  It has recently been shown that if there is a large hidden sector in Nature,
the scale of quantum gravity could be much lower than traditionally expected.
We study the production of massless gravitons at the LHC and compare our
results to those obtained in extra dimensional models. The signature in both
cases is missing energy plus jets. In case of non observation, the LHC could be
used to put the tightest limit to date on the value of the Planck mass.
