  A mass Hierarchy of magnitude O(10^16) GeV separates the gravitational and
electroweak interactions. Traditional proposed resolutions of this anomaly have
included supersymmetric theories (most notably, the MSSM and ESSM) and string
theory. However, energiers at which supersymmetric particles are expected to
appear are not accessible to experiment, and string theory is only testable at
around M_pl. A novel idea involves introducing extra dimensions into a
Minkowski space-time to reduce the effective separation between the gauge and
gravitational couplings. Theoretical developments of the so-called
Arkani-Dinopolous-Dvali (ADD) extra-dimensional scenario, and its experimental
verification, are presented here.
