The Voyage of Captain Obvious

Grading is satanic

Sunday, May 01, 2005

Why I am skeptical of string theory

Firstly, we hear nothing but endless stories about how there is only one, unique string theory, and how its competitors are infinitely less believeble due to the assumptions that they make, typically that they assume the dimension of spacetime to be four.

However, when making these claims, the string theorists, who go boasting that THEIR theory predicts the dimensionality of spacetime, rather than requiring it as an input. Fine. The problem, of course, is that we don't see n-4 dimesions that whatever string model we're talking about predicts. To solve this problem, the string theorists then say, "well, that just means that these extra dimesions are compact in some manner, so that they have a finite volume that is too small for us to observe. Ok. So now, what has been done is that one must "compactify" the spacetime, in order to produce results that don't patently disagree with our reality. So, what is a more absurd assumption? That we have a four dimensional spacetime with an ordinary topology, or that we have a 10 or 11 or 26 dimensional spacetime with a bizarre fucked-up topology (that can't get simpler than the seven sphere cross four dimensional minkowski space)? Maybe it's just aesthetics on my part, but I find the latter proposition much crazier. Add to this the problem of there being a rediculous number of acceptable vacuum states for string theory, each of which with different phenomonologies, and it begins to seem like there are actually a very large number of acceptable string theories.

Second, string theory works from the conceptual idea that Einstein's theory of relativity is a less reasonable framework from which to percieve the universe than is this set of ideas. QFT is certainly a very powerful tool, and is clearly the only tested game in town when it comes to high energy particle physics, but it is such a jury-rigged arrangement of stopgap measures. GR, in contrast requies minimal input, and follows from simple and beautiful physical ideas. I would certainly lean towards believing relativity before I would lean toward believing QFT, all things being equal.

Finally (for now), there is supersymmetry. Not only is there not a single piece of evidence that would lead anyone to believe that supersymmetry exists, but every time that people claim that it's about to be found, it isn't, and the ss-breaking scale just gets pushed to higher and higher energies. If they don't find it in the new CERN, I'm going to have real troble believing that it will ever be found. It seems that people just want it to be there, so it MUST be there. Well, at least ss-breaking would be able to explain the origins of renormalization.


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