The novel particles predicted by GUT models are expected to have extremely high masses—around the GUT scale of 10 16 GeV (just three orders of magnitude below the Planck scale of 10 19 GeV)—and so are well beyond the reach of any foreseen particle hadron collider experiments. Therefore, the particles predicted by GUT models will be unable to be observed directly, and instead the effects of grand unification might be detected through indirect observations of the following: