Today’s about the date that I’d pick for the 30th anniversary of the First Superstring Revolution. Witten’s paper Some Properties of O(32) Superstrings arrived at the journal Physics Letters on September 28,1984, so presumably was finished and sent out around September 25.
The effect of this paper on the field was a bombshell. Witten was at the time far and away the most influential person in the field, regularly producing staggeringly original work that was having a huge impact. The arrival that fall of a preprint from him announcing that he had stopped work on everything else, and now had what looked like a viable, consistent unified theory of everything, one that he claimed was determined by a single parameter and made predictions (“It predicts axions and stable Nielsen-Olesen vortex lines”) was the true First Superstring Revolution.
I wrote about this in some detail ten years ago, for the 20th anniversary, so won’t repeat what is here and here, supplemented by comments from Larry Yaffe. For something more recent along the same lines, see here.
Ten years ago the 20th anniversary of the First Superstring Revolution was celebrated with a symposium at Aspen, but as far as I know, no one has organized a 30th anniversary celebration. There are now many, many known ways of trying to get unification out of strings, with the original 1984 hope that anomaly cancellation gave a more or less unique possibility long gone. As for unification itself, thirty years later Witten remains a true believer in the vision that came to him in September 1984 (see here and here), although he now seems to see little hope for vindication during his lifetime.
How had Witten become so influential before the first superstring revolution? What had he done or worked on up to that point that made him so influential?
For his extraordinary citation record, see here:
In my book I tried to explain some of this, it’s a long story. One aspect is the relation to mathematics, a lot of that is in the book, and much of it happened after 1984, with the development of Chern-Simons theory (which got Witten the Fields Medal) and later all sorts of topological quantum field theory ideas, leading to things like Seiberg-Witten, which revolutionized 4d topology. From the purely physics point of view, some pre-84 high points were Witten’s work on “current algebra”, leading to an effective theory of mesons and Baryons, using the Wess-Zumino-Witten term, his work on WZW conformal field theory, work on analyzing in very general terms SUSY breaking, and much, much more. That period of the early 80s was quite remarkable, and he was doing things far beyond what anyone else could.
Just out of curiosity (since I am not familiar with most of Witten’s HEP papers), has any high energy (or astroparticle) prediction/model made by Ed Witten been confirmed/verified by any accelerators? I am guessing no, but I maybe wrong.
I don’t understand Witten’s logic. When it comes to landscape interpretation, he says that “universe wasn’t made for our convenience”, but somehow universe cares about “wonder, incredible consistency, remarkable elegance and beauty” of string theory?
Does a free PDF of “Some properties of O(32) superstrings” exist anywhere, or is it being kept behind firewalls by Mr Witten?
Actually, Witten’s first paper, his Ph.D. thesis, was a calculation of QCD effects on photon-photon scattering which I believe were later experimentally tested. Wikipedia has this
but I’m sure there are much better references elsewhere.
The work on Skyrmions and the effective low-energy theory for mesons that I mentioned is just an approximation, so doesn’t make sharp predictions, but quite possibly there are experimental results best understood this way.
As for BSM physics, you can’t blame Witten much for not producing anything experimentally testable, since no one else has either.
Actually nobody could have given a correct prediction different from the Standard Model, because all experiments so far confirmed the Standard Model.
The problem is that, while acritically following the naive string dream, many theorists were driven away to speculations so disconnected from any possible experiment, that institutions that once had excellent theoretical groups have now disappeared from the map of fundamental physics.
The anomaly cancellation that you are referring to in this paper by Witten was actually done by Schwartz and Green after Witten had wrongly concluded that such a thing wasn’t possible. So, contrary to what you write, it was not Witten’s brilliance that started the 1st superstring revolution. Rather, the work of Schwartz and Green influenced Witten.
Also, what I wrote above suffices to undermine what you wrote about Witten doing things far beyond anyone else. In particular, the work of Schwartz and Green was a critical development in string theory which Witten had failed to discover.
The original preprint is available here
If you read any of the earlier discussion I linked to, you’d see that I’m well aware of that argument, just disagree with it, for reasons explained in detail. You might also want to learn how to spell John Schwarz’s name correctly…
Peter: thanks for the link to Witten’s 1984 preprint. He proves SU(5) can be obtained as a subgroup to an O(32) supersymmetry theory. But wasn’t SU(5) disproved by the failure of proton decay?
Not supersymmetric SU(5), where the proton lifetime is much longer. Also, the significance of that paper is not any specific model, but the claim of existence of a class of testable TOEs with a single adjustable parameter, and that Witten was working on them. Very quickly attention turned to more promising specific models.
where do you see string theory 10 years from now when all the results of LHC will be in and analyzed?
Ed Witten agrees with you on the importance of precise prediction
Horgan: Do you agree with Sean Carroll that falsifiability is overrated as a criterion for distinguishing science from pseudo-science?
Witten: Scientists aim to get as reliable and precise an understanding of nature as we can. The gold standard is a precise prediction that can be tested in a precise way in a laboratory experiment. Experiments that disprove theories are an important part of the scientific process.
but Witten believes string theory is predictive.
“I asked Witten how he responded to the claims of critics that superstring theory is not testable and therefore is not really physics at all. Witten replied that the theory had predicted gravity. “Even though it is, properly speaking, a post-prediction, in the sense that the experiment was made before the theory, the fact that gravity is a consequence of string theory, to me, is one of the greatest theoretical insights ever.”
Witten also claims black hole entropy as a success of string theory.
HL-LHC or HE-LHC,
I think the LHC will conclusively not see supersymmetry, and this + another ten years of no progress towards getting physics out of the idea of string theory unification will continue the trend towards it being a dead idea.
As for arguments about predictivity like the “predicts gravity” one, they’ve been discussed hundreds of times here. About that one in particular though, I think the best response was Lisa Randall’s : “sure, string theory predicts gravity, ten-dimensional gravity.”
the best response was Lisa Randall’s : “sure, string theory predicts gravity, ten-dimensional gravity.”
Oh come on, String Theory predicts gravity exactly as we observe it in 3+1-dimensional macroscopic spacetime according to Einstein’s General Relativity.
THAT is amazing.
In fact it was pretty amazing when Feynman first started telling everyone back in the 60s that gravitons described the same equation as GR – but no one ever got gravitons out of a theory that also predicted SM particles – until String Theory.
So, please bear in mind this great achievement of String Theory that NO OTHER THEORY HAS COME CLOSE TO.
btw: If a SUSY particle is discovered will you still be anti-string?
A nicely formatted version of Witten’s 1983 paper Some Properties of O(32) Superstrings
I’ll let you argue that one with Lisa Randall.
And, you’re seriously abusing the word “prediction”. String theory does not “predict SM particles”, and even if Randall is mistaken, that’s called a “retrodiction”, not a prediction.
@JG – you are wrong. In D=4, superstring theory does not predict Einstein gravity, but Brans-Dicke scalar-tensor theory with an equal mix of spin 2 and spin 0 mediated gravitational forces. Experimentally it is known, to a very high accuracy, that gravity is Einstein’s pure spin 2. This is one of these rare cases when string theory makes a solid prediction — it is clear that most of the landscape has massless dilatons, so if you are a multiverse fan, you are very lucky to be here.
Ok, let’s be a little more precise, String Theory can describe Standard Model particles and gravitons. No other theory comes close to achieving this.
Yeah, ok, but I’m talking about the macroscopic low energy limit that we can currently observe – that’s predicted by String Theory. (A recent publication has claimed that, mathematically, Black-Holes should not form because of quantum effects (hawking) during star collapse, this may just be an isolated pure maths result, unrelated to real-world physics, but there should be quite severe contraints for predictions from QG theories once we get to the really strong-field regimes and high energies. (If not, then we really will have to give up on physics))
(btw I incorrectly referred to Witten’s “famous” 1984 paper as from 1983 above)
@JG – interesting paper, and also the arxiv followup. Always did find GR more aesthetically pleasing than QFT. Anyway, what I’m curious about is how one might account for what, to cosmologists, seems to be plenty of evidence for black holes? Is there some other mechanism that could account for what is seen? The papers imply if a star wants to collapse it will end up exploding. Gets rid of the information paradox, but what about the giant black hole at the center of our galaxy?
My teacher Veltman was speaking about the “desert” in the late seventies and what do we see now? I agree that ST is a framework within which certain interesting questions can be answered (after enough pleasant assumptions such as SUSY, extra dimensions and their compactifications have been made). Indeed, a theory of everything except the standard model AND of the solid state except high Tcs, has the smells of a framework. The multiverse just avoids to explain our Universe. The many words interpretation is a poor-man’s-physics denying that one has to bother about the apparatus – don’t tell Bohr. But workable models exist and in their solution “many worlds” do not show up, I would say: not to the least. But Einstein’s ensemble interpretation gets to the point. Quantum gravity I would like to see in the QFT on the “boundary”, I do not care about the bulk. Concerning Witten, may I recall: It is the task of physicist to explain Nature.
There is suprisingly little observational evidence to support GR in the strong-field regime, the “black-hole” at the centre of our galaxy could just be an incredibly dense object – we don’t have experimental resolution to conclude an actual event-horizon exists.
But, it’s not so bad, we do have concrete evidence that some of the strong-field regime in GR is correct, especially from twin pulsars. See the Experimental tests of gravitational theory section from the Particle Data Group
To tie this in with the thread’s historical overview of String Theory, note that this very same review of experimental tests of gravitational theory has been published for many decades – and only last year did they remove the reference to String Theory as a “promising” theory, which existed at least since the turn of the millenium (eg the last sentence of the introduction section of the 2006 version says ” Superstring theory offers a promising avenue toward solving this challenge”
The link above to the 2006 version of Experimental tests of gravitational theory didn’t appear
Please, enough discussion of claims about GR that have nothing to do with the topic of this posting.
I am hoping that your “many words interpretation” above was not a typo.
Did Witten actually say that he had stopped work on everything else?
I guess the paper didn’t say this explicitly, but it made clear that he all of a sudden thought he saw the way clear to a TOE. And people I know who talked to him at the time told me this is what he told them (as well as that they should drop everything and work on string theory too). Over the next couple years he wrote a very large number of papers, basically all about string theory.
Peter, are you again not going to make the Nobel Prize prediction?
I retired from the Nobel Prize prediction business after this
No idea who they’ll pick this year. If the Swedes change their mind and let groups get the prize, a Higgs prize for CERN + ATLAS + CMS would be a good idea…
I am not sure if this was already posted, apologies if it was, but here is a video-discussion with Witten from around the times:
It is actually amazing how many of the subjects discussed are still discussed in just about the same way
>> and even if Randall is mistaken, that’s called a “retrodiction”, not a prediction.
@PW Did not A.E. get NP for “retrodiction” of the photoelectric effect? PS Am not stringy fan (and my gut feeling is the ST does not predict/retrodict anything), ‘m just disliking extremisms.
Of course a good retrodiction can be very strong evidence for a theory. If string theory had a convincing calculation of any of the SM parameters, that would be very impressive and give it high credibility. It doesn’t though retrodict four-dimensional gravity. My point was just terminological: the word “prediction” is often seriously abused in this kind of argument. No one says Einstein “predicted” the photo-electric effect…