  We show that collider experiments have the potential to exclude a light
scalar field as well as generic models of modified gravity as dark energy
candidates. Our mechanism uses the spectrum radiated by black holes and can
equally well be applied to determine the number of light degrees of freedom. We
obtain the grey body factors for massive scalar particles and calculate the
total emissivity. While the Large Hadron Collider (LHC) may not get to the
desired accuracy, the measurement is within reach of next generation colliders.
