states that the $S$-matrix is invariant under local (nonlinear) field redefinitions [@Dyson48; @Blasietal99]. Since the conformal transformation is, essentially, a field redefinition, it would seem that quantum physics is invariant under the change of the conformal frame. However, the field theory in which the equivalence theorem is derived applies to gravity only in the perturbative regime in which the fields deviate slightly from the Minkowski space-time. In this regime, tree level quantities can be calculated in any conformal frame with same result, but in the non-perturbative regime field theory and the equivalence theorem do not apply.

Unfortunately, the scaling of units in the Einstein frame often produces results that either do not make sense or are incorrect in the Jordan frame, reinforcing the opposite view that the two frames are not equivalent. While Dicke’s explanation is very appealing and several claims supporting the view that the two frames are inequivalent turned out to be incorrect because they simply neglected the scaling of units in the Einstein frame, one should not forget that Dicke’s argument is not inclusive of all areas of physics and it is better to check explicitly that the physics of a certain field does not depend on 