Short Mathematical Items

Posted on October 29, 2009 by woit
  • Riemann submitted his paper on the Riemann Hypothesis October 19, 1859, and it was read by Kummer at the meeting of the Berlin academy on November 3. AIM is organizing a celebration of the 150th birthday of the Riemann Hypothesis, with a “Riemann Hypothesis Day” on November 18th. Talks will be given on that day at many institutions around the world, a list is here.
  • The Royal Society in Britain has announced the appointment of six “Royal Society 2010 Anniversary Research Professors”. Two of them are mathematicians: Timothy Gowers, of Cambridge, and Andrew Wiles, who will be leaving Princeton to take up the position at Oxford. Wiles has this comment about his current research:

    Over the last several years my work has focused primarily on the Langlands Program a web of very influential conjectures linking number theory, algebraic geometry and the theory of automorphic forms. I am trying to develop arithmetic techniques that will, I hope, help to resolve some of the fundamental questions in this field. I am delighted to be appointed a Royal Society Research Professor in their anniversary year and I look forward to the opportunities this will give me to further my research.

  • I spent a couple days earlier this week up in New Haven, attending a conference celebrating Gregg Zuckerman’s 60th birthday. Zuckerman’s specialty is representation theory, and he’s well-known in that subject for several ideas that have been important in the modern understanding of infinite dimensional representations of semi-simple Lie groups. He also has done quite a bit of work in mathematical physics, work which includes a classic paper (Proc. Natl. Acad. Sci. U.S.A. 83 (1986), pp. 8442–8446) with his Yale collaborators Howard Garland and Igor Frenkel explaining some aspects of the BRST quantization of the string in terms of semi-infinite cohomology. As far as I know, he was the first person to study (in a 1986 paper “Action principles and global geometry”) the field theory with Chern-Simons action that Witten was to make famous two years later when he worked out its significance as a TQFT giving interesting 3-manifold and knot invariants.
  • An hour or so ago I went out for a walk, stopped at the bookstore, and noticed that there’s a new book out about Grigori Perelman, entitled Perfect Rigor. It looks worth reading, perhaps they’ll be a longer blog post about it sometime soon…
    • Posted in Uncategorized | 5 Comments

    News from HEPAP

    Posted on October 27, 2009 by woit

    Last week there was a meeting of HEPAP held in Washington, presentations are available here.

    HEP has done very well recently in recent US federal government budgets, due to the stimulus and large deficit spending going on to fight the recession. The FY2010 DOE budget has been passed by Congress, and it includes $810 million for HEP (up 2% from $797 million in FY2009), and there is also $232 million in stimulus package money currently being spent on HEP. The FY2010 NSF budget has not yet made it through Congress, but the Administration request for NSF physics research is up by 9% from FY2009.

    DOE is planning to keep running the Tevatron now at least through FY 2011, since it is likely to be competitive with the LHC in the Higgs search business at least that long. The current Fermilab long-term planned run schedule is here.

    DOE will keep supporting ILC research through FY2012, but the plan to make a decision about building it at that time now seems to be off the table. The LHC will have just begun producing results, and the current estimates of the ILC cost are so high that making the case for it will be very difficult. A story in Science quotes William Brinkman, the head of DOE’s Office of Science as saying:

    With all the contingencies, you’re talking about $20 billion. In my opinion, that price pushes it way out into the future, and onto the backburner.

    Funding for new high-energy accelerators is likely to mainly be devoted to participating in any upgrade of the LHC at CERN, and the Project X/muon collider proposals at Fermilab. There will be workshops at Fermilab next month to discuss Project X and the muon collider. Brinkman in his HEPAP talk notes that the HEP community will have to come up with a compelling scientific case for these projects, which will largely revolve around an expanded neutrino program.

    There was also discussion of a report from PASAG (the Particle Astrophysics Assessment Group). For discussion of the issues surrounding proposed experiments relevant to particle astrophysics and cosmology, see stories from Eric Hand at Nature News here and here.

    Posted in Experimental HEP News | 2 Comments

    Latest from the LHC

    Posted on October 25, 2009 by woit

    This weekend successful tests of injection of a beam from the SPS into the LHC were performed. The beam only traveled through a few of the sectors before being dumped, since all sectors of the machine are not yet ready for beam commissioning.

    A week or so ago the decision was made to start beam commissioning with the magnets only fully commissioned to 2kA. This means that the machine will be limited to operation at 1.1 TeV/beam this year. The current schedule has commissioning to 2kA finishing November 16, attempts to circulate 450 GeV beams starting November 23. On December 7, the beam energy would start to ramp up to 1.1 TeV. 1.1 TeV/beam collisions would start Dec. 14, with shutdown for Christmas/New Year’s starting Dec. 16. This means that 2009 will not see physics collisions, but will perhaps see collisions at energies marginally higher than that of the Tevatron.

    By the end of the year, 2 sectors will be commissioned to 6kA, the magnet current needed to run the machine for physics at 3.5 TeV/beam. The rest of the sectors will be commissioned to 6kA and the energy ramped up to 3.5 TeV/beam starting after the shutdown ends in January.

    Update: Some more from the latest schedule. January 7 will be the start of recommissioning after the shutdown, and current plan is to have the machine ready for physics collisions at 3.5 TeV/beam by February 8.

    Update: The date to begin beam commissioning again by circulating a beam in the LHC is now set for Friday November 20.

    Posted in Experimental HEP News | 5 Comments

    Master of the Universe

    Posted on October 24, 2009 by woit

    A couple days ago I got an odd phone call, from a reporter at the Guardian, asking me to comment on the appointment of Michael Green as Lucasian Professor at Cambridge. I told the reporter that I wasn’t a really appropriate person to be asking; for one thing I’ve never met him personally. I did say that from what I knew of his scientific career, he was a quite good choice. He and John Schwarz made great progress in understanding string theory, working on it at a time that this was a very unpopular thing to do. In my view much of the problem with particle theory the past 25 years has to do with the lack of sufficient talented people willing and able to work on the kind of unpopular research that Green and Schwarz took up.

    Several people have now pointed out to me the new story in the Guardian, Michael Green: Master of the Universe, which makes clear the reason for that phone call (although none of my comments made it into the story). There’s the usual hype about string theory: “the subject’s thriving”, and the latest news is that it may lead to better understanding of high temperature superconductors and thus help solve the world’s energy problems. In a sidebar, the claim is made that:

    The Large Hadron Collider, at Cern, could provide evidence for the theory by analysing the collisions of fundamental particles at high energies.

    although Green admits:

    …that really is wildly optimistic, and I suspect that’s not going to happen.

    Green deals with criticism of string theory with a laugh and ad hominem attacks on Lee Smolin and me as “two particular people who don’t have any particular reason to be knowledgeable about the subject.” As for the idea that it might be a good idea for people to look for alternatives to string theory (much the way he and Schwarz worked in the early 80s), his comment is “But there is nothing else.”

    Green seems to be not completely sure I have a Ph.D. For those interested in the question of my qualifications, there’s an old blog entry here. It should perhaps be updated to note that, while I’m still responsible for the Math department computer system, I no longer have the odd title of “Director of Instruction”, but was moved to a non-tenured faculty position as “Lecturer”. Recently I was promoted to the position of “Senior Lecturer”, still non-tenured, but with a long-term contract.

    I wish Green the best with his promotion.

    Posted in Uncategorized | 28 Comments

    Physicists Calculate Alternative Universes

    Posted on October 22, 2009 by woit

    According to a story in the Stanford Daily, the recent arXiv preprint mentioned here and discussed many other places on the web has given us two new scientific celebrities:

    Two of Stanford’s physicists, Professor Andrei Linde and postdoctoral researcher Vitaly Vanchurin, have garnered recent celebrity-status in the scientific community for their recent discovery of the maximum number of alternate universes.

    Instead of consulting experts in this field and getting quotes about how significant this pseudo-science is, the writer asks Stanford students, who do a much better job than the experts:

    “I personally find the concept intriguing, but I think we should be wary of scientists who can use it as a way to write things off and stop looking for deeper answers to physical phenomena,” Lauren Janas ’12 said…

    Some Stanford students are not entirely convinced of Vanchurin and Linde‘s complicated methods.

    “I’m quite skeptical,” Frank Liu ’13 said. “I think it’s hard to tell how many universes there exactly are.”

    The story ends with the mystifying news that the authors hope “that in the future, they can work with modular observations to confirm their findings.”

    For more media coverage of the multiverse, see here.

    Update: Oops, last link was broken, now fixed.

    Posted in Multiverse Mania | 26 Comments

    Higgs, Dark Matter and Supersymmetry: what the LHC will tell us

    Posted on October 19, 2009 by woit

    The Council for the Advancement of Science Writing is holding a New Horizons in Science conference right now in Austin. This morning Steven Weinberg gave a talk, now available online, with the title Higgs, dark matter and supersymmetry, what the Large Hadron Collider will tell us. He described the Higgs as something definitely expected, supersymmetry as a much more speculative possibility, but had nothing to say about string theory during the talk. In the question session, Tom Siegfried of Science News asked him about why he hadn’t mentioned string theory, and what its prospects now were, 25 years after first being heavily promoted to the press. Weinberg answered:

    It’s developed mathematically, but not to the point where there is any one theory, or to the point that even if we had one theory we would know how to do calculations to predict things like the mass of the electron, or the masses of the quarks. So, I would say, although there has been theoretical progress it’s been, I find it disappointing. One of the hopes would be that the LHC would provide a clue to something we’re missing in superstring theory and I think there supersymmetry is the most likely place to look.

    One of the troubles with superstring theory is that although in a sense the theorists think there is only one theory, there are an infinite number of approximate solutions of it and we don’t know which one corresponds to our world. But at least in a large variety of the solutions of superstring theory there is supersymmetry visible at low energies, and if we see supersymmetry at low energies, superstring theorists may be able to derive from it some kind of clue as to how to solve these theories. But I haven’t talked about it in this lecture because I don’t see how that would work, it would be.. I mean I couldn’t say that that was likely with any degree of sincerity, and certainly the LHC and any other accelerator that we can imagine being built will not get up to energies which are high enough so that we can directly see the structures that are described by superstring theory, the strings or the D-branes or whatever it is. Those will not be accessible at the LHC, so any clue we get will be very indirect.

    I myself, well I was working on superstring theory in the 80s and gave it up because I… I moved into cosmology, which in the last couple of decades has had the excitement that elementary particle physics had in the 60s and 70s, a wonderful coming together of theory and observation. Cosmology now reminds me of the excitement that I felt when I was younger and doing particle physics.. and it’s a pity that superstring hasn’t developed better. I still think it’s the best hope we have, I don’t know of anything else. My own work very recently has been trying to develop an alternative to superstring theory as a way of making sense out of quantum gravity at very high energies. But even though I’m working on this I still find superstring theory more attractive, but not attractive enough…

    Siegfried gives an account of the talk here. It includes a new remarkably convoluted and misleading way of referring to the fact that string theory predicts nothing at all about observable physics:

    But despite a quarter century of intense effort, superstring theory has not produced a cohesive and clear guide to testing its fit with all the observable features of physical existence.

    Posted in Uncategorized | 32 Comments

    Short Items

    Posted on October 17, 2009 by woit
  • There’s a wonderful new research mathematics site: Math Overflow. For some discussion of it, see here and here.
  • For yet another wonderful new site about research mathematics, there’s the French Images des Mathématiques.
  • Why is there nothing in theoretical physics anywhere near as good as the above two sites?
  • Via Flip Tanedo, an NPR story about Berkeley’s parking spaces for Nobelists. He neglects to mention that, starting with Vaughan Jones in 1990, Berkeley started providing equivalent parking spaces for Fields medalists.
  • It looks like multiverse mania is not just an American phenomenon, since there’s a new popular book on the multiverse out in Germany Die verrückte Welt der Paralleluniversen, by Tobias Hürter and Max Rauner. For a synopsis in English, see here. The authors have a blog, Multiversum.
  • The Perimeter Institute has just announced more details of their expansion plans. The new 55,000 square foot expansion of their building will be named the Stephen Hawking Centre at Perimeter Institute. They have doubled the number of Distinguished Research Chairs to 20, with ten new appointments announced here. Director Neil Turok is giving a talk about their plans today, video should be on-line soon.
  • This week at Perimeter they’re having a Quantum to Cosmos Festival. It started off Thursday night with a discussion by 9 physicists organized around “what keeps them up at night”. String theorist David Tong explained that he used to be kept up at night worrying about whether string theory unification could ever be tested, scientifically justifying the subject. Nowadays though, he says he sleeps fine since he no longer needs to worry about this: even if string theory unification is untestable, string theory research can be justified because it provides approximate calculational methods that might be useful in nuclear or condensed matter physics.
    • Posted in Uncategorized | 10 Comments

    Nielsen-Ninomiya and the arXiv

    Posted on October 14, 2009 by woit

    Because of the New York Times article discussed here, four recent papers by Nielsen and Ninomiya have been getting a lot of attention in the blogosphere. Pretty much all of it has been unremittingly hostile, when not convinced that these papers must be some sort of joke (except for this from Sean Carroll). I just noticed that these papers have gotten some attention from administrators of the arXiv, who have decided to reclassify three of them, presumably since the appearance of the NYT article.

    The first in the series, arXiv:0707.1919 was originally posted in hep-ph, with a cross-listing to hep-th (see the Google cache of Oct. 5), but has now been re-classified as gen-ph (cross-listed as hep-ph and hep-th). Similarly, arXiv:0711.3080 has been reclassified from hep-ph to gen-ph, cross-listed to hep-ph (see Google cache of Sept. 12). I’m not sure what arXiv:0802.2991 was originally classified as, but the Sept. 3 Google cache has it as the same as now, gen-ph, cross-listed to hep-th. Finally, the most recent one, arXiv:0910.0359, was originally classified as hep-ph (Google cache of Oct. 7), now it has been re-classified to gen-ph, cross-listed to hep-ph.

    While the arXiv administrators seem to be indicating that they share the common opinion that these are crackpot papers, one thing there does remain constant: trackbacks appear there to various press stories and blog postings about these papers, but trackbacks to this blog seem to be censored.

    Update: Trackbacks to blog postings here on this Nielsen-Ninomiya subject have now appeared. The ways of the arXiv remain mysterious to me. About all I can tell is that trackbacks to some sources appear more or less immediately, presumably automatically (for instance the trackbacks to the original NYT article). For other sources, e.g. this one, they only appear in batches, often several days later, presumably after someone has gotten around to considering the matter…

    Posted in Multiverse Mania | 20 Comments

    Embarrassing Crackpottery

    Posted on October 12, 2009 by woit

    A while back I noticed that the arXiv had allowed the posting of the preprint Card game restriction in LHC can only be successful!, yet another in a sequence of crackpot articles about the LHC from Holger-Bech Nielsen and Masao Ninomiya. That these authors have managed to get the previous articles in the series published in the International Journal of Modern Physics A presumably has something to do with the fact that Ninomiya is an editor of the journal. I didn’t post anything about this, on the grounds that embarrassing crackpottery from well-known physicists that no one except them takes seriously is best ignored.

    Unfortunately, this particular piece of nonsense has been picked up by the New York Times, which tomorrow is running a story about it under the title The Collider, the Particle and a Theory About Fate. The writer, Dennis Overbye, presumably contacted some physicists to find out what they thought of this. If any of them told him this was just nuts and an embarrassment, that didn’t make it into the story, instead there’s:

    …craziness has a fine history in a physics that talks routinely about cats being dead and alive at the same time and about anti-gravity puffing out the universe.

    As Niels Bohr, Dr. Nielsen’s late countryman and one of the founders of quantum theory, once told a colleague: “We are all agreed that your theory is crazy. The question that divides us is whether it is crazy enough to have a chance of being correct.”

    Dr. Nielsen is well-qualified in this tradition. He is known in physics as one of the founders of string theory and a deep and original thinker, “one of those extremely smart people that is willing to chase crazy ideas pretty far,” in the words of Sean Carroll, a Caltech physicist and author of a coming book about time, “From Eternity to Here.”

    Perhaps it would be a good idea if physicists would remind journalists that often things that seem to be crazy really are crazy.

    Update: See more here from Tommaso Dorigo. I should have mentioned that his posting from a couple years back Respectable physicists gone crackpotty was linked to in the article by Overbye, who had an accurate take on the subject from at least one source.

    Update: Somehow I knew that Slashdot could not possibly resist this nonsense.

    Update: Sean Carroll has a long defense of the Nielsen-Ninomiya papers as not crackpot at all, but crazy in a positive way:

    There’s no real reason to believe in an imaginary component to the action with dramatic apparently-nonlocal effects, and even if there were, the specific choice of action contemplated by NN seems rather contrived. But I’m happy to argue that it’s the good kind of crazy. The authors start with a speculative but well-defined idea, and carry it through to its logical conclusions.

    As for the argument that prominently-placed New York Times stories promoting crazy ideas about physics might be problematic, Sean is having none of it. He argues that the public is able to differentiate between speculative ideas and solidly tested science, so it’s not a problem that:

    My own anecdotal observations are pretty unambiguous — the public loves far-out speculations like this, and happily eats them up.

    Posted in Multiverse Mania | 51 Comments

    In Search of the Multiverse

    Posted on October 12, 2009 by woit

    The ongoing pseudo-scientific multiverse mania continues, with the recent publication in the UK of a new book by John Gribbin promoting this to the public: In Search of the Multiverse.

    Gribbin expounds at length the usual string theory anthropic landscape/multiverse ideology, carefully avoiding introducing any mention of the fact that there might be quite a few scientists skeptical about it. On the crucial question of testability he invokes Raphael Bousso, who:

    hopes, and expects, that there will be ways to extract such broad rules of the behaviour of matter at what are low energies compared to the Big Bang, but high by the standards of everyday life, from string theory.

    There’s no indication given about what these broad rules implied by string theory might be, just a hint that whatever they are, we’re not going to be able to test them anytime soon:

    even the the technology of the Large Hadron Collider may not be up to the task of testing such predictions.

    Like many multiverse fans, Gribbin wants to mix together the many worlds interpretation of QM and the string theory anthropic multiverse in cosmology, attributing this insight to Susskind, and ending the next to last chapter of his book with:

    This pulls together everything discussed in this book so far in such a pleasing way that it is tempting to end it here. The Cosmic Landscape of string theory is just the many worlds theory of David Deutsch writ large, and with inflation included within itself.

    Unfortunately he doesn’t end the book there, but adds a final chapter promoting his own interpretation of the significance of the multiverse. His idea is that we are the product of a baby universe created by some race of superior beings:

    The intelligence required to do the job may be superior to ours, but it is a finite intelligence reasonably similar to our own, not an infinite and incomprehensible God. The most likely reason for such an intelligence to make universes is the same as the reason why people do things like climbing mountains or studying the nature of subatomic particles using accelerators like the LHC – because they can. A civilization that has the technology to make baby universes might find the temptation irresistible, while at the higher levels of universe design, if the superior intelligences are anything at all like us there would be an overwhelming temptation to improve upon the design of their own universes.

    This provides the best resolution yet to the puzzle Albert Einstein used to raise, that ‘the most incomprehensible thing about the Universe is that it is comprehensible.’ The Universe is comprehensible to the human mind because it was designed, at least to some extent, by intelligent beings with minds similar to our own. Fred Hoyle put it slightly differently. ‘The Universe,’ he used to say, ‘is a put-up job.’ I believe that he was right. But in order for that ‘put-up job’ to be understood, we need all the elements of this book.

    Personally, I think there’s an air-tight argument against this: any race of superior beings that produced a universe in which science descended into this level of nonsense would immediately wipe out their creation and start over. Since we’re still here, there can’t be such a race operating out there.

    Gribbin also has a Sci-Fi novel entitled Timeswitch coming out soon.

    For two reviews of the book, see here and here.

    In other multiverse news, FQXI has a story here promoting Andrei Linde, Renata Kallosh and their work on the string theory multiverse. Linde and a collaborator have a new paper How many universes are in the multiverse? on hep-th (by the way, why are these things not in qr-qc, since they’re “quantum cosmology” if anything is?). They come up with a number of 10 to the 10 to the 375 for the number of universes, and seem to argue that one needs to analyze all these to come up with predictions:

    But when we study quantum cosmology, evaluate the total number of universes and eventually apply these results to anthropic considerations, one may need to take [the number of degrees of freedom of the observer] into account. Potentially, it may become very important that when we analyze the probability of existence of a universe of a given type, we should be talking about a consistent pair: the universe and an observer who makes the rest of the universe “alive” and the wave function of the rest of universe time-dependent.

    Posted in Multiverse Mania | 24 Comments