Despite my abusive treatment of his article Stringscape here recently, Matthew Chalmers was kind enough to send me a copy of the September issue of Physics World, which contains three shorter pieces about string theory (available on-line only to subscribers).
One of the articles is by Fred Goldhaber and entitled Scientific faith put to the test. It’s a scathing attack on the anthropic string theory landscape program, describing it as “antiscience” (rather than my favorite, “pseudo-science”). Goldhaber characterizes this sort of research as “antiscience of the left”, with its adherents promoting the idea that we can’t ever understand some things since they are due to chance. He contrasts this to the “antiscience of the right”, which promotes the idea that we can’t understand things because they come from supernatural origin, and finds both attitudes equally unscientific. As for where antiscience comes from, he has this to say:
On the left, I think that it stems from arrogance (“If I can’t figure it out, no-one ever will”). On the right, I think it comes from defensiveness (“If science is right, religion must be wrong, and that can’t be”). In the end, antiscience on both side boils down to vanity. While we need to stay alert for the vanity of those advocating antiscience, we also should guard against vanity in the name of science.
He ends on a more optimistic note, writing that he does see a difference in those on the “left”. They remain physicists, and if someone finds a “promising route to picking out the right solution to string theory”, they would leap to pursue it. He doesn’t speculate on what they would do if someone shows that string theory just inherently can’t ever predict anything…
Philosopher of science Steven Weinstein has a piece with the title Philosophy pulls strings, which tries to make the case that string theory is leading to some new interaction between physics and philosophy, since it “forces us to tackle issues that cross both disciplines.” As far as one of his topics goes, the anthropic pseudo-science, the main role I see for philosophers is to forcefully point out to the scientists involved that they are doing something intellectually highly disreputable and should stop. He also discusses a much more non-trivial and interesting topic, that of the philosphical questions about space and time raised by quantum gravity, a subject where philosophers may or may not end up having something quite useful to contribute.
Philosphers Nancy Cartwright and Roman Frigg contribute a very interesting article about how scientific theories are evaluated, entitled String theory under scrutiny [available here, thanks to commenter “R” for pointing this out]. The make the important point that immediate experimental testability of a theory is not all there is to deciding whether something is science or not. When scientific ideas are new, they often are not understood well enough to be able to extract definitive predictions from them. Theorists are generally engaged in research programs, the end result of which is supposed to be something experimentally testable. In order to evaluate a research program, you can’t just note that it isn’t predicting anything, you have to evaluate its prospects for reaching its stated goals. They describe good research programs as “progressive”:
Good research programmes are those that are progressive, i.e. those whose theories get better and better, even if individual theories face serious difficulties at certain times.
The fundamental problem with string theory is that, as far as its central goal of unifying physics goes, over the last nearly 25 years it has not only not made any progress toward explaining anything about particle physics, but, quite the opposite. Everything that has been learned about string theory makes it more and more clear that the original hopes for getting unification this way were just misguided and can’t work. The derivative here is the wrong sign.
There are areas in which string theory has had successes, notably in mathematics and in strongly-coupled gauge theories. But these are really different research programs, and the fact that progress has been made in them doesn’t change the facts about the colossal failure of the unification program. Cartwright and Frigg try and put various other “dimensions” on the string theory research program, including that of “elegance and simplicity”, writing that:
Radical string critics would then conclude that string theory is progressive only in the dimensions of elegance and simplicity (in the sense that the theory only contains one class of basic objects – strings – from which all the basic particles and forces follow), while being largely stagnant in the other dimensions.
As a “radical string critic”, I don’t see things this way. According to M-theory, “string theory” is not a theory of “one class of basic objects”. Strings are just part of a hugely complicated picture, one which at the moment is neither elegant nor simple. String theorists hope that there is some elegant and simple underlying theory, but they have not been able to come up with it despite a huge amount of work. Whatever underlies M-theory, it may be something very complicated. Perhaps M-theory is just a rather obscure corner of a story very different than what string theorists are hoping to find, one that may tell us some interesting things, but just doesn’t have anything to say about how to unify particle physics.