the French popular science magazine La Recherche has the controversy over string theory on the cover (La theorie des cordes dit-elle le vrai?) and four articles on the subject inside. Unfortunately I don’t have a copy of the magazine or on-line access to the articles, but just to an English language summary. It’s hard to tell from this exactly what’s in the articles. One of them is an interview with the historian of science Peter Galison, who seems to describe string theory as having “initiated a new way of seeing, crucial for the future of physics.” No idea what that is about, but I hope it’s not about the string theory landscape….

The string theorists of the Paris region have a web-page, which recently has acquired a defensive section about La faillite de la theorie des cordes? It encourages people to read Polchinski’s review of my book and Smolin’s (my response to this is here), as well as papers critical of LQG. The same web-page also has links to other information sources about string theory, including to two blogs. Personally I don’t think Jacques Distler’s blog is much of an advertisement for the subject, but sending people to Lubos Motl’s is a pretty funny thing to do….