Positive cosmological constant, non-local gravity and horizon entropy
نویسندگان
چکیده
منابع مشابه
Cosmological Constant and Local Gravity
We discuss the linearization of Einstein equations in the presence of a cosmological constant, by expanding the solution for the metric around a flat Minkowski space-time. We demonstrate that one can find consistent solutions to the linearized set of equations for the metric perturbations, in the Lorentz gauge, which are not spherically symmetric, but they rather exhibit a cylindrical symmetry....
متن کاملNon-Local Modification of Gravity and the Cosmological Constant Problem
We propose a phenomenological approach to the cosmological constant problem based on generally covariant non-local and acausal modifications of four-dimensional gravity at enormous distances. The effective Newton constant becomes very small at large length scales, so that sources with immense wavelengths and periods — such as the vacuum energy— produce miniscule curvature. Conventional astrophy...
متن کاملQuantum gravity with a positive cosmological constant
A quantum theory of gravity is described in the case of a positive cosmological constant in 3 + 1 dimensions. Both old and new results are described, which support the case that loop quantum gravity provides a satisfactory quantum theory of gravity. These include the existence of a ground state, discoverd by Kodama, which both is an exact solution to the constraints of quantum gravity and has a...
متن کاملRole of a "local" cosmological constant in Euclidean quantum gravity.
In 4D non-perturbative Regge calculus a positive value of the effective cosmological constant characterizes the collapsed phase of the system. If a local term of the form S′ =
متن کاملUnbounded entropy in spacetimes with positive cosmological constant
In theories of gravity with a positive cosmological constant, we consider product solutions with flux, of the form (A)dSp × S. Most solutions are shown to be perturbatively unstable, including all uncharged dSp × S spacetimes. For dimensions greater than four, the stable class includes universes whose entropy exceeds that of de Sitter space, in violation of the conjectured “N -bound”. Hence, if...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Nuclear Physics B
سال: 2012
ISSN: 0550-3213
DOI: 10.1016/j.nuclphysb.2012.04.009