I haven’t been paying much attention in recent years to the philosophers of science studying “Non-empirical” or “Post-empirical” physics or theory confirmation. At various times I did write fairly extensively about this, see for instance here, here and here. By 2015 there was a conference in Munich on the topic, which led in 2019 to a volume of papers entitled Why Trust a Theory?
There’s a new paper out along similar lines, String theory, Einstein, and the identity of physics: Theory assessment in absence of the empirical, evidently to appear in a journal special issue from a 2019 conference on Non-Empirical Physics from a Historical Perspective.
The reaction of most physicists to this sort of thing is exemplified by Will Kinney’s tweet about the paper:
In the past few years I’ve been writing less and less here and elsewhere about the issue of evaluating string theory as physics, for several reasons:
- String theory has effectively gone completely post-empirical, decoupling from any possible relation to experiment. This Week’s Hype used to be a regular feature here, devoted to debunking the numerous bogus claims regularly being made for how to “test string theory”. One rarely sees these anymore, with the string theory community now having given up on this and somehow comfortably moved into a completely post-empirical mode.
- I’m actually much more sympathetic than most people to the idea that there is a serious and very interesting question about how to evaluate ideas about theoretical fundamental physics in the absence of viable experimental tests. But I haven’t had much luck finding others who share my views. The reaction to blogposts like this recent one tends to be pretty uniformly scornful, that I’m just Lost in Math. The post-empirical philosophers of science deal with me differently, pretty much doing their best to ignore me (I don’t make it into the extensive bibliography of the new paper on the arXiv).
- There are two other projects that seem to be a much better way to spend my time (the twistor unification stuff, and improving the textbook on QM and representation theory).
By the way, I notice that there is an arXiv trackback already for another blog entry about this paper, wondering if trackbacks here are still censored.
Well, that’s all about this for now, best to take my own advice and go think about something else.
Update: I just ran across this AIP interview with John Schwarz from last year. Schwarz seems to feel that string theory unification is a huge success, despite the testability problem. On the failure to find the superpartners he and other string theorists expected, that’s a problem for experimental physics, not for string theory:
As I said, if supersymmetry is not discovered, there’s a danger that experimental particle physics will die. If that happens, it would be tragic, but it wouldn’t be the end of string theory. String theory will continue, regardless, and will continue to advance.
On the topic of answering those who argued that superpartners would not be found back in the 2000s, and who have put forward detailed criticisms of string theory unification, here’s what he has to say:
There were a couple popular books that attacked string theory about a decade or so ago. The authors clearly had chips on their shoulders. For people without a physics background it’s not possible to assess whether what they’re reading makes sense or not. But anyone with at least an undergraduate education in physics I think can recognize that they should not be taken seriously.