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We construct a cosmological model of late acceleration based on the new agegraphic dark energy model in the framework of Brans-Dicke cosmology where the new agegraphic energy density $\rho_{D}= 3n^2 m^2_p /\eta^{2}$ is replaced with…

General Relativity and Quantum Cosmology · Physics 2015-05-13 Ahmad Sheykhi

The current expansion of the Universe has been observed to be accelerating, and the widely accepted spatially-flat concordance model of general relativistic cosmology attributes this phenomenon to a constant dark energy, a cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2023-04-13 Shulei Cao

The tension between measurements of the Hubble constant obtained at different redshifts may provide a hint of new physics active in the relatively early universe, around the epoch of matter-radiation equality. A leading paradigm to resolve…

Cosmology and Nongalactic Astrophysics · Physics 2021-04-28 Mariana Carrillo González , Qiuyue Liang , Jeremy Sakstein , Mark Trodden

Recent studies suggest that dark energy may be dynamical rather than being a mere cosmological constant $\Lambda$. In this work, we examine the viability of two physically well-motivated dynamical dark energy models -- holographic dark…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-03 Peng-Ju Wu , Tian-Nuo Li , Guo-Hong Du , Xin Zhang

We outline a dynamical dark energy scenario whose signatures may be simultaneously tested by astronomical observations and laboratory experiments. The dark energy is a field with slightly sub-gravitational couplings to matter, a logarithmic…

Astrophysics · Physics 2009-06-23 Nemanja Kaloper

Cosmological observations strongly suggest the presence of dark energy which comprises the majority of the current energy density of the universe. The equation of state relating the pressure and energy density of this dark energy, p = w…

Astrophysics · Physics 2007-05-23 Eric Gawiser

We explore the fate of the universe given the possibility that the density associated with `dark energy' may decay slowly with time. Decaying dark energy is modeled by a homogeneous scalar field which couples minimally to gravity and whose…

Astrophysics · Physics 2009-11-07 Ujjaini Alam , Varun Sahni , A. A. Starobinsky

The interacting dark energy model could propose a effective way to avoid the coincidence problem. In this paper, dark energy is taken as a fluid with a constant equation of state parameter $w_x$. In a general gauge, we could obtain two sets…

Cosmology and Nongalactic Astrophysics · Physics 2014-04-10 Weiqiang Yang , Lixin Xu

The dark energy that appears to produce the accelerating expansion of the universe can be characterized by an equation of state p=w\rho with w<-1/3. A number of observational tests have been proposed to study the value or redshift…

Astrophysics · Physics 2009-11-07 Jens Kujat , Angela M. Linn , Robert J. Scherrer , David H. Weinberg

We propose an uncertainty relation of space-time. This relation is characterized by GhT \lesssim \delta V, where T and \delta V denote a characteristic time scale and a spatial volume, respectively. Using this uncertainty relation, we give…

High Energy Physics - Theory · Physics 2008-11-26 N. Sasakura

We introduce a dark energy-modified minimum length uncertainty relation (DE-MLUR) or dark energy uncertainty principle (DE-UP) for short. The new relation is structurally similar to the MLUR introduced by K{\' a}rolyh{\' a}zy (1968), and…

General Relativity and Quantum Cosmology · Physics 2019-01-15 Matthew J. Lake

By simple arguments, we have shown that Karolyhazy's model overestimates the quantum uncertainty of the space-time geometry and leads to absurd physical consequences. The given model can thus not account for gradual violation of quantum…

General Relativity and Quantum Cosmology · Physics 2008-11-26 L. Diosi , B. Lukacs

We apply a new non-parametric Bayesian method for reconstructing the evolution history of the equation-of-state $w$ of dark energy, based on applying a correlated prior for $w(z)$, to a collection of cosmological data. We combine the latest…

Cosmology and Nongalactic Astrophysics · Physics 2013-03-20 Gong-Bo Zhao , Robert G. Crittenden , Levon Pogosian , Xinmin Zhang

We regard the background of space-time as a physical system composed of discrete volume elements at the Planck scale and get the internal energy of space-time by Debye model. A temperature-dependent minimum energy limit of the particles is…

General Relativity and Quantum Cosmology · Physics 2020-07-03 Qi-Qi Fan , Cong Li , Hao-Ran Zhang , Peng-Zhang He , Jian-Bo Deng

We proved that under quantum mechanics a momentum-energy and a space-time are dual vector spaces on an almost complex manifold in position representation, and the minimal uncertainty relations are equivalent to the inner-product relations…

General Physics · Physics 2007-09-03 You-gang Feng

We examine the status of various dark energy-models in light of the recently observed SN 1997ff at z \approx 1.7. The modified data still fit a pure cosmological constant \Lambda or a quintessence with an equation of state similar to that…

Astrophysics · Physics 2009-11-07 R. G. Vishwakarma

Dark energy might interact with cold dark matter in a direct, nongravitational way. However, the usual interacting dark energy models (with constant $w$) suffer from some catastrophic difficulties. For example, the $Q\propto\rho_{\rm c}$…

Cosmology and Nongalactic Astrophysics · Physics 2014-04-28 Yun-He Li , Xin Zhang

By studying the present cosmological data, particularly on CMB, SNeIA and LSS, we find that the future fate of the universe, for simple linear models of the dark energy equation-of-state, can vary between the extremes of (I) a divergence of…

Astrophysics · Physics 2009-11-10 Paul H. Frampton

We present evidence that the simplest particle-physics scalar-field models of dynamical dark energy can be separated into distinct behaviors based on the acceleration or deceleration of the field as it evolves down its potential towards a…

Astrophysics · Physics 2008-11-26 R. R. Caldwell , Eric V. Linder

We explore the theoretical possibility that dark energy density is derived from the vacuum particle pairs together with the quantum fluctuation of space-time. By assuming the vacuum particle pairs fall into the horizon boundary of the…

General Relativity and Quantum Cosmology · Physics 2023-07-24 Long Huang , Xiao feng Yang , Xiang Liu