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We have studied a cosmological model with a cosmological term of the form $\Lambda=3\alpha\fr{\dot R^2}{R^2}+\bt\fr{\ddot R}{R}+\fr{3\gamma}{R^2} \alpha, \ \bt \gamma$ are constants. The scale factor (R) is found to vary linearly with time…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Arbab I. Arbab

We propose that the observed value of the cosmological constant may be explained by a fundamental uncertainty in the spacetime metric, which arises when combining the principle that mass and energy curve spacetime with the quantum…

General Relativity and Quantum Cosmology · Physics 2025-05-20 Ahmed Farag Ali , Nader Inan

The Swampland program, which looks for low energy theories consistent with quantum gravity, has led to the introduction of a dark dimension stemming from the cosmological constant. We show that the same argument leads to the emergence of…

High Energy Physics - Theory · Physics 2025-07-23 Kazem Bitaghsir Fadafan , Giacomo Cacciapaglia

Three of the big puzzles of theoretical physics are the following: (i) There is apparently no time evolution in the dynamics of quantum general relativity, because the allowed quantum states must obey the Hamiltonian constraint. (ii) During…

General Relativity and Quantum Cosmology · Physics 2015-12-29 Shreya Banerjee , Sayantani Bera , Tejinder P. Singh

We propose a novel explanation for the smallness of the observed cosmological constant (CC). Regions of space with a large CC are short lived and are dynamically driven to crunch soon after the end of inflation. Conversely, regions with a…

High Energy Physics - Phenomenology · Physics 2021-02-03 Itay M. Bloch , Csaba Csáki , Michael Geller , Tomer Volansky

In this work, we study the cosmological constant problem and Hubble tension in the void-dominated cosmology scenario \cite{Yusofi:2022hgg}. For this goal, we will first consider the cosmic voids in the cosmic web as interconnected ideal…

Cosmology and Nongalactic Astrophysics · Physics 2022-08-26 E. Yusofi , M. A. Ramzanpour

Independent tests aiming to constrain the value of the cosmological constant $\Lambda$ are usually difficult because of its extreme smallness $\left(\Lambda \simeq 1\times 10^{-52}~\textrm{m}^{-2},~\textrm{or}~2.89\times…

General Relativity and Quantum Cosmology · Physics 2018-03-28 Lorenzo Iorio

We trace the historical appearance of Planck's constant in physics, and we note that initially the constant did not appear in connection with quanta. Furthermore, we emphasize that Planck's constant can appear in both classical and quantum…

General Physics · Physics 2018-04-10 Timothy H. Boyer

I propose an observationally and theoretically consistent resolution of the cosmological constant problem: $\Lambda$ is a counterterm -- with a running coupling -- that balances the monopole celestial sky average of the kinetic energy of…

General Relativity and Quantum Cosmology · Physics 2024-04-03 David L. Wiltshire

We describe one of the remarkable problems of theoretical physics persevering up to the beginning of the millennium. All gaugetheories with spontaneous gauge symmetry breaking from the standard model of particle physics with the electroweak…

High Energy Physics - Phenomenology · Physics 2007-05-23 F. Pisano , N. O. Reis

We make the cosmological constant, {\Lambda}, into a field and restrict the variations of the action with respect to it by causality. This creates an additional Einstein constraint equation. It restricts the solutions of the standard…

General Relativity and Quantum Cosmology · Physics 2015-05-28 John D. Barrow , Douglas J. Shaw

I review the current state of determinations of the Hubble constant, which gives the length scale of the Universe by relating the expansion velocity of objects to their distance. There are two broad categories of measurements. The first…

Astrophysics · Physics 2015-05-13 Neal Jackson

The cosmological constant $\Lambda$ is a free parameter in Einstein's equations of gravity. We propose to fix its value with a boundary condition: test particles should be free when outside causal contact, e.g. at infinity. Under this…

General Physics · Physics 2019-05-24 Enrique Gaztanaga

We point out that the standard formulation of the cosmological constant problem itself is problematic since it is trying to apply the very large scale homogeneous cosmological model to very small (Planck) scale phenomenon. At small scales,…

General Relativity and Quantum Cosmology · Physics 2020-08-05 Qingdi Wang , William G. Unruh

The cosmological constant problem is one of the greatest challenges in contemporary physics, since it is deeply rooted in the problematic interplay between quantum fields and gravity. The aim of this work is to review the key conceptual…

General Relativity and Quantum Cosmology · Physics 2025-04-23 Federico Scali

The cosmological constant problem is the principal obstacle in the attempt to interpret dark energy as the quantum vacuum energy. We suggest that the obstacle can be removed, i.e. that the cosmological constant problem can be resolved by…

General Physics · Physics 2012-01-24 Dragan Slavkov Hajdukovic

The scale of quantum mechanical effects in matter is set by Planck's constant, $\hbar$. This represents the quantisation scale for material objects. In this article, we present a simple argument why the quantisation scale for space, and…

General Relativity and Quantum Cosmology · Physics 2021-08-17 Matthew J. Lake

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

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

In addressing the cosmological constant problem, we propose that the discrepancy between the theoretical and observed values can be ascribed to the inherent uncertainty in the spacetime metric. Mach's principle, which posits that mass…

General Relativity and Quantum Cosmology · Physics 2023-09-06 Ahmed Farag Ali , Nader Inan