Various

Possibly of interest:

  • Goro Shimura, one of the major figures in twentieth century number theory and arithmetic geometry passed away on May 3 in Princeton at the age of 89. Princeton has an article about his life and work here. There’s another article about him here (in German). Back in 2008 Shimura published an autobiographical memoir, The Map of My Life, which I wrote about here.
  • The Dutch publication de Volkskrant has an article asking if theoretical physics has lost its way. Sabine Hossenfelder and Avi Loeb are quoted on the “there’s a problem side”, Robbert Dijkgraaf on the “no problem here” side.
  • A commenter here points out an article in le Monde about the currently unresolved question of what to do with the 100,000 or so pages of writings left by Grothendieck at the time of his death. There seems to be a consensus that someone should carry out the expensive project of having the pages cataloged and transcribed, but how to pay for this, and who should ultimately take ownership of the papers remains up in the air. Supposedly a sizable part of the documents deals with Grothendieck’s speculation about physics. The article starts off with a characterization of Grothendieck’s work as important in the story of the Higgs discovery, which is quite inaccurate (there is no significant relation between his work and the Higgs).
  • For many years people at SLAC have used the database there to produce “Topcites” lists of the most heavily cited papers in HEP physics, giving some insight into what topics are the most popular in current HEP research. From 1997-2003 Michael Peskin wrote up some reviews of what was going on in HEP physics each year based on these lists, and has started doing so again (for 2017 and 2018). These lists and the reviews are now dominated by astrophysical and cosmological topics, with little about HEP theory. To get an idea of what the hot topics are in HEP theory these days, take a look at the list of most frequently cited papers by hep-th preprints in 2018.
  • The series finale of The Big Bang Theory will air this week, on Thursday. Since I’ve canceled my cable TV service a while back I haven’t been following the latest episodes, which evidently feature a replacement for the failure of supersymmetry, called “super-asymmetry”. At some point I hope to catch up with these, and find out what happens to “super-asymmetry”.
  • This week the European Strategy Update for Particle Physics is holding an Open Symposium in Granada, to discuss plans for the post-LHC future (a blog posting about this from Tommaso Dorigo is here). I’ve written here about the difficult issues that CERN and European HEP physicists are facing. Looking at one of the first talks on future colliders, I was surprised to see muon colliders listed as a potentially viable possibility, since I thought that the technology needed for those was still far in the future.

Update: Kenneth Chang at the New York Times today has an obituary for Shimura.

Update: On the obituary front, it was announced today (5/24) that Murray Gell-Mann has passed away, at the age of 89. The New York Times has an obituary written by his biographer, George Johnson.

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23 Responses to Various

  1. shantanu says:

    Peter, there seems to be some mistake in the listing of top-cited papers,
    For the 2018 list, arXiv:1901.01540 is cited as a top cite, which just 4 citations.

    In a related issue I find that inspire-hep is no longer adding references to papers cited in 2nd and beyond versions of papers submitted to arXiv.

  2. Jeff Berkowitz says:

    I love these “possibly of interest” posts. Please keep them up.

  3. Grothenhiggs says:

    Was there ever a character that is a mathematician in Big Bang Theory? How was/would be the interaction of Sheldon and a pure mathematician?

  4. Hello Peter, long time no talk. Thanks for the link!

    As for muon colliders: the rationale of putting them on the table is to take the
    design of one such machine as seriously as it should. Here I summarize very succinctly the status of matters:

    – a muon collider would be a wonderful machine, enabling studies of the Higgs sector as well as searches for new physics in a cleaner environment than hadron collisions

    – muons decay in 2.2 10^-6 s in the lab rest frame, but in an accelerator they can live long enough to be accelerated, squeezed, and collided at high luminosity. This is not a heavy technical issue – we know how to get around the main hurdles.

    – there are big issues concerning the high fluxes of radiation (neutrinos!) produced around the ring, but these are also solvable

    – the main issue is how to produce them at low emittance. The conventional way to produce a muon beam is by hadron decays, but there the emittance is very large and cooling is a big issue. The alternative under study is to produce muon pairs by e+ collisions on a fixed target at threshold. There the emittance can be small, but intensity is an issue, and the target design is a bit nightmarish at the moment.

    All in all, I do believe Europe should pay attention to fostering these studies, although it is likely that a muon collider could only see the light when you and I will not be around anymore.

    Cheers,
    T.

  5. Someone who reads Dutch says:

    I am bemused by Dijkgraaf’s response to Hössenfelder’s criticism. In his first quote, he says that physicists have no need for a thought police. That’s actually a rather unfair representation of Hössenfelder’s point, especially since she’s explicitly disavowing it later on in the article (of course this might only have been after having been informed of Dijkgraaf’s objection).

  6. Peter Woit says:

    shantanu,
    I think that’s just a paper Peskin is referring to as a very recent observational result, not as a top-cite.

    Grothenhiggs,
    I don’t recall mathematicians ever making any sort of appearance on Big Bang Theory, unfortunately indicative of the point of view of most physicists, that whatever mathematicians might be doing, it has nothing to do with physics.

    Tommaso,
    Thanks for the summary!

    Someone who reads Dutch,
    I’ve also run into the phenomenon of people responding to a serious scientific argument that an idea doesn’t work with “thought police” accusations. In this case, Dijkgraaf, as IAS director, has a lot of influence on what research gets supported and what doesn’t. Accusing someone in Hossenfelder’s position of being a heavy-handed ideological enforcer is kind of comical.

  7. TME says:

    Peter,

    “Accusing someone in Hossenfelder’s position of being a heavy-handed ideological enforcer is kind of comical.”

    That might be a bit harsh, but don’t you agree that an outsider (in terms of understanding of string theory and nonperturbative QFT developments) like Hossenfelder trying to give arguments as to what research should and shouldn’t be done is at least a bad look?

  8. Peter Woit says:

    TME,
    In my experience Hossenfelder is generally careful to aim her criticisms at things she understands well enough to evaluate. Some of her arguments are about the reward structure of the field and some of the problematic results this leads to. She is more competent than most to make these arguments. I don’t see her making arguments on more technical topics unless she has a reasonably good understanding of them.

    For decades now, a favorite tactic of some theorists pursuing failed research programs has been to refuse to address criticisms of such failed research programs, resorting instead to ad hominem attacks on their critics as incompetents or “thought police”, or whatever. You can try shooting the messenger, but it doesn’t change the facts about your failure.

  9. Anonyrat says:

    Avi Loeb has a sensible suggestion:

    “He {Loeb} therefore proposes a kind of hippocratic oath for physicists, inspired by the oath that doctors take, in which physicists must swear that at least one idea they are working on can still be confirmed experimentally during their lifetime. ‘If I succeed, I would like to call them physicists again. Until then I think their ideas say nothing about reality. ” (Via Google translate)

  10. Peter Woit says:

    Anonyrat,
    I actually strongly disagree with that. Some theoretical physics is “phenomenological”, closely tied to experiment, and that should be evaluated in terms of its relation to experimental results. But other areas of theoretical physics are not closely tied to experiment. For instance, there is a huge amount we still do not understand about quantum field theory. Theorists who want to spend their careers trying to develop new techniques leading to a better understanding of quantum field theory should be able to do so, even if there’s no particular reason to believe that success would lead to some experimental test.

    The argument that you want people to be able to do pure research that advances understanding, not just research with near-term practical consequences, is clear to most scientists, and extends to the issue of experimental confirmation. The primary goal is deeper understanding. If such deeper understanding leads to new experimental tests and confirmation, great, but that’s not the most important thing.

    The real problem is how you evaluate the results of such attempts to get deeper understanding, in the absence of clear experimental tests. The problem with string theory unification is not primarily the lack of experimental confirmation. It’s a failed idea that does not lead to models that convincingly explain anything that we don’t understand about the SM.

    I don’t think you should stop people from thinking about speculative ideas. But, you need some way to get them to give up when such ideas aren’t working and try something else, and there won’t always be experimental results that can provide decisive answers to what works and what doesn’t.

  11. Someone who reads Dutch says:

    On the bright side, I think it’s a safe bet to say that the debate won’t go away anytime soon. If Hossenfelder (my apologies to her for misspelling her name earlier) and Loeb, despite going against the mainstream and not being personally involved in string theory research, have enough traction that mainstream media (even if it’s only Dutch mainstream media) are reporting on their claims, and eliciting a response from one of the most prominent faces of theoretical physics in the world, I think that in itself is an enormous victory, and I want to congratulate Hossenfelder and Loeb on that.

    My impression of Dijkgraaf in the article is that he’s mainly putting out tired clichés. I mean by comparing the 40 years in the desert of string theory to Einstein’s years of building up towards the theory of General Relativity. And I think Dijkgraaf himself surely realizes that the analogy is not beyond serious criticism, to put it very mildly. The main problem with this defense seems to be to me that he could use it no matter what. It almost seems like an abuse of Einstein’s prestige to use it to defend a potentially pointless enterprise.

    I think philosophy of science must come to grips with questions like: How can we actually distinguish between “a genuine quest for new ideas” on the one hand, and “the inmates running the asylum” on the other? I think we are already seeing that Popper’s falsification criterion is just not cutting enough ice with enough people, because many folks are rightly pointing out that a successful paradigm shift is always born of the realm of heuristics and intuitive guesses.

    However, this last argument does strike a false note with me, not so much because it is untrue but because it does not apply. If we would have asked Einstein what he had been up to between the years of 1907 and 1916, he wouldn’t have said that he was aimlessly exploring new ideas in order to bring about a paradigm shift. From very early on, Einstein had a quite definite vision in mind of what the theory of General Relativity should accomplish (starting with the “luckiest thought of his life”, or however he called it), and also he knew approximately what kind of mathematical tools should be involved in the shaping of that theory. So in that sense, string theorists are *not* doing what Einstein did, because they do not have the same sense of aim and direction that Einstein had (and it is amply documented that he did have it). At least to my understanding, all that string theory has to offer are some partial inroads into the Great Unknown. Quite a big difference. It actually seems a falsification of history to compare string theorists with Einstein.

  12. Someone who reads Dutch says:

    Of course, my statement that “philosophy of science must come to grips with questions like […]” should not be construed as meaning that there should be a Thought Police making sure philosophers of science are working on this question…

  13. Peter Woit says:

    Someone who reads Dutch,

    An interesting question for those who compare themselves to the Einstein of 1907-1916 is whether the evidence isn’t more on the side of their efforts being comparable to those of the Einstein of 1922-1955, who devoted decades to failed ideas about how to unify electromagnetism and GR. This question should be especially poignant for the director of the IAS, the institution that hosted Einstein’s failed efforts.

    From what I know of the history, if you look at Einstein’s work from 1907-1916 you see the gradual successful working out of an early vision, whereas if you look at 1922-1955 you see an increasing accumulation of evidence for why the initial vision couldn’t work. It’s the latter story which looks comparable to the string theory unification story (which in a way, is about the same thing: a failed geometrical idea of how QED and GR fit together).

    Of course one major difference is that Einstein never attracted a significant number of followers for his failed program, whereas string theory involved thousands and still has some sort of dominant role in many parts of the theory community. Arguably there’s nothing wrong with encouraging a single talented researcher to pursue their vision even long past the point it seems to others to not be working out. But you don’t want the whole community doing this.

  14. jsm says:

    One comment on Shimura that may be relevant to the current debates in physics. Throughout his career Shimura followed a very independent path — no one seems to know who his doctoral advisor was. The elliptic modular curves (quotients of the complex upper half plane by a congruence subgroup of SL(2,Z)) are initially defined over the complex numbers, but they are known to have canonical models over number fields. For the analysts, this is true because of the properties of the Fourier expansions at the cusps, and for the algebraic geometers, it is true because they can recognize the curves as a moduli varieties. There are similar complex curves attached to every quaternion algebra over Q split by R, but they have no cusps and are not moduli varieties, and so everyone knew that they did not have canonical models … until Shimura proved they did. This was perhaps his most original contribution, and was not something that someone too deeply embedded in the culture of the day could have done. Today the curves are named after him.

  15. Anonyrat says:

    Peter, I agree with what you wrote; though we would presumably value “improved understanding of QFT” higher than “improved understanding of string theory” because QFT has a well-demonstrated relevance to the physics of the universe, while string theory does not. I take it that Avi Loeb is trying to find a test to keep members of the physics department from spending their entire career on topics that are fiction though written in mathematics.

  16. workerpleb says:

    There seems to be a consensus that someone should carry out the expensive project of having the pages cataloged and transcribed, but how to pay for this, and who should ultimately take ownership of the papers remains up in the air.

    Scan the pages. Upload to the internet. The enthusiast nerds will sort the pages by themselves.
    I am being serious.

  17. Peter Woit says:

    workerpleb,

    I don’t think it’s so easy. Montpellier has conserved, organized, scanned and put on line, see
    https://grothendieck.umontpellier.fr/
    18000 pages of his earlier documents (another 10000 are not online, for legal reasons including the fact that letters can’t be made public without permission of the writer). Even with all this careful work, many of these documents are not yet in a very usable form. In particular, a lot are hand-written, with deciphering Grothendieck’s handwriting a skill most people won’t want to spend the time to acquire. They really should be transcribed into TeX to be useful, but it looks to me like this would require a sizable group of French-speaking experts in algebraic geometry with a lot of patience and a lot of time on their hands.

  18. From his reading of Grothendieck text “La clé des songes” Connes – in this video with Serres: https://youtu.be/pOv-ygSynRI?list=PLwl60Z8ihqF7C4GNQUJCxNPFXPqfN087g&t=2513 – emits roughly the hypothesis that Grothendieck ‘ father dreamed of writing but never did so the 70000 pages written & archived by Grothendieck at his home might be his tribute to some extent.

    Connes doesn’t doubt one could develop a software to decipher the handwriting (thanks to IA ? ;-).
    I guess a citizen science project like the one imagined to decode Darwin’s Handwriting would be more difficult to implement due to the manifold of subjects (from abstract math to potentially paranoïd thoughts?) & legal issues.

    About a possibly not so far-fetched connection between particle physics & Grothendieck concept of motives :

    “C’est une idée qui a émergé lors de discussions entre physiciens et mathématiciens à l’IHES, à l’heure du thé”, se rappelle Francis Brown, professeur à l’Université d’Oxford [et à l’IHES (http://www.ihes.fr/~brown/)]. Le défi était de calculer comment les particules se désintègrent lors d’une collision sans se lancer dans les calculs d’intégrales utilisés classiquement, souvent très complexes. “Et c’est là que le miracle intervient: nous pensons que derrière ces intégrales se cachent des motifs qui permettraient de les calculer beaucoup plus rapidement! s’enthousiasme Francis Brown . Aucun physicien n’aurait pu s’en apercevoir. Il a fallu que Grothendieck passe par là!”

    (https://www.science-et-vie.com/science-et-culture/grothendieck-les-archives-fantasmatiques-41922).
    cf Mathilde Marcolli too: https://arxiv.org/abs/0907.0321

  19. jsm says:

    There may be gems in the 18,000 pages (or 118,000 pages) of Grothendieck’s notes, but much of it seemed to me (when I looked at it) to be the sort of scrap paper most of us accumulate when working on a problem, and that not even we can understand five years later.

  20. Y- says:

    Historians seem to develop tools for transcribing handwritten texts, e.g. https://transkribus.eu/Transkribus/

  21. David Yager says:

    No narrative about SUSY2019? We’re half way through it. The timetable at the event site shows a lot of presentations, but I haven’t looked at it enough yet to see how much actual SUSY content is there.

    It’s the right time to start putting out predictions of what the muon g-2 delta is actually going to be, and what new particle explains it.

  22. Peter Woit says:

    David Yager,

    I took a look, and there are at least two things about this conference that strike me as peculiar:

    1. Gordon Kane as summary speaker. Why choose as summary speaker the person in your field with least credibility? What prediction for the gluino mass will he announce today?

    2. Pre-SUSY 2019. The instructional talks for grad students and postdocs gave little indication of the problems with SUSY models. Given the LHC null results, and the huge industry of several generations of theorists trained to do SUSY calculations in models that have failed, why train a new generation in the same techniques?

  23. rpo says:

    On the subject of the mortality of great figures, Caltech has just sent an email to staff announcing the death of Murray Gell-Mann.

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