The hypothesis c = h = G = 1 implies that unit mass is not a single-valued function but rather has two widely varying values, such as 7.4 × 10^-51 kg and 4.0 × 10³⁵ kg. Hence, the considerable body of work in theoretical physics that uses this common convention must be deemed suspect. In order to avoid this problem, theoreticians must limit themselves to c = h = 1 or, exclusively, c = G = 1 depending upon whether they are chiefly concerned with atomic physics or with gravity, respectively.