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It has been recently claimed that cosmologies with time dependent speed of light might solve some of the problems of the standard cosmological scenario, as well as inflationary scenarios. In this letter we show that most of these models,…

Astrophysics · Physics 2019-08-17 Susana Landau , Pablo Sisterna , Hector Vucetich

The recent local measurement of the Hubble constant based on the distance-ladder method has reached a $1.91\%$ precision, but this result is in tension with the early-universe measurements at the more than 4$\sigma$ level, bringing a crisis…

Cosmology and Nongalactic Astrophysics · Physics 2020-05-12 Rui-Yun Guo , Jing-Fei Zhang , Xin Zhang

The modern cosmology is based on inflationary models with baryosynthesis and dark matter/energy.It implies extension of particle symmetry beyond the Standard model. Studies of physical basis of the modern cosmology combine direct searches…

Cosmology and Nongalactic Astrophysics · Physics 2016-11-08 M. Yu. Khlopov

We revisit the constraints on inflation models by using the current cosmological observations involving the latest local measurement of the Hubble constant ($H_{0} = 73.00\pm 1.75$ km s $^{-1}$ Mpc$^{-1}$). We constrain the primordial power…

Cosmology and Nongalactic Astrophysics · Physics 2017-12-20 Rui-Yun Guo , Xin Zhang

At high red-shifts, the distribution of angular separations between galaxies in clusters is in tension with the standard cosmological model. The JWST data at even higher red-shifts have exacerbated this tension. However, Zwick Tired Light…

General Physics · Physics 2025-04-16 Carlos Navia

Inflation creates large-scale cosmological density perturbations that are characterized by an isotropic, homogeneous, and Gaussian random distribution about a locally flat background. Even in a flat universe, the spatial curvature measured…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Matthew Kleban , Marjorie Schillo

This review describes the discovery of the cosmic microwave background radiation in 1965 and its impact on cosmology in the 50 years that followed. This discovery has established the Big Bang model of the Universe and the analysis of its…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-08 Ruth Durrer

After 25 years of its existence, inflationary theory gradually becomes the standard cosmological paradigm. However, we still do not know which of the many versions of inflationary cosmology will be favored by the future observational data.…

High Energy Physics - Theory · Physics 2011-05-24 Andrei Linde

Inflationary cosmology predicts that the particle horizon should be generically much bigger than the present-day Hubble radius, $1/H_0$. This implies a special regime of super-Hubble scale energy density fluctuations imprinted on the cosmic…

Astrophysics · Physics 2009-10-30 Arjun Berera , Li-Zhi Fang , Gary Hinshaw

We develop a set of controlled, analytic approximations to study the effects of bubble collisions on cosmology. We expand the initial perturbation to the inflaton field caused by the collision in a general power series, and determine its…

High Energy Physics - Theory · Physics 2015-06-04 Roberto Gobbetti , Matthew Kleban

In this follow-up to our paper from 2005, we briefly discuss the implications of the apparent detection of B modes in the Cosmic Microwave Background for the issues raised in that paper. We argue that under the assumptions of eternal…

Cosmology and Nongalactic Astrophysics · Physics 2014-04-10 Ben Freivogel , Matthew Kleban , Maria Rodriguez Martinez , Leonard Susskind

In this letter, we propose a model of inflationary cosmology with a bounce preceded and study its primordial curvature perturbations. Our model gives rise to a primordial power spectrum with a feature of oscillation on large scales compared…

Astrophysics · Physics 2009-02-02 Yi-Fu Cai , Tao-tao Qiu , Jun-Qing Xia , Xinmin Zhang

We emphasize that standard quantum theory (SQT) is incomplete because it doesn't describe what is experimentally observed, namely events, nor does it satisfactorily define the circumstances under which events may occur. Simple models are…

Quantum Physics · Physics 2007-05-23 Philip Pearle

The standard model of cosmology with nearly Gaussian, isotropic, scale invariant and adiabatic initial conditions describes the cosmological observations well. However, the study of any deviation from the mentioned conditions will open up a…

Cosmology and Nongalactic Astrophysics · Physics 2018-01-31 Mohammad Ansari Fard , Shant Baghram

I motivate and discuss some recent work on theories with varying constants, and consider some possible observational consequences and tests. Particular emphasis is given to models which can (almost) exactly mimic the predictions of standard…

Astrophysics · Physics 2017-08-23 C. J. A. P. Martins

We investigate the potential of observations of anisotropies in the cosmic microwave background (CMB) and large-scale structure in the Universe to detect possible modifications of standard inflationary models by physics beyond the Planck…

Astrophysics · Physics 2009-11-10 Oystein Elgaroy , Steen Hannestad

Cosmic Microwave Background (CMB) is a powerful probe to study the early universe and various cosmological models. Weak gravitational lensing affects the CMB by changing its power spectrum, but meanwhile, it also carries information about…

Cosmology and Nongalactic Astrophysics · Physics 2021-06-09 Chandra Shekhar Saraf

The recent measurements of the power spectrum of Cosmic Microwave Background anisotropies are consistent with the simplest inflationary scenario and big bang nucleosynthesis constraints. However, these results rely on the assumption of a…

The weak gravity conjecture imposes severe constraints on natural inflation. A trans-Planckian axion decay constant can only be realized if the potential exhibits an additional (subdominant) modulation with sub-Planckian periodicity. The…

Cosmology and Nongalactic Astrophysics · Physics 2020-04-22 Martin Wolfgang Winkler , Martina Gerbino , Micol Benetti

"Non-Locality is most naturally incorporated into a theory in which there is a special frame of reference. One possible candidate for this special frame of reference is the one in which the Cosmic Microwave Background (CMB) is isotropic.…

General Physics · Physics 2022-09-16 Maurizio Consoli , Alessandro Pluchino , Paola Zizzi