منابع مشابه
Birth of a Closed Universe of Negative Spatial Curvature
We propose a modified form of the spontanteous birth of the universe by quantum tunneling. It proceeds through topology change and inflation, to eventually become a universe with closed spatial sections of negative spatial curvature and nontrivial global topology.
متن کاملScale - Invariant Spectrum of Cosmic Background Radiation as a Feature of the Universe with Negative Curvature
As was shown before (Gurzadyan and Kocharyan, 1992, 1993ab) the statistical properties (exponential mixing) of motion of CMB photon beams in Friedmann Universe with negative curvature can have definite observable consequences including the decrease of the CMB anisotropy amplitude after the last scattering, distortion of images on CMB sky maps. Here we consider one more consequence concerning th...
متن کاملThe Signature of the Negative Curvature of the Universe in Cmb Maps
The geodesics followed by cosmic microwave background (CMB) photons show different behaviours depending on the geometry of space. Namely, the effect of ‘mixing geodesics’ predicts a distinct signature in CMB maps: threshold-independent elongated anisotropy spots in negatively curved geometries. We have found statistically significant sign for spot elongation in the COBE four year maps. This can...
متن کاملMannifolds of Negative Curvature
A C∞ function f on a riemannian manifold M is convex provided its hessian (second covariant differential) is positive semidefinite, or equivalently if (f ◦σ)′′ ≥ 0 for every geodesic inM . We shall apply this notion in a variety of ways to the study of manifolds of negative or nonpositive curvature. Convexity has, of course, long been associated with negative curvature, but convex function seem...
متن کاملRigidity in Non-negative Curvature
In this paper we will show that any complete manifold of nonnegative curvature has a flat soul provided it has curvature going to zero at infinity. We also show some similar results about manifolds with bounded curvature at infinity. To establish these theorems we will prove some rigidity results for Riemannian submersions, eg., any Riemannian submersion with complete flat total space and compa...
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ژورنال
عنوان ژورنال: Physical Review Letters
سال: 1993
ISSN: 0031-9007
DOI: 10.1103/physrevlett.70.1579