  Recently it has been pointed out that the characteristic quantum-gravity
scale could be as low as the weak scale in theories with gravity propagating in
higher dimensions. The observed smallness of Newton's constant is a consequence
of the large compactified volume of the extra dimensions. We investigate the
consequences of this supposition for high-energy collider experiments. We do
this by first compactifying the higher dimensional theory and constructing a
3+1-dimensional low-energy effective field theory of the graviton Kaluza-Klein
excitations and their interactions with ordinary matter. We then consider
graviton production processes, and select photon plus missing energy and jet
plus missing energy signatures for careful study. We find that both a 1 TeV
e+e- collider and the CERN LHC will be able to reliably and perturbatively
probe the fundamental gravity scale up to several TeV, with the precise value
depending on the number of extra dimensions. Similarly, searches at LEP2 and
the Tevatron are able to probe this scale up to approximately 1 TeV. We also
discuss virtual graviton exchange, which induces local dimension-eight
operators associated with the square of the energy-momentum tensor. We estimate
the size of such operators and study their effects on two fermions to two
photons observables.
