Results 21 to 30 of about 228 (62)

Critical Robertson-Walker universes [PDF]

, 2019
The integral of the energy density function $\mathfrak m$ of a closed Robertson-Walker (RW) spacetime with source a perfect fluid and cosmological constant $\Lambda$ gives rise to an action functional on the space of scale functions of RW spacetime ...
Eshkobilov, Olimjon, Musso, Emilio, Nicolodi, Lorenzo   +2 more
core   +2 more sources

Fractional Exact Solutions and Solitons in Gravity [PDF]

, 2010
We survay our recent results on fractional gravity theory. It is also provided the Main Theorem on encoding of geometric data (metrics and connections in gravity and geometric mechanics) into solitonic hierarchies.
D Baleanu, S Anco, S Vacaru
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, O’Neill B., Peter Collas, Synge J. L.   +3 more
core   +1 more source

A Special Universe and its Massless Scalar Field Mathematical Structure

Analele Stiintifice ale Universitatii Ovidius Constanta: Seria Matematica
The 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, Nicola Aurelian   +1 more
doaj   +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, Bao, Bejancu, Cao, Hamilton, Miron, Miron R., Mrugala, Rapoport, Ruppeiner, Ruppeiner, Salamon, Sergiu I. Vacaru, Tsallis, Vacaru, Vacaru, Vacaru, Vacaru, Vacaru, Vacaru, Vacaru   +20 more
core   +4 more sources

Flat deformation of a spacetime admitting two Killing fields [PDF]

, 2010
It is shown that given an analytic Lorentzian metric on a 4-manifold, $g$, which admits two Killing vector fields, then it exists a local deformation law $\eta = a g + b H$, where $H$ is a 2-dimensional projector, such that $\eta$ is flat and admits the ...
Choquet-Bruhat Y, Eisenhart L P, Garcia-Parrado A, Jaume Carot, John F, Josep Llosa, Kobayashi S, Llosa J, Llosa J, Rainich G Y   +9 more
core   +3 more sources

A mathematical note about a FLRW universe embedded in a universe without time

Analele Stiintifice ale Universitatii Ovidius Constanta: Seria Matematica
In this paper we propose to study a six-dimensional Friedmann-Lemaître-Robertson-Walker (FLRW) universe without time. The way we study this timeless universe is the classic one: we highlight future oriented time-like loops and closed chains of future ...
Sburlan Cristina
doaj   +1 more source

Anti-self-dual Riemannian metrics without Killing vectors, can they be realized on K3?

, 2003
Explicit Riemannian metrics with Euclidean signature and anti-self dual curvature that do not admit any Killing vectors are presented. The metric and the Riemann curvature scalars are homogenous functions of degree zero in a single real potential and its
A A Malykh, Aliev A N, Atiyah M F, Boyer C P, Calabi E, Chern S S, Chern S S, Goldblatt E, Hitchin N J, Kummer E E, Lie S, M B Sheftel, Malykh A A Sheftel M B V K Andreev Yu V Shan'ko, Martina L, Mason L J, Nutku Y, Olver P, Ovsiannikov L V, Vessiot E, Y Nutku, Yau S-T   +20 more
core   +2 more sources

Fractional Curve Flows and Solitonic Hierarchies in Gravity and Geometric Mechanics

, 2011
Methods from the geometry of nonholonomic manifolds and Lagrange-Finsler spaces are applied in fractional calculus with Caputo derivatives and for elaborating models of fractional gravity and fractional Lagrange mechanics.
Dumitru Baleanu, Gorenflo R., Kilbas A. A., Sergiu I. Vacaru   +3 more
core   +1 more source

Intrinsic Spectral Geometry of the Kerr-Newman Event Horizon

, 2006
We uniquely and explicitly reconstruct the instantaneous intrinsic metric of the Kerr-Newman Event Horizon from the spectrum of its Laplacian. In the process we find that the angular momentum parameter, radius, area; and in the uncharged case, mass, can ...
Martin Engman, Ricardo Cordero-Soto, Wald R., Zelditch S., ’t Hooft G.   +4 more
core   +3 more sources