Back in 2017, after it had already become clear that negative LHC results about SUSY and WIMPs had falsified theorist’s most popular scenarios for how to extend the Standard Model, Nima Arkani-Hamed gave a summer school talk to students with the title Where in the World are SUSY & WIMPS?, which I discussed here. At the time I was encouraged that while he was still promoting SUSY and the landscape (in the split SUSY variant), at least he seemed to be arguing that the lesson to be drawn might be that the whole SUSY-GUT business was a mistake:
The disadvantage to the trajectory of going with what works and then changing a little and changing a little is that you might just be in the basin of attraction of the wrong idea from the start and then you’ll just stay there for ever.
A few weeks ago in Princeton, at a PCTS workshop on Dark Matter, he gave an updated version of the same talk. Much of it was the same material about how split SUSY is the best idea still standing. Unfortunately, at the end (1:09) he seems to now have changed his mind and be arguing that the best thing for theorists to do is to keep tweaking the models that failed at the LHC:
You could very justifiably say “look, you’re just continuing to make excuses for a paradigm that failed”, OK, and I would say that’s true, and even the paradigm most of your advisors love [e.g. usual SUSY] was already an excuse for the failure of non-supersymmetric GUTs before that.
That is a perfectly decent attitude to take, but I would like to at least tell you that you should study some of the history of physics. This very, very, very rarely happens, that some idea that seems basically right is just crap and wrong, It’s probably mostly right with a tweak or some reinterpretation. You’d have to go back over…, I don’t know how far you’d have to go back, even Ptolemy wasn’t so far from wrong…
These are two different attitudes towards connecting theory and experiment. If you like, more the theory egocentered attitude, or the just more explore from the bottom up attitude, they’re both perfectly good attitudes, we’ll see which is more fruitful in the end. If you take the more top-down attitude, just keep fixing things a little bit.
If you had to pick the single most influential theorist out there on these issues, it would probably be Arkani-Hamed. This kind of refusal to face reality is I think a significant factor in what has caused Sabine Hossenfelder to go on her anti-new-collider campaign. While I disagree with her and would like to see a new collider project, the prospect of having to spend the decades of my golden years listening to the argument “we were always right about SUSY, it just needs a tweak, and we’ll see it at the FCC” is almost enough to make me change my mind…
Update: Today Ethan Siegel at Forbes has Why Supersymmetry May Be The Greatest Failed Prediction in Particle Physics History.