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Dynamical systems in nature exhibit self-similar fractal space-time fluctuations on all scales indicating long-range correlations and therefore the statistical normal distribution with implicit assumption of independence, fixed mean and…

General Physics · Physics 2010-02-18 A. M. Selvam

Recent diffraction experiments on metallic glasses have unveiled an unexpected non-cubic scaling law between density and average interatomic distance, which lead to the speculations on the presence of fractal glass order. Using X-ray…

Previously defined covariant and gauge-invariant perturbation variables, representing, e.g., the fractional spatial energy density gradient on hypersurfaces of constant expansion, are used to simplify the linear perturbation analysis of a…

Astrophysics · Physics 2009-10-30 Winfried Zimdahl

A numerical integration is made, starting with a Kantowski-Sachs (KS) model with an added initial perturbation at time one-tenth the age of the universe, and evolving up to the present. According to a prediction by Barrow (1989), the ratio…

Astrophysics · Physics 2016-08-30 H. V. Fagundes , M. A. M. Gonzalez

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…

General Relativity and Quantum Cosmology · Physics 2007-05-23 David L. Wiltshire

Our paper introduces a new theoretical framework called the Fractional Einstein--Gauss--Bonnet scalar field cosmology, which has important physical implications. Using fractional calculus to modify the gravitational action integral, we…

Cosmology and Nongalactic Astrophysics · Physics 2024-12-12 Bayron Micolta-Riascos , Alfredo D. Millano , Genly Leon , Byron Droguett , Esteban González , Juan Magaña

We present a systematic exploration of dark energy and modified gravity models containing a single scalar field non-minimally coupled to the metric. Even though the parameter space is large, by exploiting an effective field theory (EFT)…

Cosmology and Nongalactic Astrophysics · Physics 2019-06-03 Louis Perenon , Federico Piazza , Christian Marinoni , Lam Hui

We demonstrate that local, scale-dependent non-Gaussianity can generate cosmic variance uncertainty in the observed spectral index of primordial curvature perturbations. In a universe much larger than our current Hubble volume, locally…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 Joseph Bramante , Jason Kumar , Elliot Nelson , Sarah Shandera

I propose a modification of the spherical infall model for the evolution of density fluctuations with initially Gaussian probability distribution and scale-free power spectra in Einstein-de Sitter universe as developed by Hoffman & Shaham.…

Astrophysics · Physics 2009-10-31 Ewa L. Lokas

In this paper, it is shown that the cosmological model that was introduced in a sequence of three earlier papers under the title, A Dust Universe Solution to the Dark Energy Problem can be used to analyse and solve the Cosmological…

General Physics · Physics 2008-07-13 James G. Gilson

New measurements of galaxy clustering and background radiations provide improved constraints on the isotropy and homogeneity of the Universe on large scales. In particular, the angular distribution of radio sources and the X-Ray Background…

Astrophysics · Physics 2009-10-16 Kelvin K. S. Wu , Ofer Lahav , Martin J. Rees

We discuss various space-time metrics which are compatible with Einstein's equations and a previously suggested cosmology with a finite total mass. In this alternative cosmology the matter density was postulated to be a spatial delta…

General Relativity and Quantum Cosmology · Physics 2015-05-20 L. Clavelli , Gary R. Goldstein

Deviations from the area law of the horizon entropy, in the cosmological setup, are known to lead to modified Friedmann equations governing the evolution of the universe. In this work, we propose that such modifications need not be…

General Relativity and Quantum Cosmology · Physics 2026-02-19 Amir A. Khodahami , Ahmad Sheykhi

Processes involving bursts of activity separated by quiescent periods occur across diverse systems and scales. In human dynamics, these phenomena have been described by power-law inter-event time distributions, $P(t)\sim t^{-\alpha}$, with…

Other Condensed Matter · Physics 2026-04-17 Morten Møller , Philipp Rahe , Sadegh Ghaderzadeh , Elena Besley , Philip Moriarty

We propose that the size of the universe and its rate of expansion cannot be simultaneously specified with arbitrary precision, a quantum mechanical statement encoded in a deformed commutation relation for the scale factor. The deformation…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-15 Savvas M. Koushiappas

We calculate the power spectrum of density fluctuations in the statistical non-equilibrium field theory for classical, microscopic degrees of freedom to first order in the interaction potential. We specialise our result to cosmology by…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-07 Matthias Bartelmann , Felix Fabis , Daniel Berg , Elena Kozlikin , Robert Lilow , Celia Viermann

In standard perturbation approaches and N-body simulations, inhomogeneities are described to evolve on a predefined background cosmology, commonly taken as the homogeneous-isotropic solutions of Einstein's field equations…

General Relativity and Quantum Cosmology · Physics 2012-05-11 Xavier Roy , Thomas Buchert

I show that the de Sitter Equilibrium cosmology generically predicts observable levels of curvature in the Universe today. The predicted value of the curvature depends only on the ratio of the density of non-relativistic matter to energy…

Cosmology and Nongalactic Astrophysics · Physics 2013-05-29 Andreas Albrecht

The separable analytical solution in standard perturbation theory for an Einstein de Sitter (EdS) universe can be generalized to the wider class of such cosmologies (``generalized EdS'', or gEdS) in which a fraction of the pressure-less…

Cosmology and Nongalactic Astrophysics · Physics 2023-05-12 Michael Joyce , Azrul Pohan

We perform a fractal analysis of the Southern Sky Redshift Survey 2, following the methods prescribed by Pietronero and collaborators, to check their claim that the galaxy distribution is fractal at all scales, and we discuss and explain…

Astrophysics · Physics 2007-05-23 A. Cappi , C. Benoist , L. N. da Costa , S. Maurogordato
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