Tension in the void: cosmic rulers strain inhomogeneous cosmologies

Cosmic rulers

We derive general covariant expressions for the six independent observable modes of distortion of ideal standard rulers in a perturbed Friedmann-Robertson-Walker spacetime. Our expressions are gauge invariant and valid on the full sky. These six modes are most naturally classified in terms of their rotational properties on the sphere, yielding two scalars, two vector (spin-1), and two tensor (s...

Inhomogeneous String Cosmologies

We present exact inhomogeneous and anisotropic cosmological solutions of low-energy string theory containing dilaton and axion fields. The spacetime metric possesses cylindrical symmetry. The solutions describe ever-expanding universes with an initial curvature singularity and contain known homogeneous solutions as subcases. The asymptotic form of the solution near the initial singularity has a...

Anisotropic and Inhomogeneous Cosmologies

Scalar Field Inhomogeneous Cosmologies

Some exact solutions for the Einstein eld equations corresponding to inhomogeneous G2 cosmologies with an exponential-potential scalar eld which generalize solutions obtained previously are considered. Several particular cases are studied and the properties related to generalized in ation and asymptotic behaviour of the models are discussed.

Inhomogeneous M-Theory Cosmologies

Abstract We study a class of inhomogeneous and anisotropic G2 string cosmological models. In the case of separable G2 models we show that the governing equations reduce to a system of ordinary differential equations. We focus on a class of separable G2 M-theory cosmological models, and study their qualitative behaviour (a class of models with time-reversed dynamics is also possible). We find th...