Classical general relativity from quantum gravity and the generalized Kodama states. Abstract In this paper we investigate the relation between the CDJ matrix used for construction of the generalized Kodama states and the Weyl curvature tensor. By exploiting special self-duality relations unique to four dimensional spacetime, we show that the effects of quantum gravity in Ashtekar variables are...

The presence of a constant background antisymmetric tensor for open strings or D-branes forces the space-time coordinates to be noncommutative. This effect is equivalent to replacing ordinary products in the effective theory by the deformed star product. An immediate consequence of this is that all fields get complexified. The only possible noncommutative Yang-Mills theory is the one with U(N) ...

Deep space laser ranging missions like ASTROD I (Single-Spacecraft Astrodynamical Space Test of Relativity using Optical Devices) and ASTROD, together with astrometry missions like GAIA and LATOR will be able to test relativistic gravity to an unprecedented level of accuracy. More precisely, these missions will enable us to test relativistic gravity to 10−7−10−9 of the size of relativistic (pos...

Recent work has outlined a framework for analyzing diffusion tensor gradient and covariance tensors in terms of invariant gradient and rotation tangents, which span local variations in tensor shape and orientation, respectively. This chapter hopes to increase the adoption of this framework by giving it a more intuitive conceptual description, as well as providing practical advice for its numeri...

Out of several possible extensions general relativity, the scalar-tensor theory is most popular for reasons. Since quantum description gravity yet to be formulated properly, understanding a gravitational remains incomplete until study thermodynamic and fluid-gravity aspects, which provides an alternative viewpoint understand theory. In this review, we these features (thermodynamics fluid analog...

There has been increasing interest in investigating the possible parity violating features gravity theory and on cosmological scales. In this work, we consider a class of scalar-nonmetricity theory, which Lagrangian is polynomial built nonmetricity tensor scalar field. The coupled with field through its first order derivative. Besides monomials that are quadratic tensor, also construct cubic bo...

It has been proposed that cosmic acceleration or inflation can be driven by replacing the EinsteinHilbert action of general relativity with a function f(R) of the Ricci scalar R. Such f(R) gravity theories have been shown to be equivalent to scalar-tensor theories of gravity that are incompatible with Solar System tests of general relativity, as long as the scalar field propagates over Solar Sy...

Scalar fields with inverse power-law effective potentials may provide a negative pressure component to the energy density of the universe today, as required by cosmological observations. In order to be cosmologically relevant today, the scalar field should have a mass mφ = O(10 −33eV), thus potentially inducing sizable violations of the equivalence principle and space-time variations of the cou...

The analysis of certain singularities in scalar-tensor gravity contained in a recent paper is completed, and situations are pointed out in which these singularities cannot occur. Recently, Abramo et al. [1] have investigated certain geometric singularities occurring in the gravitational sector of scalar-tensor theories described by the action