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.