72 research outputs found
SFT non-locality in cosmology: solutions, perturbations and observational evidences
In this note cosmological models coming out of the String Field Theory (SFT)
in application to the Dark Energy are reviewed. A way of constructing solutions
in the case of linear models is outlined, cosmological perturbations and
observational evidences of such models are explored. We explicitly demonstrate
the stability of the system at the linear order in the most typical
configuration.Comment: To be published in Proceedings of Invisible Universe 200
Schwarzschild -singularity is not permissible in ghost free quadratic curvature infinite derivative gravity
In this paper we will study the complete equations of motion for a ghost free
quadratic curvature infinite derivative gravity. We will argue that within the
scale of non-locality, Schwarzschild-type singular metric solution is not {\it
permissible}. Therefore, Schwarzschild-type vacuum solution which is a
prediction in Einstein-Hilbert gravity may {\it not} persist within the region
of non-locality. We will also show that just quadratic curvature gravity,
without infinite derivatives, always allows Schwarzschild-type singular metric
solution.Comment: 10 pages, title changed, discussion added, references updated,
version accepted in PR
Geodesic completeness and homogeneity condition for cosmic inflation
There are two disjointed problems in cosmology within General Relativity
(GR), which can be addressed simultaneously by studying the nature of geodesics
around , where is the physical time. One is related to the
past geodesic completeness of the inflationary trajectory due to the presence
of a cosmological singularity, and the other one is related to the homogeneity
condition required to inflate a local space-time patch of the universe. We will
show that both the problems have a common origin, arising from how the causal
structure of null and timelike geodesics are structured within GR. In
particular, we will show how a non-local extension of GR can address both
problems, while satisfying the null energy condition for the matter sources.Comment: 4 pages, 1 figur
- …