49 research outputs found
On the Green's function and iterative solutions of Loop Quantum Cosmology
Here we shall find the green's function of the difference equation of loop
quantum cosmology. To illustrate how to use it, we shall obtain an iterative
solution for closed model and evaluate its corresponding Bohmian trajectory.Comment: To appear in General Relativity and Gravitatio
Constraints Algebra and Equations of Motion in Bohmian Interpretation of Quantum Gravity
It is shown that introducing the quantum effects using deBroglie--Bohm theory
in the canonical formulation of gravity would change the constraints algebra.
The new algebra is derived and shown that it is the clear projection of general
coordinate transformations to the spatial and temporal diffeomorphisms. The
quantum Einstein's equations are derived and it is shown that they are
manifestly covariant under the above diffeomorphisms, as it would be.Comment: 9 journal page
Pure Quantum Solutions of Bohmian Quantum Gravity
In this paper we have investigated the pure quantum solutions of Bohmian
quantum gravity. By pure quantum solution we mean a solution in which the
quantum potential cannot be ignored with respect to the classical potential,
especially in Bohmian quantum gravity we are interested in the case where these
two potentials are equal in their magnitude and in fact their sum is zero. Such
a solutions are obtained both using the perturbation and using the linear field
approximation.Comment: 10 pages, LaTe
Conformal Transformations and Quantum Gravity
Recently\cite{BQG}, it was shown that quantum effects of matter could be
identified with the conformal degree of freedom of the space-time metric.
Accordingly, one can introduce quantum effects either by making a scale
transformation (i.e. changing the metric), or by making a conformal
transformation (i.e. changing all physical quantities). These two ways are
investigated and compared. Also, it is argued that, the ultimate formulation of
such a quantum gravity theory should be in the framework of the scalar-tensor
theories.Comment: 8 pages, RevTe
Scalar-Tensor Theories and Quantum Gravity
Recently, it was shown that the quantum effects of the matter, could be used
to determine the conformal degree of freedom of the space-time metric. So both
gravity and quantum are geometrical features. Gravity determines the causal
structure of the space-time, while quantum determines the scale of the
space-time. In this article, it is shown that it is possible to use the
scalar-tensor framework to build a unified theory in which both quantum and
gravitational effects are present.Comment: 12 pages, RevTe
Causal loop quantum cosmology in momentum space
We shall show that it is possible to make a causal interpretation of loop
quantum cosmology using the momentum as the dynamical variable. We shall show
that one can derive Bohmian trajectories. For a sample cosmological solution
with cosmological constant, the trajectory is plotted.Comment: 21 pages, 2 figures. To appear in Int. J. Mod. Phys. D, 200