Results 31 to 40 of about 42,432 (292)
On closed Einstein-de Sitter universes
Physics Letters A, 1998 8 pages, 1 figure. Revision includes comment on "top-down" and "bottom-up" pictures of structure formation.
Fagundes, Helio V., Gausmann, Evelise
openaire +3 more sources
Closed universes, de Sitter space, and inflation [PDF]
Physical Review D, 2005 We present a new approach to constructing inflationary models in closed universes. Conformal embedding of closed-universe models in a de Sitter background suggests a quantisation condition on the available conformal time. This condition implies that the universe is closed at no greater than the 10% level.
Lasenby, Anthony, Doran, Chris
openaire +2 more sources
Catalytic creation of baby bubble universe with small positive cosmological constant
Journal of High Energy Physics, 2019 We investigate the decay of metastable de Sitter, Minkowski and anti-de Sitter vacua catalyzed by a black hole and a cloud of strings. We apply the method to the creation of the four dimensional bubble universe in the five dimensional anti-de Sitter ...
Issei Koga, Yutaka Ookouchi
doaj +1 more source
A snapping cosmic string in a de Sitter or anti-de Sitter universe [PDF]
Classical and Quantum Gravity, 2004 We present and describe an exact solution of Einstein's equations which represents a snapping cosmic string in a vacuum background with a cosmological constant $ $. The snapping of the string generates an impulsive spherical gravitational wave which is a particular member of a known family of such waves.
Podolský, J., Griffiths, J. B.
openaire +2 more sources
Quantum field theory in the de sitter universe [PDF]
Physical Review Letters, 1994 We present a study of quantum scalar fields on de Sitter (dS) space-time based on analyticity in the complexified Riemannian manifold; a new expansion of the linear fields in terms of coordinate independent dS plane waves and an explicit form of the propagators at real or imaginary times are given.
Bros J., Gazeau J. P., MOSCHELLA, UGO
openaire +3 more sources
A quantum state for the late Universe
Physics Letters B, 2022 We consider the quantum description of a toy model universe in which the Schwarzschild-de Sitter geometry emerges from the coherent state of a massless scalar field.
Andrea Giusti +3 more
doaj +1 more source
How round is the quantum de Sitter universe?
European Physical Journal C: Particles and Fields, 2020 We investigate the quantum Ricci curvature, which was introduced in earlier work, in full, four-dimensional quantum gravity, formulated nonperturbatively in terms of Causal Dynamical Triangulations (CDT).
N. Klitgaard, R. Loll
doaj +1 more source
Can inhomogeneties accelerate the cosmic volume expansion? [PDF]
, 2006 If expanding and contracting regions coexist in the universe, the speed of the cosmic volume expansion can be accelerated. We construct simple inhomogeneous dust-filled universe models in which the speed of the cosmic volume expansion is accelerated for ...
Kai, Tomohiro +4 more
core +2 more sources
Designer de Sitter Spacetimes [PDF]
, 2008 Recent observations in cosmology indicate an accelerating expansion of the universe postulated to arise from some form of dark energy, the paradigm being positive cosmological constant.
Schleich, K., Witt, D. M.
core +1 more source
Spontaneous Creation of Inflationary Universes and the Cosmic Landscape [PDF]
, 2004 We study some gravitational instanton solutions that offer a natural realization of the spontaneous creation of inflationary universes in the brane world context in string theory.
A. Albrecht +61 more
core +2 more sources