Not Even Wrong

This semester the KITP has been running a program asking What is String Theory?, which is winding up next week, and was promising to “arrive at a deeper answer to the question in the title.” It seems though that this effort has gone nowhere, with this report from the scene:

Went to a string theory conference with many of the top researchers in the field centered around tackling the question “what is string theory” and the consensus after the conference was that nobody knows lmao

For an answer to the question from someone with a lot more experience, I recently noticed that Lubos Motl is very active on Quora, giving thousands of sensible answers to a range of questions, especially having to do with Central Europe. He explains the relation of string theory and M-theory (disagreeing with Wikipedia), and defines string theory as

the name of the consistent theory of quantum gravity which covers all the vacua found in the context of critical string theory and M-theory.

I had trouble getting my head around the concept of an undefined theory known to be consistent when I first heard about it nearly 30 years ago, but it seems to still be a thing.

Sabine Hossenfelder today posted a new video on youtube which everyone in theoretical physics should watch and think seriously about. She tells honestly in detail the story of her career and experiences in academia, explaining very clearly exactly what the problems are with the conventional system for funding research and for training postdocs.

After a string of postdocs requiring moving and living far from her husband, she decided she needed to move back to Germany and applied for a grant to fund her research (I believe for this project). This is how she describes the situation:

At this point I’d figured out what you need to put into a grant proposal to get the money. And that’s what I did. I applied for grants on research projects because it was a way to make money, not because I thought it would leave an impact in the history of science. It’s not that what I did was somehow wrong. It was, and still is, totally state of the art. I did what I said I’d do in the proposal, I did the calculation, I wrote the paper, I wrote my reports, and the reports were approved. Normal academic procedure.

But I knew it was bullshit just as most of the work in that area is currently bullshit and just as most of academic research that your taxes pay for is almost certainly bullshit. The real problem I had, I think, is that I was bad at lying to myself. Of course, I’d try to tell myself and anyone who was willing to listen that at least unofficially on the side I would do the research that I thought was worth my time but that I couldn’t get money for because it was too far off the mainstream. But that research never got done because I had to do the other stuff that I actually got paid for.

As that grant ended, she decided to try instead applying for grants to work on research that she found to be more promising and not bullshit, but those grant proposals were not successful. Since then, she has left the academic research system and concentrated on trying to make a career oriented around high-quality Youtube videos about scientific research.

It seems to me that Hossenfelder correctly analyzes the source of her difficulties: “The real problem I had, I think, is that I was bad at lying to myself.” Those more successful in the academic system sometimes criticize her as someone just not as talented as themselves at recognizing and doing good research work. But I see quite the opposite in her story. Many of those successfully pursuing a research career in this area differ from her in either not being smart enough to recognize bullshit, or not being honest enough to do anything about it when they do recognize bullshit.

I was very pleased to hear yesterday that this year’s Abel Prize has been awarded to Michel Talagrand. For more about Talagrand and his mathematics, see the Abel site, Quanta, NYT, Nature and elsewhere. Also, see lots of reactions on Twitter like this one.

Almost exactly ten years ago I got an email from someone whose name I didn’t recognize, expressing interest in the notes I had made available online which would turn into the book on quantum mechanics. He was reading the notes and had some comments which he included, saying he thought they were trivial but maybe I would want to take a look. Some of them were of the type “I don’t quite understand the argument on page X”. Figuring that I’d help out an earnest reader with a weak background by explaining the argument a bit better, I took a look at the argument on page X. After a while I realized that what I had written was nonsense, a very different argument was needed. “I don’t quite understand” was his way of politely telling me “you have this completely wrong.”

I soon ran into Yannis Karatzas and asked him if he knew anything about this “Michel Talagrand”. He told me “of course! He’s amazing, almost got a Fields Medal”. Over the next year or two I benefited tremendously from Michel continuing to read carefully through my notes and send me detailed comments. He was very much responsible for improving a lot the quality and accuracy of what I was writing. He had begun his own project of trying to understand quantum field theory by writing a book about it. The result is available as What Is a Quantum Field Theory?, which is a wonderful resource for anyone interested in a precise and accurate account of much of the basics of the subject. If you’ve seen Gerald Folland’s excellent Quantum Field Theory: A Tourist Guide for Mathematicians, you can think of Talagrand’s book as a much expanded version, giving the full story that Folland only sketched.

During many of my trips to Paris since that time I’ve gotten together with Michel and his wife Wansoo, and have also seen them here in New York. It has been a great pleasure to get to know Michel in person, he is a wonderful human being as well as a truly great mathematician.

The first entry on this blog was 20 years ago yesterday, first substantive one was 20 years ago tomorrow (first one that drew attacks on me as an incompetent was two days later). Back when I started this up, blogging was all the rage, and lots of other blogs about fundamental physics were starting around the same time. Almost all of these have gone dormant, with Sabine Hossenfelder’s Backreaction one notable exception. She and some others (like Sean Carroll) have largely moved to video, which seems to be the thing to do to communicate with as many people as possible. There are people who do “micro-blogging” on Twitter, with the descendant of Lubos Motl’s blog StringKing42069 on Twitter. I remain mystified why anyone thinks it’s a good idea to discuss complex issues of theoretical physics in the Twitter format, flooded with all sorts of random stupidity.

Looking back on what I was writing 20 years ago it seems to me to have held up well, and there is very little that I would change. The LHC experiments have told us that the Standard Model Higgs is there, and that supersymmetry is not, but these were always seen as the most likely results.

My point of view on things has changed since then, especially in recent years. When I started the blog I was 20 years past my Ph.D., in the middle of some sort of an odd career. Today I’m 66, 40 years past the Ph.D., much closer to the end of a career and a life than to a beginning. In 2004 I was looking at nearly twenty years of domination of fundamental theory by a speculative idea that to me had never looked promising and by then was clearly a failure. 20 years later this story has become highly disturbing. The refusal to admit failure and move on has to a large degree killed off the field as a serious science.

The technical difficulties involved in reaching higher energy scales at this point makes it all too likely that I’m not going to see any significant new data about what the world looks like above the TeV scale during my lifetime. Without experiment to keep it honest, fundamental theory has seriously gone off the rails in a way which looks to me irreparable. With the Standard Model so extremely successful and no hints from experiment about how to improve it, it’s now been about 50 years that this has been a subject in which it is very difficult to make progress. I’ve always been an admitted elitist: in the face of a really hard problem, only a very talented person trained as well as possible and surrounded by the right intellectual environment is likely to be able to get somewhere.

My background has been at the elite institutions that are supposed to be providing this kind of training and working environment. Harvard and Princeton gave me this sort of training in 1975-1984 and I think did a good job of it at the time, but from what I can tell things are now quite different. 40 years of training generations of students in a failed research program has taken its toll on the subject. I remember well what it was like to be an ambitious student at these places, determined to get as quickly as possible to the frontiers of knowledge, which in those times meant learning gauge field theory. These days it unfortunately means putting a lot of effort into reading Polchinski, and becoming expert in the technology of failed ideas.

One recent incident that destroyed my remaining hopes for the institutions I had always still had some faith in was the program discussed here, which made me physically ill. It made it completely clear that the leaders of this subject will never admit what has happened, no matter how bad it gets. Also having a lot of impact on me was the Wormhole Publicity Stunt, which showed that the problem is not just refusing to face up to the past, but willingness to sign onto an awful view of the future, as long as it brings in funding and can be sold as vindication of the past. Watching the director of the IAS explain that this was comparable to the 1919 experimental evidence for GR surely made more than a few of those in attendance at least queasy. This particular stunt may have jumped the shark, but what’s likely coming next looks no better (replace quantum computing with AI).

The strange thing is that while the wider world and the subject I care most about have been descending into an ever more depressing environment of tribalistic behavior and intellectual collapse, on a personal level things are going very well. In particular I’m ever more optimistic about some new ideas and enjoying trying to make progress with them, seeing several promising directions. Whatever years I have available to think about these things are looking like they should be intellectually rewarding ones. Locally, I’m looking forward to what the next twenty years will bring (if I make it through them…), while on a larger scale I’m dreading seeing what will happen.

Update: For a place with extensive comments about this blog posting, see Hacker News.

This spring I’ve been teaching a course aimed at math graduate students, starting with quantum mechanics and trying to get to an explanation of the Standard Model by the end of the semester. Course notes for the first half of the course are available here, but still quite preliminary, in particular I need to do a lot of work on section 9.4 and add material to chapter 10. Hoping to get to this tomorrow.

There won’t be much progress on the notes for the next couple weeks. This coming week I’m hoping to spend some time trying to understand Peter Scholze’s IAS lectures, will go down to the IAS on Tuesday. On Thursday I’m heading out on a spring break vacation to the Arizona-Utah desert.

Perhaps a good way to think about these notes is that they’re both aimed more at mathematicians than physicists (although I hope accessible to many physicists) and also designed more to supplement than to replace the discussions in the standard physics texts. So, a lot of the standard material is not there, since it’s well-covered elsewhere, but there are a lot of topics covered that usually aren’t.

One unusual aspect of the notes is that I spend a lot of time trying to explain non-relativistic quantum field theory, since that seems to me to be a better starting point than immediately diving into the relativistic case. I’d be curious to know if anyone can point me to a good discussion of the path integral formalism for non-relativistic quantum field theory, which is something I haven’t found. This is one reason it’s taking a while to finish writing up my own version.

Also original here I think is a careful discussion of the real forms of spinors and twistors. This in some sense is background for the new ideas about “spacetime is right-handed” which I’ve been working on. Nothing in the notes now about the new ideas, but I hope the explanation of the conventional story in these notes is useful.