Not Even Wrong

This week the Simons Center is hosting a workshop on “The Geometry and Physics of Scattering Amplitudes”, talks are available here. Last week they (and the YITP) held a one-day symposium on Trees, loops and precision QCD, based around the work of Zvi Bern, Lance Dixon and David Kosower that was recently awarded the 2014 Sakurai Prize. For more about this, see Dixon’s guest post here, or his talk at the symposium.

Bern, Dixon and Kosower started working on amplitudes more than twenty years ago, at a time that it was becoming clear that string theory was not working out as a theory of everything. Calculations in string theory did though lead to interesting new ideas about how to evaluate scattering amplitudes in gauge theory (I see from Dixon’s list of publications that in 1994 he wrote something for the SLAC Beam Line on “Whatever happened to the theory of everything?”, presumably about this, but now too deep in the past to be available on-line). The three Sakurai Prize winners have been steadily working at the problems of amplitudes in gauge theory and quantum gravity, for many years without getting much attention for their work. About ten years ago, things changed when Witten wrote a paper about getting amplitudes from the “twistor string”, a topological string theory in twistor space (the use of twistor space was originated by Penrose back in the late 1960s, and was applied by V.P. Nair to gauge theory amplitudes back in 1988 while he was here at Columbia).

About six years ago Nima Arkani-Hamed entered the subject, where he has had a dramatic effect as an impresario, arguing that this is a route to revolutionary ideas about physics, overthrowing conventional notions of space and time, locality and unitarity, and doing away with the notion that gauge invariance is important. This was partly responsible for his $3 million Milner prize.

For the latest along these lines, a paper with Trnka about “The Amplituhedron” has just appeared, a topic which got wide play in the press earlier this year as Physicists Discover Geometry Underlying Particle Physics, drawing a parody from Scott Aaronson about his own work on the “Unitarihedron” and “Diaperhedron”. Arkani-Hamed’s talk at the Symposium covers both the ideas of Bern, Dixon and Kosower and his recent work with Trnka. It includes many appreciative remarks about their work, including some interesting commentary on how theoretical physics is done. For instance, on the likely reason for people ignoring their early work:

It’s a natural reaction among theoretical physicists, right? At any given time there’s all sorts of interesting things going on, things that other people are doing and things that you are doing and especially if someone else is coming along with something that looks really exciting, in order to justify not dropping everything you have and working on it you have to sort of start inventing these reasons why what they are doing is irrelevant or crap, right? It’s a very human thing, a very human thing, a very natural thing. I think everyone does it to some extent, and really good people eventually will realize that they are fooling themselves and start changing their tune if it’s appropriate. Really bad people, well, we won’t talk about them. It was not at all obvious that this was the tip of a huge iceberg…

There’s also:

Often fields, other fields, have what you might call prophets and there’s I think usually an excessive amount of reverence for these prophets, because the prophets tend to have the property that they say some sort of vague things, I won’t name any names but you can probably figure out the sort of collection of people I’m talking about. They say some sort of vague things about what might happen with physics in the future, and then twenty years later when other people have done all the hard work and really figured out what is going on and how it works in detail and why it works that way and not another way, if it vaguely looks like something they did, they say “see, I said so all along!” They have a fair amount of attraction, I think it’s because a lot of physicists have father-figure issues. But anyway, Zvi and Lance and David were very much not like that, they weren’t just vague prophets saying something was going on, they were extremely specific: there was something going on in this area with these kind of computations in this arena and they knew it. And it took a decade or more for many other people in the field to catch up.

(Personally, I have no idea which “prophets” he’s thinking of.)

Finally, there were some personal comments contrasting Bern, Dixon and Kosower’s low-key style and use of a variety of techniques with his own high-powered hype-driven sales-job of specific ideas to himself and others. Probably a good idea to read this in conjunction with the “Outlook” section of the new paper….

I must say, and I’m really not just saying this to say it, I’m VERY envious of this, because I AM an ideologue. In my defense at least I can say that I’m a serial ideologue, in the sense that I’ll take totally different ideologies and drop the last one without thinking about it, but it’s very important for me personally to be an ideologue when I’m working on something and I think, and I’m saying this in all honesty, the difference is talent. If you’re really good, you don’t have to be an ideologue. You take this, you take that, you’re solving for things left and right, you don’t care where things come from. If you’re not as good, there are 15 million things going on, you’re holding on for dear life in the stiff wind of all the crazy stuff going on in the subject. So you have to have a strong point of view about something, you have to have a strong point of view to sort of pursue a particular direction, otherwise you’ll get beaten around all the time and get nowhere.

So, usually I’ll get up when I talk about scattering amplitudes and give a long introduction about how spacetime is doomed, we have to find some way of thinking about quantum field theory without local evolution in space time and maybe even without a Hilbert space and blah-blah-blah. This is all very high-falutin stuff, this is stuff that Lance wouldn’t be get caught dead saying. I think none of these guys would ever say something that sounds so pretentious, but I have to say it, you know I have to say it, because this is the only way I can get up in the morning, and like “I suck again, OK, here we go, I’m doing it because spacetime is doomed, I swear to God, right”. But, quite seriously, the best people in the subject have this feature, they don’t need to be ideologues, they take the most interesting ideas from every direction they can to make progress, so I really am quite envious.

The Guardian has an interesting piece about Peter Higgs, evidently their reporter talked to him on his way to the Nobel Prize ceremonies this week in Stockholm. Higgs will be speaking tomorrow (Sunday), and I’m curious to hear what he will have to say. His talk will be available live at the Nobel Prize website.

Higgs points out that the kind of work he was awarded the prize for was done in an environment that no longer exists:

He doubts a similar breakthrough could be achieved in today’s academic culture, because of the expectations on academics to collaborate and keep churning out papers. He said: “It’s difficult to imagine how I would ever have enough peace and quiet in the present sort of climate to do what I did in 1964.”

By the time he retired in 1996, he was glad to be out of academia:

After I retired it was quite a long time before I went back to my department. I thought I was well out of it. It wasn’t my way of doing things any more. Today I wouldn’t get an academic job. It’s as simple as that. I don’t think I would be regarded as productive enough.

Higgs has definitely not been a careerist sort, turning down a knighthood in 1999:

I’m rather cynical about the way the honours system is used, frankly. A whole lot of the honours system is used for political purposes by the government in power.

He thinks he likely would have been fired by his university back in the 1980s if there hadn’t been a prospect of him getting a Nobel.

The work Higgs did in 1964 was on a rather unpopular topic. At the time the reigning ideology was “S-matrix theory”, which argued that local quantum field theory was a hopeless subject, so one should be working on formulating basic physics just in terms of S-matrix amplitudes, using their holomorphicity properties (this idea has had somewhat of a comeback in recent years). The 1960s however was a time of a great expansion in the number of university positions, so people like Higgs could make a career despite working on unpopular topics.

Progress in particle theory slowed dramatically after the early 1970s. One reason for this of course has been the huge success of the Standard Model, as well as the inherent difficulties involved in getting experimental access to higher energy scales. One wonders though whether the post-1970 collapse of the HEP theory job market and very different environment that ensued might have had something to do with this. As Higgs himself is well-aware, if he had come along 10 years later, he would not have found a job in the field.

In the UK today, things seem to be getting even worse, with strong pressures from the government to only fund work likely to have an immediate economic payoff. For more about this, see this commentary at Physicsfocus by Philip Moriarty on The Spirit-Crushing Impact of Impact. The UK has just announced the founding of a new Higgs Centre for Innovation, to be built in Edinburgh and opened in 2016. It will be devoted though not to the kind of research Higgs had success with, but to “big data” and “space”, considered by the government to be among the most promising technologies for the future. It’s rather ironic that Higgs is the sort of scientist who would not be employable by the Higgs Centre.

Update: For the acceptance speech by Higgs, see here, and see here for an official interview. For a different point of view, from one of the experimenters who made the award to Higgs possible, see here.

The last posting here was about an unusually collaborative effort among mathematicians, whereas this one is about the opposite, an unusually contentious situation surrounding important recent mathematical progress.

What’s at issue is the proof of what has become known as the “Yau-Tian-Donaldson” conjecture, which describes when compact Kähler manifolds with positive first Chern class have a Kähler-Einstein metric. This is analogous to the Calabi conjecture, which deals with the case of vanishing first Chern class. Progress by Donaldson on this was first mentioned on this blog here (based on his talk at Atiyah’s 80th birthday conference in 2009). Last fall a proof of the conjecture was announced by Chen-Donaldson-Sun, with an independent claim for a proof by Gang Tian, see here. I wrote a bit about this last winter here, after the details appeared of the Chen-Donaldson-Sun proof, and that posting gives some links to expository articles about the subject.

I had heard that there were complaints about Tian’s behavior in this story, including claims that he did not have a complete proof of the conjecture and was not acknowledging his use of ideas from Chen-Donaldson-Sun. Recently this controversy has become public, with Chen-Donaldson-Sun deciding to put out a document (linked to from Donaldson’s website) that challenges Tian’s claims to have an independent proof. The introduction includes:

Gang Tian has made claims to credit for these results. The purpose of this document is to rebut these claims on the grounds of originality, priority and correctness of the mathematical arguments. We acknowledge Tian’s many contributions to this field in the past and, partly for this reason, we have avoided raising our objections publicly over the last 15 months, but it seems now that this is the course we have to take in order to document the facts. In addition, this seems to us the responsible action to take and one we owe to our colleagues, especially those affected by these developments.

I should make it clear I’m no expert on this mathematics, so ill-equipped to judge many of the technical claims being made. The Chen-Donaldson-Sun document is giving one side of a complicated story, so it would be useful to have Tian’s side for comparison, but I have no idea if he intends to respond.

On a more positive note, perhaps this controversy will not interfere much with future progress in this area, as Donaldson and Tian are jointly organizing a Spring 2016 workshop on this topic at MSRI.

Update: I hear from Tian that he has recently written a response to the Chen-Donaldson-Sun document, which is available here, and he may at some point write some more about this. Anyone who has read the CDS side of this should also take a look at what Tian has to say in response.

There’s a new paper out on the arXiv last night, Small gaps between primes, by James Maynard, which brings the bound on the size of gaps between primes down to 600. This uses some new methods, beating out the Polymath8 project, which has been improving Zhang’s original bound of 70,000,000, getting it down to 4680.

To follow the Polymath8 project, the place to look is Terence Tao’s blog, here. They’re working on a paper, with the current draft version available here. This is a remarkable collaborative project bringing together a sizable group of mathematicians in an unusual way.

For more about this, see this expository article by Andrew Granville, which is pre-Maynard. At Quanta magazine, Erica Klarreich has an excellent long popular article telling the story to date, including that of Maynard’s new result.

Philip Anderson’s 90th birthday is coming up next month, and Princeton will host a workshop commemorating the event. Witten and Wilczek will give talks on the Anderson-Higgs mechanism, for which Anderson recently was not awarded a Nobel Prize (for the history of this, more here).

Princeton condensed matter theorist Shivaji Sondhi has an article here about the role of Anderson in the Higgs story, rightly emphasizing “the remarkable intellectual unity of modern physics.”

Many have speculated that a reason for Anderson not getting a piece of this year’s Nobel Prize was his public opposition to the SSC project back in the 1980s. He was far from the only physicist opposing the project, since there was widespread concern that in the Reagan-era environment of budget-cutting, devoting large sums to an HEP project would mean reduced funding for the rest of physics. Anderson has a letter in the latest APS News about this. For a summary of his concerns about the SSC, see this opinion piece from 1987.

One thing that exacerbated conflict between HEP physicists and others at the time were claims about “spin-offs” from building large accelerators, with some people claiming that HEP physics was responsible for MRI machines. Anderson recalls:

As I was leaving the committee room behind Steve Weinberg, the particle physicist who had testified for the SSC, one of the senators accosted him and effusively thanked him for his role in the development of MRI, which had been instrumental in treatment of a relative. Since close friends and I had been responsible for most of the basic research underlying MRI’s superconductiing magnets, this was a bit of a bitter pill for me to swallow.

For Weinberg’s point of view on this, see here, where he writes:

The claim of elementary-particle physicists to be leading the exploration of the reductionist frontier has at times produced resentment among condensed-matter physicists. (This was not helped by a distinguished particle theorist, who was fond of referring to condensed-matter physics as “squalid state physics”.) This resentment surfaced during the debate over the funding of the Superconducting Super Collider (SSC). I remember that Phil Anderson and I testified in the same Senate committee hearing on the issue, he against the SSC and I for it. His testimony was so scrupulously honest that I think it helped the SSC more than it hurt it. What really did hurt was a statement opposing the SSC by a condensed-matter physicist who happened at the time to be the president of the American Physical Society.

In recent years the hot topic in the string theory end of HEP theory has become “AdS/CMT”, the attempt to apply AdS/CFT ideas to condensed matter theory models. Anderson at nearly 90 is still dealing with HEP hype, see this from the April issue of Physics Today.

• Mathematician Sasha Beilinson has a letter to the editor in this month’s AMS Notices calling on the AMS to sever all ties with the NSA (right now it manages NSA grants, and runs ads from the NSA in the Notices). Beilinson compares the NSA to the KGB of the former Soviet Union. For discussion of the Beilinson letter, see here.
• Beijing now has a Center for Future High Energy Physics, with Director the ubiquitous Nima Arkani-Hamed. The inaugural conference of the Center will be next month, on Future High Energy Circular Colliders. Nature has an article on the topic this week, Physicists plan to build a bigger LHC, about proposals to build a 100 TeV pp collider, with a possible electron-positron collider Higgs factory using the same tunnel. For the latest on TLEP, the proposal for such a Higgs factory at CERN, see here.
• I was in London a few days too early for this, but this week the Science Museum there celebrated the opening of its exhibition about the LHC with an event featuring Stephen Hawking. The Guardian has a report here. Hawking seems to think the LHC may see evidence for M-theory:
  

  “There is still hope that we see the first evidence for M-theory at the LHC particle accelerator in Geneva,” said Hawking. “From an M-theory perspective, the collider only probes low energies, but we might be lucky and see a weaker signal of fundamental theory, such as supersymmetry.

  “I think the discovery of supersymmetric partners for the known particles would revolutionise our understanding of the universe.”

  As is often the case in stories like this, the wording about evidence for string/M-theory is rather odd. We’re told:

  As yet there has been no incontrovertible experimental evidence to show that M-theory is correct.

  but “no incontrovertible experimental evidence” is a peculiar way of phrasing “absolutely zero experimental evidence of any kind whatsoever.”

• For an interview with Shiraz Minwalla, one of the winners of this year’s Milner prizes for young researchers, see here.
• Edward Frenkel’s new book, Love and Math, has been getting quite a few good reviews, with the latest from Jim Holt in the New York Review of Books.
• Finally, your best source of fascinating mathematically-related graphics is surely going to be John Baez’s new Visual Insight blog.

Update: One more. The Perimeter Institute announced yesterday the funding (half provided by the Krembil Foundation) of two new chairs in theoretical physics. These will be held by two young mathematical physicists: Kevin Costello and Davide Gaiotto. As far as I know, the hiring of Costello away from Northwestern is the first time Perimeter has hired someone with a pure mathematics background. It’s good to see them moving in this direction.

Update: More about the new Perimeter chairs here. The article discusses the fact that this is a change of direction towards mathematics:

The choice is a strategic shift and a gamble for the 12-year-old institute, which is in a global tug-of-war for talent and looking to grow its profile as a centre for high-level thinking on some of the deepest questions in the universe.

Although math is the working language of physics and equations cram every available blackboard at Perimeter, Dr. Costello’s hiring, to be announced Saturday, will mark the first time the institute has sought a pure mathematician for its faculty….

“There’s something about the situation in physics today which makes it especially important to bring in high-powered mathematics,” said Neil Turok, the institute’s director.

I’m now back to regular internet access, in London for a few days after a trip to East Africa, where I managed to see the November 3 total solar eclipse through light clouds from a location in Northern Uganda. From checking various news sources, it looks like the main pieces of HEP-related news that I missed weren’t very surprising:

• The LUX experiment reported stronger limits on WIMP dark matter, ruling out various claims for evidence of such dark matter particles at relatively low mass. For more about this, good sources are Resonaances, Matt Strassler, and Tommaso Dorigo.
• The $3 million Fundamental Physics Prize as usual identifies “Fundamental Physics” with string theory, with the announcement that the nominees for the 2014 prize are 5 string theorists (Polchinski, Green/Schwarz, and Strominger/Vafa). I confess that I can’t figure out exactly how this prize process is supposed to work. The announcement says that the nominees get a “Physics Frontiers Prize”, a shot at the $3 million, and
  

  Those who do not win it will each receive $300,000 and will automatically be re-nominated for the next 5 years.

  What I don’t understand is that Polchinski already got such a nomination and prize last year (and the $300,000 consolation prize for not getting the $3 million). It seems that he is getting another identical prize this year, with another $300,000 or $3 million. On the other hand, the only non-string theorists ever to win this prize (last year’s condensed matter group Kane/Molenkamp/Zhang) didn’t get a second one this year, and it’s unclear if they still have a possible $3 million payday in 2014. Perhaps the rules are different for string theorists, the idea being that you just can’t give too many prizes for string theory.

  I’ll bet that Green/Schwarz will be the 2014 winners, on the grounds that if you’re going to hand out lots of prizes for working on the superstring, its co-discoverers should be among the first in line. While this means that Polchinski will only get a second $300,000, it’s in his interest to lose as many times as possible before winning.

  As for the $100,000 prizes for young researchers, this year was different than last year. The winners (Cachazo/Minwalla/Rychkov) were two Princeton Ph.Ds and one ex-Princeton post-doc, whereas last year is was one Princeton Ph.D and all three were ex-Princeton post-docs.

• In other news, Max Tegmark, known for his work on the multiverse, is running a “Project Einstein”, which has found 400 theoretical physicists and mathematicians who have agreed to have their genes sequenced. The idea is that they are “math geniuses”, but no one seems to know what will be done with the genetic data for these geniuses. It’s unclear who these “geniuses” are, but we do know that one person who was asked and declined was Curt McMullen. His reaction to this project was what I suspect was a common one:
  

  “I thought it was strange that it was called ‘Project Einstein’, which seemed designed to appeal to the participants’ egos,” he says. He asked the project’s staff and the New England Institutional Review Board, which approved the study, to explain how results would be used. “The uniform answer to my questions was that ‘we are not responsible for how the information is used after the study is completed’,” he says.

  If Project Einstein identifies a common gene among its participants, and uses the knowledge to breed a race of übermenschen, they may find they have selected not for unusual mathematical genius, but for unusual ego.

Update: I realized there’s one other remarkable thing about the six winners of the “New Horizons in Physics Prize”. Besides all having a close Princeton connection, none of them has a job in the US. It seems US physics departments are not buying what Princeton is selling right now…