An interesting short interview with Ed Witten in this week’s New Scientist. Mostly straightforward stuff, but it’s always good to hear what smart people are thinking. Witten is spending the year on sabbatical at CERN; like many people, he was sort of hoping to be there when the first physics results from the LHC appeared, but reality intervened an that’s looking increasingly unlikely. Happily, CERN has developed electronic means of communication whereby interesting findings may be promulgated to researchers who are not within close physical proximity to the lab.
Longtime CV readers may be interested in Witten’s take on the String Wars:
The 1980s and 90s were dotted with euphoric claims from string theorists. Then in 2006 Peter Woit of Columbia University in New York and Lee Smolin of the Perimeter Institute for Theoretical Physics in Waterloo, Canada, published popular books taking string theory to task for its lack of testability and its dominance of the job market for physicists. Witten hasn’t read either book, and compares the “string wars” surrounding their publication – which played out largely in the media and on blogs – to the fuss caused by the 1995 book The End of Science, which argued that the era of revolutionary scientific discoveries was over. “Neither the publicity surrounding that book nor the fact that people lost interest in talking about it after a while reflected any change in the intellectual underlying climate.”
That sounds about right. For the most part, actual string theorists simply went about their business, trying to figure out what this fascinating but difficult theory really is. The irony is that a major point of the anti-string books was that the public hype concerning string theory didn’t paint an accurate picture of its more problematic features — which was true. But the backlash books gave the public a misleading impression in the other direction, leading to the somewhat amusing appearance of my own piece in New Scientist explaining that the theory was for the most part chugging along as before. Hype cuts in every direction, and it feeds on drama, not on accuracy.
There is certainly some feeling that the near-term growth area in high-energy theory is not string theory, but phenomenology (or arguably particle astrophysics). Certainly those are the people who seem to be getting the jobs these days. The explanation there is pretty straightforward: data! Or at least the promise thereof. It’s hard to do physics with little to go on other than thought experiments, but one gets by when relatively few real experiments are available. Increasingly, that’s no longer the case.
But it’s been a long time since we’ve had a good string-wars thread, so here you go. For old time’s sake.
Well, I don’t know my head from my @ss about string theory (or about any serious physics topic for that matter) but I do know some mathematics.
So I’ll just grab a bag of popcorn and enjoy the show. 🙂
Wow, an actual scientist in NS, even a successful and influential one, isn’t that against editorial policy?
OTOH, there is little to none in the way of actual physics in this article, exactly like the string wars…Probably the reason these had little to no effect on the “underlying climate”.
Hi Sean,
I always had the impression that the US string community has been largely dominated by formal stuff as well as AdS/CFT, string cosmology, black holes, etc. type of research as opposed to string phenomenology. Would you agree with that statement?
I personally got very excited when Vafa turned his attention to string pheno and I’m very happy with the fact that some of the top mathematicians like Ron Donagi and Tony Pantev are also working in this area but I can only hope that more string theorists would follow these examples.
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I personally got very excited when Vafa turned his attention to string pheno and I’m very happy with the fact that some of the top mathematicians like Ron Donagi and Tony Pantev are also working in this area but I can only hope that more string theorists would follow these examples.
Funny — I feel exactly the opposite.
“Funny — I feel exactly the opposite.”
Why?
Because we don’t understand string theory. We understand bits and pieces, but it’s not particularly likely that those bits and pieces are going to be related to the real world. The main thing that string theory has going for it is that it is a theory of quantum gravity. My feeling is that we should try to understand how it works and what it tells us about the usual problems of quantum gravity. Maybe, once we understand those things, we will know enough either to apply it to the real world or figure out something else that can be applied to the real world. But the idea that we’re going to get an experimental result from string theory as it stands now is rather implausible.
(Another thing string theory has going for it is that it tells us a ton about gauge theory, and that has the potential to be extremely worthwhile, too.)
Witten is the pontiff of string theory; he should read the books the Woit and Smolin before he pontificates thereon. His mutterings about the “intellectual underlying climate” make it clear that he is at the top of an ivory tower that is very tall indeed.
But the backlash books gave the public a misleading impression in the other direction, leading to the somewhat amusing appearance of my own piece in New Scientist explaining that the theory was for the most part chugging along as before.
Bullshit. Whether you, as a person who has his eye on an eventually-lucrative position within Caltech. will admit or not physicists have now moved beyond string theory for good. Good young grad students no longer seriously discuss string theory in their common rooms; recent postdocs are no longer interested in it; and funding bodies, those leviathans of tardy reactions, have recognised it for the intellectual cul de sac that it is.
We don’t know what the next great contribution to physics is. But the one thing everyone of my generation knows is that it’s not string theory; hell, it’s probably not even any SUSY generalization thereof.
String theory has lost. My generation no longer cares. Get over it.
It’s actually a pretty banal interview. Must be a slow news day.
“The main thing that string theory has going for it is that it is a theory of quantum gravity.My feeling is that we should try to understand how it works and what it tells us about the usual problems of quantum gravity. Maybe, once we understand those things, we will know enough either to apply it to the real world or figure out something else that can be applied to the real world. But the idea that we’re going to get an experimental result from string theory as it stands now is rather implausible.”
Well, I’m not sure if I agree with that. For instance, determining the metric of a Calabi-Yau has little to do with quantim gravity. Many problems to be solved in string pheno translate into some hard algebraic geometry problems and that is why they require input from people like Donagi. So, even if there is progress in, say, computing string amplitudes in twistor formalism, it will most likely have little impact on understanding string compactifications. By the way, if you have been following the recent work of Vafa and collaborators, one can construct successful realistic models in limits where particle physics is completely decoupled from the effects of quantum gravity and make quantitative predictions for the LHC. Ed Witten, dedicated his IAS 2008 summer school lectures to precisely this topic, so it’s not some BS of wishful thinking.
By the way, if you have been following the recent work of Vafa and collaborators, one can construct successful realistic models in limits where particle physics is completely decoupled from the effects of quantum gravity and make quantitative predictions for the LHC.
Let’s just say that there’s some disagreement on this point.
Ben Martin said:
“String theory has lost. My generation no longer cares. Get over it.”
That’s funny … every day I overhear “good young grad students” talking about strings. Granted, I am at a research institute full of good young grad students, so the law of large numbers probably has a hand in this. But I hear that it happens at other places, as well.
The funniest thing about the string wars is the way the stringophobes like to tell us that [insert influential physicist name here] thinks that string theory is speculative, over-mathematical junk….and then they advocate, as an alternative, things that [influential physicist] would surely sneer at even more contemptuously. Be careful what you wish for.
I sometimes wonder whether there was a “Hamiltonian war” when Hamiltonian mechanics was invented. Overly mathematical, there’s nothing in it that you can’t do with good old Newtonian mechanics, etc.
I think the applications to gauge theories are underrated. Many seminal string theory papers (on TQFT, CFT, tensor categories, 3-manifold invariants and Chern-Simons-Witten theory, e.g.) are basically required reading for the theoretical study of topological quantum order. While the formidable experimental challenge of observing nonabelian anyons in 2+1 dimensional quantum systems has yet to have been met, this is a much more realistic and well-defined goal than that of experimentally confirming string theory. Plus, there are tons of practical reasons for realizing topological quantum order, not least of which are superconductivity and quantum computation.
I agree with Ben Martin that the claim of no “change in the intellectual underlying climate” just doesn’t correspond with reality. What I hear from physicists in general about string theory these days is quite different than what I was hearing a few years ago. At this point, just about no departments are hiring string theorists to tenure-track positions, you have to claim to be a cosmologist or phenomenologist to get a job. This change over the past couple years is not due to any change in experimental data coming in (LHC results were a couple years away three years ago, they’re still a couple years away, and the big news from experiment about cosmology is now several years old).
Unfortunately the backlash against string theory has taken the form of a backlash against “too mathematical” work, of the sort that Witten has been and continues to be the master of. While I disagree with him about the likelihood of string theory unification using extra dimensions ever working out, I think I’m actually much more sympathetic to his current research than the rest of the particle physics community is. “The End of Physics”, included a hostile portrayal of Witten, and a dismissal of the idea that abstract theoretical work could get anywhere. My own views (including those expressed in my book) are quite different, since I have the highest regard for Witten, personally and professionally, and continue to think that the sort of deep mathematical work he continues to do is one of the best hopes for the future of particle theory.
I think Peter is right. Surely no one with an intellect capable of understanding the difficult maths of string theory has any business in a physics department. When will people realize that physics is about ego and pure dumb luck? I mean, any discipline that would allow its leaders to emerge through revolutions, vis a vis Newton, Einstein, Schrodinger, Heisenburg, Dirac, etc, is clearly about nothing more than passing fancies. The only true motto that can possibly be used by the physics community is, “I don’t know, I make it up as I go along.”
Just imagine the cacophony that would erupt if we were to ever to allow logic, reason and math to dominate physics! Such dissonance can not be permitted within the university setting!!!
So I appeal to my fellow troglodytes to really give string theory the proper thrashing it deserves since it has no proper place within the physics community at large; such nonsense should be left to bohemians!!!
Thanks Peter Woit for bringing perspective to this discussion.
I have read several books in the last year (not yours, yet: picking it up later today) on both sides of this and outside the controversy (Brian Greene, Richard Feynman, Lawrence Krauss, Roger Penrose, Bruce Rosenblum & Fred Kuttner, Carl Sagan, Lee Smolen and Leonard Susskind) and I can see, as a layman, that the theoretical physics community has gone too far one way in the past but has backed off somewhat. Some feel (incorrectly) that the Standard Model physics community has become too mundane.
I see this push back and pullback as healthy for the discipline, as there needs to be dissenting opinions and testable hypotheses generated.
I am disappointed that Ed Witten would comment on books he has not read. Old mathematical constructs are what led to the beginnings of string theory and it is hilarious that some people object to further ‘mathification’.
Cave Monster, are you responding to what Peter Woit said, or what you thought he would say?
Peter wrote: “I […] continue to think that the sort of deep mathematical work [Witten] continues to do is one of the best hopes for the future of particle theory.”
You replied: “Peter is right. Surely no one with an intellect capable of understanding the difficult maths of string theory has any business in a physics department.”
Regarding Witten commenting on books he hasn’t read, clearly the interviewer asked him about the books and Witten replied, in effect: “Well, I haven’t read them, but I haven’t noticed these books having much impact on the string theory community.” What’s wrong with that?
Well, there’s nothing wrong with that. Each part of the sentence makes the other part more likely.
The books clearly had no impact on Witten because he hadn’t read them. Witten’s environment has probably approached them in a similar way as Witten himself. They’re just not worth their time. They’re popular books, not serious scientific material, and the authors’ credentials don’t suggest that they will have something relevant to say about science.
So I guess that most Witten’s colleagues only know the books from some simplified abstracts they have heard somewhere but they don’t affect their science in any way, much like thousands of papers that are being written every year but that are not technically sound or new. By the way, I have read both books and I can confirm that Witten’s decision that reading them would be a complete waste of time to be 100% accurate.
The books may have affected a small part of the public but the public is not the same thing as the string theory community or the scientific community.
I have no idea how much influence my book or Lee Smolin’s may have had on the decisions of people in the physics community to stop hiring young string theorists for permanent jobs, but I suspect that of far greater influence has been the juvenile nature of the reaction of many string theory partisans to the books (“Weeter Poit”? Jesus, can’t you be more clever than that??).
Edward Witten was talking about the _intellectual_ underlying climate, which means the climate among the people who actually think and do research (i.e. scientists), as observed at moments when they think and do research, not about the inclinations of full-time bureaucrats and/or other people who are just acting as bureaucrats. The places whose bureaucrats don’t hire the right people, if they exist, will pay for these grave mistakes dearly in the future, especially if half of a generation of researchers in the key fields of physics will be absent. But that has nothing to do with the _intellectual_ underlying climate. The latter is determined by people like Edward Witten himself. He hasn’t read the books and it doesn’t look like he is planning to change anything about it. He’s surely not the only one.
“Peter Woit?” Jesus, can’t you be more clever than that? 😀
“Weeter Poit”,
The people who make tenure-track hiring decisions in physics departments at research universities are not “bureaucrats”, but research physicists themselves, often rather eminent ones. They are making their own judgments about the intellectual climate, specifically the intellectual health and vitality of different fields.
I wouldn’t be surprised though if some of them in the back of their mind worried that if they hired a young string theorist, it might be someone like “Weeter Poit” who thinks they’re ignorant bureaucrats unable to appreciate the glory of string theory.
At good research universities, decisions are being made by real experts who look at all the things seriously. That’s why most of these places hire a high fraction of string theorists. At worse places, the researchers are not that good or the decisions are made by bureaucrats which is why such places often end up choosing less relevant people. It’s as simple as that. At the worst places, they probably read the two books a lot.
For example, Rutgers made the first offer now, to David Shih who has written many papers on string theory and who is currently a leader in supersymmetry breaking mechanisms. Patrick Meade studies similar things and was picked by Stony Brook. MIT recently hired string theorist Allan Adams while Harvard recently hired string theorists Xi Yin and Frederik Denef. Brandeis chose string theorist Matt Headrick. It is not guaranteed that every place in Kansas can make similar offers successfully. But whether we like it or not, average places in Kansas are not at the same level as MIT, Harvard, or even Stony Brook or Rutgers.