Confronted with microwave background observations by WMAP and with consternating supernova locations in the magnitude-redshift diagram modern cosmology feels enforced to call for cosmic vacuum energy as a necessary cosmological ingredient. Most often this vacuum energy is associated with Einstein's cosmological constant or with so-called "dark energy". A positive value of describes an inflationary action on cosmic dynamics which in view of recent cosmological data appears as an absolute need. In this article, however, we question the hypothesis of a constant vacuum energy density since not justifiable on physical grounds. Instead we show that gravitational binding energy of cosmic matter, connected with ongoing structure formation during cosmic expansion, acts similar to vacuum energy, since it reduces the effective gravitating proper mass density. Thus one may be encouraged to believe that actions of cosmic vacuum energy and gravitational binding energy concerning their cosmological effects are closely related to each other, perhaps in some respects even have identical phenomenologies.Based on results presented in this article we propose that the generally wanted action of vacuum energy on cosmic spacetime dynamics inevitably leads to a decay of vacuum energy density. Connected with this decay is a decrease of cosmic binding energy and the generation of new effective gravitating mass in the universe. If this all is adequately taken into account by the energy-momentum tensor of the H.-J. Fahr · M. Sokaliwska ( ) Argelander GR field equations, one is then led to non-standard cosmologies which for the first time can guarantee the conservation of the total energy both in static and expanding universes.We describe the structuring of cosmic matter by a change in time of the 2-point correlation-function. We do show here that cosmic structure formation drives accelerated cosmic expansion and feigns the action of vacuum energy density.

By three independent hints it will be demonstrated that still at present there is a substantial lack of theoretical understanding of the CMB phenomenon. One point, as we show, is that at the phase of the recombination era one cannot assume complete thermodynamic equilibrium conditions but has to face both deviations in the velocity distributions of leptons and baryons from a Maxwell-Boltzmann distribution and automatically correlated deviations of photons from a Planck law. Another point is that at the conventional understanding of the CMB evolution in an expanding universe one has to face growing CMB temperatures with growing look-back times. We show, however, here that the expected CMB temperature increases would be prohibitive to star formation in galaxies at redshifts higher than z=2 where nevertheless the cosmologically most relevant supernovae have been observed. The third point in our present study has to do with the assumption of a constant vacuum energy density which is required by the present ΛCDM-cosmology. Our studies here rather lead to the conclusion that cosmic vacuum energy density scales with the inverse square of the cosmic expansion scale R=R(t). Thus we come to the conclusion that with the interpretation of the present-day high quality CMB data still needs to be considered carefully.

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We investigated the impact of three different modifications of Newtonian gravity on motions of Keplerian objects within the Solar system. These objects are located at distances of the order of the distance to the Oort Cloud. With these three modifications we took into account a heliocentric dark matter halo as was indicated by Diemand et al., modified Newtonian dynamics (MOND) and a vacuum-induced force due to a locally negative cosmological constant − derived by Fahr & Siewert. In gravitationally bound systems it turns out that all three modifications deliver the same qualitative results: initially circular orbits for the pure Newtonian case are forced to convert into ellipses with perihelion migrations. The quantitative consideration, however, of the orbital parameters showed strong differences between MOND on one side, and dark matter and − effects on the other side.