Various Stuff

A few links that may be of interest. Mathematics first:

  • A seminar “Lectures Grothendieckiennes” on the mathematical ideas of Alexander Grothendieck is taking place this year in Paris, and has just recently started up.
  • My ex-Columbia colleague Jeff Achter is one of the authors of an unusual new math paper: Hasse-Witt and Cartier-Manin matrices: A warning and a request. The paper points out that papers of Manin at some points confused an operator and its dual, leading to potential sign errors in later papers that reference Manin’s results. I’m quite sympathetic to the problem, having at various points fallen victim to similar confusions while writing my book (I hope they have all been resolved in the final version, wouldn’t bet anything really valuable on it…).
  • Nature has an excellent obituary of Vladimir Voevodsky, written by Dan Grayson.

On the physics side:

  • The LHC has now ended data-taking at 13 TeV for the year (a recent summary is here) and will start up again next spring. The machine ended up delivering about 50 inverse fb each to CMS/ATLAS (bettering the goal of 45), of which about 45 was recorded. Results published so far typically use 36 inverse fb from previous year’s data, so next year we should start seeing results based on a total 13 TeV data set of up to 80 inverse fb.
  • Still no WIMPs. Frank Wilczek surveys searches for his favorite dark matter alternative here.
  • At Big Think, Eric Weinstein has a take on what’s gone wrong with theoretical physics over the past 40 years that I’m mostly in agreement with.
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11 Responses to Various Stuff

  1. Eric Weinstein’s analysis is spot on. Does anyone know which Arkani-Hamed talk is he is talking about?

  2. Mozibur Rahman Ullah says:

    I liked Weinsteins bon mot – that we’ve ended up geometrising the quantum rather than quantising the geometric. I get that sense too, and that seems like an over-arching theme in that Grothendiecks work showed how we could geometrise number theory.

    Given that quantum mechanics was kick-started by experimental findings I do think more prominence should be given to just how far out of reach Planck-scale physics is experimentally.

    Is there any hope that improved sensitivity with LIGO might help there? after all one might suspect two black holes smashing into another might generate findings relevant to quantum gravity.

    Another point worth adding is that this desert isn’t unprecedented, if one takes the perspective that science began with Greek antiquity then there was great arid period of roughly two millenia before a new constellation of ideas intertwining with the old began modern physics.

  3. srp says:

    Surprised nobody has noted the resonance between the second and third bullet points in Peter’s post. Voevodsky expressed concern for exactly such problems in motivating his use of proof assistants and development of type theory.

  4. Bobito says:

    Note that the conclusion of the Achter paper is basically that the error has not caused widespread problems because most users have corrected it before using it, or not used cases in which it mattered.

  5. Pascal says:

    I find it puzzling that Eric Weinstein does not even consider new experimental discoveries as a source of progress. It’s no wonder that new generations of theoretical physiscists have a hard time “making contact with physical reality” when all or almost all of the known facts about physical reality are already explained by well established theories!

  6. Peter Woit says:

    Pascal,
    Unexpected new experimental discoveries would of course change the situation, the problem is that we haven’t been seeing any. In the past it is these that have been most often the source of inspiration driving theoretical progress. Now that the LHC has been running for a while without finding anything new at 13TeV, it seems all too possible there won’t be energy frontier discoveries from the LHC (and anything higher energy is a long ways off). One attitude is that theory can’t make progress without such input, and if you adopt that, best thing for HEP theorists to do is to change fields (lots are, going into condensed matter or quantum information theory). I think the question Eric is interested in is whether there’s an alternative to giving up for now.

  7. Peter Orland says:

    “One attitude is that theory can’t make progress without such input, and if you adopt that, best thing for HEP theorists to do is to change fields (lots are, going into condensed matter or quantum information theory).”

    Or, alternatively, they can try to solve hard problems in the territory of QFT, where the wise fear to tread…

  8. There is an obituary of Vladimir Voevodsky at Quanta Magazine, which I found to be very good:
    https://www.quantamagazine.org/visionary-mathematician-vladimir-voevodsky-dies-at-51-20171011/

  9. Scott Marks says:

    Back in 2013 when Eric gave the Geometric Unity talks, there were some “paper, or it didn’t happen” snarks. Can anyone point us to some working-out of those ideas?

  10. Mitchell Porter says:

    @Scott Marks: it didn’t happen.

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