Energy-Length Rule
  Lorentz ordering (causality) implies the following rule: for any given energy p0 of a system there is a certain interval c0 on x0 so that their product is the Lorentz ordering constant L It means p0c0 = L. The constant L=hc. Hence Planck constant h in a similar way as c are both consequences of Lorentz metric. The basic ideas are: 1. Lorentz metric implies that x0 must represent a length like the other components of x in X 2. The dual metric space X* is well defined since the Lorentz metric tensor is not singular. The components of the vectors p in X*are interpreted as representing energy. The properties of the physical systems that are direct consequences of the detailed structure of X and X*, and so expressed through the Lorentz Limit L are presented. 
Alexandru C Mihul, Eleonora A Mihul (Bucharest "University")