This week’s hype comes to us courtesy of Scientific American, which, based on this preprint, tells us: Found: A Quadrillion Ways for String Theory to Make Our Universe.

As usual in these things, the only physicists quoted are the authors of the article, as well as some others (Cumrun Vafa and Washington Taylor) who are enthusiastic about the prospects for getting the Standard Model out of “F-theory”. No one skeptical of the idea of F-theory compactifications of string theory (such theorists would not be hard to find…) seems to have been consulted. If such a person had been consulted, he or she might have pointed out:

- Models like this have been around for over two decades, see for instance this from 23 years ago.
- They have always come with claims that some sort of connection to experiment was right around the corner. A decade ago there were papers like this one (and promotional pieces like this one) explaining F-theory “predictions” for what would be seen at the LHC, “predictions” that never worked out.
- This new work doesn’t even bother trying to make “predictions”. It just works backwards, trying to match the crudest aspects of Standard Model, ones determined by a small set of small integers. Given the huge complexity and number of choices of these F-theory constructions, that some number of them would match this set of small integers is not even slightly surprising.
- The authors seem to argue that it’s a wonderful thing that they have found quadrillions of complicated constructions with this kind of crude match to the SM. The problem is that you don’t want quadrillions of these things: the more you find, the less predictive the setup becomes. What’s being promoted here is a calculation that not only predicts nothing, but provides evidence that this kind of thing can’t ever predict anything. A peculiar sort of progress…

**Update**: This hype has now been supplemented by the now common phenomenon among string theorists of having their university’s press office put something out promoting string theory. This time it’s the University of Pennsylvania, with a headline assuring us that their university’s physicists are Making sense of string theory, with a discovery that “might change the course of the field.”

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The paper is actually about the construction of a quadrillion chiral Minimal Supersymmetric Standard Models for which there is no evidence. Nothing really said about the SUSY partners just a hope that some models have a high SUSY breaking scale to avoid proton decay lifetime experimental lower bound. The title of the paper is hype and mis-leading.

This seems like a somewhat mean blog post. The erticle is an unhyped description of a calculation that is not quite routine, but certainly no breakthrough; the physicists involved seem to be claiming nothing other than being part of the conversation of modern physics — providing useful and reassuring data for their colleagues to make more insightful discoveries.

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And the basic question is profound and needs answering: What is special about the standard model, a very particular gauge theory on a very particular space — when all of the *mathematical* insights of the last 35-40 years of hepth/math conjecturally construct a web of dualities that relate all QFTs, of dimensions less than something small (but bigger than 4!)

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‘String theory’ obviously makes no physical predictions yet, and you have

been an important voice in disseminating that unpleasant truth. The

flip side of that — that in various ways it includes the standard model,

and that we cannot claim to understand the latter without

understanding what `string theory’ is, and what these equivalences are

— and we do not. And we need to.

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(For a description of an even more basic lack of collective understanding, you should go to Heselholts’ talk on Wednesday — his lovely line is that mathematicians do not yet understand what a number is; see for example

https://www.newton.ac.uk/seminar/20181008160017001

for a pleasing description, aimed a little at homotopy theorists.)

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This blog post does not engage in the anti-intellectual foolishness of pretending that string theory is nonsense, but it does seem _mean_ to a harmless paper.

@anon Thanks for that link to that talk from October. It’s a cute line, that the integers are not the real base ring for homotopically enriched algebra, but the sphere spectrum S. Just as the natural numbers are the decategorification of the 1-category of finite sets, the integers are the connected components of S. Connes of course is also promoting this idea in his current approach to the Riemann hypothesis. Describing it as mathematicians not understanding what a number is is missing the joke ðŸ™‚ It’s better to say we don’t fully understand the collection of numbers with their arithmetic (and number theorists would agree on that, I think)

anon,

I don’t think I’m being “mean” to the paper, would have just ignored it if Scientific American wasn’t publishing an extremely misleading article about it. The string theory hype problem in the popular science press remains a well-entrenched one.

I’m looking forward to the Hesselholt talk on Wednesday. For those interested, see

http://www.math.columbia.edu/2019/03/27/spring-2019-kolchin-lecture/

Hi Peter,

As PeterH points out in a comment above, the paper is not about the standard model (or standard models) but about the MSSM. And it’s not all that clear you even get the standard model out at low energies because, as the authors write themselves (p 5):

“[T]his in turn also implies that certain proton decay operators compatible with the Standard Model gauge group will in general be present… We expect that in some corners of the moduli space, which incidentally could also support high-scale SUSY breaking, these operators can be suppressed.”

Which basically means they don’t know whether they would actually get anything resembling the standard model. (This is not to say that I doubt it can be done, just pointing out it’s not in the paper.)

I surely hope that whoever reviews this paper requires that the title be changed.

From the reading of the e-print, the authors *give evidence* for the existence of many models which satisfy *necessary* conditions of compatibility with MSSM. I can’t evaluate the hype, the article is a math proof with some parts which are not rigorous. Not read: the Scientific American popularization.

@Peter,

Perhaps a little unfair to Anil? He does say clearly in the SA article:

“the work assumes supersymmetry… String theory needs this symmetry in order to ensure the mathematical consistency of solutions”

“experiments at the Large Hadron Collider (LHC) have … yet to find any supersymmetric particles”

“Vafa and Taylor both caution that these solutions are far from matching perfectly with the standard model”

etc.

I’m not convinced that statements like this are ‘hype’. More along the lines “we’ve found something interesting in the maths and it’s worth a further look”.

That said I’m with Sabine, the title of the Cvetic et al. paper is misleading, the authors themselves referring explicitly in the introduction to “exact chiral particle spectrum of the minimally supersymmetric StandardModel (MSSM)”.

It is too dated to ignore that since the early 2000’s string phenomenologists are really: “Getting just the Standard Model at Intersecting Branes” (https://arxiv.org/abs/hep-th/0105155).

But I still found no pop-sci book mentioning this fact, that is dreadful!