Results 21 to 30 of about 17,519 (197)

Spatially flat cosmological quantum spacetimes

We recently described a cosmological quantum spacetime of vanishing spatial curvature, which can be considered as background for the IKKT matrix model, assuming that the resulting gauge theory couples weakly. Building on this example, we construct a large class of spatially flat cosmological quantum spacetimes.
Anonymous, Harold Steinacker
openalex   +3 more sources

Inhomogeneous Pre-Big Bang String Cosmology [PDF]

, 1997
An inhomogeneous version of pre--Big Bang cosmology emerges, within string theory, from quite generic initial conditions, provided they lie deeply inside the weak-coupling, low-curvature regime.
Barrow, Belinskii, Brustein, Brustein, Brustein, Campbell, Copeland, Copeland, Copeland, Deruelle, Easther, G. Veneziano, Gasperini, Gasperini, Gasperini, Gasperini, Gasperini, Gasperini, Gasperini, Hassan, Hawking, Iguchi, Kaloper, Kaloper, Landau, Linde, Meissner, Meissner, Parry, Sanchez, Sen, Tseytlin, Tseytlin, Veneziano   +33 more
core   +2 more sources

Variable Speed of Light Cosmology, Primordial Fluctuations and Gravitational Waves [PDF]

, 2016
A variable speed of light (VSL) cosmology is described in which the causal mechanism of generating primordial perturbations is achieved by varying the speed of light in a primordial epoch.
Moffat, J. W.
core   +2 more sources

Entropy of flat space cosmologies from celestial dual [PDF]

Physical Review D
We construct a one-dimensional dual theory that effectively describes the sector of the (2+1)D flat gravity phase space near a flat space cosmology saddle labeled by definite mass and angular momentum. This Schwarzian-type action describes the dynamics of the (pseudo-)Goldstone bosons of BMS3 algebra on a circle as the symmetry is spontaneously and ...
Arindam Bhattacharjee, Muktajyoti Saha
openalex   +3 more sources

Pre-Big-Bang Requires the Universe to be Exponentially Large From the Very Beginning [PDF]

, 1998
We show that in a generic case of the pre-big-bang scenario, inflation will solve cosmological problems only if the universe at the onset of inflation is extremely large and homogeneous from the very beginning.
A. Buonanno, A. D. Linde, A. D. Linde, A. D. Linde, A. D. Linde, A. D. Linde, A. D. Linde, A. D. Linde, A. H. Guth, A. Linde, A. Vilenkin, A. Vilenkin, Andrei Linde, B. A. Campbell, D. Coule, E. J. Copeland, E. Witten, G. Veneziano, G. Veneziano, G. W. Gibbons, J. R. Gott, K. Yamamoto, M. Bucher, M. Gasperini, M. Gasperini, M. Maggiore, M. S. Turner, N. Kaloper, N. Kaloper, Nemanja Kaloper, P. J. Steinhardt, R. Brustein, R. Brustein, R. Brustein, R. Easther, Raphael Bousso, V. A. Rubakov, Ya. B. Zeldovich   +37 more
core   +2 more sources

The Implementation, Interpretation, and Justification of Likelihoods in Cosmology [PDF]

, 2017
I discuss the formal implementation, interpretation, and justification of likelihood attributions in cosmology. I show that likelihood arguments in cosmology suffer from significant conceptual and formal problems that undermine their applicability in ...
Albert, Arms, Asselmeyer-Maluga, Beem, Beisbart, Beisbart, Bombelli, Butterfield, Butterfield, C.D. McCoy, Callender, Cornish, Cornish, Coule, Coule, Davidson, Demarest, Dingle, Donaldson, Earman, Earman, Earman, Earman, Earman, Ellis, Ellis, Ellis, Ellis, Ellis, Ellis, Evrard, Fischer, Fletcher, Freedman, Frigg, Frigg, Geroch, Gibbons, Gibbons, Harré, Hawking, Hawking, Hawking, Henneuax, Hollands, Isenberg, Kirchner, Lachièze-Rey, Laudan, Lebowitz, Lebowitz, Lerner, Loewer, Loewer, Luminet, Magnus, Manchak, Manchak, Maudlin, McCabe, McCoy, McCoy, McMullin, Munitz, North, Norton, Norton, Penrose, Penrose, Price, Schiffrin, Shackel, Smeenk, Sładkowski, Wald, Wallace, Wallace, Wolf   +77 more
core   +5 more sources

GRAVITATIONAL LENSING CORRECTIONS IN FLAT ΛCDM COSMOLOGY [PDF]

The Astrophysical Journal, 2010
20 pages, 4 figures, ApJ in ...
Kantowski, Ronald, Chen, Bin, Dai, Xinyu
openaire   +2 more sources

Cosmic acceleration in non-flat f(T) cosmology [PDF]

General Relativity and Gravitation, 2018
We study $f(T)$ cosmological models inserting a non-vanishing spatial curvature and discuss its consequences on cosmological dynamics. To figure this out, a polynomial $f(T)$ model and a double torsion model are considered. We first analyze those models with cosmic data, employing the recent surveys of Union 2.1, baryonic acoustic oscillation and ...
Salvatore Capozziello, Orlando Luongo, Richard Pincak, Arvin Ravanpak   +3 more
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Kinematic tests of exotic flat cosmological models [PDF]

, 1986
Theoretical prejudice and inflationary models of the very early Universe strongly favor the flat, Einstein-deSitter model of the Universe. At present the observational data conflict with this prejudice. This conflict can be resolved by considering flat models of the Universe which possess a smooth component by energy density.
J. C. Charlton, M. S. Turner
openalex   +3 more sources

The Flatness Problem and the Variable Physical Constants

Galaxies, 2019
We have used the varying physical constant approach to resolve the flatness problem in cosmology. Friedmann equations are modified to include the variability of speed of light, gravitational constant, cosmological constant, and the curvature constant ...
Rajendra P. Gupta
doaj   +1 more source