First some personally relevant items:

- I finally have a finished version 2.0 of my euclidean twistor unification paper (discussed here), it’s uploaded to the arXiv, should appear there Monday.
- I’ll be giving a talk October 30th at the Foundations 2021 conference in Paris, something about the unity of math and physics, and will take the opportunity to spend about two weeks in Europe, mostly in Paris.
- In other travels, I’ll be in the Bay area for a week or so mid-November.
- For entertainment I tried out a WordPress plugin that dumps all my blog content into a single pdf. If you want 8,518 pages to read at your leisure when you’re not connected to the internet, this would be one way to spend your time.

In math and physics news, there’s:

- David Mumford has a had a remarkable career, first as an algebraic geometer (he won a Fields Medal for his work in this area) and later in the field of computer vision. He’s also known as a talented expositor, with his books and papers the standard references for several different topics. He’s moved into physics this month, with a wonderful article about cosmology in the Notices. His blog is well-worth following, it had the cosmology piece a few months back.
- Also in the Notices is a set of memorial articles about Lucien Szpiro, who passed away last year. I wrote a little bit about him here, am very pleased to see these articles which give a detailed picture of both the person and his mathematics.
- The Simons Collaboration on Global Categorical Symmetries had its kick-off meeting this week in Stony Brook, videos available here. There are many interesting talks to watch. I got very excited for a minute (around :05:00 in this video) when Greg Moore started talking about some of my favorite questions (e.g. what is the representation theory of gauge groups in dimension greater than one?). But then I realized he had labeled these “Traditional Questions”, in Fraktur font to emphasize how old and out of date they were. He described these as “old-fashioned questions”, that people were not seriously working on anymore. As he explained, you’re no longer supposed to be thinking about a fixed topology, but looking for something more general that treats all topologies. My problem with this is that one tends to get interesting results about topology this way, but the physics applications seem to be in condensed matter physics, with little relevance to questions about local fundamental physics that have always been my main interest.
- I really don’t understand the thinking in physics theses days at all. Nima Arkani-Hamed is a remarkable theorist who came up with a lot of highly speculative ideas about particle physics that have never worked out, then moved on to brilliant work leading efforts that have transformed the study of scattering amplitudes. The APS just announced that he’s getting the 2022 J. J. Sakurai Prize for Theoretical Particle Physics, for “the development of transformative new frameworks”. These “transformative new frameworks” are listed as “work on large extra dimensions, the Little Higgs, and more generally for new ideas connected to the origin of the electroweak scale”, none of which has had any success, while the amplitudes work is ignored.

Congratulations to Nima. He did so many things that we can joke that a good motivation would have been: “for amplitudes… despite extra dimensions, little Higgs…”. A look at recent editions (https://en.wikipedia.org/wiki/Sakurai_Prize) shows that, given the lack of new discoveries, it become a prize for US physicists who proposed new theories not confirmed or disfavoured by experimental tests. But then, why not extending the prize to theories that cannot be tested? Or suspending this kind of prizes until something is discovered?

Some random comments:

– Read Graham Farmelo’s “The Universe Speaks in Numbers” to see that a fair prize to Amplitudes surely should go to Freddy Cachazo first! (I nowadays believe one should rethink what a recognition of high-quality contributions should be instead of… well, money and medals. People getting it are already wealthy as scholarships to new pos-docs around the world only diminishing particularly to the kind of physics most of us reading this blog regularly are interested.)

– Now, more interestingly, I find amusing Mumford’s take on cosmology and an excellent example of physicists vs. mathematicians approaches. The latter are clearly far more open minded even while superficially looking otherwise, sometimes maybe for the rigorous style of mathematical writing mystifying untrained minds. But of course, this “open” mindedness could be a characteristic more of David Mumford himself, but my personal experience (Peter surely have far longer than I of course!) most mathematicians are generally open minded in private but rarely are willing to publish any physics-intuition that inspired their works under their names. Another exception I liked was Connes’ interview in “Conversation on Quantum Gravity,” possibly one of the few interesting chapters, given string theorists self-denial depressing. (Witten’s interview is a indeed just a single page or my edition allowed by my university access is limited?). Particularly Connes’ answer to mathematician’s rôle in society, that was witty.

– I looked at the Foundations conference website and their program. It will be fun to see your highly mathematical motivated talk alongside philosophers of science. Good luck to you!

“Nima Arkani-Hamed is a remarkable theorist who came up with a lot of highly speculative ideas about particle physics that have never worked out, then moved on to brilliant work [sic] leading efforts that have transformed the study of scattering amplitudes.”

Or, this week’s hype.

QCD is not my field, and I have never contributed to it at a technical level, but over the 15 or so years I have been in particle theory, it is clear that

(a) the ability to compute QCD amplitudes with increasing numbers of loops and legs, of direct relevance to the LHC, has developed enormously over this period

(b) Nima Arkani-Hamed is, by quite some way, not the leading contributor to (a)

Instead this rather illustrates one of the systemic problems with the subject, which is the idea that problems are only interesting (and progress is only made) when someone from Princeton (or Harvard, or MIT, …..) works on them.

Joseph Conlon,

My point was more that assuming you’re going to give him a prize, why do it for the part of his work that was a failure?

I can’t evaluate the relative technical contributions of the many people working in the amplitudes area. But, besides having a position at Princeton, Arkani-Hamed is quite a phenomenon: the two-hour long inspirational talks about how advances in the study of amplitudes are going to revolutionize physics, replace space, time and maybe quantum mechanics have sometimes even almost convinced me. Whatever else he is, he’s certainly the driving force responsible for turning “Amplitudes” into a major and vibrant part of theoretical physics.

They already gave the prize for amplitudes in 2014 to Bern, Dixon and Kosower who well deserved the prize.

I don’t expect that amplitudes will revolutionise physics. Because amplitudes satisfy non-trivial properties already at tree level, i.e. classical physics. How can you expect that simple classical physics hides flat-space holography, or something better than the usual local Lagrangians in space-time? It seems more likely that amplitudes satisfy non-trivial mathematical relations with no deep fundamental meaning, and that we care about amplitudes because that’s how colliders happen to practically measure small distances. Relations among amplitudes that allow to quickly compute scatterings among many gluons are useful, but maybe only to those who want to compute these higher-order processes.

Alessandro Strumia:

You say:

One comment: I don’t see how you can dismiss any mathematical relations like these as having no deep fundamental meaning. These mathematical relations certainly didn’t happen just by chance, and I don’t believe we understand the reason for them yet.

Now, whether the fundamental meaning underlying amplitudes is interesting for physicists, or just for mathematicians, is a different question. But either way, it’s worth investigating.

Dear Peter (Shor): because these are perturbative relations, that satisfy interesting mathematical properties that appear *already at classical level*. I don’t expect that a classical field theory has a hidden formulation where big surprising things happen, such as emergence of space-time and locality. So, while I agree that it’s interesting and worth investigating, I am skeptical about highest expectations that amplitudes are the magic door that will open a new level of quantum reality. I would be happy to be wrong.

Nima is certainly charismatic – no arguing that. But, NLO and NNLO QCD – surely the beating heart of amplitudes as they relate to the real world – happened without him. I think it does a disservice to the subject when people who did the real work get written out of the subject in favour of charismatic personalities. Give people who do the work the credit they deserve.

A similar thing was true of the film Particle Fever, which left out the theorists responsible for actually working out how to see the Higgs, in favour of Nima talking about the multiverse.

Although if we are talking about emergence of spacetime – it is perhaps more remarkable that 2-dimensional supersymmetric conformal field theories can be reinterpreted as describing the dynamics of 10 spacetime dimensions……

Could you direct me to an explanation for laymen of what your twistor unification theory does?

COliveros,

Unfortunately such a thing does not now exist. At the moment I’m trying to figure out how to get experts interested in these ideas, with the project of getting laymen interested something for the future.

Dr Woit,

Are you planning to give a talk on your twister unification work during your visit to

the Bay Area mid November? If so, could you please post

the time and venue?

Thanks

Kingsuk Maitra

a statement of the year? “the naturalness paradigm is devoid of physical meaning”

QFT without infinities and hierarchy problem: https://arxiv.org/abs/2110.05175