Not Even Wrong

On the pseudo-science front, the Resonaances blog describes a talk at CERN by string theory enthusiast Jim Cline, about a variant of the anthropic principle called the “Entropic Principle” as “pushing the idea to the edge of absurd.” For beyond the edge of absurd, there’s today’s NYT Science Times section, which features a piece by John Tierney about the ideas of philosopher of science Nick Bostrom. Bostrom runs a web-site called anthropic-principle.com and has made a career for himself in the anthropic principle business which now has him running a Templeton Foundation-funded [actually this is not accurate, see here] Institute at Oxford called the Future of Humanity Institute. The New York Times article is about Bostrom’s idea that there’s a significant probability that our universe is just a simulation being conducted by a more advanced civilization, an idea that he considers to be one of the “interesting applications” of the anthropic principle. He has yet another web-site, simulation-argument.com, where he propounds this argument. Tierney supplements the NYT article with an on-line discussion of how we should we all behave, given that we are just simulated creatures. Maybe we should be trying to entertain our creators so they will not turn off the simulation? Anyone who thinks it is a good idea to discuss these questions seriously is encouraged to do so at Tierney’s site, not here.

Today’s Science Times also has an interview with Gino Segre, who has a new book called Faust in Copenhagen: A Struggle for the Soul of Physics, about the 1932 conference in Copenhagen hosted by Neils Bohr at the time of the beginnings of modern nuclear physics. Segre says that he became a physicist for an unusual reason. His father was an historian, brother of Emilio Segre, the co-discoverer of the antiproton, and the two siblings were estranged. When he was 15, Segre’s father told him “I think you should become a theoretical physicist, and I want you to surpass your uncle”, and he did as he was told.

American Scientist has a review of the Segre book, together with David Lindley’s recent Uncertainty: Einstein, Heisenberg, Bohr, and the Struggle for the Soul of Science.

American Scientist also has an interview with Frank Wilczek about books he is reading and that have influenced him. He strongly recommends a book by an author I’d never heard of, Olaf Stapledon’s Star Maker.

Unfortunately two well-known scientists, mathematician Atle Selberg, and physicist Julius Wess, are no longer with us.

Victor Kac is giving a series of lectures on vertex algebras in Brazil, with video to be available here.

A Turkish mathematician, Ali Nesin, ran into trouble with the authorities for running a mathematics summer school without permission. Alexandre Borovik has set up a web-site with a petition about this. Latest news is that the summer school has been re-opened, although Nesin still may face charges of “education without permission”.

As anthropic pseudo-science spreads through the particle theory community, I’m finding it harder and harder to tell what’s a joke and what isn’t. Maybe I’m wrong, but I fear that recent examples from hep-th contributors and prominent physics bloggers aren’t actually jokes, largely because if they are, they’re not funny.

The book Universe or Multiverse?, based on a series of Templeton Foundation supported conferences, and published by Cambridge University Press, is finally out. It’s edited by Bernard Carr, whose ventures into pseudo-science include not just this, but a stint as director of the Society for Psychical Research. He’s also on the board of directors of the Scientific and Medical Network, where his blurb tells us that:

My interests span science, religion and psychical research (which I see as forming a bridge between them)… My approach to the subject is mainly theoretical: I’m particularly keen to extend physics to incorporate consciousness and associated mental and spiritual phenomena.

The memoir by Jane Hawking that I recently wrote about contains her recollections of both Don Page and Bernard Carr (since they worked with Hawking).

I just ran into my editor at Cambridge University Press, who found that opposition from string theorists made it impossible for Cambridge to publish my book a few years ago, with one of their arguments being that doing so would damage the reputation of the Press. Publishing pseudo-science like this however seems to be fine. Yes, I’m aware that this book also contains criticism of anthropic arguments, and probably has some of the most intelligent and informed writing on the subject, but still… I suppose I should get a copy of the book and write a review (I’ve already read many of the articles, they’re available as preprints on-line), but the thing costs $85, the Columbia library doesn’t have a copy, and I’m not sure I should encourage them to buy one.

This week’s string theory hype: Universe’s Stringy Birth Revealed by Young Czech Physicist, which is not about Lubos Motl, but about an award to Martin Schnabl. Schnabl’s work on string field theory is one of the more interesting recent results in string theory, but the title of the article is, well, complete bullshit.

There will be an opening celebration in October for the Berkeley CTP, which was founded a few years ago and recently moved into renovated quarters. The BCTP is just one of a bunch of other CTPs that have been founded in recent years, including the MCTP and the PCTP (and one dead one, the CIT-USC CTP). The center’s web-site and opening conference appear to be heavily dominated by string theory, quite a change from a few years ago, when Berkeley was one of the leading US physics departments where string theory was not so dominant.

The PCTP has begun construction of its new home in Jadwin, the physics building at Princeton. Artist’s renderings are here. An art historian friend once told me that the proper technical name for the architectural style of Jadwin was “brutalist”. The new construction will add lots of glass, perhaps mitigating the “brutalism”. The large Calder featured in front of the building is called “Five Disks: One Empty”, and it has its own rather brutal history. It collapsed during construction, killing two of the men working on it. According to a local Princeton web-site:

The steel structure has four disks, one of which was originally painted orange, in a fervor of enthusiasm for the school’s colors. The structure was named “Many Disks: One Orange,” but then all of them were painted orange in anticipation of the artist’s visit in 1971. Upon seeing the structure, he asked that all the disks be painted black, and renamed it to its current title.

Over at SciTalks August is String Theory Month, and they’ll have Jonathan Shock as guest blogger later in the month.

At the Stony Brook YITP, the fifth of a series of workshops funded by Jim Simons on mathematics and physics, but mainly devoted to string theory, is now going on. Talks are online here.

Some online conference summary talks that one might want to take a look at are those of Michael Dine at the IAS PITP summer school, and John Ellis at SUSY 07. Both Dine and Ellis discuss prospects for observing supersymmetry at the LHC. Dine lists some of the reasons one might be skeptical that this will happen, including string theory anthropic landcape arguments (he avoids using the term “anthropic principle”, insteard referring to it as “NBN, that principle which cannot be named”). Ellis recalls his own role in the “discovery” of supersymmetry by UA1 back in 1984, indicating it’s likely that there will be such premature claims again at the LHC if anything at all anomalous is seen by the experiments. He also discusses the possibility of searching for long-lived particles produced at the LHC by using the muon system to locate where they left the detector, and then taking core samples of the surrounding rock to look for them.

For some excellent detailed postings about recent experimental HEP results from Tommaso Dorigo, see here and here. For blogging from CHARM 07 by Alexey Petrov, see here.

David Vogan has a wonderful expository piece about the recent heavily publicized results on the representation theory of E₈; it’s intended for a future issue of the Notices of the AMS.

The September issue of the AMS Notices is now available. It includes an article about “Higgs Bundles”, a version of the Higgs that physicists won’t really recognize, and a book review of Lee Smolin’s The Trouble With Physics. The review is quite positive about the book and mostly a straight-forward summary of what it is in it. The reviewer, like many mathematicians, had been misled by a lot of the hype about string theory, and so found Smolin’s book quite enlightening. In particular, about M-theory, he writes:

This explanation [that M-theory is not a complete theory] was, to me personally, a great shock since I had always believed M-theory was a complete theory.

Last year about this time the entire editorial board of the Elsevier journal Topology resigned, this August it’s the turn of the Springer journal K-theory. The editors of this journal have all resigned, issuing the following statement:

Dear fellow mathematicians,

The Editorial Board of ‘K-Theory’ has resigned. A new journal titled ‘Journal of K-theory’ has been formed, with essentially the same Board of Editors. The members are A.Bak, P.Balmer, S.J.Bloch, G.E.Carlsson, A.Connes, E.Friedlander, M.Hopkins, B.Kahn, M.Karoubi, G.G.Kasparov, A.S.Merkurjev, A.Neeman, T.Porter, D.Quillen, J.Rosenberg, A.A.Suslin, G.Tang, B.Totaro, V.Voevodsky, C.Weibel, and Guoliang Yu.

The new journal is to be distributed by Cambridge University Press. The price is 380 British pounds, which is significantly less than half that of the old journal. Publication will begin in January 2008. We ask for your continued support, in particular at the current time. Your submissions are welcome and may be sent to any of the editors.

Board of Editors
Journal of K-theory

The subscription cost for the Springer journal had been $1590, $1325 for electronic-only access.

I notice that while the editorial board of Topology has resigned, that hasn’t caused Elsevier to stop publishing and selling the journal. While I’m sure that a recent paper copy of the journal that I saw did not carry the names of the editors that resigned, the online version of the journal appears to still carry the names of the old editors, giving no indication that they have resigned. As far as I know, Elsevier has not been able to recruit a replacement editorial board, but they are still selling the journal, at a yearly subscription price of $1665.

Update: Via the comment section, there’s the related news that

Update: It turns out that there may be more to this story. See in particular the comment posted here by Andrew Ranicki, who says that no papers submitted to K-theory since April 2006 have been forwarded to Springer, and that he and Wolfgang Lueck will be acting as interim managing editors for the Springer journal to sort out this situation.

The Fermilab Steering Group is about to come out with its report. Their roadmap for Fermilab proposes that if the ILC project is delayed “Fermilab should pursue additional neutrino and flavor physics opportunities”, in particular with “Project X”, a high-intensity proton linac. One of their remaining tasks is to pick a name for Project X.

In the category of magazine articles that I hear have just come out, but I don’t have a copy of, and aren’t available on-line, there’s

The talks at the recent Imperial College event in honor of Abdus Salam are now on-line. This is the event Steven Weinberg boycotted, but Gerard ‘t Hooft was there to talk about Salam and the state of theoretical physics. His talk was entitled “The Grand View of Physics”, and is available here.

Among the recent large “’07” conferences with talks available on-line are:

The HEPAP University Grants Program Subpanel has just issued a report, concerning the “University Grants Program” in US HEP, that part of the DOE and NSF high energy physics budget which supports research based mainly at universities (as opposed to government laboratories such as Fermilab). Obviously this is the part of the HEP budget that is of most direct concern to university researchers, especially theorists, who receive most of their government funding this way (a small number of theorists are supported by national labs, not universities).

On the experimental side much of the report is concerned with how to manage what will happen over the next few years as many researchers move from working on experiments in the US to the LHC, in particular how to deal with the higher travel and living expenses this will require. I’ll concentrate here on some comments on the extensive parts of the report that deal with theoretical particle physics.

The report is surprisingly light on actual budget data, with few specific numbers about past budget trends, current budget levels or future budget plans. 2006 NSF university grant funding is given as $19 million for experimental particle physics, and $11.8 million for particle theory, astrophysics and cosmology. DOE university grant funding is described as about $110 million per year, with no breakdown between experiment and theory. The only historical data given is that this kind of DOE funding peaked in 1992, at a level of $150 million in current dollars, supporting a total of 1685 people back then, as opposed to 1495 in 2005. The main budgetary recommendation of the report is that 1 % of the total US HEP budget (about $8 million) be redirected to the university grants program as the SLAC and Fermilab collider programs wind down over the next few years.

The recommendations for theoretical particle physics mostly concern funding for graduate students, calling for increasing the number of graduate students in particle theory, especially students working on calculations directly relevant to LHC experiments:

Funding directed at university-based theoretical particle physics for the purpose of increasing the number of HEP-grant-supported graduate students should be given a higher priority in the overall HEP program. Support for students and postdocs doing calculations related to upcoming experiments is particularly urgent.

Though the universities are strong in formal theory, there has been a decline over the years in conventional particle theory (phenomenology), for a variety of reasons. Phenomenology embraces a number of different areas, including data analysis, collider physics, computational physics, perturbative QCD, lattice field theory, model building, flavor physics, and neutrinos; it overlaps with such areas as strings, astrophysics, and cosmology. All these areas are important; but those directly connected with the LHC are increasingly critical. The entire LHC experimental program requires a strong theoretical component involving calculating Standard Model backgrounds and new physics processes, together with interpreting the experimental results and teasing out their implications. However, the number of theorists working on such topics in the United States, especially at the universities, is inadequate. For example, there are only a handful of people in the U.S. working on computational physics, such as event generators. Many more will be needed to fully utilize the physics potential of the LHC. It is important that much of this effort be centered at universities because (a) much of the experimental analysis will be done at
universities, and (b) a university presence is needed to attract graduate students. A general concern is the overall decline in the agencies’ support of graduate students in theory, both formal theory and phenomenology. This decline makes it difficult to train a sufficient number of students. The problem is aggravated by increasing competition for the limited number of available teaching assistantships (TAs) from students in other subfields of physics.

A key component of a strong Terascale physics program (at the LHC and the ILC) is a strong theoretical program involving the calculation of Standard Model backgrounds and new physics processes, together with interpretation of the experimental results. However, as pointed out in this report, the number of theorists working on such topics in the United States, especially at the universities, is inadequate. Addressing this vital need requires an additional level of effort.

Overall, the field of high energy physics faces several critical manpower and infrastructure problems. Declining graduate student support affects the intake of new physicists and therefore the future of particle physics overall.

The report gives no actual numbers (which, presumably are available, since the DOE and NSF should have counts of how many students they support each year), but, based on responses from a survey of university grant PIs, it says that the number of grant-funded RAs for HEP grad students has been decreasing, with, especially for theorists, student support having to come from TAs:

The overwhelming response stressed that the level of (NSF and DOE) grant support for RAs for graduate students is insufficient and has indeed been declining over the last decade. At the same time, respondents noted that the cost of supporting a graduate student on a grant has increased, especially because of stricter university requirements regarding tuition remission and fringe benefits.

As a result, particle physics groups routinely rely on other sources of funds for all or part of their graduate student support. One major resource is TA positions for particle physics students, addressed in more detail below. Some respondents noted that their universities have limited fellowship support for some students. A handful also mentioned seeking outside support from other federal agencies. Many said that they had been forced to turn away qualified students due to a lack of grant support. Some also indicated that students had turned down the chance to join a particle physics research group because other departmental areas could promise steadier RA support, rather than a mixture of TA and RA support…

Survey respondents brought up several difficulties caused by this reliance on TA support. First, spending time as a TA slows senior students’ research progress (increasing their time to graduation) and hampers experimental students’ ability to travel to particle physics labs. Second, TA support is also currently a declining resource for particle physics at many institutions, because university administrations are providing less overall TA money to physics departments, departments are reducing the number of semesters any student may spend as a TA, or other physics subfields are requesting more TA slots. Third, if a particular research group (usually particle physics theory) makes unusually large demands on the available TA slots, this creates friction and resentment within the department as a whole.

The report has no mention at all of what the desirable level of particle theory Ph.D.s might be from a larger perspective. There is zero discussion of the relationship between how many such Ph.Ds are produced, and how many jobs doing particle theory research are likely to be available in the future. This is presumably because the authors are well aware that there remains a huge imbalance between the number of smart people getting Ph.D.s in this subject, and the number of opportunities for them to make a career in the subject. The reference to “friction and resentment within the department as a whole” over TAs makes clear what one of the main concerns driving this recommendation is. The amount of power and influence one’s group has in an academic department, including prospects for being allowed to hire more people, is heavily influenced by how much grant money one brings in, especially how much funding for the graduate program one can provide. This is made even more explicit at another point in the report:

Because of eroding support, more and more theoretical graduate students are being required to teach more and more of the time. This is unfortunate for at least two reasons: first, it lengthens the time to degree; and second, it signals to physics departments a hint of declining support for HEP research, exacerbating hiring worries.

While the report mentions the need to find some more money for postdocs (since those working on experiments will need to travel to Europe more often), it emphasizes support for grad students, not postdocs. It does this even though it is postdocs who are doing much of the most original work in the field, and the small number of postdocs (and junior faculty positions) is what makes career prospects for particle theory students extremely problematic. I can’t even really make sense of this one paragraph from the report that deals with this:

Given the choice between hiring more graduate students and taking on a postdoc, many faculty members will opt for the latter when faced with limited available funding. However, while this may seem be the best solution in terms of immediate research workload, the long-term negative effects of this choice on the field as a whole are clear.

One of the most interesting things in the report is the set of numbers from survey responses about how many grant-supported theory researcher are working in which areas, and what hiring plans by area are for the next 5 years. Figure 3 on page 43 divides theory researchers into six categories, and gives counts for how many are working in each category now, how many expected in 2012. The number of string theorists is supposed to drop from 103 to 84, “field theorists” from 91 to 77, “model builders” from 88 to 70, and “QCD/Lattice QCD” from 50 to 41. “Particle phenomenologists” are supposed to increase from 188 to 194, and “astrophysicists and cosmologists” from 136 to 176. Obviously boundaries of these fields are unclear, especially since string theory in recent years has to some extent moved away from formal theory, with more people describing themselves as “string cosmologists”, “string phenomenologists”, “string-inspired model-builders”, and much of the attention of the field devoted to trying to do QCD calculations with string theory.

If you take these numbers seriously, a grad student would be nuts to work on anything except cosmology or phenomenology, since all other subfields show about as many people leaving them as would be accounted for by retirements, so essentially no new hiring. My suspicion though is that these numbers reflect what departments say they would like to do, not what they will do. Most departments now say they want to hire in the areas of cosmology and phenomenology. But faced with the fact that competition for the best people in those areas is tough, and finding it much easier to get good people in other subfields, I suspect there will continue to be quite a lot of hiring in these other subfields, in string theory especially, which seems to be what looking at the latest data from the Rumor Mill shows.

Given the huge and supposedly increasing dominance of these numbers by the “particle phenomenology” category, the report’s call for an urgent increase in funding to produce more phenomenologists is not so easy to understand. However, the authors make clear that what they want to see is more of a very specific sort of phenomenology: people working on things like event generators to precisely calculate standard model backgrounds for the LHC experiments, something which has always been more popular in the Europe than in the US. The recent NSF-funded “LHC Theory Initiative” is specifically designed to address this, and is being promoted with nationalistic calls to fight the “outsourcing” of these calculations to European theorists. The authors of the report are calling for more Ph.D.s in conventional, experiment-based phenomenology, not more Ph.D.s in string theory or “string phenomenology”. They choose to do so, for obvious political reasons, not by calling for a reallocation of resources within the field of particle theory, but for new resources for this purpose, even if it will lead to a smaller fraction of particle theory Ph.D.s being able to find jobs doing the research they have been trained to do.

The New York Times has an article this morning by Dennis Overbye in its Science Times section about the hunt for the Higgs and the various rumors that were circulating earlier this year. It does a good job of accurately summarizing and reviewing the situation (although of course the blogs were and remain the place to go for breaking news, up-to-date and accurate information…). Steven Weinberg recalls the time back in 1977 when he quickly wrote up a paper with Ben Lee about a model concocted to explain rumored “trimuon” events (which turned out not to be there). There are quotes from bloggers Tommaso Dorigo, Gordon Watts and John Conway, and, in a new posting on his blog, Gordon is now trying to deny that he uses the term “Dude” in actual conversation. Unfortunately, anyone at D0 who knows anything seems to have clammed up, no more rumors that I’m aware of about whether they’re seeing anything exciting.

The 2007 Europhysics Conference on High Energy Physics is going on in Manchester, England, and many of the talks are already on-line. This is a conference more aimed at experimentalists than theorists, so there doesn’t seem to be much new in the theory talks. There are so many experimental talks that I think I’ll have to wait for the summary talk to appear to figure out what to pay attention to.

There’s a long list of things I was going to write about, but Sabine and Stefan at Backreaction got there first (here, here and here):

There’s a new chapter out of the particle physics novel The Newtonian Legacy (blogged about here) by Nick Evans. Not often that the Cern Courier carries material about Higgsless models and lingerie in its pages…

There’s a potentially important new paper on the arXiv from Terry Tomboulis, entitled Confinement for all values of the coupling in four-dimensional SU(2) gauge theory. Tomboulis claims to prove that SU(2) lattice gauge theory has confining behavior (area law fall off of Wilson loops at large distances) for all values of the coupling at the scale of the cutoff, no matter how small. This conjectured behavior is something that quite a few people tried to prove during the late seventies and eighties, without success. Tomboulis is one of the few people who has kept seriously working on the problem, and it looks like he may have finally gotten there. The method he is using goes back to work of ‘t Hooft in the late 1970s, and involves considering the ratio of the partition function with an external flux in the center of SU(2) and the partition function with no such flux. For a recent review article about this whole line of thinking by Jeff Greensite, see here. For shorter, less technical articles by Tomboulis about earlier results in the program he has been pursuing, see here, here, and here.

As far as I can tell, even if this holds up, it won’t get Tomboulis the million-dollar Clay prize being offered for the solution of the Yang-Mills Millenium Prize Problem. There the problem is stated as rigorously constructing Yang-Mills for any gauge group, not just SU(2), showing that it has the expected properties, and a mass gap. I don’t know whether Tomboulis’s methods can prove that there is a mass gap. In any case, I also don’t know why the Clay prize asks for a mass gap rather than confinement, which seems more physically relevant.

The latest HEPAP meeting was this past weekend in Washington and presentations are available here. The news from the DOE is that it looks like Congress will approve a FY 2008 HEP budget at or above the White House request of $782.2 million, an increase of at least 4%. This will include $60 million for ILC R and D (up from $42 million in FY2007). This will include funds for site surveys in the US, which in principle will include sites other than Fermilab, although I find it hard to believe a US site other than Fermilab would end up being chosen.

There’s a report from the University Research subpanel that puts near the top of its recommendations “A higher priority in the overall HEP program should be given to funding directed at university-based theoretical particle physics for the purpose of increasing the number of HEP-grant supported graduate students.” Given the continuing high ratio between students getting Ph.Ds in particle theory and jobs for them when they get out, I would have thought the priority would go to finding ways to fund jobs for students once they get out, rather than increasing the number of Ph.Ds.

There’s a recommendation from the P5 panel that the Tevatron should definitely run through FY2009, and in September they’ll start looking at the case for running even longer than that. There’s also a discussion of “European reaction” to comments from the DOE’s Ray Ohrbach that the US needs a plan in case the ILC doesn’t start happening soon. Typical reaction from the Europeans was said to be that the US is not a reliable partner, and makes unilateral decisions without consultation. CERN has recently been promised a budget supplement over the next few years that could pay for an LHC upgrade (they were in hock over the LHC), and by 2016 that would be done and paid for. At that time CERN will have money to spend on a new big project and a higher energy linear collider using CLIC technology would be a possibility (the semi-joke made was that the work advancing this possibility is now going on mainly in the US, at SLAC).

A progress report from the Fermilab Steering Group, which is supposed to report to the Director on Aug. 1, included extensive discussion of “Project X”, a proposal to dramatically increase the power of proton beams by building an 8 GeV proton linac. Part of the idea is that building this smaller linac would help get experience needed for doing the ILC.

Also at Fermilab, I noticed that they have a web-site devoted to the history of the place, and here is a recent talk by Adrienne Kolb on the subject.

According to CNN, one of the “Geniuses who will change your life” is Harvard’s (soon to be Princeton’s) Nima Arkani-Hamed, who is described as follows:

Nima Arkani-Hamed thinks big. He has a theory that our universe is one of an infinite number of universes — meaning the largest thing we can wrap our minds around is actually pretty tiny

He didn’t pull the “multiverse” out of thin air, though. After becoming a Harvard professor at age 30, Arkani-Hamed first made a name for himself by suggesting that our universe is five-dimensional. Then he moved on to the multiverse, theorizing that our own universe has a hidden feature called “split supersymmetry,” which means that half of all particles have partner particles.

The theory will be tested soon in Switzerland’s brand-new Large Hadron Collider (LHC), and if the LHC finds Arkani-Hamed’s partner particles, it could prove that the multiverse is real — and that our place in it is that much smaller.

The claim that if you see split supersymmetry, this proves that the multiverse is real seems pretty much laughable to me.

Clifford Johnson is in Aspen, at what its director describes as a “summer camp for physicists”. He has a posting about his experiences there, describing how the big topic of conversation is the recent Strings 2007 conference. He asks for people to write in telling about which of the Strings 2007 talks they found most interesting (although so far, a half day later, no one seems to have taken him up on this). Like Jacques Distler, after Witten’s talk, Clifford seems to be most impressed by Seiberg’s talk on BMSSM (Beyond the Minimal Supersymmetric Standard Model) physics, based on his recent paper with Dine and Thomas. The idea is that, even with its 105 extra parameters, the MSSM still requires a lot of fine-tuning to get around the LEP bound on the Higgs mass, so you should analyze adding even more terms to the Standard Model besides the minimal supersymmetric ones. Distler was very excited by the Seiberg talk, arguing that these results should have been found years ago but weren’t. Various people wrote into his blog to point out to him that this wasn’t right, that mostly these things had been done a while ago, including by several authors back in 2003 (see hep-ph/0301121 and hep-ph/0310137). Seiberg et. al. issued a revised version of their paper where they added quite a few references, including one to work back in 1999 by Alessandro Strumia (hep-ph/9906266) where he already discussed the impact of the two operators identified by Dine et. al on the Higgs mass.

Update: The debate over string theory really has reached the general public, at least in New York: a few months ago there was a cartoon in the New Yorker, this week, it has made the New York Magazine web-site celebrity coverage.

There’s an interesting exchange today between Sean Carroll and George Johnson on bloggingheads.tv. They cover a range of topics, including the controversy over string theory and the role of blogs. Johnson describes his time last fall at the KITP, telling about drinking very expensive Scotch with Steve Shenker, and many discussions with the string theorists there who were concerned that they were getting bad publicity and didn’t know what to do about it. Some were concerned that Lubos Motl was not exactly representing them well.

Sean gives a fairly standard defense of the landscape (“maybe it really is the way the world works”), with no discussion of the main problem with the landscape, that it shows no signs of making falsifiable predictions that would make it legitimate science. Some other points of the discussion include speculation about “what if Feynman and Gell-Mann had blogs?”, and Sean’s analogy of the string/LQG debate with mainstream/”heterodox” academic economics.

Update: Sean has his own posting about this.

The public perception of string theory has definitely changed over the last few years, with the latest evidence this week’s cover story in New Scientist, which begins:

It’s the theory everyone loves to hate.

The article (available fully only to subscribers, I fear) is entitled String Theory: The Fightback, and its story line is that, because of all this criticism, after nearly 25 years of work, finally:

string theorists themselves have realised they must find ways to put their models to the test. They may still be far from being able to observe a string in a laboratory, but experiments planned for the near future – and even one currently under way – could provide tantalising evidence either for or against string theory…

Now the string community is fighting back by devising creative, if indirect, ways to look for signs of strings – from hidden dimensions to ripples in space-time and other potential signatures of a stringy universe. The time has come to put string theory to the test…

Critics should take heed. Experiments now show that string theory may be testable after all. One study at a time, string theorists seem to be homing in on models that will make specific, falsifiable predictions.

What follows is the usual misleading hype of bogus “tests” of string theory, of the sort I’ve written about extensively here. They are:

For one of my postings about this, see here. More than three years ago Polchinski and the KITP at Santa Barbara issued a press release about this trumpeting the idea that such superstrings could be observed by LIGO “over the next year or two.” The problem with this kind of “test” of string theory is that you can easily come up with string theory models that produce lots of cosmic superstrings (already falsified), no observable amount of cosmic superstrings (can’t use to test string theory), or precisely the amount of cosmic superstrings such that no hint of them would be seen until now, but there would be networks of the things lurking just below the threshold of measurability, to be discovered by the next generation of experiments (highly unlikely, pretty much pure wishful thinking). Polchinski has now stopped talking about LIGO and a year or two, and instead is promoting measurements of pulsars and five to ten years:

According to Polchinski, though, our best bet for observing gravitational waves emanating from strings is to use pulsars. A pulsar is a rapidly spinning neutron star that fires out a beam of electromagnetic radiation as it rotates, like a lighthouse. These flashing beacons act as some of the most accurate clocks in the universe, and a gravitational wave rippling between a pulsar and Earth would disturb the otherwise precise timing of the pulses arriving here. The most likely cause of such fluctuations would be black holes colliding, but waves from strings would yield a unique timing pattern that would make them stand out. “Over the next five to 10 years,” Polchinski says, “these [pulsar observations] will probe the most interesting models.”

My colleague Brian Greene is quoted about this, making the essential point about this kind of “test”:

Sure, catching sight of a cosmic string would be a boon for string theory, but is there any observation that would serve as a death knell? For many sceptics, it’s not that string theory is so hard to prove correct that puts them off, but rather that you can’t falsify it. “I’m not aware of any test that if it fails will prove string theory wrong,” says physicist Brian Greene of Columbia University in New York. “That’s a real headache. You’d like to have a situation where you have a prediction, and if it’s right the theory is right, and if it’s wrong the theory is wrong.”

The problem is that the quoted paper doesn’t actually say that. Here’s the paper’s concluding paragraph:

However, a possible discovery of tensor modes may force us to reconsider several basic assumptions of string cosmology and particle phenomenology. In particular, it may imply that the gravitino must be superheavy. Thus, investigation of gravitational waves produced during inflation may serve as a unique source of information about string theory and about the fundamental physics in general.

Given the wealth of possible string theory scenarios, I have no doubt that if an imprint of gravity waves is found in the CMB, there will be string theory models that would “predict” it. As for the idea that not seeing such gravity waves would be evidence for string theory, here’s what Glashow has to say:

Not everyone thinks these tests will be useful, however. “Not seeing something is hardly evidence for string theory,” says Nobel laureate Sheldon Glashow of Boston University, Massachusetts, an outspoken critic of string theory. He feels that such a result would mean very little. “String theorists are very wise. They can come up with a way to explain anything.” String theory is simply not testable, he says. “There are an enormous number of string theories and they describe zillions and zillions of universes, none of them observable in any way. It sounds to me like angels dancing on the head of a pin.”

“We’re still very far from being able to say, here is the exact string theory that describes QCD,” Susskind says. “But the connections that show up between nuclear physics and string theory are fascinating. Sceptics won’t consider this evidence for string theory, but nuclear physicists will use string theory and in time discover how accurately it describes these experiments.”

What Susskind is neglecting to mention here is that these are tests of whether string theory is a useful way to do calculations in an already tested theory of the strong interactions, and has nothing to do with the question of testing the idea of string theory as a unified theory of quantum gravity and particle physics.

Also in New Scientist, there’s a story about Neil Turok’s recent talk at PASCOS entitled “Is the Cold Spot in the CMB a Texture?” which links to the string theory article. Evidently there’s a patch of CMB where the temperature is anomalously low (the probability of this happening supposedly being 2 percent) and one can speculate that this may be due to a topological defect of some kind. Amusingly, the online version of the New Scientist article includes an interpolated editorial comment that someone forgot to take out before publication:

Turok presented the findings at a conference on particles Hi Anil. This threw me a bit. We say the team noticed previous work by Turok, and then before we know it Turok is the one presenting the work. When did he join them, strings and cosmology at Imperial College London last week.