Cosmic vacuum energy with thermodynamic and gravodynamic action power

Abstract

In this paper we investigate the suspected effect of cosmic vacuum energy on the dynamics of cosmic space, while nevertheless still now the phenomenon of vacuum energy is not yet physically settled in a rigorous form. In view of what one needs for general relativistic approaches, we start here with considerations of the specific energy-momentum tensor of cosmic vacuum energy in the standard hydrodynamical form, and derive relations between vacuum energy density and vacuum pressure. With the help of fundamental thermodynamic relations we then find relations of the two quantities, vacuum pressure and energy density, to the scale R of the universe. These, however, allow for a multitude of power exponents n , including the case of a constant vacuum energy density with n=0 and Rn=const. Then we argue that for spaces of cosmic dimensions not only thermodynamical relations have to be fulfilled, but also, as we call them "gravodynamical relations", meaning that vacuum pressure has to work against the inner gravitational binding of space, mostly due to the gravitating masses distributed in this cosmic space. When we include this effect in addition to the thermodynamics we find that the vacuum energy density ρΛ then can not anymore be considered as constant, but unavoidably as falling off with the scale of the universe according R−2 . At the end of this article we then suspect, since vacuum energy even nowadays is not yet a physically well founded and understood quantity, that the Hubble expansion of the present universe is not driven by vacuum pressure, but by the change of gravitational binding energy at the ongoing structure formation of cosmic matter during the Hubble expansion.