Various Math and Physics News

First some items on the mathematics side:

  • The latest AMS Notices has some memorial pieces about Vaughan Jones and Robert Hermann. I contributed a piece to the Hermann memorial, for more about him, see here.
  • If you read French you might enjoy Yves André’s Dix regards sur la mathématique contemporaine, freely available here.
  • There’s a wonderful overview of various conjectures in number theory last year from Barry Mazur, About Main Conjectures.
  • The Harvard Math department seems to not have had a lot of luck with its funders. Last spring they had to close their Program in Evolutionary Dynamics, which was funded by Jeffrey Epstein. The very active Center of Mathematical Sciences and Applications has been funded by the Evergrande Group, a real estate investment company that has now run into serious financial problems. I haven’t heard what the implications will be for the CMSA in the future.

On the physics side:

  • The 2021 Physics Nobel Prize will be announced tomorrow morning. I gave up predicting these things after this prediction back in 2004.
  • Gian Giudice has put on the arXiv a written version of his Theory closing talk at LCHP2021. He ends with

    These are interesting times for particle physics: times of great uncertainty, in which our physics perspective is changing, and in which we are laying the foundations for the future of our field. As a community, we must rise to the challenge.

    What worries me is that the much of the rest of the article contains a lot of

    1. Arguing for multiverse pseudo-science:

      The multiverse describes a physical reality that challenges the presumption that there must be a single unified theory in the deep UV. In a sense, it is the ultimate Copernican revolution since not even the patch of the universe we live in is special. It implies a revision of the cosmological principle because the universe is approximately homogeneous and isotropic only within our horizon, but may be globally highly non-homogeneous. The multiverse is not an abstract idea, but it is a generic consequence of a large class of inflationary theories, where unavoidable quantum fluctuations of the inflaton spark a chain process with eternal creation of regions that expand faster than the surrounding space.

      The multiverse is actually a familiar instrument of our everyday physics toolkit.

    2. Arguing against the fundamental significance of symmetry principles:

      There are also theoretical indications for questioning the concept of symmetry. It is nowbelieved (and to a certain extent proven) that any global symmetry is violated at the level of quantum gravity. This means that any global symmetry that we observe in nature is only an accidental effect of looking at a system without sufficient short-distance resolution. The case of gauge symmetries is more subtle. Gauge symmetries are not real physical symmetries, in the sense
      that they don’t correspond to an invariance under a physical transformation, but only to a redundancy of the coordinate parametrisation. We often confuse our students on this point by showing them the Mexican-hat potential and leading them to believe that there is a degeneracy of vacua, when in reality there is only one single vacuum state that breaks EW symmetry, as it is clear from the fact that the physical spectrum doesn’t contain any Goldstone boson corresponding to zero-energy excitations. Gauge symmetries may not be as fundamental as we thought, but only an emergent phenomenon. They could be a mirage of a different reality that takes place at a more fundamental level.

    It’s looking depressingly possible that leaders of the field will push through as new “foundations for the future of our field” the argument that “the multiverse did it and symmetry is a mirage.” Instead of moving forward, the field will take a huge step backwards.

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16 Responses to Various Math and Physics News

  1. Martin S. says:

    Hi, the article on closing the “program for evolutionary dynamics” (it does not mention genetics) only notices past inappropriate contacts. I have not seen anything about financial issues there. Why is a scientific program closed then? I guess that I do not understand it because I am not in USA.

  2. Peter Woit says:

    Martin S.
    My mistake about the name of the program, fixed. I believe the program was shut down because the main faculty member involved in it was Martin Nowak, and the main funding had come from Epstein. Nowak was sanctioned by the university after a report was issued which detailed the university’s involvement with Epstein and Nowak’s role in this. The report is at
    https://ogc.harvard.edu/files/ogc/files/report_concerning_jeffrey_e._epsteins_connections_to_harvard_university.pdf

  3. mqt says:

    Here is a link to André’s book that lets you download the PDF:
    https://spartacus-idh.com/pdfs/078/

  4. anon says:

    Surely Harvard could have easily kept funding PED if it was only a question of money. But the centre was very much Nowak’s/Epstein’s creation, so keeping it going would have looked very bad.

    CMSA doesn’t have the same PR issues, so maybe Harvard is more willing to increase its own contribution. Or maybe S-T Yau (I think CMSA is his pet project) can find another sponsor.

  5. Sabine says:

    Well I agree that the community of particle physicists must “rise to the challenge”. This means they should get rid of theorists who make a living by putting forward useless speculations, like inventing particles that no one will ever see (or extra-dimensions, or unparticles, etc). If your methods of theory-development allow you to retrodict any possible fluctuation in the data, then those methods are obviously unscientific and must be discontinued.

    And, needless to say, they should also make sure that the group-think which made such practices acceptable in the first place doesn’t happen again. Even psychologists have managed to clean up their act and have taken steps to throw out unscientific methods. I find it depressing that particle physicists still don’t even acknowledge their problem.

  6. Shantanu says:

    My prediction : Aharanov and Berry

  7. martibal says:

    As many Italian colleagues think: they gave back to Parisi what they had stolen to Cabibbo!

  8. AcademicLurker says:

    Once again, my prediction of Aspect Clauser and Zeilinger is off.

    I’ve been wondering for years whether Parisi would get it. His work has certainly been far reaching and influential enough. I confess I’ve never heard of the other two.

  9. AcademicLurker says:

    Re: Parisi and the Nobel prize, I must say I don’t envy the poor science journalists who are now stuck with the task of trying to explain spin glass theory and replica symmetry breaking to a general audience. If they thought that the topology stuff in 2016 was difficult to popularize…

  10. CM says:

    Gauge symmetry as an emergent phenomenon has indeed been explicitly demonstrated in condensed matter systems. A notable example is the emergent QED in quantum spin ice. So the “different reality that takes place at a more fundamental level” could be that the fundamental theory of our world is some complex bosonic spin model, as envisioned by people like Xiao-Gang Wen or Laughlin.

  11. Peter Woit says:

    CM,
    Sure, you can make a model of emergent QED, but emergent from what.? QED itself is hugely successful, tested to absurd accuracy, why replace it with a bosonic spin model or any such thing. This explains nothing at all, replaces a highly constrained beautiful theory based on deep geometry with something much less interesting? Why do this if there’s not the slightest bid of evidence for such a supposedly more fundamental structure?

  12. OB says:

    @Peter
    I don’t think anyone’s really advocating to replace QED with a spin model or any such thing. The point is to realize that just because symmetry principles, including gauge symmetries, are very useful doesn’t necessarily imply that they are fundamental truths about the universe, valid at all length scales. What the Condensed Matter examples demonstrate is that one can end up with beautiful looking gauge theories as the effective theory, even if the underlying reality is quite unsymmetric and ugly (from a high energy theorist’s POV)*. Indeed, there’s no present experimental motivation to replace the standard model with some short distance Condensed Matter like model from which it could emerge, but philosophically its worth knowing that the success of the SM doesn’t imply that its symmetries are necessarily fundamental.

    *I’m a CM theorist, so I don’t find lattice models ugly or boring, but each to their own.

  13. CM says:

    Peter Woit:

    To answer your question, the QED could be viewed as emergent from some qubits defined on a lattice of extremely small length scale. I mean, if people can entertain the idea that the fundamental constituents are tiny strings, perhaps it is not too absurd to speculate that the world is build on a super-tiny lattice model.

    Yes, QED is hugely successful and elegant. But until we figure out the consistent fundamental theory (super-string or not), one cannot rule out the possibility that the standard model QED is emergent from some bosonic model defined on a lattice. And the fact that such a beautiful gauge structure can emerge from a local bosonic theory is not “something much less interesting”. This construction could be deeper than the “deep geometry” you mentioned.

  14. CM,

    the quantum spin ice does not give standard QED since it has magnetic monopoles and a fine structure constant which is far too large (besides being dependent on microscopic details of the model):

    Pace, S. D., Morampudi, S. C., Moessner, R., & Laumann, C. R..
    Emergent Fine Structure Constant of Quantum Spin Ice is Large.
    Physical Review Letters 127 (2021), 117205.

  15. Peter Woit says:

    OB/CM,
    I don’t disagree that it’s possible that the SM and its gauge symmetries are emergent from a more fundamental complicated/ugly/unsymmetric collection of qubits or whatever. But at this point, there’s not a shred of evidence for this, it’s completely unmotivated speculation. The string theorists at least started out with a model (10d superstring compactified on a Calabi-Yau) that in principle could explain things and that you could argue about. Replacing string theory conventional wisdom about a flawed theory by a new conventional wisdom that there’s an ugly complicated fundamental theory we know nothing about isn’t progress, it’s just a way of convincing everyone to give up.

  16. Lowell Brown says:

    ” Gauge symmetries are not real physical symmetries, in the sense …”
    The reason people such as this guy can dispense expert knowledge is that they have no knowledge of what they are talking about.
    Let’s examine a nonabelian gauge theory. The group requires a specific form for the field strength F^a_{mu nu}.
    F^a_{mu nu} = A^a_mu , nu – A^a_nu , mu
    won’t do.

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