The
grand unification energy , or the
GUT scale, is the energy level above which, it is believed, the
electromagnetic force,
weak force, and
strong force become equal in strength and unify to one force governed by a
simple Lie group. Specific
Grand unified theories (GUTs) can predict the grand unification energy but, usually, with large uncertainties due to model dependent details such as the choice of the
gauge group, the
Higgs sector, the matter content or further free parameters. Furthermore, at the moment it seems fair to state that there is no agreed
minimal GUT.