Various Links

  • This week there’s a conference in Oxford I’d have loved to have been at. Slides from some of the talks are already posted here. The conference is in honor of Graeme Segal’s 70th birthday. Happy Birthday Graeme!
  • Physics Today has a very interesting piece about the current state of HEP posted today by Burton Richter, focused on the topic of Should the US join CERN?. On the ILC, with Japan the prospective location, he takes the point of view that it’s most likely to be interesting as a Higgs factory, so a 250 GeV machine will suffice:

    The ongoing International Linear Collider (ILC) program is aimed at building and running a 500-GeV machine by 2020. A new ILC design study is scheduled for release in a few months, but by 2020 the LHC should have delivered enough cumulative output to make anything the ILC can produce irrelevant beyond what its lower-energy Higgs-factory option can do.

    Besides this, at the energy frontier the LHC is the only game in town, with HL-LHC and HE-LHC challenging and expensive projects that will dominate the future of the subject. If the US wants to participate, Richter argues that a new, closer formal relationship is needed. The politics here is likely to be tricky, with the US Congress not exactly keen on spending money outside the US, through an organization where the US has little influence.

    About the future he’s most worried about the too high cost of getting to higher energy permanently delivering us into the hands of multiverse mania:

    If our only theory of everything comes down to the landscape model, where we are only one of a zillion universes with the parameters we see as only a statistical accident necessary for life, the game is over. I hope not.

  • One of the landscapeologists whose influence Richter is worried about is Joe Polchinski at Santa Barbara. Courtesy of the Milner prize competition, Polchinski is in line for about $3 million more influence if he beats out his two competitors next March, and UCSB has a press release about this. The press release explains that Polchinski is being rewarded for his discovery of “one of the basic building blocks of space time”

    According to the award citation, the Physics Frontier Prize recognizes Polchinski’s broad contributions to fundamental physics, most notably the discovery of D-branes. These have been shown to provide the atomic structure of black holes, predicted long ago by Stephen Hawking, and, as such, are one of the basic building blocks of spacetime.

    One goal of the Milner prize is to raise the profile of work that is not Nobel-worthy because it isn’t testable science, by creating a bigger prize for it than the Nobel. Unfortunately I think one side-effect of this is to blur the distinction between things we have evidence for and those that are pure speculation (with “D-branes=basic building block of spacetime” the latter, being promoted to the public as if it were the former).

  • Steven Weinberg’s graduate level text on QM, Lectures on Quantum Mechanics, is now out, and I’m very much looking forward to getting a copy soon.
  • The Higgs boson is Time Magazine’s Particle of the Year, Fabiola Gianotti runner up for Person of the Year.
  • I recently read Benoit Mandelbrot’s posthumously published autobiography The Fractalist: Memoir of a Scientific Maverick, but don’t really have the time or interest to write a review here. Mandelbrot has an unusual life-story, starting with being hidden in war-time France to escape the Nazis.

    The thing that struck me most about the book though was that I had always assumed he was an academic outsider, but the true story is quite different. His family was academic mathematics royalty, with uncle Szolem Mandelbrojt a highly influential French mathematician at the College de France guiding him closely. A big theme of the book is Mandelbrot’s detailed explanation of the debates involved at each stage of his life over what would be his best next career move. There’s more about this than about the mathematics.

    Another reason not to write a review is that I can point to two interesting ones already out there. The Wall Street Journal got Stephen Wolfram to write one, see here, and American Scientist has one by Brian Hayes here. Hayes isn’t exactly kind to Mandelbrot, emphasizing his egotism and desire for recognition:

    Mandelbrot begins one chapter of his memoir with the declaration: “A blessing throughout life: I never wonder who I am.” He is untroubled by doubts or regrets, and untainted by false humility. In these pages you will find no self-effacing disclaimers about standing on the shoulders of giants; if Mandelbrot has seen a little farther, it is because he’s taller. From an early age his scientific hero was Johannes Kepler, and his goal in life was to accomplish something worthy of a modern Kepler, overthrowing an outworn orthodoxy. By his own account, he succeeded brilliantly, with quite a number of “Kepler moments.” (As far as I know, Kepler himself had only one.)

  • For another, mathematically more interesting, discussion of a recently departed mathematician with an amazing career, see the AMS Notices article on I. M. Gelfand. Gelfand’s career and influence is a huge topic, so this is just Part I.
  • A significant new advance in representation theory is explained nicely by its authors here in terms of the general philosophy of representation theory laid out by Gelfand. A standard topic in representation theory courses is to classify the unitary representations of compact semi-simple Lie groups (highest weight theory), but the question of what happens in the non-compact case is much, much more difficult and still open, with one problem that the representations are infinite-dimensional. This latest paper reports “a finite algorithm for computing the set of irreducible unitary representations of a real reductive group G” with the authors describing their result as follows”

    The third step in Gelfand’s program is to describe all of the irreducible
    unitary representations of G. This is the problem of “finding the unitary dual”

    G^u =def {equiv. classes of irr. unitary representations of G}

    It is this problem for which we offer a solution (for real reductive G) in this paper. It is far from a completely satisfactory solution for Gelfand’s program; for of course what Gelfand’s program asks is that one should be able to answer interesting questions about all irreducible unitary representations. (Then these answers can be assembled into answers to the questions about the reducible representation π, and finally translated into answers to the original questions about the topological space X on which G acts.) We offer not a list of unitary representations but a method to calculate the list. To answer general questions about unitary representations in this way, one would need to study how the questions interact with our algorithm.

    All of which is to say that we may continue to write papers after this one.

    This sort of representation theory is ferociously technical, with many papers in the subject appearing to have been written only to be read by the very small number of people expert in all these technicalities. This document is surprisingly different, starting off with an accessible introduction to the subject, and then devoting a lot of space to a careful, readable exposition of the details of the necessary technicalities. The subject is still ferociously complex and technical, but this paper gives one a fighting chance to actually understand what is going on if one has the time and energy to read one’s way through it. An admirable and unusual choice of how to write a modern math paper.

Update: A commenter points out a nice article that just appeared in Scientific American, Strange and Stringy, by Subir Sachdev, who explains some recent ideas about using dualities to understand certain condensed matter phenomena.

This entry was posted in Uncategorized. Bookmark the permalink.

25 Responses to Various Links

  1. Bernhard says:

    “It’s a quirk of CERN that team leaders like Gianotti — with their power over so many people and so much machinery — do not have titles like chief scientist or project director. They are simply called spokespeople”

    It is actually a quirk of the reporter who wrote this article, that clearly has no clue how a HEP experiment is actually run. Spokespersons are called this way, because this is actually what they do, speak for the collaboration. Somehow this Jefrey Kluger fellow think Gianotti or Incandela had actually something to do with the Higgs discovery. Very funny…

  2. Yatima says:

    String Theory and Condensed Matter Physics meet in the January 2013 issue of SciAm: String Theory Helps To Explain Quantum Phases Of Matter by Subir Sachdev.

    We read:

    “For my purposes, the picture of strings dancing in some higher-dimensional spacetime is not important. It does not even matter to me whether string theory is a correct explanation of particle physics at very high energies. What is significant is that the duality lets me exchange a mathematically intractable problem for an easy one.

    When electrons in crystals have only a limited degree of entanglement, they can still be thought of as particles (either the original electrons or pairs of them). When large numbers of electrons become strongly entangled with one another, however, they can no longer be viewed as particles, and conventional theory struggles to predict what happens. In our new approach,
    we describe these systems in terms of strings that propagate in an extra dimension of space.

    My Harvard University colleague Brian Swingle has drawn an analogy between the extra spatial dimension and the network of quantum entanglement. Moving up and down the network is mathematically just like moving through space. The strings can wriggle and fuse together within the extra dimension, and their motion mirrors the evolving entanglement of particles. In short, the spooky connections that troubled Einstein make sense when you think of the degree of entanglement as distance through an extra spatial dimension.”

  3. Peter Woit says:

    Thanks Yatima,
    Nice article. I’ll add this to the posting itself.

  4. bjm says:

    Bernhard said, “Somehow this Jefrey Kluger fellow think Gianotti or Incandela had actually something to do with the Higgs discovery. Very funny…”

    She had nothing to do with the discovery? Now I’m really confused. Maybe it’s different in Europe, but in the US, a spokesperson is not assumed to have any managerial responsibility. Other statements I’ve seen convinced me that at CERN the “spokesperson” was actually the project manager Now, your quote above implies she did have no managerial responsibility for the team the co-discovered the Higgs. Confusing.

  5. P says:


    “Somehow this Jefrey Kluger fellow think Gianotti or Incandela had actually something to do with the Higgs discovery.”

    Define “had to do with,” or this statement runs the risk of sounding *really* silly.

    I’m not sure about Gianotti, but Incandela is a HEP professor and it is safe to assume that he has been guiding his group in building the CMS detector and analyzing data for the last number of years. Senior members of experimental HEP groups at universities are crucial in organizing younger members to execute on the building and commissioning of an experiment, and also in data analysis. If I understanding correctly, sokespeople are handed the reins after years of hard work.


  6. Simon says:

    At a HEP experiment, the spokesperson is the de facto chief executive. However, as mentioned in a previous comment, a large collaboration behaves pretty much like a semi-headless organic entity. The leader does play an important role but I think it would be fair to say that the Higgs-like object would have been discovered if they had been replaced with any number of their equally well qualified colleagues. The scientist who spent his/her nights ensuring that, eg, the calorimeter read-out works has just a great a claim on the discovery.

    It should also be pointed out that I’ve never seen spokespersons behave in any way which suggests that they feel a greater ownership of an experiments’ physics results than any other member of the collaboration.

    This whole business of awarding prizes to the bosses puts them in a difficult position.

  7. Bernhard says:

    P, Simon, bjm, et al,

    Yes, this statement was actually silly one, one that I have no real intention to defend it… I was being flippant on purpose.

    I exaggerated what I had in mind to compensate I found no other way of expressing my frustration with this whole business of giving the experiments spokespersons more credit that they deserved. This is not to say they don´t deserve some credit, of course they do… But in terms of who should really be right on the spotlights, I´m sorry, it should not be them, and I´m uncomfortable with this. The people who did the work and its direct leaders (of the ATLAS and CMS Higgs groups) should be those really getting the biggest attention, in my view. The spokespersons had they share of contribution but it´s way smaller then those people, in comparison. The general public has really no idea how this works. Reading the article, one might for example think that a spokesperson actually is leading a Higgs analysis. While they definitely have a say on what goes out or not from ATLAS and CMS I know they were not in front of the actual work (and with actual work I mean, the event selections, understanding the systematics, doing the actual statistical analysis and the plots). This is what I had in mind. I think, no, I know, that the people doing the hard work are not being properly acknowledged for that and this will just be forgotten from history. What will remain is just the spokespersons and to me this is both sad and unfair. I will not defend my stupid comment further than that, but hopefully you can understand my frustration…

  8. P says:


    Your frustration is totally understandable. Sorry to jump on you – a few times already I’ve heard some sentiment of “the spokespeople don’t actually do any science, and feel the need to correct it. Clearly you know what you’re talking about, seeing your recent response 🙂

    For awhile I believe they were considering the boson itself for “person of the year.” If they were willing to break with tradition there, why not break with tradition and consider the entire ATLAS and CMS collaborations? Or maybe ATLAS + CMS + accelerator guys without whom none of this would happen?


  9. emile says:

    Awards and other forms of public recognition like Time Magazines’ “person of the year” are aimed at individuals, not groups. The media in particular want a “human story” which you can’t tell if you give it to 7000 people. For prizes like the Nobel or Milner, I really wish the collaborations could receive them. But I’d rather have one or two experimentalists get those prizes than to see those prizes go to theorists only. And if you are going to pick one person from an experimental collaboration, the spokesperson is the logical choice.

  10. Noah Smith says:

    Seems like the scientific revolution started by Galileo, Bacon, Newton, etc. might be over.

  11. Bernhard says:


    I ´m not sure it is really the logical choice. One could think that different ideas could go for different persons. Assume one discovers besides the Higgs, SUSY and other BSM physics that are Nobel worthy. Should all these go to spokespersons? If one face no other choice than giving the prizes to “leaders”, than the logical choice would be, to me, the conveners, not the sppekespersons. The thing with spokesperson is not one of logic, but of tradition, one that I advocate should be broken to adapt to the reality of the modern HEP collaborations.

  12. Here is a link Peer-review turned on its head has market value

    which might be interesting for those who appreciated the post
    Why Author Pays Open Access is a Bad Idea (which has comments closed).

  13. Trevor says:

    The piece by Richter was interesting and raised some good points but I think his take on CERN isn’t really justified. It’s not fair to lump all of the European member states into one group that simply has one vote. I believe that most of those nations contributed independently of each other.

  14. Marcel van Velzen says:

    Hello Peter,

    I already have Weinberg’s book on QM at home and read large part of it 🙂
    It says “First published 2013”!

    Great book, reads well, too many good things to enumerate. The more advanced parts are similar to his “The Quantum Theory of Fields”.

    One of the last problems asks you to calculate the decay rate of the 2p-1s transition in hydrogen. It leads to a funny formula with 2 and 3 to the power eight! I already asked this on Matt’s blog but want to ask it here also. Everyone seem to agree that it corresponds well to the experimental value but I can’t find the experimental value anywhere on the Internet. I get the impression it has never been measured and people just use the calculated value assuming that it is correct. The best thing I could find is this:
    but formally it is calculated there also, although it has to be more or less correct to lead to the right frequency. So if anybody knows where to find it, thanks.

  15. Chris Oakley says:

    It says “First published 2013″!

    I am impressed already. Weinberg has clearly mastered something that other physicists only talk about – closed timelike lines.

  16. Serge says:

    Just interesting fact – Gelfand’s “Linear Algebra” was basis (pan intended) for Linear Algebra courses for all Soviet Union technical colledges(“Institutes”).

  17. Martin says:

    Merry Christmas, Peter.

    I read your blog for two years and I am glad that I have this source of informations. I wish you merry Christmas and happy New year.


  18. crossing symmetry says:

    To all the desperate phenomenologists out there who are waiting for the appearance of another anomaly so that they can do some “science”, ATLAS experiment is seeing a resonance of the same-sign dimuon at 105 GeV. With 13fb-1 data, the significance of the bump is 5.02 sigma–around 14 events at the resonance. I hope this will keep our brilliant phenomenologists busy over the holidays in a race to build model.
    My personal hunch: looks like nature has Higgs triplet for us, the signature looks very similar to the doubly charged Higgs. If that is the case, as Philip Gibbs has written in his blog, a doubly charged Higgs would explain the H->gg excess.

    PS: Dear Peter, I have been following your blog for quite some time. I got the information from on my friend who works in the atlas collaboration. I hope out of courtesy, my IP address will not be released.

  19. Peter Woit says:

    Crossing symmetry,

    Thanks! Looking a bit at published results, it seems that conventional wisdom is that 105 GeV is much too light to be a doubly charged Higgs, such a thing should have been visible at the Tevatron.

    Looking at the published ATLAS results based on 5 inverse fb, there does appear to be an anomalously high number of events around 100 GeV (but also around 60 GeV), see
    I’d guess people are not taking this too seriously, assuming that new physics at that mass would have shown up earlier. The big question of course is whether CMS sees the same thing, but the only relevant CMS results I could find don’t even plot data at that low a mass.

    Don’t worry, the only time I would ever disclose anything about the identity of an anonymous commenter is if they were behaving extremely obnoxiously, and spreading rumors doesn’t qualify at all as far as I’m concerned, quite the opposite if they’re well-informed…

    Merry Christmas to all!

  20. Robert Rehbock says:

    @Chris Oakley:
    But Weinberg will, like the LHC spokespersons, need find an appropriate way to share the credit for publishing in the future with the many proofreaders and editors at his publishing house without whom this would not have been possible.
    A special Happy Holidays to you and yours. You may recall our meeting last year , or was it next year time gets so uncertain now. 🙂

  21. Chris Oakley says:


    Of course.

    Happy Christmas 2016!

  22. Peter Woit says:

    About the rumor from “crossingsymmetry”.

    This has propagated to some other blogs, but from what I’ve been able to gather, this rumor should be taken with a large grain of salt. It doesn’t seem to correspond to anything known to many people at ATLAS (or CMS for that matter).

  23. Yatima says:

    A bit late: Rolf-Dieter Heuer in Nature’s Ten People Who Mattered This Year

  24. camillo vidani says:

    > The media in particular want a “human story” which you can’t tell
    > if you give it to 7000 people.

    Well, the media is very much concerned with team sports, and people seem to like stories about it and find plenty of “human factor” in them. These are quite smaller teams, granted, but I think it wouldn’t be so difficult to explain to journalists that experimental physics is a team sport now, and not about single geniuses.

    If we wanted to.

    Obviously, the leading figures still like the genius mystique very much 😉

Comments are closed.