Related papers: Lemaitres Limit
The Pierre Auger Observatory has collected data for more than 15 years, accumulating the world's largest exposure to ultrahigh energy cosmic rays (UHECRs). The energy spectrum of the UHECRs has been measured up to $10^{20.2}$ eV, and their…
It would be reasonable to recall some critical issues in physical cosmology development. GR was created by A. Einstein in 1915. In 1917 Einstein proposed the first (static) cosmological model. Soon after the A. Eddington proved that the…
Time delays between multiple images of lensed sources can probe the geometry of the universe. We propose a novel method based on free-form modelling of gravitational lenses to estimate time-delay distances and, in turn, cosmological…
The Hubble parameter H0 still not very well measured. Although the Hubble Key Project, Chandra and WMAP gave good estimates, the uncertainties remain quite large. In this brief report, we suggest an original and independent method to derive…
At present, the strongest upper limit on $\sum m_{\nu}$, the sum of neutrino masses, is from cosmological measurements. However, this bound assumes that the neutrinos are stable on cosmological timescales, and is not valid if the neutrino…
Recent observations of Cepheids in the Virgo cluster have bolstered the evidence that supports a Hubble constant in 70-90 km/s/Mpc range. This evidence, by and large, probes the expansion of the Universe within 100 Mpc. We investigate the…
Using new cosmological doomsday argument Page predicts that the maximal lifetime of de Sitter universe should be $t_{max}=10^{60}$ yr which is way too small in comparison with strings predictions ($t_f>$googleplex). However, since this…
The maximum size of a bound cosmic structure is computed perturbatively as a function of its mass in the framework of the cubic galileon, proposed recently to model the dark energy of our Universe. Comparison of our results with…
A new model of the observed universe, using solutions to the full Einstein equations, is developed from the hypothesis that our observable universe is an underdense bubble, with an internally inhomogeneous fractal bubble distribution of…
The paper extends the 2003 radius of metric regularity theorem by Dontchev, Lewis & Rockafellar by providing an exact formula for the radius with respect to Lipschitz continuous perturbations in general Asplund spaces, thus, answering…
The prevailing cosmological model with the lambda-term, in which the space is flat, is studied (section 1). The corresponding age of the Universe (t0) is calculated (assuming a Hubble constant consistent with the measurements of the Hubble…
The Megamaser Cosmology Project inferred a value for the Hubble constant given by $H_0=73.9 \pm 3.0 $ km/sec/Mpc. This value was obtained using Bayesian inference by marginalizing over six nuisance parameters, corresponding to the…
A low matter density decaying vacuum cosmology is proposed on the assumption that the universe's radius is a complex quantity \hat{R} if it is regarded as having a zero energy-momentum tensor. But we find that when the radius is real, it…
Based on the observed increase of $\Omega _0$ as a function of cosmic scale, the Robertson--Walker metric and the Einstein equation are generalized so that $ \Omega_0$, $H_0$, and the age of the Universe, $t_0$, all become functions of…
Observational tests for the homogeneity of the Universe on large scales are reviewed. Assuming the Cosmological Principle we then estimate cosmological parameters by joint analysis of the Cosmic Microwave Background, Supernovae Ia, peculiar…
This is the third article in a series aimed at computing accurate and precise ages of galactic globular clusters from their full color-magnitude diagram in order to estimate the age of the Universe and in turn constrain the cosmological…
Present day estimates of the Hubble constant based on Cepheids and on the cosmic microwave background radiation are uncertain by roughly 10% (on the conservative assumption that the universe may not be PERFECTLY flat). Gravitational lens…
In the past decade, observational cosmology has had one of the most exciting periods in the past century. The precision with which we have been able to measure cosmological parameters has increased tremendously, while at the same time, we…
A precise measurement of the curvature of the Universe is of primeval importance for cosmology since it could not only confirm the paradigm of primordial inflation but also help in discriminating between different early Universe scenarios.…
Over the last nine years of cosmic microwave background observations, the Wilkinson Microwave Anisotropy Probe ($WMAP$) results were consistent with a $\Lambda$CDM cosmological model in which the age of the Universe is one Hubble time, and…