Physics / Fizik
Permanent URI for this collectionhttps://hdl.handle.net/11147/6
Browse
3 results
Search Results
Article Citation - WoS: 17Citation - Scopus: 19Cosmological Consequences of a Variable Cosmological Constant Model(World Scientific Publishing Co. Pte Ltd, 2017) Azri, Hemza; Bounames, A.We derive a model of dark energy which evolves with time via the scale factor. The equation-of-state is studied as a function of a parameter α introduced in this model as = (1 - 2α)/(1 + 2α). In addition to the recent accelerated expansion, the model predicts another decelerated phase. These two phases are studied via the parameter α. The age of the universe is found to be almost consistent with the observation. In the limiting case, the cosmological constant model, we find that vacuum energy gravitates with a tiny gravitational constant which evolves with the scale factor, rather than with Newton's constant. This enables degravitation of the vacuum energy which in turn produces the tiny observed curvature, rather than a 120 orders of magnitude larger value.Conference Object Towards the Solution of Cosmological Constant and Zero Point Energy Problems Through Metric Reversal Symmetry(IOP Publishing Ltd., 2009) Erdem, RecaiIn this talk I review my studies on metric reversal symmetry and their further implications. The talk is mainly concentrated on the relevance of the metric reversal symmetry to the solutions of the cosmological constant and zero point energies. However the use of metric reversal symmetry to hide higher Kaluza-Klein modes at the scales larger than the size of extra dimensions is also discussed, and speculations on its possible relevance to Pauli-Villars and Lee-Wick model are also briefly mentioned.Article Citation - WoS: 21Citation - Scopus: 22Vacuum Energy as the Origin of the Gravitational Constant(Springer Verlag, 2009) Demir, Durmuş AliWe develop a geometro-dynamical approach to the cosmological constant problem (CCP) by invoking a geometry induced by the energy-momentum tensor of vacuum, matter and radiation. The construction, which utilizes the dual role of the metric tensor that it structures both the spacetime manifold and energy-momentum tensor of the vacuum, gives rise to a framework in which the vacuum energy induced by matter and radiation, instead of gravitating, facilitates the generation of the gravitational constant. The non-vacuum sources comprising matter and radiation gravitate normally. At the level of classical gravitation, the mechanism deadens the CCP yet quantum gravitational effects, if strong, can keep it existent.