Yesterday’s Hype

Every summer CERN runs a summer student programme, designed to bring in a group of students to participate in scientific activities at CERN and provide lectures for them about the basics and latest state of the field of high energy physics. Because of the COVID situation, this summer they have not been able to bring students in, but are providing instructional lectures and Q and A’s. This year’s sessions are based on having students follow materials from last year’s lectures, followed by a Q and A to answer their questions.

One of the topics the students are presented is What is String Theory?, and you can watch the 2019 video or look at the slides. Timo Weigand’s presentation can be accurately described as pure, unadulterated hype, with not a hint of the existence of any significant problem with ideas presented. In the Q and A yesterday, Weigand did come up with a new piece of “evidence for string theory”: it “predicts” no continuous spin representations.

I can’t begin to understand why anyone thinks it’s all right for CERN to subject impressionable students to this kind of thing. Someone, not me, should be complaining to the organizers and to CERN management.

This is unfortunately now an all too common example of what passes for “Sci Comm” in much of the field of fundamental physics: endless repetition of old discredited arguments in favor of a failed theory, coupled with pretending not to know about what is wrong with these arguments. The field that was once one of the greatest examples of the power of the human mind and the strength of the scientific method has become something very different and quite dangerous: all-too-visible ammunition for those who want to make the case that scientists are as deluded and tribalistic as anyone else, so not to be trusted.

Posted in This Week's Hype | 28 Comments

Philip Anderson 1923-2020

I heard this morning about the death yesterday of Philip Anderson, at the age of 96. It’s not hard to make the case that Anderson was the most important condensed matter theorist of the twentieth century, with a huge influence on how we think about the subject. I believe he was even responsible for the name “condensed matter”. There are already obituaries at Princeton, and at the New York Times. For more about his work, Douglas Natelson has written something here.

Anderson’s career intersected with the field of high energy physics in several ways. Most importantly, what is often called the Higgs phenomenon really is a discovery of Anderson’s, and this should have been recognized by a second Nobel for him (he already had one for some of his work in condensed matter). I’ve written extensively about this story on the blog, see for example here, here and here. The story is a bit complicated, but it’s undeniable that in November 1962 Anderson submitted the paper Plasmons, Gauge Invariance and Mass to the Physical Review, and it was published on April 1, 1963. This was more than a year before the Higgs/Brout/Englert/Guralnik/Hagen/Kibble papers that HEP theorists always point to as the original ones. If you read Anderson’s paper, you’ll find a discussion of the “Higgs mechanism” which gets at the basic physics in much the same way we think of it today. There was no reason for HEP theorists to miss this paper, Anderson had written and published it not as a condensed matter paper, but as a contribution to current high energy theory. The only counter-argument I’ve gotten about this is that “Anderson’s explicit model was non-relativistic”, but this is a physical phenomenon for which relativity is not particularly relevant. Does it really make sense to argue that recognition should not go to a theorist who discovers a new phenomenon, but to others who later show that a possible problem (e.g. inconsistency with special relativity) not considered by the discoverer really isn’t there?

My time as a student at Princeton during 1979-84 (during which years Anderson split his time between Princeton and Bell Labs) was a high point of interaction between the condensed matter and HEP theory groups. HEP theorists trying to understand QCD investigated many examples of non-perturbative quantum field theory behavior that were of common interest with Anderson and others working on condensed matter. Anderson did have a major philosophical difference with the reductionist point of view of many HEP theorists, with his 1972 paper More is Different providing a strong critique of reductionism and emphasizing the importance of emergent behavior. In some sense, leading HEP theorists in recent years have come around to his point of view, often working on emergent models of space-time, with little interest in what microscopic physics space-time might be emerging from.

Anderson made no friends among the HEP community when he came out in 1987 against building the SSC (which was cancelled in 1993), for more about this, see this blog entry. He was also a skeptic about string theory, which perhaps made for some discomfort as Princeton HEP theory centered around this subject starting in 1984.

The two personal interactions with Anderson that I remember both involved him providing me with significant encouragement. When I took my general exams at Princeton, one component was an exam on condensed matter theory. This was not then and is not now a subject I know much about. After the exam there later was a gathering of students and faculty, and Anderson came up to me to tell me that he had graded my condensed matter exam. On one problem evidently I had gone about it wrong, but at some point had stopped and written that the result I was getting wasn’t sensible. Anderson complimented me on this, telling me that knowing when a calculation wasn’t making sense was an important skill. This was the nicest way imaginable to encourage a student who didn’t really know what he was doing.

Twenty years later, in early 2001, after I had written this article and had distributed it to several theorists including Anderson asking for comments, this is what he wrote back to me:

(Jan 19, 2001)
Dear Peter, I’m sorry to have been so slow to get back to you; my printer blew out when I tried to print out your attachment. When I finally got it it blew my mind–I loved seeing my vague misgivings made explicit. I would say that perhaps a stronger argument is the way of coping with black hole entropy, but since hearing about that i have never had it made clear to me that the story is unique to string theory except as a representative of sane quantum theories of gravity–the point made is that the gravitational theory provides its own cutoff.

I would hope but wouldn’t guarantee that P Today would publish it–I would be glad to introduce you as a guest columnist but they might not accept that.

When Lewontin and friends wanted to do a similar, but less well justified, job on sociobiology they wrote a broadside for the New York Review of Books.Since there are so many popular books I see no reason not to do that. If that doesn’t work I could perhaps insert you into John Brockman’s “third culture” chat room.. Anyhow, good luck–pwa

I wrote back to Anderson, telling him in particular that a prominent theorist had advised me not to publish the piece, since it would be counterproductive and the problems I discussed were well-known. He responded:

(Jan 23, 200)
Dear Peter, thanks for your reply. Of course [Prominent Theorist] would feel that the article would be counterproductive. Wasn’t that just the point? And to whom is it all well-known? The general public? Deans and department chairmen who make the hiring decisions? Science journalists who create the buzz? Politicians and bureaucrats who control the purse strings? Bullshit!

Yes, i agree that the version you sent me was too technical for a general journal like the NY review, but actually not much–the Lewontin arguments were pretty technical. Anyhow, good luck with this one. I showed it to a knowledgeable colleague, not a stringy but one who collaborates with them, and he also liked it.–pwa

Anderson then put me in touch with an editor at Physics Today. They decided not to publish the piece, first suggesting that instead I write a letter to the editor, and finally rejecting even that as “too inflammatory”. Anderson’s positive response to the piece though provided significant encouragement for my decision to start writing publicly about this issue.

He was one of the greats, and will be missed.

Update: More about Anderson from Physics World, Horganism, and Science magazine.

Update: David Derbes reminds me to point out that Higgs himself always properly credited Anderson, generally referring to the “Anderson mechanism”, or more specifically describing what he had done as the “relativistic Anderson mechanism”. For instance, he wrote here:

I call this the relativistic Anderson mechanism because Anderson described it first: it was his misfortune not to do so explicitly enough.

Posted in Obituaries | 12 Comments

HEP News

The CERN Council is meeting today and tomorrow, and should approve the long-awaited 2020 update of the European Strategy for Particle Physics. There will be a live webcast of the open part of the Council meeting on Friday.

My understanding is that the most difficult and contentious decision, that of how and whether to go forward with a new energy frontier collider, has been put off until 2026, when there will be a new update. In the meantime, design work will emphasize studies for the leading contender: a new large circular electron-positron machine. Studies of a linear collider design (CLIC) will continue at a reduced rate. New work will begin on the possibility of a muon collider, as well as other advanced accelerator technologies that might someday be usable.

There will be some move in the direction of the US program, which has abandoned the energy frontier, including more participation in the US and Japanese neutrino programs. A “scientific diversity program”, Physics Beyond Colliders, will receive new support. This program will try and come up with new experiments that don’t require a new energy frontier machine. For more about it, see this CERN report and this article in Nature.

In other news from CERN, work on the LHC should start resuming this summer, with the ongoing LS2 extended by a few months because of the COVID shutdown, so beams back in the LHC late next summer. There likely will be no significant new data coming from the LHC during 2021. The extended shutdown may provide the time for magnet quench training needed to bring the machine to its design energy of 7 TeV/beam.

Update: The CERN strategy report is here, also see here, here and a press release here. There is press coverage here, here and here.

The headline news is that this backs the FCC plan: a 100km new ring, first run as an electron-positron collider, then as a much higher energy proton-proton collider. There are however a whole bunch of very significant caveats:

  • No plan for how to finance this very expensive proposal.
  • The press release mentions a construction start timescale of “less than 10 years after the full exploitation of the HL-LHC, which is expected to complete operations in 2038”. This is twenty years or so away, a very long time.
  • The main near-term goal mentioned is work on designing the magnets needed for the proton-proton machine, to know by 2026 whether a pp machine is feasible. If the design of appropriate magnets with an acceptable cost for the pp machine is not possible, the implication is that there would be no point in building the large ring and ee machine.
  • The main competitor to the FCC plan, CLIC, is not at all canceled, but work will continue on it.
  • A new project to try and design a muon collider will be funded, with a planned 2026 decision about whether to move forward on a test facility for that. The technology for this still does not exist (muons decay very quickly…) but if such a collider were feasible, it would be much smaller and likely much cheaper than something like the FCC project.

So, those who want to argue one way or another about whether it’s a good idea to spend a lot of money on building a new collider should rest assured that the future holds many, many more years in which to conduct such arguments…

Update: I find it very frustrating to see that the online discussion of this is dominated by a pointless argument about whether, as reported, CERN should be going ahead and spending more than \$20 billion or so on a new machine. THEY ARE NOT DOING THIS. What has happened is that, after a lot of work, they have identified the best possible way forward at the energy frontier (the FCC proposal) and decided not to go ahead with it now but to keep studying it and the required technologies. If the cost of this proposal had been a few billion dollars, they likely would have tried to come up with a plan to allocate much of the over billion \$/year CERN budget in future years to the project and start construction. Instead, for the next six years they are allocating .1 – .2% of the CERN budget to further studies of the proposal. Those who have been loudly complaining that this is too expensive a proposal for the HEP community to afford should declare victory, not go to war over this.

Update: The CERN press release has been changed, with “construction” starting within ten years after 2038 changed to “operation” starting within ten years after 2038. This makes more sense, the earlier version seemed absurdly far in the future. My understanding is that the current plan is essentially to put off to 2026 a decision about going ahead with FCC. By 2027 the HL-LHC will be in place, freeing up some money for a new project, possibly the FCC. A 2027 start to FCC construction would allow a start of operations within ten years after the 2038 HL-LHC end date.

Update: Adrian Cho at Science magazine has a report on this that gets it right, headlined European physicists boldly take small step toward 100-kilometer-long atom smasher. It includes the crucial:

However, CERN Director-General Fabiola Gianotti emphasizes that no commitment has been made to build a new mammoth collider, which could cost $20 billion. “There is no recommendation for the implementation of any project,” she says. “This is coming in a few years.”

Posted in Experimental HEP News | 37 Comments

HEP Theory Job Situation

Way back in the 1980s and 1990s I was, for obvious personal reasons, paying close attention to the job situation for young HEP theorists. They were not good at all: way more talented young theorists than jobs, many if not most Ph.D.s who wanted to continue in the field unhappily spending many years in various postdocs before giving up and doing something else. By the later part of the 1990s I had found a satisfying permanent position in math, so this problem seemed much less interesting. When I was writing “Not Even Wrong” I did spend quite a bit of time gathering numbers to try and quantify the problem, and wrote about them in the book.

Since then I haven’t paid a lot of attention to the HEP theory job situation, hoped that it might have gotten a bit better as the wave of physicists hired during the 1960s hit retirement age, opening up some permanent positions. Today someone sent me a link to a personal statement on Facebook (sorry, but you need to login to a Facebook account to see this) from a young theorist (Angnis Schmidt-May) who has recently decided to leave the field, for reasons that she explains. These include:

We are put in competition with each other from day one, and only very few of us will be given prestigious positions in the end. Most of us never see a permanent contract, keep jumping from place to place and eventually need to find a second career after having sacrificed our entire 20s and 30s to academia. After having made it through the worst part of this and more or less securing my career, it still made me sick to see young physicists entering this spiral. I felt terrible about encouraging them to continue on this path because it is impossible to tell who will make it in the end and who will end up miserable with regrets…

Science itself is severely suffering from the poor working conditions and lack of genuine career prospects. I personally found it extremely hard to focus on the science while constantly being worried about the duration and location of my next contract. #PublishOrPerish. Interactions with and among colleagues are often dominated by the drive to “show off”. Very few people focus on removing misunderstandings or ask honest questions in order to fill their knowledge gaps. The general atmosphere is dominated by doubt instead of trust. We constantly need to outshine our peers. Better to demonstrate superficial knowledge of broad subjects than to focus on the details of a deep problem. Your next result needs to be “groundbreaking”, otherwise you’re out of a job. But produce it and have it published at least one year before your contract ends because that’s when you need to apply for a new one. Science has become a show…

I see absolutely no chance that any of the above will change any time soon.

She also makes important points about the personal cost of this system:

During the last 10 years, I was forced to constantly move around, losing contact to people who meant a lot to me and not being able to establish new lasting relationships.

Sadly, it seems pretty much nothing at all has changed in the last 30-40 years, and I continue to believe this is one reason the subject has been intellectually stagnant during this period. About the only positive suggestion I can make for anyone who wants to try and do anything about this is to take a look at the analogous job situation in mathematics. My knowledge of this is mostly anecdotal, but my impression is that while, like most academic fields, the career path for a new math Ph.D. is not easy, the situation is not at all as bad as the one in HEP theory described above.

Completely Off-Topic: Xenon1T has reported new results today. This seems to me unlikely to be new physics (extraordinary claims require extraordinary evidence), so if you want to follow this story, you should be consulting Jester, not me.

Posted in Uncategorized | 30 Comments

Feynman Lectures on the Strong Interactions

Available at the arXiv this evening is something quite fascinating. Jim Cline has posted course notes from Feynman’s last course, given in 1987-88 on QCD. There are also some audio files of a few of the lectures available here. The course was interrupted by Feynman’s final illness, with the last lecture given just a couple weeks before Feynman’s death in February of 1988. There’s an introduction to the notes by Cline in which he explains more about the course and how the notes came to be.

The course was given over thirty years ago, and many textbooks have appeared since then, but it seems to me this has held up well as an excellent place for a student to go to learn the subject.

Posted in Uncategorized | 2 Comments

An Advertisement for Representation Theory

There’s a new article at Quanta today promoting representation theory, Kevin Hartnett’s The ‘Useless’ Perspective that Transformed Mathematics. Representation theory is a central, unifying theme in modern mathematics, one that deserves a lot more attention than it usually gets, with undergraduate math majors often not exposed to the subject at all. My book on quantum mechanics is very much based on the idea that the subject is best understood in terms of representation theory. Unfortunately, physics students typically get even less exposure to representation theory than math students.

While I think the article is a great idea, and well-worth reading, I do have two quibbles, one minor and one major. The minor quibble is that one example given of a group, the real numbers with multiplication, is not quite right: you need to remove the element 0, since it has no inverse. If the group law is the additive one, then the real number line with nothing removed truly is a group.

The major quibble is with the theme of the article that a group representation can be thought of as a simplification of something more complicated, the group itself. This is a good way of thinking about one aspect of the use of representation theory in number theory, where representations provide a tractable way to get at the much more complicated structure of the absolute Galois group of a number field. The talk by Geordie Williamson linked to in the article (slides here) explains this well, but Williamson also gets right the more general context, where the group can be easy to understand, the representations complicated. For a simple example of this, in the case of the circle group $S^1$ the group is very easy to understand, its representation theory (the theory of Fourier series) is much more complicated (and much more interesting).

As Williamson explains, a good way to think about what is going on is that representation theory does simplify something by linearizing it, but it’s not the group, it’s a group action. When people talk about the importance of the study of “symmetry” in mathematics, physics, and elsewhere, they often make the mistake of only paying attention to the symmetry groups. The structure you actually have is not just a group (the abstract “symmetries”), but an action of that group on some other object, the thing that has symmetries. When you talk about “rotational symmetry” you have a rotation group, but also something else: the thing that is getting rotated. Representation theory is the linearization of this situation, often achieved by going from the group action on an object to the corresponding group action on some version of functions on the object. Once linearized, the group action becomes a problem in linear algebra, with the group elements represented as matrices, which act on the vectors of the linearization.

To further add to the confusion, “symmetry” is often described in popular accounts as meaning “invariance”. In typical examples given, “invariance” just means that you have a group action, since the group is taking elements of the set to other elements of the set (e.g. rotations not of an arbitrary object, but of a sphere). In representation theory, you have a different notion of invariance. For instance, for the representation of rotations on functions on the sphere, the constant functions are a one-dimensional invariant subspace, giving a trivial representation. But, there are lots of more interesting invariant subspaces of higher dimensions. These are the irreducible representations on the sets of spherical harmonics.

Posted in Uncategorized | 10 Comments

The Week’s Anti-Hype

I never thought I would see this happen: a university PR department correcting media hype about its research. You might have noticed this comment here a week ago, about a flurry of media hype about neutrinos and parallel universes. A new CNN story does a good job of explaining where the nonsense came from. The main offender was New Scientist, which got the parallel universe business somehow from Neil Turok and from here.

The ANITA scientists and their institution’s PR people were not exactly blameless, having participated in a 2018 publicity campaign to promote the idea that they had discovered not a parallel universe, but supersymmetry. They reported an observation here, which led to lots of dubious speculative theory papers, such as this one about staus. The University of Hawaii in December 2018 put out a press release announcing that UH professor’s Antarctica discovery may herald new model of physics. One can find all sorts of stories from this period about how this was evidence for supersymmetry, see for instance here, or here.

It’s great to see that the University of Hawaii has tried to do something at least about the latest “parallel universe” nonsense, putting out last week a press release entitled Media incorrectly connects UH research to parallel universe theory. CNN quotes a statement from NASA (I haven’t seen a public source for this), which includes:

Tabloids have misleadingly connected NASA and Gorham’s experimental work, which identified some anomalies in the data, to a theory proposed by outside physicists not connected to the work. Gorham believes there are more plausible, easier explanations to the anomalies.

The public understanding of fundamental physics research and the credibility of the subject have suffered a huge amount of damage over the past few decades, due to the overwhelming amount of misleading, self-serving BS about parallel universes and failed speculative ideas put out by physicists, university PR departments and the journalists who mistakenly take them seriously. I hope this latest is the beginning of a new trend of people in all these categories starting to fight hype, not spread it.

Posted in Uncategorized | 6 Comments

Various Items

A few short items:

  • Things had been going quite well at the LHC, they were ahead of schedule, starting to ramp up intensity for the new run. Then at 5:30 this morning a weasel decided to visit a 66kV transformer, which did not end well either for the weasel or for the LHC power grid. The machine and a lot of its cryogenics lost power, and recovery is going to take a week or so.
  • For some commentary on the excitement about the new run building up (pre-weasel), see Tommaso Dorigo (at least I’m guessing he’s the author) here. He points to the twitter #MoarCollisions hashtag.
  • In various Breakthrough Prize related news, first there’s an announcement from Terry Tao about the new IMU Graduate Breakout Fellowships, funded by him and some of the other math prize winners.

    On the physics front, Caltech has Glitz and Qubits, about Alexei Kitaev and John Schwarz’s experience with the prize. Schwarz still hopes for vindication of his string theory prize by a discovery of SUSY at the LHC, assigning a much higher probability to this than I think most other people would these days:

    I would say the probability is on the order of 50 percent or so that it will show up.

    As for the glitz:

    At the 2014 award ceremony, Schwarz says, he and his wife, Patricia, were “both struck by the fact that the Hollywood types showed no interest in mingling with scientists.” And the media coverage also seemed to focus on the movie stars rather than the award winners.

    Kitaev points out a major positive effect of the $3 million: more respect from one’s family:

    But for Kitaev, the biggest impact of awards like the Breakthrough Prize in Fundamental Physics is on his family. “They don’t really understand what I’m working on,” he says. But thanks to these awards, they at least realize his research is a pretty big deal. “It helps me do more work because they have more respect for it,” he says. “My wife is really proud of me.”

  • In other big money news the Perimeter Institute and the Stavros Niarchos Foundation have announced a new professorship for Asimina Arvanitaki, funded by $8 million. More about her here.
  • At Nautilus you can read an interview with IAS director, theoretical physicist Robbert Dijkgraaf.
  • At Edge, there’s a conversation with Frank Wilczek. I’m quite curious what the following is about, have no idea:

    What I’ve been thinking about today specifically is something of a potential breakthrough in understanding our fundamental theories of physics. We have something called a standard model, but its foundations are kind of scandalous. We have not known how to define an important part of it mathematically rigorously, but I think I have figured out how to do that, and it’s very pretty. I’m in the middle of calculations to check it out.


Update
: Two more:

  • Jim Baggott has a post on Status Anxiety, with more thoughts about the Munich conference and the use of the term “theory”.
  • Discover magazine has an article in the upcoming June issue on The Fall and Rise of String Theory. The story seems to be that String theory for some reason ran into a little trouble in 2006, but now it’s back, because Strominger has done some “string-inspired” black hole calculations, and some people are claiming inspiration from AdS/CFT for an approximate calculational method in some condensed matter models. The idea now seems to be that, starting from this, string theory is on its way to again finding a theory of everything. No comment on its hype problem.

Update: A special 2016 physics Breakthrough Prize has been awarded to the LIGO people. \$1 million split by Drever, Thorne and Weiss, \$2 million for the rest of the collaboration.

Posted in Uncategorized | 20 Comments

Oral Histories

I recently ran across a recent interview with Mary K. Gaillard, which encouraged me to look again at the AIP’s oral histories site. For a review of her autobiographical book, see here.

She has the following comments on the current state of HEP theory:

Zierler:

What do you see as the future of theoretical physics? Where is the field headed?

Gaillard:

Well, I think it’s headed towards insanity [laugh] by itself. I mean, no, if we don’t have experiments, people can let their imaginations run wild, and invent anything without it being verified or disproven. So I think it—I mean, if we want to understand more about what happens at higher energies, we have to have higher energy colliders. I don’t think—well, cosmology is tied to particle physics, and that’s probably something from—I mean, there is a lot of data coming from cosmology. And there is some data that will be coming from very low energy precision physics. But I don’t think that theory by itself—it needs to be kept in line by [laugh] experiments.

Zierler:

And so what advice do you have sort of globally for people entering the field in terms of the kinds of things they should study, and the way they should study those things?

Gaillard:

That’s a [laugh]—actually, I often advise people to go into astro-particle physics just because I think that it has more promise of getting data because I don’t—I mean, I strongly believe you can’t go forward without good data, and unless—well, of course, if they do have another generation of colliders, that would be great. I just don’t know if that’s going to happen…

Another very recent interview I found interesting was that of Vipul Periwal. Periwal arrived as a Ph.D. student at Princeton around the time I was on my way out, starting his career right about when string theory hit in late 1984. He worked as a string theorist for quite a few years, ending up in a tenure-track faculty position at Princeton, but then left the HEP field completely, starting a new career in biology. Here are some extracts from his interview:

Zierler:

And what was David [Gross]’s research at this point? What was he pursuing?

Periwal:

String theory. He was just 100 percent in string theory. Right? They just did the heterotic string, and so everyone was — every seminar at Princeton at that time was all string theory. It was all string theory. Curt was working on it, David was working on it. Edward was working on it. Larry Yaffe was probably the only person — no, two people, Larry Yaffe and Ian Affleck were not doing string theory. Not that they couldn’t, but they just would not do it.

Zierler:

So you mean, despite at this point all of the work on string theory, there were still existential questions about what string theory was, that remained to be answered?

Periwal:

There still are.

Zierler:

Yeah.

Periwal:

No one has ever figured out what is string theory. I mean, if you go ask all the eminent string theorists, none of them can answer for you this one simple question. Can you show me a consistent string theory, where supersymmetry is broken?

Zierler:

Was it good for your research? Was it a good time for you [his postdoc at the IAS]?

Periwal:

I don’t think I did particularly interesting research. I did — I mean, I did okay, but I’m not particularly proud of anything I did there, except for one little paper I wrote, in which [laughs] — see, this is called the contrarian part — is I showed — people were very excited about the large N limit, so I took this toy model, and I showed that in the large N limit, it actually produced something nonanalytic, as in like, you could not, in any order of 1 over an expansions, ever see what the answer was that was exact at N equals infinity. So, in other words, it was to me a cautionary tale. Like, you think you’re doing large N and then getting an intuition for finite N. But here’s this very simple model where you can do the calculation exactly, and you can do all your 1 over N expansion as far as you want, and it’ll never tell you [laughs] about what’s going to happen at N equals infinity. But you know, it’s a — at this point, string theory was already at that time pretty much a sociological thing.

Zierler:

What do you mean “sociological”?

Periwal:

So, it’s something that was borne home to me gradually, that there’s no experimental proof. Like, are you a good physicist or a bad physicist? Who’s going to tell? How do you know? Right?

Zierler:

Yeah.

Periwal:

I mean, I’d go and give a talk somewhere, and I remember this very clearly. I went and gave a talk at SUNY Stony Brook, what’s now called, I guess, Stony Brook University. And at the end of the talk, I was talking to one of the faculty there who’d invited me. And he said, “So, what does XYZ think of this work?” And I was just taken aback. I was like, wait, you’re a physicist. I’m a physicist. Why do we need to know what XYZ thinks of this?

Zierler:

Yeah.

Periwal:

Right? That’s what I mean by sociology.

Zierler:

I see. It’s as much about what a certain group of peers thinks about the theory.

Periwal:

Yeah, and this really perturbed me. As far as I was concerned, after the string perturbation theory diverges thing, I was not interested in doing perturbative calculations. So, what the solution was that people did was: okay, we’ll work on various supersymmetric theories where there is no higher contribution, and under the assumption that there is supersymmetry, you can use holomorphicity to deduce things from the structure of the fact that there’s so much supersymmetry. And this really bothered me, as in okay, there’s this really amazingly beautiful structure, and lots of very pretty mathematical results that are coming out — mathematical results that are suggested by these correlations. But I just don’t get — as a physicist, I don’t to want to have to worry about, “What does XYZ think about what I’m doing?”

Zierler:

Yeah, because you’re pursuing a truth, and it’s either true or it’s not. It doesn’t really matter what other people think about it.

Periwal:

Right. I really don’t care. I mean, no matter how much I respect — and I do — Edward, or David, or whoever, I really don’t need to know what they think about my work. Right? I just — anyhow —

Zierler:

How does that attitude serve you in an academic setting, though? Right?

Periwal:

It doesn’t.

Zierler:

How does that attitude affect you in terms of tenure considerations and things like that?

Periwal:

Yeah, so when I was — no, so I actually — I mean, when I was — well, I have no — I’m really stupid sociologically, as in, I have no instinct for self-preservation. So, I could see I had role models in front of me of how people with tenure…

Zierler:

Succeeded.

Periwal:

…succeed, not just getting tenure at Princeton, but getting tenure at very good places after Princeton, too. And I paid zero attention to all this. So, while I was at Princeton, I tried doing some lattice gauge theory.

With this attitude, it’s not surprising that in Periwal didn’t get tenure at Princeton. He didn’t soon get job offers elsewhere in HEP theory, and decided in 2001 better to try another field than keep going in the one he was in. The interview ends with:

Zierler:

Alright. So, really, the last question. What does the big breakthrough moment look like for you? How would you conceptualize this in terms of putting all of this together? What does that big breakthrough look like?

Periwal:

If I could make a prediction that was clinically testable, that would make me very happy.

Zierler:

Do you think you’ll get there? It’s the thing that motivates you.

Periwal:

Yeah. I want — you know, I said this once. We had someone visiting when I was managing the physics seminar at Princeton once, as an assistant professor. So, this guy asked me, “So, Vipul, what are you working on?” And I was very jaundiced at that time about making a prediction. So, I said, “Well, lattice gauge theory,” which, you know, nobody at Princeton did lattice gauge theory. You were all supposed to be doing string theory. I said, “Yeah, I want a number before I die.” [laughs] People are looking at me like, “What kind of lunatic is this?” But you know, a number. That would be nice.

Looking through the old interviews, I found one of very personal interest, that of Gerald Pearson, who worked with my grandfather Gaylon Ford at Bell Labs. Some of his stories mentioned work with my grandfather (whose main expertise was in the design and construction of vacuum tubes) at Bell Labs during the 1930s. During this period both studied at Columbia, where my grandfather got a master’s degree in physics.

Pearson:

Gaylon Ford worked with Johnson. When Kelly was head of the tube department, he worked in that area. And then they had a big shakeup after which the job was no longer available. Much against his desires, he came over to work with us.

Hoddeson:

In 1938 you were moved over from Johnson’s group into Becker’s. In fact, you and Sears seem to have changed places.

Pearson:

Before that took place, I remember Johnson called me into his office one day and he wanted to know if I would like to work on… well, Buckley had sent a memorandum asking for temperature regulators for buried cable. Johnson wanted to know if I would like to work in this area. Of course, no one likes to change their jobs but I said, “Fine” and we agreed that I would spend a portion of my time on this problem and that’s where thermistors came from. This continued on and it was very successful. Then it was decided that the work fit in better with Becker’s area than it did with Johnson’s. And, well you asked me about Ford. He was the one who was brought from the tube shop to work on this. And then he later went to work on something else.

Hoddeson:

Let’s see if we can date that time. Ford wasn’t working with you yet. Ford is here with you in 1934. But this move didn’t take place until ’38.

Pearson:

Yes, that’s what I was saying. He first came over to work on change of resistance with temperature. And he was working with a sulfide compound. And then, let’s see, what happened to him. He went someplace else and Johnson called me into his office and asked me if I would like to carry on Ford’s work and we agreed that I should do it part time and still work on noise. But I said I didn’t want to work with sulphur, it smelled too bad. I said if I work in that area, I’m going to use some other materials. So I made a study of that. First I worked on boron and then on a combination of oxides. A lot of my patents are on such materials and devices. These devices are still used today in the buried cable system as volume regulators.

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Fourier Analysis Notes

This semester I’ve been teaching a course on Fourier Analysis, which has, like just about everything, been seriously disrupted by the COVID-19 situation. Several class sessions have been canceled, and future ones are supposed to resume online next week. To improve matters a bit, I’ve been writing up lecture notes for the material since in-person lectures were canceled, and we’ll see how long I have the energy to keep this up.

The website for the course is here, giving detailed information about what it covers. In terms of level of mathematical rigor, the concept is to use the course as an opportunity to give students some motivation for a conventional real analysis course. The only prerequisite for the course is our usual Calculus sequence, which is not proof-based. In this class students are expected to try and follow proofs given in the book and in class, but not expected to be very good at coming up with their own proofs in the assignments, which mostly are computational. The textbook (Stein-Shakarchi) is based on a Princeton course with a somewhat similar philosophy of providing an introduction to analysis, but it is very challenging for the students to follow. I’ve looked around, but not found a better alternative. Other books on the subject tend to be either books for mathematics students that are even more abstract and challenging, or books for engineers that focus on either signal analysis or PDEs. Since the math department already has a PDE class I want to emphasize other things you can do with the subject.

The first set of lecture notes I wrote up were only loosely connected to Fourier analysis, through the Poisson summation formula. They dealt with theta functions and the zeta function, giving the standard proof of the functional equation for the zeta function that uses Poisson summation. I confess that one reason for covering this material is that I’ve always been fascinated by the connection between theta functions, quantization, representation theory (through the Heisenberg and metaplectic groups), and number theory. This subject contains a wealth of ideas that bring together fundamental physics and deep mathematics. On the mathematics side, this story was generalized by Tate in his thesis, where he developed what is essentially the GL(1) case of the modern theory of automorphic forms that underpins the Langlands program. On the physics side, one can think of what is going on as the standard canonical quantization of a finite-dim phase space, but with a lattice in the phase space giving a discrete subgroup of the usual Heisenberg group, and lots of new structure. For the details of this, one place to look is volume III of Mumford’s books on theta functions.

The second set of lecture notes, which I’ve just started on, are intended as an introduction to the theory of distributions, a topic that isn’t in Stein-Shakarchi. I highly recommend the book by Strichartz referred to in the notes for more details, with the notes maybe best used just as an introduction to that book.

I don’t want to turn this blog into yet one more place for discussion of the COVID-19 situation that just about all of us are obsessed with at the moment. If you’re interested in my personal experience, I’m doing fine. Almost all of us in New York are now pretty much confined to our apartments (it helps that the weather outside today is terrible), other than for short ventures out to get food or some exercise. I’d like to optimistically think that New York started taking action to stop the virus spread early enough to avoid disaster at the local hospitals. The best place I’ve seen to try and follow what is happening there is this web page. We’ll see in the next couple days if the problem has started to peak, or has much further to go.

I’m in much better shape than most people, having left town early for a spring break vacation. I had been planning a trip to Paris, at the very last minute instead rented a car and started out on a road trip in the general direction of New Orleans, consulting coronavirus report maps for where to avoid. Ended up in Memphis and then the Mississippi Delta (it had become clear New Orleans was a bad idea) before finally deciding that the situation was getting serious everywhere and it was time to head home. So, ended up back here in New York in relatively good mental shape for the confinement to come. Good luck to all of us in dealing with the coming challenges…

Update: The semester is now over, and I’ve put together all the notes I wrote up in one document, available here. This fixes mistakes/typos/etc. in earlier versions of the notes, so I’m changing the links to point to the final version.

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