Various News

First some mathematics items:

  • Igor Shafarevich, one of the great figures of twentieth century algebraic geometry and algebraic number theory, died this past weekend at the age of 93. Besides his many contributions to mathematics research, he was also a remarkably lucid expositor. His two volume Basic Algebraic Geometry is a wonderful introduction to that subject, his survey volume Basic Notions of Algebra emphasizes the connections to geometry, and his volume on number theory (with Borevich) struck the AMS reviewer as “delectable”.

    Shafarevich was also known for his religiously-motivated nationalistic views which to many were distressingly anti-Semitic. In the spirit of respect for the recently deceased, I’ll just link to a quite interesting recent discussion (very sympathetic to Shafarevich) of the issue by David Mumford here (and ruthlessly delete attempts to argue about this in the comment section).

  • The AMS Notices has a set of articles in honor of Andrew Wiles and his work, which include some great explanations of the mathematics, as well as a long in-depth interview.
  • For another detailed interview with a mathematician, see Quanta magazine for a piece by Siobhan Roberts about Sylvia Serfaty of the Courant Institute.

On the physics front, there’s:

  • For his contribution to the Why Trust a Theory? conference (see here and here), Helge Kragh has a new paper which examines the question of whether history of science can help evaluate recent claims about the need to change the way theories are assessed. He sees in the unsuccessful “vortex theory” of the late nineteenth century an analog of string theory, with many of the same claims and justifications for lack of success. He quotes as a typical example of the enthusiasm of the time:

    I feel that we are so close with vortex theory that – in my moments of greatest optimism – I imagine that any day, the final form of the theory might drop out of the sky and land in someone’s lap. But more realistically, I feel that we are now in the process of constructing a much deeper theory of anything we have had before and that … when I am too old to have any useful thoughts on the subject, younger physicists will have to decide whether we have in fact found the final theory!

    but then explains that this is actually a quote from Witten, with “string” replaced by “vortex”.

  • Scientific American this month has an article (also available here) about the problems with the theory of inflation. The authors end by pointing out the dangers to science of multiverse inflationary scenarios (which they call the “multimess”):

    Some scientists accept that inflation is untestable but refuse to abandon it. They have proposed that, instead, science must change by discarding one of its defining properties: empirical testability. This notion has triggered a roller coaster of discussions about the nature of science and its possible redefinition, promoting the idea of some kind of nonempirical science.

    A common misconception is that experiments can be used to falsify a theory. In practice, a failing theory gets increasingly immunized against experiment by attempts to patch it. The theory becomes more highly tuned and arcane to fit new observations until it reaches a state where its explanatory power diminishes to the point that it is no longer pursued. The explanatory power of a theory is measured by the set of possibilities it excludes. More immunization means less exclusion and less power. A theory like the multimess does not exclude anything and, hence, has zero power. Declaring an empty theory as the unquestioned standard view requires some sort of assurance outside of science. Short of a professed oracle, the only alternative is to invoke authorities. History teaches us that this is the wrong road to take.

  • Nautilus has an article by Juan Collar about the increasing skepticism about Wimps as dark matter candidates, and the interest in alternatives.

Update: With results from the full 13 TeV dataset just a few weeks away, SUSY enthusiasts have given up hope for the LHC. A new paper just out argues that pre-LHC claims that naturalness + SUSY implied a gluino mass upper bound of 350 GeV (the latest LHC limits are more like 1900 GeV, likely to go up next month) were misguided. According to these authors, the right number for the upper bound is 5200 GeV and the “HE-LHC with [cm energy] 33 TeV is required to either discover or falsify natural SUSY”. So, claims that the LHC could falsify natural SUSY are no longer operative now that it has done so by earlier metrics, and such discovery or falsification is still just around the corner. All that’s needed is to rebuild the LHC into a higher energy version (that’s what the HE-LHC proposal is, may take a while…).

Update: Another excellent article by Natalie Wolchover at Quanta, this time about progress in studying conformal quantum field theories in higher dimensions (above 2). Definitely one of the more interesting things going on in theory at the moment. The reference in the subtitle to “geometry underlying all quantum theories” I don’t think though is really justified, this is really just about conformal field theories.

There’s probably lots more to be learned about these, with this conformal symmetry still not fully exploited. I’m somewhat fond of the point of view that you really shouldn’t try and think of QFTs just as effective theories for some different physics at short distances. Rather, what might be going on at short distances is not some new kind of theory at the cutoff scale, but a conformal theory valid at all scales.

Update: From the comments, unfortunately two other deaths to report, those of Bert Kostant (I’ve written something here) and Ludwig Faddeev.

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15 Responses to Various News

  1. The model of fuzzy dark matter, which the article by Collar refers to, with massive but ultralight axion particles of de Broglie wavelength the scale of galaxies is interesting, in that it interpolates between the extremely sucessful WIMP-style phenomenology on cosmological scale and the observed MOND-like deviation from WIMP-style dark matter on galactic scales, because on just those scales the quantum nature of these axionic particle kicks in to. That’s the point amplified in much detail by Hui-Ostriker-Tremaine-Witten 16. And hence axion cosmology looks attractive, as witnessed for instance recently by the SMASH model.

    But if axions fit the data a question will remain: why axions, theoretically? As Svrcek-Witten 06 wrote way back:

    An obvious question about the axion hypothesis is how natural it really is. Why introduce a global PQ “symmetry” if it is not actually a symmetry? What is the sense in constraining a theory so that the classical Lagrangian possesses a certain symmetry if the symmetry is actually anomalous? It could be argued that the best evidence that PQ “symmetries” are natural comes from string theory, which produces them without any contrivance.

    Indeed, the funny coupling of the axion to the instanton number, which seems contrived from the point of QFT, generically drops out from string theory, as shown by entertaining little computations.

    (Interestingly, it is the special properties of higher gauge fields in string theory which give the axionic behaviour in 4d: for type II its the K-theoretic nature of the RR-fields, and for HET its the Green-Schwarz mechanism on the B-field gerbe. Hence if Witten’s arguments as above are right, then axionic dark matter is potentially the first direct phenomenological signature of higher gauge theory.)

  2. Peter Woit says:

    Urs,
    I have no doubt that, if we ever find evidence for new physics that explains dark matter, no matter what that new physics is, we will be assured that it “generically drops out from string theory”, just like the now-becoming-unpopular WIMPs did…

  3. Anon says:

    Regarding the new paper on SUSY, it says that the LHC(14) at 3000 inv fb will probe up to 2.8 TeV of gluino mass — that corresponds already to 10% fine tuning (\Delta_EW = 10) as per fig 1 in their paper (1702.06588).

    Assuming nothing is found with full running of at LHC(14), the 33 TeV machine will search among models that are between 10% and 3% fine tuned (gluion mass between 2.8 and 5 TeV).

    I guess this implies that, even now, LHC(14 Tev) is more likely to discover SUSY as it continues to run and search for gluinos between 1.9 TeV and 2.8 TeV which according to the authors is a region that is not 10% fine tuned. If the the LHC does not find anything in this region, the 33 TeV collider will be searching a region that is at least 10% fine tuned and is less likely to find SUSY, compared to the LHC runs between now and 3000 inv. fb.

  4. Balazs Vagvolgyi says:

    Dang, Scientific American and Juan Collar, inflation and strings just got burned!
    In other news, the first designs for the Church of the Holy Superstring have just been submitted for review.

  5. Anonyrat says:

    Recent lectures on the conformal bootstrap by Simmons-Duffin
    https://arxiv.org/pdf/1602.07982.pdf

  6. Mike Weiss says:

    “One major question,” writes Natalie Wolchover in Quanta magazine, “is how black holes manage to preserve quantum information, even as Einstein’s theory says they evaporate.”

    Surely the last clause is in error as classical black holes in GR do not evaporate. Hawking predicted black-hole evaporation in the 1970s based on an amalgam of quantum field theory and GR.

  7. Anon says:

    Another unfortunate recent death is that of Bertram Kostant. I know you Peter have been interested in his ideas on Lie algebra cohomology and the symplectic Dirac operator, as well as on geometric quantization more generally.

  8. Peter Woit says:

    Anon,

    I’m sorry to hear that, thanks for letting us know. I’ll write a posting very soon about Kostant’s mathematics, which has had a lot of influence on me.

  9. Pingback: Bertram Kostant 1928-2017 | Not Even Wrong

  10. anon says:

    Yet another death: Ludvig Faddeev has passed away.

  11. Peter Woit says:

    anon,

    Thanks for letting us know. I’ll add a mention above, unfortunately I never met Fadeev and am not familiar enough with his work to write much about it.

  12. Casual reader says:

    Observations of spatial flatness and large-scale homogeneity required very special initial conditions for the universe. Scientists did not like that, so they came up with inflation.

    Planck CMB observations require very special initial conditions for inflation. Ijjas, Steinhardt and Loeb do not like that, so they come up with a bouncing universe.

  13. lars says:

    “Inflation”

    The universe inflated
    Is really overrated
    Though lack of proof is stated
    The hype is unabated
    Perhaps it should be traded
    But those who are quite jaded
    Are almost surely fated
    To wait with breath that’s bated
    For end to things inflated

  14. Doug McDonald says:

    “With results from the full 13 TeV dataset just a few weeks away”

    I recall a discussion late last year about a skipped meeting then, mentioning this.

    Do you recall dates and places of the upcoming (presumably non-) news?

    I do admit that probable SUSY or even better axions would be fun.

  15. Peter Woit says:

    Doug McDonald,

    As far as I know, the target has been to release these results at the Moriond conferences scheduled to begin March 19th (also at the Aspen conference to begin March 20)
    Watch for results to appear at
    http://moriond.in2p3.fr/
    http://indico.cern.ch/event/550030/
    I suppose there might also be events scheduled at CERN for these announcements.

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