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The cosmological constant problem is explained by a theory based on the discrete space-time hypothesis. The calculated cosmological constant value is of the order of 10^-52[m]^-2 or equivalent to about 0.7 of the critical mass density. It…

Astrophysics · Physics 2007-05-23 H. M. Mok

Most of the literature on general relativity over the last century assumes that the cosmological constant $\Lambda$ is zero. However, by now independent observations have led to a consensus that the dynamics of the universe is best…

General Relativity and Quantum Cosmology · Physics 2021-04-02 Abhay Ashtekar

We outline a method to infer the global history of star formation in galaxies with input only from absorption-line observations of quasars. The application of the method to existing data leads to the conclusion that most stars formed at…

Astrophysics · Physics 2007-05-23 S. Michael Fall

As a compelling pattern for the holographic principle, our covariant entropy bound conjecture is proposed for more general dynamical horizons. Then we apply our conjecture to $\Lambda$CDM cosmological models, where we find it imposes a…

General Relativity and Quantum Cosmology · Physics 2009-03-20 Song He , Hongbao Zhang

The discovery that the expansion of the universe is accelerating in time is a major discovery which still awaits adequate explanation. It is generally agreed that this implies a cosmic repulsion as a result of the existence of a…

General Physics · Physics 2008-11-26 R. F. O'Connell

Recent observations of the Universe have led to a conclusion suppressing an up-to-now supposed deceleration of the Universe caused by attractive gravitational forces. Contrary, there is a renaissance of the cosmological member lambda and…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Jozef Sima , Miroslav Sukenik

In theories in which different regions of the universe can have different values of the the physical parameters, we would naturally find ourselves in a region which has parameters favorable for life. We explore the range of anthropically…

High Energy Physics - Phenomenology · Physics 2011-05-12 V. Agrawal , S. M. Barr , J. F. Donoghue , D. Seckel

A brief explanation of the meaning of the anthropic principle - as a prescription for the attribution of a priori probability weighting - is illustrated by various cosmological and local applications, in which the relevant conclusions are…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Brandon Carter

The anthropic principle implies that life can emerge and be sustained only in a narrow range of values of fundamental constants. Here we show that anthropic arguments can set powerful constraints on {\em transient} variations of the…

The structure formation in the local Universe is considered within the weak-field modification of General Relativity involving the cosmological constant. This approach enables to describe the dynamics of groups and clusters of galaxies, to…

General Relativity and Quantum Cosmology · Physics 2025-02-06 V. G. Gurzadyan

In this article the cosmological constant problems, as well as the astronomical evidence for a cosmologically significant homogeneous exotic energy density with negative pressure (quintessence), are reviewed for a broad audience of…

Astrophysics · Physics 2007-05-23 Norbert Straumann

In this methodological note we discuss some details and peculiarities of the cosmic expansion as viewed by a realistic observer. We show that the velocity $v_\Theta$ related to a change (measured by observer's clock) of the angular…

Popular Physics · Physics 2015-06-17 A. V. Toporensky , S. B. Popov

We extend the usual gravitational action principle by promoting the bare cosmological constant (CC) from a parameter to a field which can take many possible values. Variation leads to a new integral constraint equation which determines the…

General Relativity and Quantum Cosmology · Physics 2011-03-21 John D. Barrow , Douglas J. Shaw

The aim of this thesis is to question some of the basic assumptions that go into building the $\Lambda$CDM model of our universe. The assumptions we focus on are the initial conditions of the universe, the fundamental forces in the universe…

Cosmology and Nongalactic Astrophysics · Physics 2020-06-25 Darsh Kodwani

From the time the first stars formed over 13 billion years ago to the present, star formation has had an unexpectedly dynamic history. At first, the star formation rate density increased dramatically, reaching a peak 10 billion years ago…

Cosmology and Nongalactic Astrophysics · Physics 2013-10-25 Mordecai-Mark Mac Low

I discuss recent theoretical work on the formation and evolution of galaxies paying particular attention to the ability of current models to make detailed comparisons with observations of the galaxy population both nearby and at high…

Astrophysics · Physics 2007-05-23 Simon D. M. White

Thanks to new technology of observations and fresh inputs from particle physics, cosmology has advanced on both observational and theoretical fronts. It is therefore opportune that we take stock of the cosmological situation today and…

Astrophysics · Physics 2016-08-30 J. S. Bagla , T. Padmanabhan , J. V. Narlikar

The common nature of dark matter and dark energy is argued in [1] based on the approach that the cosmological constant \Lambda enters the weak-field General Relativity following from Newton theorem on the "sphere-point mass" equivalency…

General Physics · Physics 2019-02-27 V. G. Gurzadyan , A. Stepanian

We consider different observational effects to test modified gravity approach involving the cosmological constant in the common description of the dark matter and the dark energy. We obtain upper limits for the cosmological constant by…

Cosmology and Nongalactic Astrophysics · Physics 2022-01-19 A. Amekhyan , S. Sargsyan , A. Stepanian

We study the evolution of the configuration entropy for different combinations of $\Omega_{m0}$ and $\Omega_{\Lambda0}$ in the flat $\Lambda$CDM universe and find that the cosmological constant plays a decisive role in controlling the…

Cosmology and Nongalactic Astrophysics · Physics 2019-03-06 Biswajit Pandey , Biswajit Das