Observational Bounds on Quantum Gravity Signals using Existing Data

We consider a new set of effects arising from the quantum gravity corrections to the propagation of fields, associated with fluctuations of the spacetime geometry. Using already existing experimental data, we can put bounds on these effects that are more stringent by several orders of magnitude than those expected to be obtained in astrophysical observations. In fact, these results can already be interpreted as questioning the whole scenario of linear (in ${\ell }_P$) corrections to the dispersion relations for free fields in Lorentz violating theories.