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Related papers: Is the Universe Flat?

200 papers

We explore the possibility that the entire departure of galactic rotational velocities from their luminous Newtonian expectation be cosmological in origin, and show that within the framework of conformal gravity (but not Einstein gravity…

Astrophysics · Physics 2016-08-30 Philip D. Mannheim

We present the final nine-year maps and basic results from the WMAP mission. We provide new nine-year full sky temperature maps that were processed to reduce the asymmetry of the effective beams. Temperature and polarization sky maps are…

We propose a model of the Universe based on Minkowski flat space-time metric. In this model the space-time does not evolve. Instead the matter evolves such that all the mass parameters increase with time. We construct a model based on…

Cosmology and Nongalactic Astrophysics · Physics 2012-11-15 Pankaj Jain

We construct a model for the universe based on the existence of quantum fields at finite temperature in the background of Robertson-Walker spacetime in presence of a non-zero cosmological constant. We discuss the vacuum regime in the light…

General Relativity and Quantum Cosmology · Physics 2011-10-10 M. B. Altaie , U. Al-Ahmad

General relativity predicts a singularity in the beginning of the universe being called big bang. Recent developments in loop quantum cosmology avoid the singularity and the big bang is replaced by a big bounce. A classical theory of…

General Physics · Physics 2011-02-08 Walter Petry

The large scale geometry of the late Universe can be decomposed as R$\times {\Sigma}_3$, where R stands for cosmic time and ${\Sigma}_3$ is the three dimensional spatial manifold. We conjecture that the spatial geometry of the Universe's…

Cosmology and Nongalactic Astrophysics · Physics 2023-12-08 Yassir Awwad , Tomislav Prokopec

In this letter we will show that, contrary to what is widely believed, an almost isotropic cosmic microwave background (CMB) temperature does not imply that the universe is ``close to a Friedmann-Lemaitre universe''. There are two important…

Astrophysics · Physics 2009-10-31 U. S. Nilsson , C. Uggla , J. Wainwright , W. C. Lim

Assuming that the relativistic universe is homogeneous and isotropic, we can unambiguously determine its model and physical properties, which correspond with the Einstein general theory of relativity (and with its two special partial…

General Physics · Physics 2010-12-27 Vladimir Skalsky

The plethora of recent cosmologically relevant data has indicated that our universe is very well fit by a standard Friedmann-Lema\^{i}tre-Robertson-Walker (FLRW) model, with $\Omega_{M} \approx 0.27$ and $\Omega_{\Lambda} \approx 0.73$ --…

Astrophysics · Physics 2009-06-23 M. E. Araújo , W. R. Stoeger

Modern cosmology is closely linked to our understanding of radial null geodesics as these model the propagation of light signals through an expanding universe. Azimuthal geodesics, on the other hand, are perhaps best known for their…

General Relativity and Quantum Cosmology · Physics 2024-01-10 Christian G. Boehmer , Antonio d'Alfonso del Sordo , Betti Hartmann

The influence of the generalized uncertainty principle (GUP) and extended uncertainty principle (EUP) on the thermodynamics of the Friedmann-Robertson-Walker (FRW) universe has been investigated. It is shown that the entropy of the apparent…

High Energy Physics - Theory · Physics 2009-04-06 Tao Zhu , Ji-Rong Ren , Ming-Fan Li

A geometric spacetime map of the universe is presented, addressing problems inherent in deep space observations and cosmology. Implications for the observer's perspective, the cosmological "horizon" and "flatness" problem, "inflation", and…

General Relativity and Quantum Cosmology · Physics 2011-11-22 John A. Gowan

The global geometry of the universe is in principle as observable an attribute as local curvature. Previous studies have established that if the universe is wrapped into a flat hypertorus, the simplest compact space, then the fundamental…

Astrophysics · Physics 2009-10-30 Janna Levin , Evan Scannapieco , Joseph Silk

We introduce "anamorphic" cosmology, an approach for explaining the smoothness and flatness of the universe on large scales and the generation of a nearly scale-invariant spectrum of adiabatic density perturbations. The defining feature is…

Cosmology and Nongalactic Astrophysics · Physics 2015-10-02 Anna Ijjas , Paul J. Steinhardt

The spatial curvature of the universe is not yet known. Even though at present the Universe is very close to being essentially flat and most signatures of curvature appear to have been diluted by inflation, if the number of e-foldings…

High Energy Physics - Theory · Physics 2021-12-23 Sebastian Cespedes , Senarath de Alwis , Francesco Muia , Fernando Quevedo

Many cosmological measurements today suggest that the Universe is expanding at a constant rate. This is inferred from the observed age versus redshift relationship and various distance indicators, all of which point to a cosmic equation of…

General Physics · Physics 2018-09-14 Fulvio Melia

The discovery of scale acceleration evidenced from supernovae luminosities and spatial flatness of feature evolution in the cosmic microwave background presents a challenge to the understanding of the evolution of cosmological vacuum…

General Relativity and Quantum Cosmology · Physics 2007-05-23 James Lindesay

Assuming a closed universe with slight positive curvature, cosmic expansion is modeled as a heat engine where the '"system'" is defined collectively as those regions of space within the observable universe which will later evolve into voids…

General Relativity and Quantum Cosmology · Physics 2020-08-03 Christopher Pilot

Here, we consider a flat FRW universe whose its horizon entropy meets the R\'enyi entropy of non-extensive systems. In our model, the ordinary energy-momentum conservation law is not always valid. By applying the Clausius relation as well…

General Physics · Physics 2018-01-17 H. Moradpour , Alexander Bonilla , Everton M. C. Abreu , Jorge Ananias Neto

This article explores the cosmological scenario in which our Universe contains a hidden thin-shell configuration. We investigate a degenerate modification of the Friedmann-Robertson-Walker metric obtained through a coordinate transformation…

General Relativity and Quantum Cosmology · Physics 2025-12-16 Mauricio Cataldo , Antonella Cid , Pedro Labraña