Thursday, 5 November 2009

String Theory and The Goodies

The 1990s "string theory" boom was an example of what happens when a critical mass of researchers realise how to game the system. If enough people start churning out work on the same subject, and eagerly citing each other in multi-author papers, they levitate up the scientific citation indexes together. You get a bubble. It's in most players' interests to keep inflating the bubble – the more new people they attract to the subject, the more seniority they have in a growth area of science. It becomes like a pyramid scheme. So in the 1990s we had some pretty absurd claims being made for string theory and what it was going to do for us, and when.

I wasn't unsympathetic to string theory as such - It seemed like something that needed to be researched ... just not by everybody. The talk was that string theory was The Future, and sometimes it seemed as if anyone who wasn't already committed to some other line of "mathematical physics" research was scrabbling to get onto the bandwagon. There were people doing worthy work on the subject before the boom, and once the bubble burst, those people would probably continue doing worthy work. What was wrong was the hype.

And all though this time, I kept remembering the old 1970's episode of The Goodies, where the guys use their advertising agency to promote string as the wonder product that's good for everything. Here's just the clip of the Goodies "String" song, courtesy of YouTube:

"String, string, string, string, ev'rybody needs string!"

It also seemed to me that we'd been here before. String theory was supposed to be a ToE, a "Theory of Everything", but in the 1990s, it actually seemed to be more of a ToA, a "Theory of Anything". It sounded like a great way of being able to remodel any given physical theory, but didn't seem to offer any clues as to what sort of theory we should be trying to model. It sounded was a bit like Jean Luis Borges' fictional "Library of Babel", that contained every book ever written, and every book that might ever be written - but whose total inclusivity meant that it ultimately contained no information at all.

String theory in the 1990s seemed to suffer from the same problem that aether theory had had in the 1890s - what had made aether theory lose credibility as a subject wasn't that it gave wrong answers, or that it was limited – its problem was that it was too flexible. With enough arbitrary variables, you could construct an aether model to reproduce almost any behaviour you could possibly want – we had aerodynamic aether theories, sink-and-source aether theories, Lorentzian ether theory (LET), and so many other variants that even experts started to lose track of them. Without a guiding set of principles to eliminate possibilities, generalised aether theory as a field couldn't actually make any solid falsifiable predictions.

Aether theory had degenerated into a "Theory of Anything", and if you eventually managed to isolate a set of rules to derive a single preferred set of physical relationships from some amophous theoretical soup, then the process of logical deduction that you'd used to decide on a particular set of properties for the theory, was the theory.

And the worry with string theory was that perhaps some people in the "string" community hadn't quite understood this. Some of its more enthusiastic proponents insisted that string theory was already "discovered" – string theory was fundamental truth, and "all we had to do now" was to learn how to decode it. But without the decoding process there was only a metatheory that defined a context within which an actual physical theory might later emerge. Without an extraction process we might as well be trying to divine "ultimate truth" from tealeaves or goat entrails.

It also didn't help that the "We already have the secrets of the universe in our grasp, we just need to take a few more generations to work out how to decode them" argument, the apparent nonchalance about the lack of falsifiability, and the use of "mystical" language to try to attract public support were all things that people more usually associated with the Nostradamians and Bible Code numerologists than with the physics and math communities.

There was only so long that the string theory hype could last without the subject actually making any physical predictions, and eventually the field got hit by a nasty dose of reality, with Lee Smolin and Peter Woit both publishing critical books on what had actually been achieved. There simply wasn't a physical theory yet. Just because something was pretty didn't automatically make it physics.

I was happy to criticise when the hype was underway, but I'm uncomfortable kicking a theory when it's already down. It's too easy. Good work is probably still being done with string theory, it's just not getting headlines in New Scientist every single week as it used to. Perhaps the fashionistas will drift away and find some other fad to attach themselves to, and it'll be just the hardcore guys left, who were there from the beginning, and aren't reliant on a fortnightly press release cycle. And perhaps that's an appropriate situation.

Heck, if it gets too fashionable to knock string theory I might even have to start defending it.

Meanwhile I'm going to watch the video again. "String, string, string, string ..."

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