Gravity test confines string theory

Researchers have conducted the most sensitive search to date for gravitational-strength forces between masses separated by only twice the diameter of a human hair, but they have observed no new forces. The results rule out a substantial portion of parameter space for new forces with a range between one-tenth and one-hundredth of a millimeter, where theoretical physicists using string theory have proposed that “moduli forces” might be detected, according to the researchers.