Nature 433, 10 (06 January 2005); doi:10.1038/433010a In search of hidden dimensions So far, string theory has defied experiments, but Nima Arkani-Hamed thinks he has found a way to put the idea to the test. Geoff Brumfiel finds out how. J. IDE/HARVARD UNIV. NEWS OFFICE String fellow: Nima Arkani-Hamed hopes that particle-collision experiments will show that gravity leaks into other dimensions. Ask most theorists when they think their calculations will be tested experimentally and you'll be told "decades" or sometimes, more honestly, "never".But ask Nima Arkani-Hamed, a physicist at Harvard University, and he will give you a far closer...