author={F. Melia and M. Abdelqader},
  journal={International Journal of Modern Physics D},
We present here the transformations required to recast the Robertson–Walker metric and Friedmann–Robertson–Walker equations in terms of observer-dependent coordinates for several commonly assumed cosmologies. The overriding motivation is the derivation of explicit expressions for the radius Rh of our cosmic horizon in terms of measurable quantities for each of the cases we consider. We show that the cosmological time dt diverges for any finite interval ds associated with a process at R → Rh… Expand
Physical basis for the symmetries in the Friedmann–Robertson–Walker metric
Modern cosmological theory is based on the Friedmann–Robertson–Walker (FRW) metric. Often written in terms of co-moving coordinates, this well-known solution to Einstein’s equations owes its elegantExpand
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Cosmological redshift z grows as the Universe expands and is conventionally viewed as a third form of redshift, beyond the more traditional Doppler and gravitational effects seen in otherExpand
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The metrics of gravitational and cosmological models are brought into canonical form in comoving coordinates. The FWR curvature parameter k is read from this and it is shown that k=0 does notExpand
The Rh=ct universe
The backbone of standard cosmology is the Friedmann-Robertson-Walker solution to Einstein's equations of general relativity (GR). In recent years, observations have largely confirmed many of theExpand
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The R_h=ct Universe Without Inflation
The horizon problem in the standard model of cosmology (LDCM) arises from the observed uniformity of the cosmic microwave background radiation, which has the same temperature everywhere (except forExpand
Photon Geodesics in FRW Cosmologies
The Hubble radius is a particular manifestation of the Universe’s gravitational horizon, Rh(t0) ≡ c/H0, the distance beyond which physical processes remain unobservable to us at the present epoch.Expand


The cosmic horizon
The cosmological principle, promoting the view that the Universe is homogeneous and isotropic, is embodied within the mathematical structure of the Robertson‐Walker (RW) metric. The equations derivedExpand
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Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant
We present spectral and photometric observations of 10 Type Ia supernovae (SNe Ia) in the redshift range 0.16 " z " 0.62. The luminosity distances of these objects are determined by methods thatExpand
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WMAP precision data enable accurate testing of cosmological models. We find that the emerging standard model of cosmology, a flat � -dominated universe seeded by a nearly scale-invariant adiabaticExpand
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Absorption cross section of RN black hole
The behavior of a charged scalar field in the RN black hole space time is studied using WKBapproximation. In the present work it is assumed that matter waves can get reflected from the eventhorizon.Expand
Int. J. Mod. Physics D
  • Int. J. Mod. Physics D
  • 2008
  • ApJS
  • 2003
  • ApJ
  • 2000
  • ApJ
  • 1999