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A particle subject to successive, random displacements is said to execute a random walk (in position or some other coordinate). The mathematical properties of random walks have been very thoroughly investigated, and the model is used in…

Statistical Mechanics · Physics 2007-05-23 M. Wilkinson , B. Mehlig

This paper introduces a brand-new phase definition called the segmental phase for multi-input multi-output linear time-invariant systems. The underpinning of the definition lies in the matrix segmental phase which, as its name implies, is…

Systems and Control · Electrical Eng. & Systems 2025-05-20 Chao Chen , Wei Chen , Di Zhao , Jianqi Chen , Li Qiu

We present a link between parametrizations of alternative theories of gravity on large and small scales in cosmology. This relationship is established using theoretical consistency conditions only. We find that in both limits the "slip" and…

General Relativity and Quantum Cosmology · Physics 2019-01-09 Timothy Clifton , Viraj A. A. Sanghai

Complex metrics are a double-edged sword: they allow one to replace singular spacetimes, such as those containing a big bang, with regular metrics, yet they can also describe unphysical solutions in which quantum transitions may be more…

High Energy Physics - Theory · Physics 2022-08-31 Caroline Jonas , Jean-Luc Lehners , Jerome Quintin

The previous version of this article was a first attempt to confront the Dark Gravity theory to cosmological data. However, more recent developments lead to the conclusion that the cosmological principle is probably not valid in Dark…

Astrophysics · Physics 2007-10-24 Frederic Henry-Couannier

The tracing of cosmological relics from the early string dynamics may enhance the theory and provide new perspectives on the major cosmological problems. This point is illustrated in a leading-order Bianchi-type $VII_0$ string background,…

High Energy Physics - Theory · Physics 2009-10-28 Nikolaos A Batakis

Bimetric theory describes gravitational interactions in the presence of an extra spin-2 field. Previous work has suggested that its cosmological solutions are generically plagued by instabilities. We show that by taking the Planck mass for…

General Relativity and Quantum Cosmology · Physics 2015-07-07 Yashar Akrami , S. F. Hassan , Frank Könnig , Angnis Schmidt-May , Adam R. Solomon

We re-examine claims that anthropic arguments provide an explanation for the observed smallness of the cosmological constant, and argue that correlations between the cosmological constant value and the existence of life can be demonstrated…

High Energy Physics - Theory · Physics 2008-11-26 Irit Maor , Lawrence Krauss , Glenn Starkman

Recent independent observations using several different telescope systems an analysis methods have provided evidence of parity violation between the number of galaxies that spin in opposite directions. On the other hand, other studies…

Cosmology and Nongalactic Astrophysics · Physics 2023-09-08 Lior Shamir

While purely philosophical in the early times, and still very speculative at the beginning of the twentieth century, Cosmology has gradually entered into the realm of experimental science over the past eighty years. It has raised some…

Astrophysics · Physics 2007-05-23 Julien Lesgourgues

It is well known that a closed universe with a minimally coupled massive scalar field always collapses to a singularity unless the initial conditions are extremely fine tuned. We show that the corrections to the equations of motion for the…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Parampreet Singh , Alexey Toporensky

The Planck collaboration has provided us rich information about the early universe, and a host of new observational missions will soon shed further light on the `anomalies' that appear to exist on the largest angular scales. From a quantum…

General Relativity and Quantum Cosmology · Physics 2015-11-18 Abhay Ashtekar , Aurelien Barrau

Let $X$ be a two-sided subshift on a finite alphabet endowed with a mixing probability measure which is positive on all cylinders in $X$. We show that there exist arbitrarily small finite overlapping union of shifted cylinders which…

Dynamical Systems · Mathematics 2018-09-12 Kevin G. Hare , Nikita Sidorov

General relativity predicts a singularity in the beginning of the universe being called big bang. Recent developments in loop quantum cosmology avoid the singularity and the big bang is replaced by a big bounce. A classical theory of…

General Physics · Physics 2011-02-08 Walter Petry

We define and study equivariant periodic cyclic homology for locally compact groups. This can be viewed as a noncommutative generalization of equivariant de Rham cohomology. Although the construction resembles the Cuntz-Quillen approach to…

K-Theory and Homology · Mathematics 2007-05-23 Christian Voigt

I review the basis and limitations of plausible inference in cosmology, in particular the limitation that it can only provide fundamentally true inferences when the hypotheses under consideration form a set that is exhaustive. They never…

Cosmology and Nongalactic Astrophysics · Physics 2009-10-20 David W. Hogg

We compute periodic, analytic and local cyclic cohomology for convolution algebras of compact Lie groups in order to exhibit differences between these theories. A surprising result is that the periodic and analytic cyclic cohomology of the…

K-Theory and Homology · Mathematics 2007-05-23 Ralf Meyer

The separate contributions to cosmology of the above researchers are revisited and a cosmology encompassing their basic ideas is proposed. We study Dirac's article on the large number hypothesis (1938), Sciama's proposal of realizing Mach's…

General Physics · Physics 2009-02-12 Alexander Unzicker

Chiral spin textures are researched widely in condensed matter systems and show potential for spintronics and storage applications. Along with extensive condensed-matter studies of chiral spin textures, photonic counterparts of these…

Optics · Physics 2021-12-14 Peng Shi , Luping Du , Mingjie Li , Xiaocong Yuan

Loop quantum cosmology is an application of recent developments for a non-perturbative and background independent quantization of gravity to a cosmological setting. Characteristic properties of the quantization such as discreteness of…

Astrophysics · Physics 2009-11-13 Martin Bojowald