Related papers: Unimodular Quadratic Gravity and the Cosmological …
The cosmological constant problem is studied in a two component cosmological model. The universe contains a cosmological constant of an arbitrary size and sign and an additional component with an inhomogeneous equation of state. It is shown…
In the framework of the minimal quartet-metric gravity/systogravity, a scalar graviton/systolon is stated as a universal dark component, with supplementary manifestations in the different contexts either as dark matter or dark energy. An…
This is an essay sketching the line of thinking which has led the present author to propose the constituent or atomic model of gravitation more than a decade ago. It turns out that viewing the problem of gravitation as a quantum many body…
We study the quantum contributions to the classical cosmological constant in a quantum gravity theory for GR with matter on a piecewise linear spacetime corresponding to a triangulation of a smooth manifold. We use the effective action…
With attempts to quench the cosmological constant $\Lambda$ having so far failed, we instead investigate what could be done if $\Lambda$ is not quenched and actually gets to be as big as elementary particle physics suggests. Since the…
We show that in generic supergravity theories the mass of the moduli during inflation is larger (or at least of the same order of magnitude) than the Hubble constant. This fact does not depends on the details of the inflation and on the…
When one takes into account gravitation, the measurement of space and time cannot be carried out with infinite accuracy. When quantum mechanics is reformulated taking into account this lack of accuracy, the resolution of the measurement…
An accelerated universe should naturally have a vacuum energy density determined by its dynamical curvature. The cosmological constant is most likely a temporary description of a dynamical variable that has been drastically evolving from…
The holographic dark energy model is obtained from a cosmological constant generated by generic quantum gravity effects giving a minimum length. By contrast, the usual bound for the energy density to be limited by the formation of a black…
Deconstruction provides a novel way of dealing with the notoriously difficult ultraviolet problems of four-dimensional gravity. This approach also naturally leads to a new perspective on the holographic principle, tying it to the…
The recently suggested generalized unimodular gravity theory, which was originally put forward as a model of dark energy, can serve as a model of cosmological inflation driven by the effective perfect fluid -- the dark purely gravitational…
General Relativity (GR) and Unimodular Gravity (UG) provide two equivalent descriptions of gravity that differ in the nature of the cosmological constant. While GR is based on the group of diffeomorphisms that permits the cosmological…
According to general relativity, the present analysis shows on geometrical grounds that the cosmological constant problem is an artifact due to the unfounded link of this fundamental constant to vacuum energy density of quantum…
Despite the ultraviolet problems with canonical quantum gravity, as an effective field theory its infrared phenomena should enjoy fully quantum mechanical unitary time evolution. Currently this is not possible, the impediment being what is…
In this paper we provide both a diagnosis and resolution of the cosmological constant problem, one in which a large (as opposed to a small) cosmological constant $\Lambda$ can be made compatible with observation. We trace the origin of the…
We discuss predictions for cosmology which result from the scaling solution of functional flow equations for a quantum field theory of gravity. A scaling solution is necessary to render quantum gravity renormalizable. Our scaling solution…
The quantization of unimodular gravity in minisuperspace leads to a time evolution of states generated by the Hamiltonian, as in usual quantum mechanics. We revisit the analysis made in Ref. \cite{unruh}, extending it to phantom scalar…
We propose a new approach to the Cosmological Constant Problem which makes essential use of an extra dimension. A model is presented in which the Standard Model vacuum energy ``warps'' the higher-dimensional spacetime while preserving 4D…
The two major goals in fundamental physics are: 1) Unification of all forces incorporating relativity and quantum theory, 2) Understanding the origin and evolution of the Universe as well as explaining the smallness of the cosmological…
We show that a positive cosmological constant is incompatible with the quantum-corpuscular resolution of de Sitter metric in form of a coherent state. The reason is very general and is due to the quantum self-destruction of the coherent…