Tuesday, November 28, 2006

Stringing us along (in ten dimensions)?

Although I'm not a physicist, I am disappointed to read (via a very readable review by David Lindley in The Wilson Quarterly) of an increasing tide of skepticism about string theory.

This is not because I have any vested interest in string theory as such, but rather because it's just one of those enjoyable theories which make scientists sound like the babbling acid freaks I used to run into every now and then at college parties who would go on at length about the curvature of reality and their ability to perceive other dimensions. (You may know the type. You may, of course, even be the type. If so, best of luck.)

This sort of thing is good: for humanitites scholars in particular, it is always reassuring to have evidence that at least some of the 'real' sciences have as many wacky-sounding notions as we do.

String theory, if you need a reminder, runs like this:
Elementary ­particles—­electrons, photons, quarks, and their numerous ­cousins—­are not ­point­like objects but “strings” of energy forming tiny, wiggly loops. If a stringy loop vibrates one way, it manifests itself as an electron. If it shimmies some other way, it looks like a quark.


There was one little difficulty: The systems these theories described existed only in 10 ­dimensions.

Since we live in a world that has but three dimensions of space and one of time, that last point might seem to be a ­deal ­breaker, but so appealing were the other virtues of string theory that physicists found a solution. The “extra” dimensions, they proposed, could be wrapped up so tight that we couldn’t see them. In effect, what we thought of as points in our world were tiny ­six-­dimensional structures. A little bizarre, to be sure, but not ­impossible.

A little bizarre, yes. Which is in itself fine, but Lindley suggests that it might be leading 'physics into a rarefied regime beyond the reach of experimental scrutiny'.

In any case, he reviews two new books pointing out the limits (or abject failure) of string theory. One tension which immediately arises is that, if the critique is true, this questionable theory has become dominant in theoretical physics.

Lindley adds some of his own insights along the way (he is also a critic of string theory). One of them is particularly insightful and of broader relevance:
Both authors plead for universities and granting agencies to consciously find room, every now and then, for the mavericks and eccentrics who might bring ­much-­needed new ideas into the excessively closed world of theoretical physics. Fat chance, unfortunately, was my instant reaction, given the way the scientific world, like academia in general, rewards careerism more than ­brilliance.

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