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Unique features of particle orbits produce novel signatures of gravitational observable phenomena, and are quite useful in testing compact astrophysical objects in general relativity or modified theories of gravity. Here we observe a…

General Relativity and Quantum Cosmology · Physics 2023-10-24 Shao-Wen Wei , Yu-Peng Zhang , Yu-Xiao Liu , Robert B. Mann

New solution for two interpenetrating universes is found. Higher derivative gravity acting in 6-dimensional space is the basis of the study that allows to obtain stable solution without introducing matter of any sort. Stability of the…

General Relativity and Quantum Cosmology · Physics 2016-07-20 Sergey G. Rubin

We investigate the existence, and lack of unicity, of a holomorphic fibration by discs transversal to a rational curve in a complex surface.

Algebraic Geometry · Mathematics 2016-02-03 M. Falla Luza , F. Loray

Wormholes are hypothetical topologically-non-trivial structures of the spacetime. From the theoretical point of view, the possibility of their existence is challenging but cannot be ruled out. This article is a compact and non-exhaustive…

General Relativity and Quantum Cosmology · Physics 2021-05-11 Cosimo Bambi , Dejan Stojkovic

The review is a brief description of the state of problems in percolation theory and their numerous applications, which are analyzed on base of interesting papers published in the last 15-20 years. At the submitted papers are studied both…

General Physics · Physics 2022-10-25 Alexander Herega

A calculation of the no-boundary wave-function of the universe is put forward for a spacetime with negative curvature. A semi-classical Robertson-Walker approximation is attempted and two solutions to the field equations, one Lorentzian and…

General Relativity and Quantum Cosmology · Physics 2007-05-23 G. Oliveira-Neto

An attempt is made in order to clarify the so called regular black holes issue. It is revisited that if one works within General Relativity minimally coupled with non linear source, mainly of electromagnetic origin, and within a static…

General Relativity and Quantum Cosmology · Physics 2017-05-24 Stefano Chinaglia , Sergio Zerbini

The remarkably long-standing problem of cryptography is to generate completely secure key. It is widely believed that the task cannot be achieved within classical cryptography. However, there is no proof in support of this belief. We…

Cryptography and Security · Computer Science 2008-12-27 Arindam Mitra

The concept of dark matter in the Universe and its components has been discussed in the 1930s by several authors, and in particular by Oort (1932) and Zwicky (1933). However, it is only in the 1970s that the existence of dark matter was…

Popular Physics · Physics 2023-09-13 Albert Bosma

The quantum plasma theory has flourished in the past few years without much regard to the physical validity of the formulation or its connection to any real physical system. It is argued here that there is a very limited physical ground for…

Plasma Physics · Physics 2012-07-27 J. Vranjes , B. P. Pandey , S. Poedts

Heisenberg-like spins lying on the pseudosphere (a 2-dimensional infinite space with constant negative curvature) cannot give rise to stable soliton solutions. Only fractional solutions can be stabilized on this surface provided that at…

Strongly Correlated Electrons · Physics 2009-11-11 L. R. A. Belo , N. M. Oliveira-Neto , W. A. Moura-Melo , A. R. Pereira , E. Ercolessi

We consider a class of overdetermined problems in rotationally symmetric spaces, which reduce to the classical Serrin's overdetermined problem in the case of the Euclidean space. We prove some general integral identities for rotationally…

Analysis of PDEs · Mathematics 2016-10-31 Giulio Ciraolo , Luigi Vezzoni

Recently, the authors of the present work (together with M. N. Kolountzakis) introduced a new version of the non-commutative Delsarte scheme and applied it to the problem of mutually unbiased bases. Here we use this method to investigate…

Combinatorics · Mathematics 2017-09-20 Máté Matolcsi , Mihály Weiner

The actual existence of collections of universes -- multiverses -- is strongly suggested by leading approaches to quantum cosmology, and has been proposed earlier as an attractive way to explain the apparent fine-tuned character of our…

Astrophysics · Physics 2007-05-23 William R. Stoeger

We consider the proposition that multiple universes exist by reviewing the various manifestations. In recent years, this idea has been elevated from science fiction and introduced in separate guises as an explanation for coincidence…

General Physics · Physics 2007-05-23 Alasdair Macleod

We make the case for the existence of a, hitherto unknown and unobserved, hierarchy of ever more compact cosmic objects in the universe. This hypothesis is based on i) the assumption of "elementary" particle sub-constituents on several…

Astrophysics · Physics 2011-03-17 Johan Hansson

We use global bifurcation techniques to establish the existence of arbitrarily many geometrically distinct nonplanar embedded smooth minimal 2-spheres in sufficiently elongated 3-dimensional ellipsoids of revolution. More precisely, we…

Differential Geometry · Mathematics 2025-11-05 Renato G. Bettiol , Paolo Piccione

In an Euclidean $d$-space, the container problem asks to pack $n$ equally sized spheres into a minimal dilate of a fixed container. If the container is a smooth convex body and $d\geq 2$ we show that solutions to the container problem can…

Metric Geometry · Mathematics 2011-10-20 Achill Schuermann

We explain an error in our paper "A smooth foliation of the 5-sphere by complex surfaces", Ann. Math 156 (2002), p.915-930.

Geometric Topology · Mathematics 2011-06-06 Laurent Meersseman , Alberto Verjovsky

In this paper we prove a topological nonrealizability theorem: certain classes of graded $BP_*$-modules are shown to never occur as the $BP$-homology of a spectrum. Many of these $BP_*$-modules admit the structure of $BP_*BP$-comodules,…

Algebraic Topology · Mathematics 2016-07-06 A. Salch