Cosmic Vacuum Energy Determining the Space-Time Geometry of the Empty Universe
Advances and Trends in Physical Science Research Vol. 2,
Page 99-110
Abstract
Different from energies constituted by baryons or photons both of which are expressed as energies per particle, vacuum energy by its nature represents a ”volume energy”, i.e. an energy represented by the sheer space volume, however, not simply reacting to the temporal change of this space volume, but rather in a non-evident way which we here try to fix using thermodynamic principles. Vacuum energy is interpreted as a phenomenon of a polarization of empty space by real cosmic matter with the consequence that the prevailing vacuum energy should depend on the cosmic matter density. We try to interpret vacuum energy as a form of a heat capacity of cosmic volumes and study by the use of thermodynamical principles how the heat content of cosmic volumes should change with the change of the volumes themselves. In the present days of modern cosmology, it is assumed that the main ingredient to cosmic energy presently is vacuum energy with an energy density ϵ that is constant over the cosmic evolution. This paper shows that this assumption of constant vacuum energy density is unphysical, since it conflicts with the requirements of cosmic thermodynamics. The study starts from the total vacuum energy including the negatively valued gravitational binding energy and shows that cosmic thermodynamics then requires the cosmic vacuum energy density which can only vary with cosmic scale R = R(t) according to ϵ with only two values of ν being allowed, namely ν 1 = 2 and ν 2 vac ∼ R = 5/2. The study then discusses these two remaining solutions and find, when requiring a universe with a constant total energy, that the only allowed power index is ν = 2. The consequences of this scaling of ϵ are discussed and the results for a cosmic scale evolution of a quasi-empty universe are presented.
Keywords:
- Cosmic Vacuum energy density
- Friedmann equations
- thermodynamics
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