Almost exactly twenty years ago I started writing a short article about the problems with string theory. I had been thinking about doing this for quite a while, and the timing of entering the twenty-first century seemed appropriate for evaluating something that had long been advertised as “a piece of 21st-century physics that had fallen by accident into the 20th”. The piece was done in a week or two, after which I sent it around to a group of physicists to ask for comments. The reaction was mostly positive, although at least one well-known theorist told me that publicly challenging string theorists in this way would be counter-productive.
One person who wrote back was Phil Anderson, I’ve quoted some of what he wrote to me in this posting. He suggested I send it to Gloria Lubkin at Physics Today, and evidently talked to her about it. I did do this, and after not hearing anything back for a week or two, decided to go ahead and post the article to the arXiv, where it appeared as String Theory: An Evaluation.
Rereading that article today, there’s little I would change. Its argument is even more valid now than then. The problems of the theory and how it was pursued evolved over the next twenty years in ways far worse than what I could have imagined back then. In particular, the “multiverse” argument explaining away why string theory predicts nothing is something I could not have conceived of in 2001. The tribalistic sociology that has led to a large group of people calling themselves “string theorists” when what they do has nothing to do with string theory is also something I would have thought impossible.
In many ways, twenty years of further failure have had less than no effect. Lubos Motl is still arguing that string theory is the language in which God wrote the universe, and Michio Kaku has a new book about to appear, in which it looks like string field theory is described by the God Equation. Ignoring these extreme examples, string theory remains remarkably well-entrenched in mainstream physics: for example, my university regularly offers a course training undergraduates in string theory, and prestigious \$3 million prizes are routinely given for work on the subject. The usual mechanisms according to which a failed scientific idea is supposed to fall by the wayside for some reason have not had an effect.
While string theory’s failures have gotten a lot of popular press, the situation is rather different within the physics community. One reason I was interested in publishing the article in Physics Today was that discussion of this issue belongs there, in a place it could get serious attention from within the field. To this day, that has not happened. The story of my article was that I finally did hear back from Lubkin on 2/21/2001. She told me that she would talk to the Physics Today editor Stephen Benka about it. I heard from Benka on 5/6/2001, who told me they wouldn’t publish an article like that, but that I should rework it for publication as a shorter letter to the editor. I did this and sent a short letter version back to them, never heard anything back (a few months later I wrote to ask what had happened to my letter, was told they had decided not to publish it, but didn’t bother to let me know). In 2002 an editor from American Scientist contacted me about the article, and it ended up getting published there.
Looking back at how Physics Today has covered string theory and related speculation over the past 25 years, I did a search and here’s what I found:
- Reflections on the Fate of Spacetime (Witten) (April 1996)
- String Theory Is Testable, Even Supertestable (Kane) (Feb. 1997)
- Duality, Spacetime and Quantum Mechanics (Witten) (May 1997)
- Large Extra Dimensions: A New Arena for Particle Physics (Arkani-Hamed, Dimopoulos, Dvali) (Feb. 2002)
- Is string theory phenomenologically viable?(Gates) (June 2006)
- The case for extra dimensions (Randall) (July 2007)
- String theory in the era of the Large Hadron Collider (Dine) (Dec. 2007)
- String theory and the real world (Kane) (Nov. 2010)
- What every physicist should know about string theory (Witten) (Nov. 2015)
The only thing I could find anywhere during those 25 years indicating to Physics Today readers that none of this speculation had worked out was a short opinion column by Burt Richter
- Theory in particle physics: Theological speculation versus practical knowledge (Richter) (October 2006)
It seems to me that those now in charge of Physics Today should be thinking about this history, their role in it, and what they might be able to do to make up for this heavily one-sided coverage of a controversial issue.
On another blog, people were answering a “What should I keep in mind when applying to graduate school?” question from a physics student who seemed interested primarily in theory.
One respondent, who identified themselves as being at a “top” department said that perfect test scores, perfect grades and undergraduate research experience weren’t enough to winnow the field of candidates, so the big deciding factor was the number of papers published as an undergrad. I don’t know if this person was exaggerating or not.
No doubt the requirements described select for people who are very good at what they do, but they likely also select for a very specific type, when maybe some variety is what’s needed (Lee Smolin addresses something like this point in his book).
Thanks for your comments. I appreciate that especially non-tenured theorists have a very good reason to comment anonymously. When I started the blog I was thinking that anonymity was necessary for younger people critical of string theory to be able to speak without fear of retribution, soon realized that young string theory enthusiasts also had reason to be fearful (a lot of the physics community has never been sympathetic to string theory). The tribalistic aspects of this controversy are disturbing.
A lot of what people worry about does have to do with funding and with the always precarious job situation (by the way, the job situation was just as bad if not worse before string theory became popular). Many people seem to react to the yearly multi-million dollars in prize money from Milner/Zuckerberg by arguing that it’s money going to theorists, so good. I’d love to see pressure put on the Breakthrough Prize people to change what they’re doing to fund modestly paid permanent positions for theorists, rather than give huge amounts to people who already have a permanent position.
I think one thing that is true is that there has been significant grade inflation over the years, so having a transcript with a string of As isn’t worth what it once was. This is not good for the unusually talented, who now need to find other ways to distinguish themselves.
One problematic aspect of string theory for a long time has been that ambitious young people are told that it’s “the best hope for a unified theory” or some such, so naturally try to study the subject. But, it’s a very technical business and working your way through Polchinski requires a huge investment of time and energy, arguably a really bad way for the best young theorists to be getting trained. A modest proposal would be that physics departments should serious considering getting rid of any courses teaching supersymmetric field theory and string theory. What students are learning in these courses is not very useful, and giving them a warped perspective as they try and enter the field and become researchers in their own right.
What about https://physics.aps.org/ ?
How do they compare to PT and PW with regards to the presentation of string theory and other speculations?
That’s kind of a different sort of publication, essentially news articles based on new papers. There’s not a lot about string theory there, because not a lot of new developments. Physics Today also does news stories (as opposed to the kind of promotional feature articles I was counting and linking to), and relatively few of those have been about string theory. Actually, an editor at Physics Today wrote a blog entry
responding to someone asking why there were so few news stories about string theory (he didn’t address the sort of problems I’m raising).
AcademicLurker, I think that’s a major overstatement. It is true that undergraduate (co)authorship is something that gets noticed in admissions, but smart people know that some of that is a matter of access (e.g., students who can’t do REU programs over the summer and may come from smaller schools just might not ever have a credible opportunity to be on a paper as an undergrad. That doesn’t imply something about their ability to succeed at the doctoral level.).
Regarding the lack of humbleness, the problem may not be so much in the attitude of postdocs or young researchers than in the mind of whom is in position to hire other people. And sadly this is not limited to string theory.
Some 20 years ago, when a renowned center for theoretical physics was founded, it seemed easier to be hired there as a postdoc by claiming great ideas about foundations of quantum mechanics or quantum gravity, than by presenting humble calculations on, say, the metric interpretation of the Higgs field in noncommutative geometry.
I remember some (non-stringy) conferences on quantum gravity with highly non-humble plenary talks about some models – a little bit more evolved that Ising-1D – that were presented as bright new paths towards quantum gravity just because a potential in 1/r popped out. When someone asked “how do you go from this to full gravity”, the answer was “well yes, the technical details are still to be worked out”.
Humbleness is not a value appreciated by hiring committees. In a french maths department, I was once asked what I was hoping for the future of mathematical physics. I answered “more humbleness”. I thought this was a smart answer. I learnt later on that the committee did not appreciate it at all.
As a last example, some years ago, french CNRS edited some guideline to apply to ERC grant (the main european funding agency). One of the main advice was to use key-words like “breakthrough”, “multidisciplinary”, “high-risk, high-gain” and – my favorite one – “to be at the cutting edge of knowledge”. Quite far from humbleness…
The irony is, in my experience in the US at least, is that reviewers of proposals (and papers) are generally extremely conservative and tend to strongly prefer well-trodden paths. This is independent of what the funding agencies call for. For example, NSF proposals explicitly must include some component that addresses a broader social good (this isn’t the exact wording), but typically reviewers hate anything more than ‘train the next generation.’ Anything the slightest bit of out-of-the-ordinary outreach will get slammed as a waste of time. That goes for the scientific part of the proposal as well–even though the funding agencies ask for ‘innovative’ scientific visions, in practice most reviewers are harsh towards anything save incrementalism. Maybe other people’s experience is different…
As a chemist who has always enjoyed your blog tremendously, I have the following question. What do you think about the argument that string theory, even if it may not lead to productive ends in itself, provides excellent training in physics and mathematics that would set up students for careers in other fields?
The reason I ask is because it reminds me of the field of “total synthesis” of organic molecules in chemistry where graduate students spend five or six years undertaking very arduous, risky syntheses of complex organic molecules, many of which don’t have an obvious use. The argument has often been made that while the field itself provides little benefits, it’s an excellent training ground for students because it exposes them to multiple techniques, ideas and arguments in organic chemistry that are hard to find in other subfields.
The problem is that how to calculate in string theory is an extremely specialized subject, which doesn’t have a lot of overlap with more useful fields. The really weird thing that is going on is that there’s also little overlap between what theory students are getting trained in (for example, the content of Polchinski’s two-volume textbook) and mainstream current theoretical research by “string theorists”. I’m not sure what function studying Polchinski now fulfills, other than as a tribal rite of passage.