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Using our anholonomic frame deformation method, we show how generic off-diagonal cosmological solutions depending, in general, on all spacetime coordinates and undergoing a phase of ultra-slow contraction can be constructed in massive…

高能物理 - 理论 · 物理学 2017-06-05 Sergiu I. Vacaru

We show how generic off--diagonal cosmological solutions depending, in general, on all spacetime coordinates can be constructed in massive gravity using the anholonomic frame deformation method. Such metrics describe the late time…

广义相对论与量子宇宙学 · 物理学 2015-02-23 Sergiu I. Vacaru

In this work, we apply the anholonomic deformation method for constructing new classes of anisotropic cosmological solutions in Einstein gravity and/or generalizations with nonholonomic variables. There are analyzed four types of, in…

数学物理 · 物理学 2015-05-18 Sergiu I. Vacaru

Modified gravity theories (MGTs) have long been studied as alternatives to general relativity (GR) and the standard Lambda CDM cosmological model. For example, exponential f(R) models often yield better fits to observational data,…

综合物理 · 物理学 2026-05-01 Sergiu I. Vacaru

This article is a status report on the Anholonomic Frame and Connection Deformation Method, AFCDM, for constructing generic off-diagonal exact and parametric solutions in general relativity, GR, relativistic geometric flows, and modified…

广义相对论与量子宇宙学 · 物理学 2025-10-07 Laurenţiu Bubuianu , Julia O. Seti , Douglas Singleton , Panayiotis Stavrinos , Sergiu I. Vacaru , Elşen Veli Veliev

We elaborate on the anholonomic frame deformation method, AFDM, for constructing exact solutions with quasiperiodic structure in modified gravity theories, MGTs, and general relativity, GR. Such solutions are described by generic…

综合物理 · 物理学 2018-05-29 Laurenţiu Bubuianu , Sergiu I. Vacaru

We find general parameterizations for generic off-diagonal spacetime metrics and matter sources in general relativity (GR) and modified gravity theories when the field equations decouple with respect to certain types of nonholonomic frames…

广义相对论与量子宇宙学 · 物理学 2014-12-25 Tamara Gheorghiu , Olivia Vacaru , Sergiu I. Vacaru

The gravitational field equations in general relativity (GR) consist of a sophisticated system of nonlinear partial differential equations. Solving such equations in some generic off-diagonal forms is usually a hard analytic or numeric…

广义相对论与量子宇宙学 · 物理学 2025-08-18 Sergiu I. Vacaru , Elşen V. Veliev

The anholonomic frame method is generalized for non--Riemannian gravity models defined by string corrections to the general relativity and metric-affine gravity (MAG) theories. Such spacetime configurations are modeled as metric-affine…

高能物理 - 理论 · 物理学 2007-05-23 Sergiu I. Vacaru , Evghenii Gaburov , Denis Gontsa

The goal of this work is to elaborate on new geometric methods of constructing exact and parametric quasiperiodic solutions for anamorphic cosmology models in modified gravity theories, MGTs, and general relativity, GR. There exist…

广义相对论与量子宇宙学 · 物理学 2017-10-24 Marcelo M. Amaral , Raymond Aschheim , Laurenţiu Bubuianu , Klee Irwin , Sergiu I. Vacaru , Daniel Woolridge

Off-diagonal vacuum and nonvacuum configurations in Einstein gravity can mimic physical effects of modified gravitational theories of $f(R,T,R_{\mu \nu}T^{\mu \nu})$ type. To prove this statement, exact and approximate solutions are…

广义相对论与量子宇宙学 · 物理学 2015-07-01 Emilio Elizalde , Sergiu I. Vacaru

A generalized geometric method is developed for constructing exact solutions of gravitational field equations in Einstein theory and generalizations. First, we apply the formalism of nonholonomic frame deformations (formally considered for…

广义相对论与量子宇宙学 · 物理学 2008-11-26 Sergiu I. Vacaru

Certain off-diagonal vacuum and nonvacuum configurations in Einstein gravity can mimic physical effects of modified gravitational theories of $ f(R,T,R_{\mu\nu}T^{\mu\nu})$ type. We prove this statement by constructing exact and approximate…

数学物理 · 物理学 2015-06-30 Emilio Elizalde , Sergiu I. Vacaru

There are explored off-diagonal deformations of "prime" metrics in Einstein gravity (for instance, for wormhole configurations) into "target" exact solutions in f(R,T)-modified and massive/ bi-metric gravity theories. The new classes of…

广义相对论与量子宇宙学 · 物理学 2014-03-25 Sergiu I. Vacaru

We prove that the Einstein equations can be solved in a very general form for arbitrary spacetime dimensions and various types of vacuum and non-vacuum cases following a geometric method of anholonomic frame deformations for constructing…

广义相对论与量子宇宙学 · 物理学 2014-11-20 Sergiu I. Vacaru

We show how the Einstein equations with cosmological constant (and/or various types of matter field sources) can be integrated in a very general form following the anholonomic deformation method for constructing exact solutions in four and…

综合物理 · 物理学 2017-10-19 Sergiu I. Vacaru

Many papers on modified gravity theories (MGTs), and metric-affine geometry have been published. New classes of black hole (BH), wormhole (WH), and cosmological solutions involving nonmetricity and torsion fields were constructed.…

综合物理 · 物理学 2025-06-13 Sergiu I. Vacaru

It is formulated a new 'anholonomic frame' method of constructing exact solutions of Einstein equations with off--diagonal metrics in 4D and 5D gravity. The previous approaches and results are summarized and generalized as three theorems…

高能物理 - 理论 · 物理学 2007-05-23 Sergiu I. Vacaru

We study how massive ghost-free gravity $f(R)$-modified theories, MGFTs, can be encoded into generic off-diagonal Einstein spaces. Using "auxiliary" connections completely defined by the metric fields and adapted to nonholonomic frames with…

综合物理 · 物理学 2017-06-13 Sergiu I. Vacaru

We study new classes of generic off-diagonal and diagonal cosmological solutions for effective Einstein equations in modified gravity theories, MGTs, with modified dispersion relations, MDRs, encoding possible violations of (local) Lorentz…

综合物理 · 物理学 2021-06-02 Panayiotis Stavrinos , Sergiu I. Vacaru
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