As an amusing follow-up to Friday's post, have a look at this lengthy op-ed from McGill University physicist Jim Cline, in The Ottawa Citizen. Here's an excerpt:
Why is it that string theory has become such a favoured paradigm? Have theoretical physicists deluded themselves? Have they been pressured by social forces to blind themselves to other possible theories? Is there a behind-the-scenes string-theory conspiracy that is propping up a pseudoscientific house of cards?
We could ask a similar question about cars. Let's suppose, for the sake of argument, that Hondas have been the most popular car on the market for the past 10 years. This is a source of great consternation to General Motors. Strangely, though, nobody has been writing books about how the North American public has been hoodwinked or brainwashed or pressured into thinking that Hondas are better than GM vehicles.
Somehow it is accepted that the public has enough common sense to form a correct opinion based on its collective experience.
True, some will be influenced by factors unrelated to the intrinsic quality of the car. But as a society we like to think that the free-market system will ultimately lead to the triumph of better cars over mediocre ones.
Although not so familiar to the general public, and comprising a much smaller number of participants, the economy of theoretical physics is not so different from the car business. Physicists choose which theory they are going to “buy” based on many considerations. After weighing the pros and cons of the different theoretical frameworks competing for their attention, they decide which ones seem most promising -- which ones are worth investing (perhaps gambling!) years of hard work on, in the hope that they will provide the right description for experimental breakthroughs that we are anticipating, to shed light on the new physics we are so eager to discover.
I lack the technical expertise to fully assess the various claims and counterclaims regarding string theory. So I don't have strong feelings one way or the other. But the paragraph above captures part of the reason I tend to be more suspicious of the string theory critics than of the string theorists themselves.
Which is not to say the critics don't have some good points to make. Mathematician Peter Woit, of Columbia Univeristy, offers this reply to Cline. Woit begins:
The Ottawa Citizen today has an Op-Ed by string cosmologist Jim Cline, headlined The Big Idea That Won't Die, with a subtitle “The fact that string theory is suddenly under attack only underscores its success as a path to a unified description of nature.” There's a lot that it outrageous about this piece, beginning with the subtitle. Normally scientists don't start going on about the success of their theories until they have some experimental evidence for them.
Most outrageous are Cline's claims that Smolin's book and mine are written in a "defamatory style", and are “slandering” string theory. Since he gives no evidence for either of these claims, there's not much to say about them except that they're defamatory and slanderous.
Cline makes the standard claim that string theory should be accepted since it has legitimately triumphed in the marketplace of ideas, while clearly being rather upset about the success that critics of string theory have recently been having in this same marketplace. Somehow, overhyping string theory is a legitimate marketplace activity, pointing out its problems is not.
He makes many of the by now standard bogus claims about supposed predictions and tests of string theory. At some point I suppose I should write a FAQ about these, since the string theory hype machine keeps promoting these things in a less than honest way to a public that is not well-equipped to see through the hype. Here's a pretty complete list of the bogus “predictions.”
From here Woit discusses in detail some of the predictions Cline attributes to string theory. Well worth reading.
While you're at it, have a look at Woit's reply to the Brian Greene essay I quoted in Friday's post. You might also have a look at the comments to Friday's post.
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The reason why I don't mind string theory, even though I'm a little skeptical, is that it doesn't need to be physics to be good science. String theory may turn out to be merely a very elegant bit of pure maths. If so, a generation of physicists will have added a huge amount to scientific knowledge, even if they haven't answered any questions about particle physics.
I say go for it. And go for it, you skeptics: coming up with alternative theories adds to our knowledge too
I don't find Cline's car analogy to be at all persuasive. It fails in at least two key ways.
First, different cars can actually be tested to see which performs best (by whatever criteria one prefers). The big knock on string theory is that there is supposedly no known way to test it, even in principle. (Not that I have the training to judge that for myself, you understand.)
The other flaw is that, compared to car buying, the popularity and funding of science is arguably much more subject to the bandwagon effect. Obviously, an idea has to have some potential merit to become popular. But at a certain point, the popularity can be self-reinforcing. Everybody wants to work on the latest hot idea. As funding increases, there's even more incentive for people to work on that idea, since that's were all the funding's going. Not that these are overwhelming forces, of course, but they often play a role.
That said, my only real gripe with string "theory" is that it's not yet a true scientific theory, as far as I can tell. I wish there was a better name for it, although I admit that 'string hypothesis' or 'string conjecture' aren't very catchy.
I'd say it's worth making a distinction between mathematical knowledge and scientific knowledge here, since you're noting the string theory contribution to math.
Scientific knowledge is knowledge about the real world. Mathematical knowledge does not, in and of itself, have any connection whatsoever to the real world. Rather, the sciences tend to find ways to make use of the tools developed within mathematics for their own ends. Usually I shorten this by saying "mathematics is the language of science."
So if the only thing the string theorists accomplish is to make great mathematical contributions, it's still fair for their critics to say they're not doing science.
Cline's analogy is hokum from beginning to end. Science is not a popularity contest. Either defend your theories or get off the pot. In any case, he even spots where the analogy breaks down: "Strangely, though, nobody has been writing books about how the North American public has been hoodwinked or brainwashed or pressured into thinking that Hondas are better than GM vehicles." Exactly.
Has anyone compared Science to a Free Market type exchange model?
In a sense the "market" should gravitate to the ideas with the most support. I can see this applying to ID as well as string theory.
While it is important to have people backing the losers, the winners are the ones with the most "capital."
Re qetzal
The mention of the bandwagon effect is something I have pointed out in a previous thread relative to super string theory. When I was active in elementary particle physics, several such bandwagons roared through the landscape (e.g. group theory, particularly a group known as SU6) greatly expanding the green mold known as the Physical Review, but, for the most part, not contributing much to the advancement of knowledge. This appears to be what is happening to super string theory, which is not to say that it may eventually turn out to be a great advance in explaining the physical world (unfortunately, SU6 was not such an advance, despite its contribution to the size of the Physical Review).
I did a study once looking at citations of scientific journal articles. The study's conclusion: an article is more likely to be cited if it in turn cites a lot of other recently-published papers. More than half the variance in article citation rates could be accounted for by this crude indicator of "hot topics," regardless of the content or quality of the paper. It's like googling, or box office at the movies, or blog hit rates: measures of popularity don't equal measures of quality. (Popularity doesn't necessarily equal poor quality either, though sometimes I think it might.)