Various Stuff

A few links that may be of interest. Mathematics first:

  • A seminar “Lectures Grothendieckiennes” on the mathematical ideas of Alexander Grothendieck is taking place this year in Paris, and has just recently started up.
  • My ex-Columbia colleague Jeff Achter is one of the authors of an unusual new math paper: Hasse-Witt and Cartier-Manin matrices: A warning and a request. The paper points out that papers of Manin at some points confused an operator and its dual, leading to potential sign errors in later papers that reference Manin’s results. I’m quite sympathetic to the problem, having at various points fallen victim to similar confusions while writing my book (I hope they have all been resolved in the final version, wouldn’t bet anything really valuable on it…).
  • Nature has an excellent obituary of Vladimir Voevodsky, written by Dan Grayson.

On the physics side:

  • The LHC has now ended data-taking at 13 TeV for the year (a recent summary is here) and will start up again next spring. The machine ended up delivering about 50 inverse fb each to CMS/ATLAS (bettering the goal of 45), of which about 45 was recorded. Results published so far typically use 36 inverse fb from previous year’s data, so next year we should start seeing results based on a total 13 TeV data set of up to 80 inverse fb.
  • Still no WIMPs. Frank Wilczek surveys searches for his favorite dark matter alternative here.
  • At Big Think, Eric Weinstein has a take on what’s gone wrong with theoretical physics over the past 40 years that I’m mostly in agreement with.
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Where the Money Comes From

Since returning from a vacation partly spent isolated from the internet, I’ve been catching up and noticed that some of the most prominent sources of funding for math and physics research have been making the news:

  • The New York Times and other sources have extensive reports based on leaked records from an offshore law firm that specializes in helping you avoid inconvenient US tax and reporting requirements. The story starts out with the example of Jim Simons, who has become the largest non-governmental funder of math and physics research. His Simons Foundation has been doing an excellent job of providing such funding. They have about \$3 billion in assets, annual income of around \$500 million. The Times reports that Simons (with a net worth of about \$18.5 billion) has an offshore version of the Foundation, the Simons Foundation International, with assets of \$8 billion, dwarfing the onshore version.
  • The assets of these Foundations are presumably largely invested in the secretive and extremely successful Renaissance Technologies hedge fund, which also is the employer of quite a few physicists and mathematicians. I’ve asked many people over the years, but have never found anyone who knows (or will admit to knowing) what it is that RenTech does that is so successful. A peculiar aspect of the coming age of private math/physics research funding is that no one getting this funding really knows where the money comes from.

    In other news while I was away the CEO of RenTech, Robert Mercer, was finally induced to leave. Mercer had drawn a lot of attention recently since he in recent years has been taking the opposite tack to Simons, funding institutions devoted to promoting untruth over truth (e.g. Breitbart News), achieving fantastic success last year. He also has branched out from doing whatever secretive things RenTech does to make mountains of money using computers and data, starting up a firm called Cambridge Analytica, a firm involved in secretively using computers and data to undermine democracy in the US and elsewhere. I had been wondering for quite a while what Simons thought of Mercer’s activities. My understanding of highly-paid finance jobs was that your employer pays you a lot of money in return for having your full attention and devotion to not having negative stories about them come to public attention, so Mercer’s continued employment was surprising. It seems that Simons finally had enough, after realizing how much damage Mercer was doing to his firm, in particular by creating a situation that would discourage many people from wanting to work there (there also was a campaign underway to get institutions to divest from investments with RenTech).

  • Another high profile source of funding for math and physics, in this case for cash prizes to mathematicians and physicists, has been venture capitalist Yuri Milner, with his Breakthrough Prize organization. New prizes will be announced in three weeks at a December 3 prize ceremony (I also believe there will be an associated Breakthrough Prize symposium held at Stanford shortly thereafter). It has always been well-known that much of Milner’s wealth derived from investments in Facebook and Twitter. Less well-known and recently revealed was that a major source of the funds for these investments was Russian state organizations closely tied to Vladimir Putin.
  • Turning to sources of public funding, there’s not very positive news about a possible ILC collider in Japan, with reports of a cutback of the proposal from a 500 GeV to a 250 GeV machine (which would still cost about $7 billion).
  • Foreign policy magazine has an article discussing the proposal for a huge new collider in China (discussed here). The point of view of the article is quite critical of the idea of locating a huge new project in a country with an increasingly authoritarian regime:

    China’s next-generation supercollider will unlock secrets of the universe — and destroy the ideals of the scientists running it.

    Luckily, for another more local prominent large country with an increasingly authoritarian and xenophobic regime, the issue of a possible problem with locating an international collider project there isn’t likely to come up since its leaders have no interest in funding such projects.

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Quantum Theory, Groups and Representations

While I was away last week on vacation, it seems that Springer has published my book on quantum mechanics and representation theory (previously discussed in various blog posts). The Springer page is here, your institution may provide access to the content (and a $24.99 MyCopy softcover) at the Springer Link page for the book. I’ve retained copyright for the content of the book and a version with essentially the same content as the Springer version is available from my website here. The Springer version has their formatting, copy-editing and metadata. The Amazon webpage for the book (if you’re in the mood to write a review there, feel free) is here.

I haven’t yet seen a physical copy of the book, don’t know how long it will take for them to start printing copies. From people at Springer I learned last year that they no longer print and store copies of such books, they’re now always printed on demand (with the quality of the printing dependent on where you order your book from, German printers are quite good I hear..).

Just before leaving on vacation, I gave an introductory talk on some of the themes of the book at LaGuardia Community College (slides here). This week I’ll be giving a similar talk at a math department colloquium at Queensborough Community College this Wednesday (1 pm, Science building, S-213).

Posted in Quantum Theory: The Book | 10 Comments

This Week’s Hype

Yet another entry in the long line of nonsensical hype about fundamental physics driven by misleading university press releases is today’s news that CERN Scientists Conclude that the Universe Should Not Exist. Tracking this back through various press stories (see here, here and here), one finds that the original source, as always, is a university press release designed to mislead journalists. In this case it’s Riddle of matter remains unsolved from Johannes Gutenberg University Mainz, a press release designed to promote this paper in Nature.

The paper reports a nice experimental result, a measurement of the antiproton magnetic moment showing no measurable difference with the proton magnetic moment. This is a test of CPT invariance, which everyone expects to be a fundamental property of any quantum field theory. The hype in the press release confuses CPT invariance with CP invariance. We know that physics is not CP invariant, with an open problem that of whether the currently known sources of CP non-invariance are large enough to produce in cosmological models the observed excess of baryons over antibaryons. An accurate version of the press release would be: “experiment finds expected CPT invariance, says nothing about the CP problem.”

If this experiment had found CPT non-invariance, the implications for early universe baryon-antibaryon asymmetry would have been of minor interest compared to the revolutionary discovery that a fundamental theorem of quantum field theory was violated, shattering our understanding of fundamental physics in terms of quantum field theory.

Posted in This Week's Hype | 24 Comments

Short Items

A few short items:

  • My graduate school roommate Nathan Myhrvold has a new book coming out this month, a five-volume series about the science of bread, based on several years of research into the subject at his laboratory near Seattle. Robert Crease has gone out to visit, and gives a wonderful detailed report on The physics of bread in this month’s Physics World.
  • An article at FQXI on multiverse research they are funding seemed to finally give me an understanding of what this is all about:

    These are the two conceptually hardest questions in cosmology, according to Raphael Bousso, a theoretical physicist at the University of California, Berkeley. They go to the core of what it means to exist as a human being making sense of the universe we find ourselves in. And, he adds, unfortunately, there is very little physical knowledge to go on when it comes to working out the answer.

    Undaunted by the lack of tools to help them, theatrical physicists Eugene Lim of King’s College London, UK, and Richard Easther of the University of Auckland, New Zealand, are…

    This all of a sudden made things clear: what is going on is “theatrical physics”, not “theoretical physics”. Going on like this about the multiverse is performance art.

    Unfortunately I just noticed that this page has been edited (new version here), removing the enlightening characterization of what this is about.

  • I’m glad to see that Natalie Wolchover has just won an AIP award for her writing about physics, in particular for a piece on how physicists are dealing with the “nightmare scenario”. While she’s perhaps the best professional journalist writing about these topics, for coverage of this from a professional physicist, the best you can find is Sabine Hossenfelder’s blogging at Backreaction. I’m pleased to hear that the two of them will be appearing at an event here next month in NYC, talking about Making Sense of Mind-Blowing Physics at NYU on Nov. 16.

Update: Sabine Hossenfelder has a book coming out next year, which should be fascinating (although I suspect I’ll have something to disagree with…).

Gian Francesco Giudice has a long essay about the status of particle physics, post-negative LHC results. For better and worse, I think it captures well the view of many mainstream theorists.

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Shut Up and Calculate!?

I noticed recently that Nima Arkani-Hamed was giving a talk at Cornell, with the title Three Cheers For “Shut Up And Calculate!” In Fundamental Physics. No idea whether or not video is now or will become available.

From the abstract one can more or less guess what sort of argument he likely was making, and it’s one I’m mostly in agreement with. “Shut Up and Calculate!” is pretty much my unspoken reaction to almost everything I read purporting to be about foundational issues in quantum mechanics. I have in mind in particular discussions of the measurement problem, which often consist of endless natural language text where one struggles to figure out exactly what the author is claiming. An actual calculation showing what happens in a precise mathematical model of a “measurement” would be extremely helpful and likely make much clearer exactly what the problem is (or, sometimes, whether or not there even is a problem…). Such calculations are all too few in a huge literature.

Over the last few years, while teaching and writing a book about the mathematics of quantum mechanics, the tedious exercise of trying to get all signs right in calculations has sometimes turned out to be quite illuminating, with tracking down a mysterious inconsistency of minus sign leading me to realize that I wasn’t thinking correctly about what I was doing. I’m all too aware that this kind of calculational effort is something I too often avoid through laziness, in favor trying to see my way through a problem in some way that avoids calculation.

On the other hand, I’m not quite ready to sign up for “Three Cheers”, might just stick to “Two Cheers”. For a perfect example of what’s wrong with the “Shut Up and Calculate!” philosophy, one can take a look at the forthcoming Workshop on Data Science and String Theory planned for Northeastern in a month or so. They have a Goals and Vision statement which tells us that they plan to:

treat the landscape as what it clearly is: a big data problem. In fact, the data that arise in string theory may be some of the largest in science.

About being the “largest”, I think they’re right. The traditional number of 10500 string theory vacua has now been replaced by 10272,000 (and I think this is per geometry. With 10755 geometries the number should be 10272,755). It’s also the case that “big data” is now about the trendiest topic around, and surely there are lots of new calculational techniques available.

The problem with all this is pretty obvious: what if your “data set” is huge but meaningless, with nothing in it of any significance for the problem you are interested in (explaining the Standard Model)? This is not a new project, it’s an outgrowth of the String Vacuum Project, which I wrote about here, here and here. This started with a 2005 funding proposal, ended up getting funded by the NSF during 2010-2014. From the beginning there were obvious reasons this sort of calculational activity couldn’t lead to anything interesting, and as far as I can tell, nothing of any value came out of it.

For an opposite take to mine on all this, see the paper Big Numbers in String Theory, by Bert Schellekens. It contains an odd June 2017 preface explaining that it was supposed to be part of special issue of Advances in High Energy Physics devoted to “Big Data” in particle and string phenomenology (“all the ways we use high performance computing in addressing issues in high energy physics, and (in particular) the construction of databases of string vacua”). This issue was cancelled “as requested by the Guest Editors”. I wonder what the reason for this cancellation was, in particular whether it had anything to do with part of the topic of the special issue being considered by some to be obvious nonsense.

Posted in Multiverse Mania | 61 Comments

50 Years of Electroweak Unification

The 50th anniversary of electroweak unification is coming up in a couple days, since Weinberg’s A Model of Leptons paper was submitted to PRL on October 17, 1967. For many years this was the most heavily cited HEP paper of all time, although once HEP theory entered its “All AdS/CFT, all the time” phase, at some point it was eclipsed by the 1997 Maldacena paper (as of today it’s 13118 Maldacena vs. 10875 Weinberg). Another notable fact about the 1967 paper is that it was completely ignored when published, only cited twice from 1967 to 1971.

The latest CERN Courier has (from Frank Close) a detailed history of the paper and how it came about. It also contains a long interview with Weinberg. It’s interesting to compare his comments about the current state of HEP with the ones from 2011 (see here), where he predicted that “If all they discover is the Higgs boson and it has the properties we expect, then No, I would say that the theorists are going to be very glum.”

Today he puts some hope in a non-renormalizable Majorana mass term for neutrinos as evidence for new physics. As for the future:

As to what is the true high-energy theory of elementary particles, Weinberg says string theory is still the best hope we have. “I am glad people are working on string theory and trying to explore it, although I notice that the smart guys such as Witten seem to have turned their attention to solid-state physics lately. Maybe that’s a sign that they are giving up, but I hope not.”

On this last sentiment, I have the opposite hope. He also shares what I think is a common hope for what will save the field (a smart graduate student with a new idea):

Weinberg also still holds hope that one day a paper posted in the arXiv preprint server by some previously unknown graduate student will turn the SM on its head – a 21st century model of particles “that incorporates dark matter and dark energy and has all the hallmarks of being a correct theory, using ideas no one had thought of before”.

Perhaps current training of graduate students in theory should be rethought, to optimize for this.

Update: A colloquium talk by Weinberg on this topic will be live-streamed here on October 17.

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Various Topics in Interpretation of Quantum Mechanics

A couple of recent discussions about quantum mechanics that may be of interest:

  • There’s a recent paper out by Don Weingarten that looks looks like it might have a different take on the fundamental “many-worlds” problem of, as he writes:

    how in principle the definite positions of the macroscopic world emerge from the microscopic matter of which it is composed, which has only wave functions but not definite positions.

    My naive feeling about this has always been that the answer should lie in a full understanding of the initial state of the measurement apparatus (+ environment), that it is our imperfect probabilistic understanding of the initial state that limits us to a probabilistic understanding of the final state. I found Weingarten’s investigation of this intriguing, although I’m not sure that the language of “hidden variables” is a good one here, given the use of that language in other kinds of proposals. By the way, Weingarten is an ex-lattice gauge theorist who I had the pleasure of first meeting long ago during his lattice gauge theory days. He at some point left physics to go work for a hedge fund, I believe he’s still in that business now.

    Luckily for all of us, Jess Riedel has looked at the paper and written up some detailed Comments on Weingarten’s Preferred Branch, which I suggest that anyone interested in this topic look at. Discussion would best be at his blog, a much better informed source than this one.

  • Gerard ‘t Hooft has a remarkable recent preprint about quantum mechanics, with the provocative title of Free Will in the Theory of Everything. I fear that the sort of argument he’s engaging in, trying to ground physics in very human intuitions about how the world should work, is not my cup of tea at all. Instead, what has always fascinated me about quantum mechanics has always been its grounding in very deep mathematical ideas, and the surprising way in which it challenges our conventional intuitions by telling us about an unexpected new way to think about physics at a fundamental level.

    For more discussion of the paper, there are Facebook posts by Tim Maudlin here and here in which he argues with ‘t Hooft. I confess that I wasn’t so sure whether to take the time to read these, and after a short attempt gave up, unable to figure out precisely what the argument was about (and put off by Maudlin’s style of argument. Do philosophers really normally behave like that?). Links provided here in case you have more interest in this than I do, or better luck getting something out of it.

Posted in Quantum Mechanics | 19 Comments

The Big Bang Theory and the Death of SUSY

If you’re a fan of The Big Bang Theory, perhaps you’ve seen the latest episode, The Retraction Reaction. If not, you might be interested in the following transcript (taken from here). The show has always done a good job of getting the science right, for an interview with their physics consultant David Saltzberg, see here.

The episode begins with a Science Friday interview of physicist Leonard Hofstadter by Ira Flatow:

FLATOW: So, it has been five years since the discovery of the Higgs boson– what’s the next big thing gonna be?

LEONARD: Wow, that’s hard to say. There’s so much going on. We’ve been collecting tons of data that could revolutionize the way we understand the universe. For instance, there’s a particle called a squark, which could prove supersymmetry.

FLATOW: That is interesting. Have you found it?

LEONARD: What, the squark?


LEONARD: No, no. Wouldn’t that be exciting? But we’re also looking for the selectron, the gluino and the neutralino.

FLATOW: Well, and have you found that?

LEONARD: No. Another fun sidenote– I went to high school with a girl named Theresa Gluino, but it didn’t cost $2 billion to find her. She was smoking behind the gym. (laughs)

FLATOW: So, what have you found?

LEONARD: Uh, nothing, actually. We’ve got the best equipment and the best minds all working on it. Although, some days I’m, like, ugh we’ve spent so much money. Why haven’t we found anything? What are we doing?

After a segment in which neuroscientist Amy explains that she doesn’t tell physicist boyfriend Sheldon about her new lab equipment since

AMY: We’ve been getting so much more funding than physics, he’s been a little sensitive.

another scene features Leonard called into the office of a university administrator:

LEONARD: I have to say I’m a little nervous.

Ms. DAVIS: You should be.

LEONARD: Look, I know I screwed up, but it was only one interview.
How much damage could it have caused?

Ms. DAVIS: Would you like for me to read you the e-mails from donors asking why are they giving us money if physics is a dead end?

LEONARD: I didn’t say it was a dead end. I just said that I was worried it might be.

Ms. DAVIS: So if I just said I was worried you might not have a job next week, how would you feel?

LEONARD: Light-headed, and glad you asked me to sit down. Okay, just tell me what I can do.

Ms. DAVIS: I’m gonna need you to make a statement saying that you misspoke, and that you’re confident the physics community is close to a major breakthrough.

LEONARD: You want me to lie.

Ms. DAVIS: Look, Dr. Hofstadter, I’m counting on you. I think that you are the smartest physicist at this university.

LEONARD: Really?

Ms. DAVIS: See? Lies. They’re not that hard.

Leonard then has this exchange with Penny:

PENNY: Hey, come on, look, you said a few dumb things on the radio– what is the worst that could happen?

LEONARD: I may get fired.

PENNY: Okay, well, even if you did, you could find another job.

LEONARD: Yeah, who wouldn’t want to hire the physicist who publicly said physics is dead? Well, I wouldn’t put that under “special skills”. I can fix it, I just need to write a retraction I don’t believe in– basically sell out to keep my job.

PENNY: Great, I’ll leave you to it.

He then goes to talk to string theorist Sheldon Cooper:

LEONARD: Sheldon, it’s me.


LEONARD: Look, I know you’re mad, but I have to write a statement that says the physics community is close to a breakthrough, and since you actually believe that, I could really use your help.

SHELDON: Sorry, I can’t.

LEONARD: Come on, don’t be like that.

SHELDON: What? Look. (sighs) Not all science pans out. You know, we’ve been hoping supersymmetry was true for decades, and finally, we built the Large Hadron Collider, which is supposed to prove it by finding these new particles, and it-it hasn’t. And maybe supersymmetry, our last big idea, is simply wrong.

LEONARD: Well, that sounds awful. Now I get why everyone hates me.

Penny later comes in:

PENNY: So you guys are upset because the collider thing disproved your theories?

LEONARD: It’s worse than that. It hasn’t found anything in years, so we don’t know if we’re right, we don’t know if we’re wrong. We don’t know where to go next…

PENNY: Come on. You guys are physicists. Okay? You’re always gonna be physicists. And sure, sometimes, the physics is hard, but isn’t that what makes it boring?

The episode ends with a visit to the grave of Richard Feynman, and a reference to Feynman’s story about how he got himself out of a slump in his work when he was at Cornell:

WOLOWITZ: He did so much. And here we are, stuck and letting him down. You know, Feynman used to say he didn’t do physics for the glory or the awards, but just for the fun of it. He was right. Physics is only dead when we stop being excited about it.

All in all, a pretty accurate portrayal of the situation in high energy physics theory, with a reasonable take on what to do about it.

Update: A correspondent points me to a rather Leonard Hofstadter-ish interview with Steven Weinberg back in 2011, where he says:

It may be that they’ll only discover the Higgs boson and nothing else, and we’ll be left looking at our toes and wondering what we’re going to do next. There may be nothing really new that can be reached with the LHC,

I have fears… If all they discover is a Higgs boson with roughly the properties that the theory predicts and nothing else, I don’t know where the field is going to go.

When asked a rather Ira Flatow-ish question: “Wouldn’t you say to a young person that now would be a very exciting time to go into physics?” his answer is

Whether or not it would be a good career move depends on what they are going to discover.

If all they discover is the Higgs boson and it has the properties we expect, then No, I would say that the theorists are going to be very glum.

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2017 Nobel Prize in Physics

At this point, Kip Thorne and Rainer Weiss of LIGO have (deservedly) won just about every scientific prize out there, for the first observation of gravitational waves. I don’t know of anyone who doesn’t believe they’ll be getting the Physics Nobel tomorrow morning. With an open spot in the usual limitation to three (Ronald Drever passed away earlier this year), perhaps Barry Barish will also get the nod. Most appropriate would be to use the third slot to give an award to the entire LIGO collaboration, but it seems likely that the tradition of not honoring collaborations will continue. There will be a live webcast of the announcement at 5:45am EST available here.

Update: Congratulations to the winners. I think Natalie Wolchover speaks for all science journalists when she writes:

Thrilled they won, thrilled not to spend this morning speed-reading about some bizarre condensed matter phenomenon.

Update: A couple things I’ve learned from comments and other coverage of this:

  • Some physicists have no sense of humor and are either unaware of or ungrateful for the excellent job Natalie Wolchover and others at Quanta magazine have been doing in writing high-quality stories about a wider range of topics in physics than anyone else (see here and here, related here).
  • All evidence is that on October 16th we’ll get announcement of observation of gravitational waves with an optical counterpart, with details at this conference in Baton Rouge.
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