On the one hand, Einstein said E=mc. On the other hand, a theory of quantum space-time says E=S/c where S represents the space-time continuum equivalent to the nothingness of the vacuum. However, S is divisible if and only if it is quantifiable. In order to quantify S, first a new definition of linear momentum must be given as p=H/S where H is now the squares of energy of the whole universe. Transposing algebraically gives S=H/p. Moreover, H is the integral of e where e is the unit of zero-point energy of the quantum vacuum fluctuations given by f(a)´y(a)×f(b)´y(b) where f’s are infinitesimal equal magnitudes primary forces and y’s are the infinitesimal space-time metric multiples of Planck length. Direct substitutions give E=òe/pc. Since pc=E=hn from quantum mechanics, E=òe=cp+mc. This explicitly connects the integral of zero-point energy of the quantum vacuum fluctuations to the total relativistic energy of quantum mechanics.