The past few years I’ve been noticing more and more claims like this one, supposedly finding a way to “connect string theory to experiment”. When you look into such claims you don’t find anything at all like a conventional experiment/theory connection of the usual scientific method, giving testable predictions and a way to move science forward. As for what you do find, for many years I tried writing about this in detail (see here and here), but that’s clearly a waste of time.
One thing that mystifies me about such claims is that I find it very hard to believe that most theorists take them seriously, always assumed that the great majority was with Nima Arkani-Hamed, who recently characterized the track record of this kind of thing as “really garbage”. But if most theorists think this is garbage, why am I seeing more and more of it? A hint of an answer comes from the paper with the supposed connection, which describes the Harvard Swampland Initiative as the place the work initiated.
I hadn’t been aware there was a Harvard Swampland Initiative, but it is a Research Center at Harvard, running an “immersive program” in which “participants collectively navigate the Swampland”. More importantly, it has no less than ten associated postdoc positions. On the scale of different ways of having influence on a field, being able to hand out ten postdoc positions at Harvard is right up there. This goes a long way towards explaining to me what I’ve been seeing in recent years. It also makes me quite depressed: when I started my career in that department in the late seventies, the idea that fifty years later this is what it would come to is something beyond any one’s worst nightmare at the time.
One aspect that is also becoming increasingly obvious is the intent of getting such works through in a prestigious journal such as PRL (arxiv format of the present one suggests the same for this work as well). Quote some numbers, throw in some data analysis, make some vague references to experiments, put in big names in Acknowledgements, and PRL is usually happy to accept. If you see timelines of some recently accepted PRL papers, you will see a few stringy ones that had merely 2-3 weeks between submission and publication!
In a few years from now, one of them postdocs will fall off the bandwagon and draw attention to themselves as a critic of string theory. Someone will set up a blog. Someone will write a book.
“The word is about, there’s something evolving,
Whatever may come, the world keeps revolving,
They say the next big thing is here,
That the revolution’s near,
But to me it seems quite clear
That’s it’s all just a little bit of history repeating.”
> Quote some numbers, throw in some data analysis, make some vague references to experiments, put in big names in Acknowledgements, and PRL is usually happy to accept.
That’s just nonsense. PRL remains extremely selective and demanding. About half of all submissions to PRL are desk rejected in a few working days. Go ahead and try.
fwiw,
About PRL’s extremely selective and demanding standards for string theory papers, I’ll just point to
https://www.math.columbia.edu/~woit/wordpress/?p=14001
Enough about PRL, the real question here is why anyone thinks this is science or why any journal would publish it.
hang on, is the harvard swampland initiative definitely a research center as opposed to an initiative to create seminar series, visitors, discussions etc on swampland? aren’t the participants just harvard researchers who are joining in those activities, cf. ten post-doc positions handed out by the swampland research center, all hired by funding from the harvard swampland ‘research center’ for swampland
fwiw,
https://www.physics.harvard.edu/research-centers
I’m a bit confused. The Swampland is broader than the string theory landscape, and I’d think much of the work being done there would have nothing to do with strings. Isn’t that exactly what you’ve been advocating for? Quantum gravity and other steps towards unification outside of string theory?
Some guy idk,
The swampland is Vafa’s program, and in different places he emphasizes different aspects of it. He is certainly not setting it up as an alternative to string theory. For what he has in mind, look at his original 2005 swampland paper
https://arxiv.org/abs/hep-th/0509212
and for something more recent, lecture notes from two Harvard courses
https://arxiv.org/abs/2212.06187
In both places he makes very clear what the motivation for the program is: to fight the argument that “string theory predicts nothing” because you can get any low energy physics you want with an appropriate choice of “string vacuum”. The origins back in 2005 were in the context of arguments over Susskind’s “landscape”, see
https://arxiv.org/abs/hep-th/0302219
Susskind essentially argued that you could get just about anything out of string theory, then anthropic arguments would determine where we were in the landscape. Vafa realized this was disastrous for string theory, and that at least one blogger was doing a lot of damage to string theory by pointing this out.
So, his motivation from the beginning has been to try to fight the “string theory makes no predictions” argument, sometimes by arguing “string theory gives a consistent quantum theory of gravity coupled to matter and maybe we can find generic consistency conditions for such things, so these would be string theory predictions”.
I think if you listen to what he says about the swampland and string theory, you’ll see that the whole point is to mount a defense of string theory and of the study of “string theory vacua”. String theory is taken as an assumption that cannot be challenged. When asked if he would abandon string theory if the “predictions” he finds are disconfirmed, he says that no, he wouldn’t. Such disconfirmation would just mean that one needed to modify one’s understanding of “string vacua”.
If you don’t believe me that a main motivation here is responding to all too effective criticism that string theory can’t predict anything, see here
https://www.math.columbia.edu/~woit/wordpress/?p=10486
Thanks for responding!
What about “swampland conjectures” like the completeness of spectrum hypothesis (satisfied by string theory but not necessarily motivated by it) and weak gravity conjecture (has little or nothing to do with strings)? These things, as I understand, try to establish a network of conditions for a future complete theory of quantum gravity, and I would think that’s worthy research that anyone could get behind.
In “The Swampland: Introduction and Review” (arXiv:1903.06239), Eran Palti writes:
“One approach towards providing evidence for a Swampland conjecture is by utilising known vacua of string theory as a type of experimental data…
“Another approach that is commonly adopted to study Swampland criteria is utilising quantum gravity arguments directly in the low-energy effective theory. There are low-energy aspects of quantum gravity that are expected to be universal, in particular relating to black holes and to the holographic nature of gravity. Relative to [the first approach], this approach has the advantage of broader generality. On the other hand, the arguments often lack the explicit details and concreteness of string theory based evidence.”
So there is a part of the Swampland program which is logically independent of string theory. It would be useful for this discussion, to know how extensive it is.
Some guy idk/Mitchell Porter,
I just don’t see any point to these string-inspired conjectures about which low energy physics is compatible with string-inspired general ideas about gravity. If your conjecture says that the SM is compatible with gravity, you’ve learned nothing. Whatever the correct explanation of gravity is, it has to be compatible with the SM at low energies because that is the way the world is. If your conjecture says that the SM is not compatible with gravity you’ve also learned nothing (beyond that your conjecture is wrong).
The main motivation for all this activity is to justify continuing doing meaningless calculations about “string vacua”, partly in order to be able to make bogus claims about “connecting string theory with experiment”, partly in order to not have to admit you’ve wasted 40 years on a wrong idea.