Results 21 to 30 of about 202 (38)
A Special Universe and its Massless Scalar Field Mathematical Structure
Analele Stiintifice ale Universitatii Ovidius Constanta: Seria MatematicaThe present paper highlights an exotic universe having a metric which is partially suggested by the metric of an universe without time seen in [2]. The new metric is globally defined and depends on an exotic matter created by some classical waves.
Boskoff Wladimir-Georges +1 more
doaj +1 more source
Generating potentials via difference equations
, 2006 The condition for pressure isotropy, for spherically symmetric gravitational fields with charged and uncharged matter, is reduced to a recurrence equation with variable, rational coefficients.
Debnath +10 more
core +1 more source
Partner symmetries and non-invariant solutions of four-dimensional heavenly equations [PDF]
, 2004 We extend our method of partner symmetries to the hyperbolic complex Monge-Amp\`ere equation and the second heavenly equation of Pleba\~nski. We show the existence of partner symmetries and derive the relations between them for both equations.
A A Malykh +15 more
core +1 more source
Exact Nonnull Wavelike Solutions to Gravity with Quadratic Lagrangians
, 1999 Solutions to gravity with quadratic Lagrangians are found for the simple case where the only nonconstant metric component is the lapse $N$ and the Riemann tensor takes the form $R^{t}_{.itj}=-k_{i}k_{j}, i,j=1,2,3$; thus these solutions depend on cross ...
Roberts, Mark D.
core +1 more source
Geodesic completeness of generalized space-times
, 2015 We define the notion of geodesic completeness for semi-Riemannian metrics of low regularity in the framework of the geometric theory of generalized functions.
Steinbauer, Roland, Sämann, Clemens
core +1 more source
, 2003 We present the method of group foliation for constructing non-invariant solutions of partial differential equations on an important example of the Boyer-Finley equation from the theory of gravitational instantons.
Sheftel, M. B.
core +1 more source
Exact Fermi coordinates for a class of spacetimes
, 2009 We find exact Fermi coordinates for timelike geodesic observers for a class of spacetimes that includes anti-de Sitter spacetime, de Sitter spacetime, the constant density interior Schwarzschild spacetime with positive, zero, and negative cosmological ...
David Klein +3 more
core +1 more source
LRS Bianchi type-I cosmological model with constant deceleration parameter in $f(R,T)$ gravity
, 2017 A spatially homogeneous anisotropic LRS Bianchi type-I cosmological model is studied in $f(R,T)$ gravity with a special form of Hubble's parameter, which leads to constant deceleration parameter.
Bishi, Binaya K. +3 more
core +1 more source
The Entropy of Lagrange-Finsler Spaces and Ricci Flows
, 2007 We formulate a statistical analogy of regular Lagrange mechanics and Finsler geometry derived from Grisha Perelman's functionals generalized for nonholonomic Ricci flows. There are elaborated explicit constructions when nonholonomically constrained flows
Antonelli +20 more
core +4 more sources
New anisotropic models from isotropic solutions
, 2005 We establish an algorithm that produces a new solution to the Einstein field equations, with an anisotropic matter distribution, from a given seed isotropic solution.
Bowers +18 more
core +2 more sources