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Proving string theory

String theory - the idea that the fundamental constituents of matter are tiny strings or multidimensional membranes vibrating in particular ways - currently offers the best hope of bringing together the seemingly inconsistent theories that make up modern physics. Many consider it the best path to a "theory of everything."

But there's a big problem with string theory: How do you test whether it's true? Some physicists fear that the theory can never be put to the acid test - which would place it in the realm of philosophy rather than science. Theoretical physicist Lawrence Krauss is fond of saying that string theory is really a "theory of anything" - and therefore, a theory of nothing.

However, other researchers claim that string theory can indeed be put to the test, by checking the data from experiments aimed at producing the stuff of the early universe. And they say the theory already has passed an initial test.

The argument is outlined in one research paper published by Physical Review Letters, plus another yet-to-be-published paper from the same team. A summary appears in the latest edition of Physics News Update from the American Institute of Physics.

I have to admit the papers themselves are way beyond me - but the condensed version in Physics News Update says string theory explains some of the puzzling behavior observed in the "Big Bang soup" already created by the Relativistic Heavy-Ion Collider.

Physicists had expected that the particle collisions would create energetic jets of quarks, but it turned out that those jets were not as energetic as expected. The researchers - Hong Liu and Krishna Rajagopal of the Massachusetts Institute of Technology and Urs Wiedemann of CERN - used string theory to explain the suppression of the jets (appealing to the existence of a fifth dimension in the process). And in the upcoming paper, they say that future experiments at the Relativistic Heavy-Ion Collider as well as at the Large Hadron Collider could strengthen the case for string theory.

The Large Hadron Collider is due to start operations this year, and although it may take several years to reach a conclusion, there's increasing hope that we'll eventually find out whether or not string theorists have just been stringing us along.