The Japanese are getting in on the string theory hype business, with KEK issuing a press release today with the title: The mechanism that explains why our universe was born with 3 dimensions: a 40-year-old puzzle of superstring theory solved by supercomputer. As usual for this kind of press release, the claim is that researchers at the institution issuing the press release have finally solved the age-old problem of string theory predicting nothing. In this case the prediction is that there are 3 dimensions of space (I think that, technically, this is a “post-diction”). According to the press release:
A group of three researchers from KEK, Shizuoka University and Osaka University has for the first time revealed the way our universe was born with 3 spatial dimensions from 10-dimensional superstring theory in which spacetime has 9 spatial directions and 1 temporal direction. This result was obtained by numerical simulation on a supercomputer…
… it is expected that superstring theory allows the investigation of the birth of the universe. However, actual calculation has been intractable because the interaction between strings is strong, so all investigation thus far has been restricted to discussing various models or scenarios…
… It is almost 40 years since superstring theory was proposed as the theory of everything, extending the general theory of relativity to the scale of elementary particles. However, its validity and its usefulness remained unclear due to the difficulty of performing actual calculations. The newly obtained solution to the space-time dimensionality puzzle strongly supports the validity of the theory.
Furthermore, the establishment of a new method to analyze superstring theory using computers opens up the possibility of applying this theory to various problems. For instance, it should now be possible to provide a theoretical understanding of the inflation that is believed to have taken place in the early universe, and also the accelerating expansion of the universe, whose discovery earned the Nobel Prize in Physics this year. It is expected that superstring theory will develop further and play an important role in solving such puzzles in particle physics as the existence of the dark matter that is suggested by cosmological observations, and the Higgs particle, which is expected to be discovered by LHC experiments.
This goes back to the pre-arXiv days, before many of our current graduate students were even born, but some of us are old enough to remember similar claims being made back in the late 1980s. For example there’s the 1989 Brandenberger-Vafa paper claiming that string theory predicts 3 dimensions, using a “string gas” cosmology. I don’t remember if there was a “finally, physicists find a way to make a prediction based on string theory” press release back in 1989 or not.
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