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Related papers: Isotropy, homogeneity and dipole saturation

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We report a new type of restoration of macroscopic isotropy (homogenization) in fractals with microscopic anisotropy. The phenomenon is observed in various physical setups, including diffusions, random walks, resistor networks, and Gaussian…

Condensed Matter · Physics 2011-02-28 Martin T. Barlow , Kumiko Hattori , Tetsuya Hattori , Hiroshi Watanabe

In this paper we construct a discrete simulation of an expanding homogeneous and isotropic space-time that expands via expansion of its basic elements to figure out properties and characteristics of such a space-time and derive conclusions.…

General Physics · Physics 2021-07-13 Faycal Ben Adda , Helene Porchon

The (measure-theoretical) entropy of a diffeomorphism along an expanding invariant foliation is the rate of complexity generated by the diffeomorphism along the leaves of the foliation. We prove that this number varies upper…

Dynamical Systems · Mathematics 2018-12-13 Jiagang Yang

The power-law dependence of the angle in the angular projection of galaxy distribution is explained by assuming that in the spherical shells within a small angle the distributions are also fractal. If this local angular fractal is…

Astrophysics · Physics 2008-02-03 Yu Shi

We present the results of a study of the spectral properties of galaxies in the central part of the Shapley Concentration, covering an extremely wide range of densities, from the rich cluster cores to the underlying supercluster…

Astrophysics · Physics 2016-08-30 Alessandro Baldi , Sandro Bardelli , Elena Zucca

The notion of entropy appears in many fields and this paper is a survey about entropies in several branches of Mathematics. We are mainly concerned with the topological and the algebraic entropy in the context of continuous endomorphisms of…

General Topology · Mathematics 2013-08-20 Dikran Dikranjan , Anna Giordano Bruno

Various theoretical obstacles are associated with a homogeneous and isotropic distribution of ``charge'' which is subject to a repulsive, long-range force. We show how these can be overcome, for all practical purposes, by the simple device…

General Relativity and Quantum Cosmology · Physics 2009-11-07 M. Brisudova , R. P. Woodard , W. H. Kinney

The existence of a generalized fluctuation-dissipation theorem observed in simulations and experiments performed in various glassy materials is related to the concepts of local equilibration and heterogeneity in space. Assuming the…

Statistical Mechanics · Physics 2009-11-10 Ludovic Berthier

A general overview of the phenomenon of automatic continuity of homomorphisms between Polish groups is given. In particular, we study variants and improvements of the closed graph theorem, applying these to the problem of continuity of…

Group Theory · Mathematics 2025-09-16 Christian Rosendal , Luis Carlos Suarez

In this note, we study the delooping of spaces and maps in homotopy type theory. We show that in some cases, spaces have a unique delooping, and give a simple description of the delooping in these cases. We explain why some maps, such as…

Algebraic Topology · Mathematics 2025-04-14 David Wärn

We prove homological stability for two different flavours of asymptotic monopole moduli spaces, namely moduli spaces of framed Dirac monopoles and moduli spaces of ideal monopoles. The former are Gibbons-Manton torus bundles over…

Algebraic Topology · Mathematics 2023-10-19 Martin Palmer , Ulrike Tillmann

We study the connections between volume growth, spectral properties and stochastic completeness of locally finite graphs. For a class of graphs with a very weak spherical symmetry we give a condition which implies both stochastic…

Spectral Theory · Mathematics 2012-10-01 Matthias Keller , Daniel Lenz , Radoslaw K. Wojciechowski

The predictions of homogeneous and isotropic cosmological models with ordinary matter and gravity are off by a factor of two in the late universe. One possible explanation is the known breakdown of homogeneity and isotropy due to the…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-17 Syksy Rasanen

We prove that uniform hyperbolicity is invariant under topological conjugacy for dissipative polynomial automorphisms of C^2. Along the way we also show that a sufficient condition for hyperbolicity is that local stable and unstable…

Complex Variables · Mathematics 2020-06-04 Eric Bedford , Romain Dujardin

We define a natural topology on the collection of (equivalence classes up to scaling of) locally finite measures on a homogeneous space and prove that in this topology, pushforwards of certain infinite volume orbits equidistribute in the…

Dynamical Systems · Mathematics 2019-08-15 Uri Shapira , Cheng Zheng

We obtain sufficient conditions for the vanishing of higher homotopy groups of the complements to hypersurfaces in ${\mathbb C}^n$ in terms of the behavior at infinity and relate the monodromy of non isolated singularities to the position…

Algebraic Geometry · Mathematics 2007-05-23 Anatoly Libgober , Mihai Tibar

We obtain explicit formulas for the rational homotopy groups of generalised symmetric spaces, i.e., the homogeneous spaces for which the isotropy subgroup appears as the fixed point group of some finite order automorphism of the group. In…

Algebraic Topology · Mathematics 2007-05-23 S. Terzic

We point out that the horizon problem encountered in standard text-books or review papers on cosmology is, in general, derived for world models based on Robertson-Walker line element where homogeneity and isotropy of the universe -- \`a la…

General Relativity and Quantum Cosmology · Physics 2024-04-18 Ashok K. Singal

Galaxies and clusters distributions show two major properties: (i) the positions of galaxies and clusters are characterized by a power law distribution indicating properties with respect to their positions. (ii) The distribution of masses…

Astrophysics · Physics 2009-09-25 Francesco Sylos Labini , Luciano Pietronero

Given a singular foliation, we attach an "essential isotropy" group to each of its leaves, and show that its discreteness is the integrability obstruction of a natural Lie algebroid over the leaf. We show that a condition ensuring…

Differential Geometry · Mathematics 2013-11-18 Iakovos Androulidakis , Marco Zambon