  Considering that gravitational force might deviate from Newton's
inverse-square law (ISL) and become much stronger in small scale, we propose a
kind of optical spectroscopy experiment to detect this possible deviation and
take electronic, muonic and tauonic hydrogen atoms as examples. This experiment
might be used to indirectly detect the deviation of ISL down to nanometer scale
and to explore the possibility of three extra dimensions in ADD's model, while
current direct gravity tests cannot break through micron scale and go beyond
two extra dimensions scenario.

General Relativity and Quantum Cosmology;High Energy Physics - Experiment;High Energy Physics - Theory;Atomic Physics