Not Even Wrong

As discussed here, here, here, and here, the arXiv is now putting on each abstract page a link to trackbacks from weblogs which contain a link to the paper in question. This is an interesting mechanism for integrating the discussion of various papers on weblogs with the arXiv site.

I remember more than ten years ago Paul Ginsparg talking about the idea of setting up a mechanism for having commentary on papers on the arXiv, but this idea seems to have not gotten off the ground at the time. Part of the idea was that the author of the paper would be able to delete any posted commentary he or she didn’t like. When asked about whether this would stop people from being able to use the commentary section to point out that a paper was wrong, Ginsparg noted that if there was no commentary on a specific paper, did you really care whether it was because the author had deleted the comments, or because no one thought the paper was worth commenting on?

My latest posting from earlier this evening contained a couple links to arXiv papers (I didn’t know about this trackback business at the time). Jacques Distler explains that one’s weblog has to be on a list of “serious physicist-bloggers” in order for one’s trackbacks to appear. So far mine haven’t, so I guess I’m not a “serious physicist-blogger” by the standards of Jacques (or whoever is managing this thing).

Update: The trackbacks are there now, as pointed out by Sean Carroll. Not sure when this happened, partly because there seems to be a bug in their system. The abstract page for the Mickelsson paper I linked to counts only one trackback, when there really are two (the other, from Urs Schreiber was there yesterday).

There have been two quite interesting Oberwolfach workshops this summer with some relation to my favorite ideas about K-theory and quantum field theory. The most recent was a workshop on Gerbes, Twisted K-theory and Conformal Field Theory, with blogging from Urs Schreiber at The String Coffeee Table. Jouko Mickelsson gave a talk on “Twisted K-theory and the index on G” which from Urs’s description was mostly about the material in Mickelsson’s paper Families Index Theorem in Supersymmetric WZW Model and Twisted K-theory. This is closely related to the Freed-Hopkins-Teleman theorem, and their construction of a twisted K-theory class using Dirac operators on a circle, parametrized by connections on the circle.

Urs wasn’t sure what to make of this talk or how to connect it to string theory. My own point of view is that this is very interesting not because of the relation to strings, but because one can think of it as a possible new way of describing the Hilbert space for 2d chiral gauge theory. Perhaps this can provide a 2d toy model to test out new approaches to gauge theories in 3 and 4 dimensions. From this point of view, the QFT involved is best thought of not as the supersymmetric WZW model, but as a chiral fermion coupled to a gauge field, with BRST gauge fixing. In some sense what is going on here is an index-theoretic version of BRST.

Earlier in the summer there was an Oberwolfach workshop on Geometric Topology and Connections With Quantum Field Theory. One of the main topics there was recent work on elliptic cohomology, with a survey talk by Graeme Segal and Jacob Lurie speaking on a new “derived algebraic geometry” approach to the related theory of “topological modular forms”. Greg Moore’s talk looked interesting, especially his comments on various QFTs which he thinks of as special cases of AdS/CFT, and generalizations of the Chern-Simons/CFT correspondence. In a footnote he writes “It would constitute a major step forward in mathematics if someone could state the AdS/CFT correspondence in a mathematically precise way.”

The same Oberwolfach workshop also had a talk by Nitu Kitchloo on “The Baum-Connes Conjecture for Loop Groups”, which really was also about Freed-Hopkins-Teleman in disguise. I’ve talked a little bit with Paul Baum about this idea that FHT is Baum-Connes for loop groups, but Kitchloo has tried to do something with it. The general idea behind Baum-Connes is that one can study the representation theory of a group in terms of the topological K-theory of a classifying space for the group. In the case of loop groups, the classifying space is the space of connections on a trivial bundle over the circle, and the topological K-theory is FHT’s twisted K-theory of the group. The information about the loop group representation theory is encoded in the Verlinde algebra. An ongoing project of mine is to try and sort out the relations of this story to 2d QFT (see comment above about Mickelsson’s work), hoping that if one gets the right point of view on the 2d case one can use this to define gauge theories in 3 and 4 dimensions in terms of some sort of K-theory, implementing some sort of Baum-Connes correspondence for higher dimensional gauge groups.

In reference to my recent posting about the status of the WMAP experiment, an anonymous (but as far as I can tell, well-informed) source writes:

Hi Peter,

6. The conspiratorial “Cosmology News” that you have linked to looks pretty slanted to me. They are talking about the famous missing power in low multipoles, discussed in the first year data release. Note that COBE also saw this missing power. IMO, I very much doubt this is due to systematics, as that site alleges, and statements that the team thinks –at the late date of 2004 — otherwise are almost certainly made up.

The WMAP mission has now been in place and taking data near the L2 Lagrange point for four years, with two more years still to go. Spectacular results from the analysis of the first year’s worth of data were reported in Feb. 2003, and the second year’s data was initially supposed to appear a year later, in Feb. 2004, but they’re now a year and a half late. For some reporting on this, see this site with cosmology news. Just recently the WMAP team has put up something new on their mission status page, where they state:

While the first-year results were based mainly on temperature measurements, the continued mission operations are now primarily focused on the much weaker polarized signals – an invaluable “stretch” goal of the extended mission. Analyses of these weaker signals are more difficult and continue with steady progress. The data and results will be provided as soon as calibration and systematic error analyses have been completed, and the data files have been adequately documented for use by researchers.

Are they seeing the effects of gravitational waves in this polarization data? Anyone with inside information want to take advantage of the ability to post here anonymously and tell us what is going on? Or e-mail me, I promise to protect the confidentiality of my sources, even going to jail with Judith Miller if necessary.

This week and next there are workshops at Snowmass on the particle and accelerator physics aspects of the proposed International Linear Collider (ILC). There’s a new weekly newsletter and a new website devoted to the ILC project which has twice-daily updates from the Snowmass workshops. Kind of like blogging, except done by professionals. Soon every conference or workshop will have their official blogger (two ongoing mathematical physics ones that link to blogs on their website are at the KITP and at Oberwolfach. I really should write more about twisted K-theory here sometime….)

For more about plans for the ILC, and for a presentation about CERN’s plans for the future, see the talks from the EPP2010 meeting at Cornell earlier this month.

In other particle physics news, the RSVP project at Brookhaven has been terminated.

Update: There’s another collider physics workshop going on in the Colorado mountains, this one is at Aspen and is concentrating on LHC physics.

Chad Orzel has interesting posts here and here about electric dipole moment experiments and their implications for particle physics. He claims that these experiments will ultimately be capable of getting down to three to four orders of magnitude below the current limits, and since they already put constraints on beyond the standard model physics, these results could be very significant.

A commenter points out that the Edge web-site has put up John Horgan’s recent New York Times Op-Ed piece about science and common sense, together with some quite hostile responses to it. I’ve already explained what I think about Horgan’s piece, and I agree with some of the points of his critics, but I think their reaction to his quite accurate point that string theory is untestable is pretty remarkable.

John McCarthy, a computer scientists, writes the following bizarre paragraph:

“When Horgan says that string theory is untestable, he is ignoring even the popular science writing about string theory. This literature tells us that the current untestability of string theory is regarded by the string theorists as a blemish they hope to fix.”

Ignoring the peculiar characterization of the untestability of a theory as a “blemish” rather than a serious problem, does this make any sense to anyone? McCarthy seems to be trying to make the argument that one isn’t allowed to point out a problem with a scientific theory if the scientists involved agree it is a problem and say they wish they could do something about it.

McCarthy at least has figured out that string theory is currently untestable, unlike Lenny Susskind, who invokes the heavy artillery of big names to (seem to) claim that it is:

“Finally I must take exception to Horgan’s claim that “no conceivable experiment can confirm the theories [string theory and cosmological eternal inflation] as most proponents reluctantly acknowledge.” Here I speak from first hand knowledge. Many, if not all, of the most distinguished theoretical physicists in the world — Steven Weinberg, Edward Witten, John Schwarz, Joseph Polchinski, Nathan Seiberg, Juan Maldacena, David Gross, Savas Dimopoulos, Andrei Linde, Renata Kallosh, among many others, most certainly acknowledge no such thing. These physicists are full of ideas about how to test modern concepts — from superstrings in the sky to supersymmetry in the lab.”

First of all, his parenthetical elaboration “[string theory and cosmological eternal inflation]” isn’t quite right, Horgan never said anything about “cosmological eternal inflation”, although he did criticize as untestable claims for the existence of “parallel universes”. Susskind attacks Horgan’s claim that string theory is untestable by claiming that he and lots of illustrious physicists have ideas about how to test “superstrings in the sky to supersymmetry in the lab”. Note that Horgan never said anything about supersymmetry not being testable. The “superstrings in the sky” presumably refer to Polchinski’s claims that in some of the infinite variety of possible string theory scenarios there are cosmic strings that might be observable. I fail to see how this counts as a “test” of string theory, since if, as is likely, astronomers don’t see these things, that in no way shows that string theory is wrong.

After this piece of intellectual dishonesty, Susskind ends with the favorite tactic of string theorists on the losing side of an argument, the ad hominem attack:

“Instead of dyspeptically railing against what he plainly does not understand, Horgan would do better to take a few courses in algebra, calculus, quantum mechanics, and string theory.”

Today’s New York Times contains an Op-Ed piece by science writer John Horgan entitled In Defense of Common Sense. In it, Horgan takes an iconoclastic view of this year’s many celebrations of the 100th anniversary of Einstein’s great work of 1905, writing “In the midst of all this hoopla, I feel compelled to deplore one aspect of Einstein’s legacy: the widespread belief that science and common sense are incompatible.”

Horgan stirred up controversy in 1996 with the publication of his book The End of Science, where he claimed that most of the big discoveries in science have been made, forcing scientists to instead engage in what he calls “ironic science”. By this he means science done in a “speculative post-empirical mode”, something more like literary criticism, where claims are made that can never be shown to be right or wrong. While he saw this phenomenon taking place in many different areas of science, theoretical physics was where he had his strongest argument, pointing to controversies over the interpretation of quantum mechanics which seem to never be resolvable by experiment, and especially to string theory, which he describes in a later book as “science fiction in mathematical form.” Publication of his book made him rather unpopular in the science community and ultimately led to his leaving his position as an editor at Scientific American. At the time I thought he somewhat overstated his case, especially in trying to see the same pattern in a wide range of different sciences, but he had the insight and courage to put his finger on something very important that was going on in physics. Since 1973, the field has been a victim of its own success, suffering greatly from the fact that the Standard Model is just so good that it has been impossible to find experimental results that disagree with it, as well as impossible to find any convincing improvement on the model that would address any of the issues it leaves open. Horgan’s critique of string theory was forceful and on target, although to me his depiction of Witten seemed unnecessarily personally unkind.

I have mixed feelings about this latest piece of his, both strongly agreeing and strongly disagreeing with his defense of “common sense”. This comes down to what one means by “common sense”. One aspect of common sense is basically the standard scientific method and the norms traditionally used by scientists to evaluate what is good science and what isn’t. The sub-headline on Horgan’s piece “Beware of scientific theories that can’t be tested” involves this aspect. It’s just common sense to be skeptical of people who are making grandiose and radical claims unless they’ve got some good evidence for them, and string theory violates this notion of common sense. But I’m afraid Horgan conflates this kind of common sense with a different kind of “common sense”, the common sense about how the physical world behaves that is built into us based on the evolution of our species and our growing up in an enviroment where we interact with the world on a very specific scale of distances. This kind of common sense may not help us at all to understand how nature behaves at the atomic scale, near a black hole, etc., instead quantum mechanics and relativity are required, and these are subjects that don’t fit well with our notions of “common sense”, in the second of the two meanings. But even if they were initially counter-intuitive, both quantum mechanics and relativity were based on a wide range of detailed experimental evidence, something that overcame people’s qualms about whether they were violating “common sense”. Absent this kind of evidence, string theory is a very different story….

On a completely different topic, Lubos Motl has a posting about amazon.com censoring any criticism of a certain crackpot physics book. He’s started a contest, grand prize $3.00, which people may want to participate in.

Update: Lubos seems to have trouble telling apart John Horgan and John Hagelin….

The KITP program on Mathematical Structures in String Theory has a new weblog associated with it where Andrew Neitzke has been posting summaries of the talks given there. The idea of having such weblogs attached to programs like the one at the KITP seems to be an excellent one, it will be interesting to see how it works out.